Cirrus Logic CS5508 User Manual

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CS5505/6/7/8

http://www.cirrus.com

CS5505/6/7/8

Very Low Power, 16-bit & 20-bit A/D Converters

OCT ‘09

DS59F7

Very Low Power, 16-Bit and 20-Bit A/D Converters

Features

Description

l Very Low Power Consumption

- Single supply +5 V operation: 1.7 mW

- Dual supply ±5 V operation: 3.2 mW

l Offers superior performance to VFCs and

multi-slope integrating ADCs

l Differential Inputs

- Single-channel (CS5507/8) and Four-channel (CS5505/6) pseudo-differential versions

l Either 5 V or 3.3 V Digital Interface l Linearity Error:

- ±0.0015% FS (16-bit CS5505/7)

- ±0.0007% FS (20-bit CS5506/8)

l Output update rates up to 100 Sps l Flexible Serial Port l Pin-Selectable Unipolar/Bipolar Ranges

The CS5505/6/7/8 are a family of low power CMOS A/D converters which are ideal for measuring low-frequency signals representing physical, chemical, and biological processes.

The CS 5507/8 have single-channel differential anal

og and reference inputs while the CS5505/6 have four pseudo-differ

ential analog input channels. The CS5505/7 have a 16-bit output word. The CS5506/8 have a 20-bit output word.The CS5505/6/7/8 sample

ommand up to 100 Sps

upon c

The on-chip digital filter offers superior li ne rejection at 50 and 60 Hz when the device is operated from a

32.768 kHz clock (output word rate = 20 Sps).

The CS 5505/6/7/8 include on-chip self-calibration circuitry whi

ch c

an be initiated at any time or temperature

to ensure minimum offset and full-scale errors.

The CS5505/6/7/8 serial port offers two general-purpose modes for the direct interface to shift r egisters or synchr microcontroll

s serial ports of indust

onou

ers.

ry-standard

ORDERING INFORMATION

See page 30.

Cirrus Logic, Inc. Crystal Semiconductor Products Division

P.O. Box 17847, Austin, Texas 78760 (512) 445 7222 FAX: (512) 445 7581 http://www.crystal.com

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MAR ‘95

DS59F4

CS5505/6/7/8

2 DS59F7

CS5505/6/7/8

ANALOG CHARACTERISTICS

3.3V

5%; VREF+ = 2.5V(external); VREF- = 0V; f

(TA = T

to T

MIN

= 32.768kHz; Bipolar Mode; R

CLK

; VA+ = 5V ± 10%; VA- = -5V ± 10%; VD+ =

MAX

= 1kΩ with a 10nF

source

to AGND at AIN; Anal og input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2)

CS5505/7-A CS5507-S

Parameter* Min Typ Max Min Typ Max Units

Specified Temperature Range -40 to +85 -55 to +125

Accuracy

Linearity Error - 0.0015 0.003 - 0.0015 0.003

Differential Nonlinearity -

Full Scale Error (Note 3) -

Full Scale Drift (Note 4) -

Unipolar Offset (Note 3) -

Unipolar Offset Drift (Note 4) -

Bipolar Offset (Note 3) -

Bipolar Offset Drift (Note 4) -

0.25

± ± ±

0.25

0.5

0.25

0.5

-LSB

%FS

LSB

Noise (Referred to Output) - 0.16 - - 0.16 - LSB-

rms

Notes: 1. The AIN pin presents a very high input resistance at dc and a minor dynamic load which scales to the

master clock frequency. Both sour ce resistance and shunt capacitance are therefore critical in determining the CS5505/6/7/8’s source impedance requirements. For more information refer to the text section

Analog Input Impedance Consi derations.

2. Specifications guaranteed by desi gn, characterization and/or test.

3. Applies after calibration at the temperature of interest.

4. Total drift over the specified temperature range since calibration at power-up at 25°C. Recalibration at any temperature will remove these errors.

Unipolar Mode Bipolar Mode

mV LSB’s % FS ppm FS LSB’s % FS ppm FS

10 0.26 0.0004 4 0.13 0.0002 2 19 0.50 0.0008 8 0.26 0.0004 4 38 1.00 0.0015 15 0.50 0.0008 8 76 2.00 0.0030 30 1.00 0.0015 15

152 4.00 0.0061 61 2.00 0.0030 30

VREF = 2.5V

CS5505/7; 16-Bit Unit Conversion Factors

* Refer to the Specification Definitions immediately following the Pin Description Section.

Specifications are subject to change without notice.

2 DS59F7

CS5505/6/7/8

DS59F7 3

CS5505/6/7/8

ANALOG CHARACTERISTICS

3.3V ± 5%; VREF+ = 2.5V (external); VREF- = 0V; f

(TA = T

to T

MIN

= 32.768kHz ; Bipolar Mode; R

CLK

; VA+ = 5V ± 10%; VA- = -5V ± 10%; VD+ =

MAX

source

= 1kΩ with a

10nF to AGND at AIN; Analog input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2)

CS5506/8-B CS5508-S

Parameter* Min Typ Max Min Typ Max Units

Specified Temperature Range -40 to +85 -55 to +125

Accuracy

Linearity Error - 0.0007 0.0015 - 0.0015 0.003

Differential Nonlinearity

%FS

Bits

(No Missing Codes) 20 - - 20 - -

Full Scale Error (Note 3) -

Full Scale Drift (Note 4) -

Unipolar Offset (Note 3) -

Unipolar Offset Drift (Note 4) -

Bipolar Offset (Note 3) -

Bipolar Offset Drift (Note 4) -

LSB

-LSB

LSB

-LSB

LSB

-LSB

Noise (Referred to Output) - 2.6 - - 2.6 - LSB-

rms

Unipolar Mode Bipolar Mode

mV LSB’s % FS ppm FS LSB’s % FS ppm FS

0.596 0.25 0.0000238 0.24 0.13 0.0000119 0.12

1.192 0.50 0.0000477 0.47 0.26 0.0000238 0.24

2.384 1.00 0.0000954 0.95 0.50 0.0000477 0.47

4.768 2.00 0.0001907 1.91 1.00 0.0000954 0.95

9.537 4.00 0.0003814 3.81 2.00 0.0001907 1.91 VREF = 2.5V

CS5506/8; 20-Bit Unit Conversion Factors

DYNAMIC CHARACTERISTICS

Parameter Symbol Ratio Units

Modulator Sampling Frequency f Output Update Rate (CONV = 1) f Filter Corner Frequency f

Settling Time to

⁄2 LSB (FS Step)

out

-3dB

/2 Hz

clk

/1622 Sps

clk

/1928 Hz

clk

1/f

out

DS59F7 3

CS5505/6/7/8

4 DS59F7

CS5505/6/7/8

ANALOG CHARACTERISTICS

3.3V ± 5%; VREF+ = 2.5V (external); VREF- = 0V; f 10nF to AGND at AIN; Analog input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2)

Parameter* Min Typ Max Min Typ Max Units

Specified Temperature Range -40 to +85 -55 to +125

(TA = T

to T

MIN

= 32.768kHz ; Bipolar Mode; R

CLK

CS5505/7 CS5506/8 CS5507/8-S

; VA+ = 5V

MAX

10%; VA- = -5V ± 10%; VD+ =

= 1kΩ with a

source

Analog Input

Analog Input Range: Unipolar (VAIN+)-(VAIN-) Bi polar (Note 5)

Common Mode Rejection: dc

50, 60 Hz (Note 6)-120

Off Channel Isolation - 120 - - 120 - dB

Input Capacitance - 15 - - 15 - pF

DC Bias Current (Note 1) - 5 - - 5 - nA

0 to +2.5

2.5

105

0 to +2.5

2.5

120

105

Volts Volts

dB dB

Voltage Reference (Output)

VREFOUT Voltage - (VA+)-2.5 - - (VA+)-2.5 - Volts

VREFOUT Voltage Tolerance - - 4.0 - - 4.0 %

VREFOUT Voltage Temperature Coefficient - 60 - - 60 -

VREFOUT Line Regulation - 1.5 - - 1.5 - mV/Volt

VREFOUT Output Voltage Noise

0.1 to 10 Hz

VREFOUT: Sour ce Current

Sink Current

-50- -50-

ppm/°C

p-p

Power Supplies

DC Power Supply Currents: I

Power Dissipation: (Note 7)

SLEEP inactive SLEEP active

Power Supply Rejection: Positive Supplies

Negative Supplies

Notes: 5. Common mode voltage may be at any value as long as AIN+ and AIN- remain within the VA+ and

VA- supply voltages.

6. XIN = 32.768 kHz. Guaranteed by design and / or characterization.

7. All outputs unloaded. Al l inputs CMOS levels. SLEEP mode controlled by M/SLP pin. SLEEP active = M/SLP pin at (VD+)/2 input level.

Total

Analog

Digital

340 300

3.2 5

80 80

450

4.5 10

340 300

3.2 10

80 80

450

4.5 25

dB dB

4 DS59F7

CS5505/6/7/8

DS59F7 5

CS5505/6/7/8

5V DIGITAL CHARACTERISTICS

(TA = T

MIN

to T

; VA+VD+ = 5V ± 10%; VA-= -5V ± 10%;

MAX

DGND = 0.) All measurements below are performed under static conditions. (Note 2)

Parameter Symbol Min Typ Max Units

High-Level Input Voltage: XIN

M/SLP

All Pins Except XIN and M/SLP

Low-Level Input Voltage: XIN

M/SLP

All Pins Except XIN and M/SLP

M/SLP SLEEP Active Threshold (Note 8) V

High-Level Output Voltage (Note 9) V

Low Level Output Vol tage I

= 1.6 mA V

out

Input Leakage Current I

3-State Leakage Current I

Digital Output Pi n Capacitance C

V V V

SLP

out

IH IH IH

IL IL IL

3.5

0.9VD+

2.0

1.5

0.1VD+

0.8

V V V

0.45VD+ 0.5VD+ 0.55VD+ V

(VD+)-1.0 - - V

--0.4V

-110

±10µ

-9-pF

Notes: 8. Under normal operation this pin should be tied to VD+ or DGND. Anytime the voltage on the M/SLP

pin enters the SLEEP active threshold range the device will enter the power down condition. Returning to the active state r equires elapse of the power-on reset period, the oscillator to start-up, and elapse of the wake-up period.

9. I

= -100 µA. This guarantees the ability to drive one TTL load. (VOH = 2.4V @ I

out

= -40 µA).

out

3.3V DIGITAL CHARACTERISTICS

(TA = T

MIN

to T

; VA+ = 5V ± 10%; VD+ = 3.3V ± 5%;

MAX

VA-= -5V ± 10%; DGND = 0.) All measurements below are performed under static conditions. (Note 2)

Parameter Symbol Min Typ Max Units

High-Level Input Voltage: XIN

M/SLP

All Pins Except XIN and M/SLP

Low-Level Input Voltage: XIN

M/SLP

All Pins Except XIN and M/SLP

M/SLP SLEEP Active Threshold (Note 8) V

High-Level Output Voltage I

Low Level Output Vol tage I

= -400 µA

out

= 400 µA

out

Input Leakage Current I

3-State Leakage Current I

Digital Output Pi n Capacitance C

VIH

VIL

SLP

out

0.7VD+

0.9VD+

0.6VD+

0.3VD+

0.1VD+

0.16VD+

0.43VD+ 0.45VD+ 0.47VD+ V

(VD+)-0.3 - - V

--0.3V

-110

-9-pF

±10 µA

V V V

µA

DS59F7 5

CS5505/6/7/8

6 DS59F7

CS5505/6/7/8

5V SWITCHING CHARACTERISTICS

VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+; C

(TA = T

to T

MIN

MAX;

= 50 pF.) (Note 2)

VA+, VD+ = 5V ± 10%;

Parameter Symbol Min Typ Max Units

Master Clock Frequency: Internal Oscillator: -A,B

-S

External Clock:

XIN

clk

30.0

32.768

53.0

34.0

163

kHz

Master Clock Duty Cycle 40 - 60 %

Rise Times: Any Digital Input (Note 10)

Any Digital Output

Fall Times: Any Digital Input (Note 10)

Any Digital Output

rise

fall

1.0

Start-Up

Power-On Reset Period (Note 11) t

Oscillator Start-up Time XTAL=32.768 kHz (Note 12) t

Wake-up Period (Note 13) t

res

osu

wup

-10-ms

- 500 - ms

- 1800/f

clk

-s

Calibration

CONV Pulse Width (CAL = 1) (Note 14) t

CONV and CAL High to Start of Calibration t

Start of Calibration to End of Calibration t

ccw

scl

cal

100 - - ns

--2/f

- 3246/f

clk

clk+200

-s

Conversion

Set Up Time A0, A1 to CONV High t

Hold Time A0, A1 after CONV High t

CONV Pulse Width t

CONV High to Start of Conversion t

Set Up Time BP/UP stable prior to DRDY falling t

Hold Time BP/UP stable after DRDY falls t

Start of Conversion to End of Conversion (Note 15) t

sac

hca

cpw

scn

bus

buh

con

Notes: 10. Specified using 10% and 90% points on waveform of interest.

11. An internal power-on-reset is activated whenever power is applied to the device, or when coming out of a SLEEP state.

12. Oscillator start-up time var ies with the crystal parameters. This specification does not apply when using an external clock source.

13. The wake-up period begins once the oscillator starts; or when using an external f

, after the power-on reset time elapses.

clk

14. Calibration can also be initiated by pulsing CAL high while CONV=1.

15. Conversion time will be 1622/f

if CONV remains high continuously.

clk

50 - - ns

100 - - ns

--2/f

82/f

clk

--s

+200 ns

clk

0--ns

- 1624/f

clk

-s

6 DS59F7

CS5505/6/7/8

DS59F7 7

CS5505/6/7/8

3.3V SWITCHING CHARACTERISTICS

(TA = T

MIN

to T

VA+ = 5V ± 10%;

MAX

VD+ = 3.3V ± 5%; VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+ ; CL = 50 pF.) (Note 2)

Parameter Symbol Min Typ Max Units

Master Clock Frequency: Internal Oscillator: -A,B

-S

External Clock:

XIN

clk

30.0

32.768

53.0

34.0

163

kHz

Master Clock Duty Cycle 40 - 60 %

Rise Times: Any Digital Input (Note 10)

Any Digital Output

Fall Times: Any Digital Input (Note 10)

Any Digital Output

rise

fall

1.0

Start-Up

Power-On Reset Period (Note 11) t

Oscillator Start-up Time XTAL=32.768 kHz (Note 12) t

Wake-up Period (Note 13) t

res

osu

wup

-10-ms

- 500 - ms

- 1800/f

clk

-s

Calibration

CONV Pulse Width (CAL = 1) (Note 14) t

CONV and CAL High to Start of Calibration t

Start of Calibration to End of Calibration t

ccw

scl

cal

100 - - ns

--2/f

- 3246/f

clk

200 ns

clk+

-s

Conversion

Set Up Time A0, A1 to CONV High t

Hold Time A0, A1 after CONV High t

CONV Pulse Width t

CONV High to Start of Conversion t

Set Up Time BP/UP stable prior to DRDY falling t

Hold Time BP/UP stable after DRDY falls t

Start of Conversion to End of Conversion (Note 15) t

sac

hca

cpw

scn

bus

buh

con

50 - - ns

100 - - ns

--2/f

82/f

clk

--s

+200 ns

clk

0--ns

- 1624/f

clk

-s

DS59F4 7

XIN

CS5505/6/7/8

8 DS59F7

XIN/2

CS5505/6/7/8

CAL

CONV

STATE

XIN

XIN/2

A0, A1

CONV

DRDY

ccw

scl

cal

Calibration StandbyStandby

Figure 1. Calibration Timing (Not to Scale)

sac

cpw

hca

BP/UP

STATE

scn

con

Conversion StandbyStandby

bus

buh

Figure 2. Conversion Timing (Not to Scale)

8 DS59F4

CS5505/6/7/8

DS59F7 9

CS5505/6/7/8

5V SWITCHING CHARACTERISTICS

(TA = T

MIN

VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+; C

Parameter Symbol Min Typ Max Units

SSC Mode (M/SLP = VD+)

Access Time: CS Low to SDATA out (DRDY = low)

DRDY falling to MSB (CS = low)

SDATA Delay Time: SCLK falling to next SDATA bit t

SCLK Delay Time SDATA MSB bit to SCLK rising t

Serial Clock (Out) Pulse Width High

Pulse Width Low

Output Float Delay: CS high to output Hi-Z (Note 16)

SCLK rising to SDATA Hi-Z

SEC Mode (M/SLP = DGND)

Serial Clock (In) f

Serial Clock (In) Pulse Width High

Pulse Width Low

Access Time: CS Low to data valid (Note 17) t

Maximum Delay time: (Note 18)

SCLK falling to new SDATA bit t

Output Float Delay: CS high to output Hi-Z (Note 16)

SCLK falling to SDATA Hi-Z

Notes: 16. If

CS is returned high before all data bits are output, the SDATA and SCLK outputs will complete the

current data bit and then go to high impedance.

CS is activated asynchronously to DRDY, CS will not be recognized if it occ urs when DRDY is high

17. If for 2 clock cycles. The propagation delay time may be as great as 2 f guarantee proper clocking of SDATA when using asynchronous sooner than 2 f

+ 200 ns after

clk

CS goes low.

18. SDATA transitions on the falling edge of SCLK. Note that a rising SCLK must occur to enable the serial port shifting mechanism before falling edges can be recognized.

to T

= 50 pF.) (Note 2)

csd1

dfd

dd1

cd1

ph1

pl1

fd1

fd2

sclk

ph2

pl2

csd2

dd2

fd3

fd4

VA+, VD+ = 5V ± 10%;

MAX;

- 80 250 ns

-1/f

0-2.5MHz

200 200

- 60 200 ns

- 150 310 ns

CS, SCLK(i) should not be taken high

2/f

clk

1/f

clk

1/f

clk

1/f

clk

160

cycles plus 200 ns. T o

clk

2/fclk 3/f

clk

-ns

2/f

clk

150 300

ns ns

DS59F7 9

CS5505/6/7/8

10 DS59F7

CS5505/6/7/8

3.3V SWITCHING CHARACTERISTICS

(TA = T

MIN

to T

5%; VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+; C

Parameter Symbol Min Typ Max Units

SSC Mode (M/SLP = VD+)

Access Time: CS Low to SDATA out (DRDY = low)

DRDY falling to MSB (CS = low)

SDATA Delay Time: SCLK falling to next SDATA bit t

SCLK Delay Time SDATA MSB bit to SCLK rising t

Serial Clock (Out) Pulse Width High

Pulse Width Low

Output Float Delay: CS high to output Hi-Z (Note 16)

SCLK rising to SDATA Hi-Z

csd1

dfd

dd1

cd1

ph1

pl1

fd1

fd2

SEC Mode (M/SLP = DGND)

Serial Clock (In) f

Serial Clock (In) Pulse Width High

Pulse Width Low

Access Time: CS Low to data valid (Note 17) t

sclk

ph2

pl2

csd2

Maximum Delay time: (Note 18)

SCLK falling to new SDATA bit t

Output Float Delay: CS high to output Hi-Z (Note 16)

SCLK falling to SDATA Hi-Z

dd2

fd3

fd4

VA+ = 5V ± 10%; VD+ = 3.3V

MAX

= 50 pF.) (Note 2)

2/f

clk

- 265 400 ns

-1/f

1/f 1/f

1/f

clk

clk clk

clk

0 - 1.25 MHz

200 200

- 100 200 ns

- 400 600 ns

320

2/fclk 3/f

clk

ns ns

-ns

2/f

150 500

clk

ns ns

10 DS59F4

XIN

CS5505/6/7/8

DS59F7 11

XIN/2

CONV

csd1

CS5505/6/7/8

STATE

DRDY

SCLK(o)

SDATA(o)

Hi-Z

STATE (CONV held high)

DRDY

SDATA(o) Hi-Z

SCLK(i)

StandbyStandby Conversion Conversion

ph1

pl1

Conversion1

cd1

MSB MSB-1

Conversion2

dd1

Figure 3. Timing Relationships; SSC Mode (Not to Scale)

csd2

dd2

MSB-1MSB MSB-2

fd2

LSB+1 LSB

fd3

Hi-Z

DRDY

SDATA(o) Hi-Z

SCLK(i)

csd2

dd2

MSB-1MSB LSB+2 LSB+1 LSB

ph2

pl2

fd4

Figure 4. Timing Rela tionships; SEC Mode ( Not to Scale)

DS59F4 11

CS5505/6/7/8

12 DS59F7

RECOMMENDED OPERATING CONDITIONS (DGND = 0V) (Note 19)

Parameter Symbol Min Typ Max Units

CS5505/6/7/8

DC Power Supplies: Positive Digital

(VA+)-(VA-) Positive Analog Negative Analog

Analog Reference Voltage (Note 20) (VREF+)-(VREF-) 1.0 2.5 3.6 V

Analog Input Voltage: (Note 21)

Unipolar Bipolar

Notes: 19. All voltages with r espect to ground.

20. The CS5505/6/7/8 can be operated with a reference voltage as low as 100 mV; but with a corresponding reduction in nois e-free resolution. The common mode voltage of the voltage reference may be any value as long as +V REF and -VREF remain inside the supply values of VA+ and VA-.

21. The CS5505/6/7/8 can acc ept input voltages up to the analog supplies (VA+ and VA-). In unipolar mode the CS5505/6/7/8 will output all 1’s if the dc input magnitude ( (AIN+)-(AIN-)) exceeds ((VREF+)-(VREF-)) and will output all 0’s if the input becomes more negative than 0 Volts. In bipolar mode the CS5505/6/7/8 will output all 1’s if the dc input magnitude ((AIN+)-(AIN-)) exceeds ((VREF+)-(VREF-)) and will output all 0’s if the input becomes more negative in magnitude than

-((VREF+)-(VREF-)).

VD+ V

diff

VA+

VA-

VAIN VAIN

-((VREF+)-(VREF-))--

3.15

4.75

4.5 0

5.0 10

5.0

-5.0

(VREF+)-(VREF-)

+((VREF+)-(VREF-))VV

5.5 11 11

-5.5

ABSOLUTE MAXIMUM RATINGS*

Parameter Symbol Min Typ Max Units

V V V V

DC Power Supplies: Digital Ground (Note 22)

Positive Digital (Note 23) Positive Analog Negative Analog (VA+)-(VA-) (VA+)-(VD+)

Input Current, Any Pin Except Supplies (Notes 24, 25) I

Analog Input Voltage AIN and VREF pins V

Digital Input Voltage V

Ambient Operating Temperature T

Storage Temperature T

Notes: 22. No pin should go more positive than (VA+)+0.3V.

23. VD+ must always be less than (VA+)+0.3 V,and can never exceed 6.0V.

24. Applies to all pins including continuous overvoltage conditions at the analog input (AIN) pin.

25. Transient currents of up to 100mA will not cause SCR latch-up. Maximum input current for a power

supply pin is ± 50 mA.

* WARNING: Operation at or beyond these limits may result in permanent damage to the device.

Normal operation is not guaranteed at these extremes.

DGND

VD+ VA+

VA-

diff1

diff2

INA

IND

stg

-0.3

+0.3

-0.3

(VA-)-0.3 - (VA+)+0.3 V

-0.3 - (VD+)+0.3 V

-55 - 125

-65 - 150

(VD+)-0.3

6.0 or VA+

12.0

-6.0

12.0

V V V V V V

12 DS59F4

CS5505/6/7/8

DS59F7 13

CS5505/6/7/8

GENERAL DESCRIPTION

The CS5505/6/7/8 are very low power monolithic CMOS A/D converters designed specifically for measurement of dc signals. The CS5505/7 are 16-bit converters (a four channel and a single channel version). The CS5506/8 are 20-bit converters (a four channel and a single channel version). Each of the devices includes a delta-sigma charge-balance converter, a voltage reference, a calibration microcontroller with SRAM, a digital filter and a serial interface. The CS5505 and CS5506 include a four channel pseudo-differential (all four channels have the same reference measurement node) multiplexer.

The CS5505/6/7/8 include an on-chip reference but can also utilize an off-chip refere nce for precision applications. The CS5505/6/7/8 can be used to measure either unipolar or bipolar signals. The devices use self-calibration to insure excellent offset and gain accuracy.

The CS5505/6/7/8 are optimized to operate from a 32.768 kHz crystal but can be driven by an external clock whose frequency is between 30 kHz and 163 kHz. When the digital filter is operated with a 32.768 kHz clock, the filter has zeros precisely at 50 and 60 Hz line freque ncies and multiple s thereof.

The CS5505/6/7/8 use a "start convert" command to latch the input channel selection and to start a convolution cycle on the digital filter. Once the filter cycle is completed, the output port is updated. When operated with a

32.768 kHz clock the ADC converts and updates its output port at 20 samples/sec. The throughput rate per channel is the output update rate divided by the number of channels being multiplexed. The output port includes a serial interface with two modes of operation.

The CS5505/6/7/8 can operate from dual polarity power supplies (+5 and -5), from a single +5 volt supply, or with +10 volts on the analog and

+5 on the digital. They can also operate with dual polarity (+5 and -5), or from a single +5 volt supply on the analog and + 3.3 on the digital.

THEORY OF OPERATION FOR THE CS5505/6/7/8

The front page of this data sheet illustrates the block diagram of the CS5505/6.

Basic Converter Operation

The CS5505/6/7/8 A/D converters have four operating states. These are start-up, calibration, conversion and sleep. When power is first applied, the device enters the start-up state. The first step is a power-on reset delay of about 10 ms which resets all of the logic in the device. To proceed with start-up, the oscillator must then begin oscillating. After the power-on reset the device enters the wake-up period for 1800 clock cycles after clock is present. This allows the delta-sigma modulator and other circuitry (which are operating with very low currents) to reach a stable bias condition prior to entering into either the calibration or conversion states. During the 1800 cycle wake-up period, the device can accept an input command. Execution of this command will not occur until the complete wake-up period elapses. If no command is given, the device enters the standby mode.

Calibration

After the initial application of power, the CS5505/6/7/8 must enter the calibration state prior to performing accurate conversions. During calibration, the chip executes a two-step process. The device first performs an offset calibration and then follows this with a gain calibration. The two calibration steps determine the zero reference point and the full scale referenc e point of

the converter’s transfer function. From these points it calibrates the zero point and a gain

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CS5505/6/7/8

14 DS59F7

CS5505/6/7/8

slope to be used to properly scale the output digital codes when doing conversions.

The calibration state is entered whenever the CAL and CONV pins are high at the same time. The state of the CAL and CONV pins at poweron and when coming out of sleep are recognized as commands, but will not be executed until the end of the 1800 clock cycle wake-up period. Note that any time CONV transitions from low to high, the multiplexer inputs A0 and A1 are latched internal to the CS5505 and CS5506 devices. These latched inputs select the analog input channel which will be used once conversion commences.

If CAL and CONV become active (high) during the 1800 clock cycle wake-up time, the converter will wait until the wake-up period elapses before executing the calibration. If the wake-up time has elapsed, the converter will be in the standby mode waiting for instruction and will enter the calibrat ion cycle immediately. The calibration lasts for 3246 clock cycles. Calibration coefficients are then retained in the SRAM (static RAM) for use during conversion.

At the end of the calibration cycle, the on-chip microcontroller checks the logic state of the CONV signal. If the CONV input is low the device will enter the standby mode where it waits for further instruction. If the CONV signal is high at the end of the calibration cycle, the converter will enter the conversion state and perform a conversion on the input channel which was selected when CONV transitioned from low to high. The CAL signal can be returned low any time after calibration is initiated. CONV can also be returned low, but it should never be taken low and then taken back high until the calibration period has ended and the converter is in the standby state. If CONV is taken low and then high again with CAL high while the converter is calibrating, the device will interrupt the current calibration cycle and start a new one. If CAL is taken low and CONV is taken low and

then high during calibration, the calibration cycle will continue as the conversion command is disregarded. The states of A0, A1 and BP/UP are not important during calibrations.

If an "end of calibration" signal is desired, pulse the CAL signal high while leaving the CONV signal high continuously. Once the calibration is completed, a conversion will be performed. At the end of the conversion, DRDY will fall to indicate the first valid conversion after the calibration has been completed.

See Understanding Converter Calibration for details on how the converter calibrates its transfer function.

Conversion

The conversion state can be entered at the end of the calibration cycle, or whenever the converter is idle in the standby mode. If CONV is taken high to initiate a calibration cycle ( CAL also high), and remains high until the calibration cycle is compl eted (CAL is taken low after CON V transitions high), the converter will begin a conversion upon completion of the calibration period. The device will perform a conversion on the input channel selected by the A0 and A1 inputs when CONV transitioned high. Table 1 indicates the multiplexer channel selection truth table for A0 and A1.

A1 A0 Channel addressed

00 AIN1

01 AIN2

10 AIN3

11 AIN4

Table 1. Multiplexer Truth Table

The A0 and A1 inputs are latched internal to the 4-channel devices (CS5505/6) when CONV rises. A0 and A1 have internal pull-down circuits which default the multiplexer to channel

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CS5505/6/7/8

AIN1. The BP/UP pin is not a latched input. The BP/UP pin controls how the output word from the digital filter is processed. In bipolar mode the output word computed by the digital filter is offset by 8000H in the 16-bit CS5505/7 or 80000H in 20-bit CS5506/8 (see Understanding Converter Calibration). BP/UP can be changed after a conversion is started as long as it is stable for 82 clock cycles of the conversion period prior to DRDY falling. If one wishes to intermix measurement of bipolar and unipolar signals on various input channels, it is best to switch the BP/UP pin immediately after DRDY falls and leave BP/UP stable until DRDY falls again. If the converter is beginning a conversion starting from the standby state, BP/

UP can be changed at

the same time as A0 and A1.

The digital filter in the CS5505/6/7/8 has a Finite Impulse Response and is designed to settle to full accuracy in one conversion time. Therefore, the multiplexer can be changed at the conversion rate.

If CONV is left high, the CS5505/6/7/8 will perform continuous conversions on one channel. The conversion time will be 1622 clock cycles. If conversion is initiated from the standby state, there may be up to two XIN clock cycles of uncertainty as to when conversion actually begins. This is because the internal logic operates at one half the external clock rate and the exact phase

of the internal clock may be 180° out of phase relative to the XIN clock. When a new conversion is initiated from the standby state, it will take up to two XIN clock cycles to begin. Actual conversion will use 1624 clock cycles before DRDY goes low to indicate that the serial port has been updated. See the Serial Interface Logic section of the data sheet for information on reading data from the serial port.

In the event the A/D conversion command (CONV going positive) is issued during the conversion state, the current conversion will be

terminated and a new conversion will be initiated.

Voltage Reference

The CS5505/6/7/8 uses a differential voltage reference input. The positive input is VREF+ and the negative input is VREF-. The voltage between VREF+ and VREF- can range from 1 volt minimum to 3.6 volts maximum. The gain slope will track changes in the reference without recalibration, accommodating ratiometric applications.

The CS5505/6/7/8 include an on-chip voltage reference which outputs 2.5 volts on the VREFOUT pin. This voltage is referenced to the VA+ pin and will track changes relative to VA+.

The VREFOUT output requires a 0.1 µF capacitor connected between VREFOUT and VA+ for stability. When using the internal reference, the VREFOUT signal should be connected to the VREF- input and the VREF+ pin should be connected to the VA+ supply. The internal voltage

reference is capable of sourcing 3 µA maximum and sinking 50 µA maximum. If a more precise

reference voltage is required, an external voltage reference should be used. If an external voltage reference is used, the VREFOUT pin of the internal reference should be connected directly to

VA-. It cannot be left open unless the 0.1 µF capacitor is in place for stability.

CS5505/6/7/8

+VA

LT1019,

REF43

LM368

-VA

Figure 5. External Reference Connections

2.5V

VA+

VREF+

VREFVREFOUT VA-

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CS5505/6/7/8

16 DS59F7

CS5505/6/7/8

+VA

0.1 µF

-VA

Figure 6. Internal Reference Connections

VA+

VREF+

VREF-

VREFOUT

VA-

External reference voltages can range from 1.0 volt minimum to 3.6 volts maximum. The common mode voltage range of the external reference can allow the reference to lie at any voltage between the VA+ and VA- supply rails. Figures 5 and 6 illustrate how the CS5505/6/7/8 converters are connected for external and for internal voltage reference use, respectively.

Analog Input Range

The analog input range is set by the magnitude of the voltage between the VREF+ and VREFpins. In unipolar mode the input range will equal the magnitude of the voltage reference. In bipolar mode the input voltage range will equate to plus and minus the magnitude of the voltage reference. While the voltage reference can be as great as 3.6 volts, its common mode voltage can be any value as long as the reference inputs VREF+ and VREF- stay within the supply volt-

ages for the A/D. The differential input voltage can also have any common mode value as long as the maximum signal magnitude stays within the supply voltages.

The A/D converter is intended to measure dc or low frequency inputs. It is designed to yield accurate conversions even with noise exceeding the input voltage range as long as the spectral components of this noise will be filtered out by the digital filter. For example, with a 3.0 volt reference in unipolar mode, the converter will accurately convert an input dc signal up to

3.0 volts with up to 15% overrange for 60 Hz noise. A 3.0 volt dc signal could have a 60 Hz component which is 0.5 volts above the maximum input of 3.0 (3.5 volts peak; 3.0 volts dc plus 0.5 volts peak noise) and still accurately convert the input signal (XIN = 32.768 kHz). This assumes that the signal plus noise amplitude stays within the supply voltages.

The CS5505/6/7/8 converters output data in binary format when converting unipolar signals and in offset binary format when converting bipolar signals. Table 2 outlines the output coding for the 16-bit CS5505/7 and the 20-bit CS5506/8 in both unipolar and bipolar measurement modes.

CS5505 and CS5507 (16 Bit) CS5506 and CS5508 (20 Bit)

Unipolar Input

Voltage

>(VREF - 1.5 LSB) FFFF >(VREF - 1.5 LSB) >(VREF - 1.5 LSB) FFFFF >(VREF - 1.5 LSB)

VREF - 1.5 LSB FFFF

VREF/2 - 0.5 LSB 8000

+0.5 LSB 0001

<(+0.5 LSB) 0000 <(-VREF + 0.5 LSB) <(+0.5 LSB) 00000 <(-VREF + 0.5 LSB)

Note: VREF = (VREF+) - (VREF-); Table excludes common mode voltage on the signal and reference inputs.

16 DS59F7

Output Codes

FFFE

7FFF

0000

Bipolar Input

Voltage

VREF - 1.5 LSB VREF - 1.5 LSB FFFFF

-0.5 LSB VREF/2 - 0.5 LSB 80000

-VREF + 0.5 LSB +0.5 LSB 00001

Table 2. Output Coding

Unipolar Input

Voltage

Output Codes

FFFFE

7FFFF

00000

Bipolar Input

Voltage

VREF - 1.5 LSB

-0.5 LSB

-VREF + 0.5 LSB

CS5505/6/7/8

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CS5505/6/7/8

Understanding Converter Calibration

Calibration can be performed at any time. A calibration sequence will minimize offset errors and set the gain slope scale factor. The deltasigma modulator in the converter is a differential modulator. To calibrate out offset error, the converter internally connects the modulator differential inputs to an internal VREF- voltage and

measures the 1’s density output from the modulator. It stores the digital code representation for this 1’s density in SRAM and remembers this code as being the zero scale point for the A/D conversion. The converter then connects the negative modulator differential input to the VREF- input and the positive modulator differential input to the VREF+ voltage. The 1’s density output from the modulator is then recorded. The converter uses the digital representation of this 1’s density along with the digital code for the zero scale point and calculates a gain scale factor. The ga in scale factor is stored in SRAM and used for calculating the proper output codes during conversions.

The states of A0, A1 and BP/UP are ignored during calibration but should remain stable throughout the calibration period to minimize noise.

When conversions are performed in unipolar mode or in bipolar mode, the converter uses the same calibration factors to compute the digital output code. The only difference is that in bipolar mode the on-chip microcontroller offsets the computed output word by a code value of

8000H (16-bit) or 80000H (20-bit) and multiplies the LSB size by two. This means that the bipolar measurement range is not calibrated from full scale positive to full scale negative. Instead it is calibrated from the bipolar zero scale point to full scale positive. The slope factor is then extended below bipolar zero to accommodate the negative input signals. The converter can be used to convert both unipolar and bipolar signals by changing the BP/UP pin. Recalibration is not required when switching between unipolar and bipolar modes.

Converter Performance

The CS5505/6/7/8 A/D converters have excellent linearity performance. Calibration minimizes the errors in offset and gain. The CS5505/7 devices have no missing code performance to 16-bits. The CS5506/8 devices have no missing code performance to 20-bits. Figure 7 illustrates the DNL of the 16-bit CS5505. The converters achieve Common Mode Rejection (CMR) at dc of 105 dB typical, and CMR at 50 and 60 Hz of 120 dB typical.

The CS5505/6/7/8 can experience some drift as temperature changes. The CS5505/6/7/8 use chopper-stabilized techniques to minimize drift. Measurement errors due to offset or gain drift can be eliminated at any time by recalibrating the converter.

+1/2

DNL (LSB)

-1/2

-1 0 65,535

Figure 7. CS5505 Differential Nonlinearity plot.

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32,768

Codes

CS5505/6/7/8

18 DS59F7

CS5505/6/7/8

Analog Input Impedance Considerations

The analog input of the CS5505/6/7/8 can be modeled as illustrated in Figure 8 (the model ignores the multiplexer switch resistance). Capacitors (15 pF each) are used to dynamically sample each of the inputs (AIN+ and AIN-). Every half XIN cycle the switch alternately connects the capacitor to the output of the buffer and then directly to the AIN pin. Whenever the sample capacitor is switched from the output of the buffer to the AIN pin, a small packet of charge (a dynamic demand of current) is required from the input source to settle the voltage of the sample capacitor to its final value. The voltage on the output of the buffer may differ up to 100 mV from the actual input voltage due to the offset voltage of the buffer. Timing allows one half of a XIN clock cycle for the voltage on the sample capacitor to settle to its final value. The equation which defines the settling time is:

−

⁄

Ve = V

Where Ve is the final settled value, V

max

is the

max

maximum error voltage value of the input signal, R is the value of the input source resistance, C is the 15 pF sample capacitor plus the value of any stray or additional capacitance at the input pin. The value of t is equal to 1/(2XIN).

CS5505/6/7/8

AIN+

AIN-

< 100 mV

Vos< 100 mV

Figure 8. Analog Input Model

15 pF

Internal Bias Voltage

15 pF

occurs the instant the sample capacitor is

max

switched from the buffer output to the AIN pin. Prior to switching, AIN has an error estimated as being less than or equal to Ve. V

is equal to

max

the prior error (Ve) plus the additional error from the buffer offset. The estimate for V

15pF

(

15pF + C

Where C

= Ve + 100mV

max

is the combination of any external

EXT

max

)

or stray capacitance.

From the settling time equation, an equation for the maximum acceptable source resistance is derived.

EXT

−1

) ln

  

Ve +

 

15pF(100mv)

(15pF

+ C

EXT

max

2XIN (15p F + C

This equation assumes that the offset voltage of the buffer is 100 mV, which is the worst case. The value of Ve is the maximum error voltage which is acceptable.

For a maximum error voltage (Ve) of 10 µV in the CS5505 (1/4LSB at 16-bits) and 600 nV in the CS5506 (1/4LSB at 20-bits), the above equation indicates that when operating from a

32.768 kHz XIN, source resistances up to 110 kΩ in the CS5505 or 84 kΩ in the CS5506

are acceptable in the absence of external capacitance (C

= 0). If higher input source

EXT

resistances are desired the master clock rate can be reduced to yield a longer settling time.

The VREF+ and VREF- inputs have nearly the same structure as the AIN+ and AIN- inputs. Therefore, the discussion on analog input impedance applies to the voltage reference inputs as well.

is:

   

)



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CS5505/6/7/8

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CS5505/6/7/8

Digital Filter Characteristics

The digital filter in the CS5505/6/7/8 is the combination of a comb filter and a low pass filter. The comb filter has zeros in its transfer function which are optimally placed to reject line interference frequencies (50 and 60 Hz and their multiples) when the CS5505/6/7/8 is clocked at

32.768 kHz. Figures 9, 10 and 11 illustrate the magnitude and phase characteristics of the filter.

X1 = 32.768kHz X2 = 163.00kHz

XIN = 32.768 kHz

120

160

795.10

993.87

200

240

1193.85

-100

Attenuation (dB)

-120

-140

-160

X1 X2

-20

-40

-60

-80

198.9780397.95

596.92

Frequency (Hz)

Figure 9 illustrates the filter attenuation from dc to 260 Hz. At exactly 50, 60, 100, and 120 Hz the filter provides over 120 dB of rejection. Table 3 indicates the filter attenuation for each of the potential line interference frequencies when the converter is operating with a 32.768 kHz clock. The converter yields excellent attenuation of these interference frequencies even if the fun-

damental line frequency should vary ±1% from its specified frequency. The -3 dB corner frequency of the filter when operating from a

32.768 kHz clock is 17 Hz. Figure 11 illustrates that the phase characteristics of the filter are precisely linear phase.

Frequency

(Hz)

50 125.6

60 126.7 100 145.7 120 136.0 150 118.4 180 132.9 200 102.5 240 108.4

Notch Depth

(dB)

Frequency

(Hz)

50±1%

60±1% 100±1% 120±1% 150±1% 180±1% 200±1% 240±1%

Minimum

Attenuation

(dB)

55.5

58.4

62.2

68.4

74.9

87.9

94.0

104.4

Figure 9. F ilter Magnitude Plot to 26 0 Hz

-20

-40

-60

-80

Attenuation (dB)

-100

-120

-140

0 5 10 15 20 25 30 35 40 45 50

Flatness

Frequency

-0.010

-0.041

-0.093

-0.166

-0.259

-0.374

-0.510

-0.667

-0.846

-1.047

-3.093

Frequency (Hz)

XIN = 32.768 kHz

Figure 10. Filter Magnitude Plot to 50 Hz

Table 3. Filter Notch Attenuation (XIN = 32.768 kHz)

180

135

-45

Phase (Degrees)

-90 XIN = 32.768 kHz

-135

-180

0 5 10 15 20 25 30 35 40 45 50

Frequency (Hz)

Figure 11. Filter Phase Plot to 50 Hz

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20 DS59F7

CS5505/6/7/8

If the CS5505/6/7/8 is operated at a clock rate other than 32.768 kHz, the filter characteristics, including the comb filter zeros, will scale with the operating clock frequency. Therefore, optimum rejection of line frequency interference will occur with the CS5505/6/7/8 running at

32.768 kHz. The CS5505/6/7/8 can be used with external clock rates from 30 kHz to 163 kHz.

Anti-Alias Con sideratio ns for Spec tral Measurement Applications

Input frequencies greater than one half the output word rate (CONV = 1) may be aliased by the converter. To prevent this, input signals should be limited in frequency to no greater than one half the output word rate of the converter (when CONV =1). Frequencies close to the modulator sample rate (XIN/2) and multiples thereof may also be aliased. If the signal source includes spectral components above one half the output word rate (when CONV = 1) these com-

ponents should be removed by means of lowpass filtering prior to the A/D input to prevent aliasing. Spectral components greater than one half the output word rate on the VREF inputs (VREF+ and VREF-) may also be aliased. Filtering of the reference voltage to remove these spectral components from the reference voltage is desirable.

Crystal Oscillator

The CS5505/6/7/8 is designed to be operated using a 32.768 kHz "tuning fork" type crystal. One end of the crystal should be connected to the XIN input. The other end should be attached to XOUT. Short lead lengths should be used to minimize stray capacitance. Figure 12 illustrates the gate oscillator, and a simplified version of the control logic used on the chip.

Over the industrial temperature range (-40 to +85 °C) the on-chip gate oscillator will oscillate

CONV

CAL

CS5505/6

Channel A0 A1

XIN

CLK

Start

Conversion

Start

Calibration

Modulator Sample Clock

22.5 pF

XOUT

CLK

10 M

19 umho

Input

Mux

Decoder

Ω

15 pF

XTL=32.768 kHz

Figure 12. Gate Oscillator and Control Logic

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CS5505/6/7/8

with other crystals in the range of 30 kHz to 53 kHz. Over the military temperature range (-

55 to +125 °C) the on-chip gate oscillator is designed to work only with a 32.768 kHz crystal. The chip will operate with external clock

frequencies from 30 kHz to 163 kHz.over all

temperature ranges. The 32.768 kHz crystal is

normally specified as a time-keeping crystal with tight specifications for both initial frequency and for drift over temperature. To maintain excellent frequency stability, these crystals are specified only over limited operating temperature ranges

(i.e. -10 to +60 °C) by the manufacturers. Applications of these crystals with the CS5505/6/7/8 do not require tight initial tolerance or low tempco drift. Therefore, a lower cost crystal with looser initial tolerance and tempco will generally be adequate for use with the CS5505/6/7/8 converters. Also check with the manufacturer about wide temperature range application of their standard crystals. Generally, even those crystals specified for limited temperature range will operate over much larger ranges if frequency stability over temperature is not a requirement.

The frequency stability can be as bad as ±3000 ppm over the operating temperature range and still be typically better than the line frequency (50 or 60 Hz) stability over cycle to cycle during the course of a day. There are crystals available

for operation over the military temperature range (-55 to +125 °C). See the Appendix for suppliers

of 32.768 kHz crystals.

Serial Interface Logic

When new data is put into the port DRDY will go low.

Data can be read from the serial port in either of two modes. The M/SLP pin determines which serial mode is selected. Serial port mode selection is as follows:

SSC (Synchronous Self-Clocking) mode; M/SLP = VD+, or SEC (Synchronous External Clocking) mode; M/SLP = DGND. Timing diagrams which illustrate the SSC and SEC timing are in the tables section of this data sheet.

Synchronous Self-Clocking Mode

The serial port operates in the SSC mode when the M/SLP pin is connected to the VD+ pin on the part. In SSC mode the CS5505/6/7/8 furnishes both the serial output data (SDATA) and the serial clock (SCLK). When the serial port is updated at the end of a conversion, DRDY falls. If CS is low, the SDATA and SCLK pins will come out of the high impedance state two XIN clock cycles after DRDY falls. The MSB data bit will be presented for two cycles of XIN clock. The SCLK signal will rise in the middle of the MSB data bit. When SCLK then returns low the (MSB - 1) bit will appear. Subsequent data bits will be output on each falling edge of SCLK until the LSB data bit is output. After the LSB data bit is output, the SCLK will fall at which time both the SDATA and SCLK outputs will return to the high impedance output state. DRDY will return h igh at this time.

The digital filter in the CS5505/6/7/8 takes 1624 clock cycles to compute an output word once a conversion begins. At the end of the conversion cycle, the filter will attempt to update the serial port. Two clock cycles prior to the update DRDY will go high. When DRDY goes high just prior to a port update it checks to see if the port is either empty or unselected (CS = 1). If the port is empty or unselected, the digital filter will update the port with a new output word.

If CS is taken low after DRDY falls, the MSB data bit will appear within two XIN clock cycles after CS is taken low. CS need not be held low for the entire data output. If CS is returned high during a data bit the port will complete the output of that bit and then go into the Hi-Z state. The port can be reselected any time prior to the completion of the next conversion (DRDY falling) to allow the remaining data bits to be output.

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22 DS59F7

CS5505/6/7/8

Synchronous External-Clocking Mode

The serial port operates in the SEC mode when the M/SLP pin is connected to the DGND pin. SDATA is the output pin for the serial data. When CS goes low after new data becomes available (DRDY goes low), the SDATA pin comes out of Hi-Z with the MSB data bit present. SCLK is the input pin for the serial clock in the SEC mode. If the MSB data bit is on the SDATA pin, the first rising edge of SCLK enables the shifting mechanism. This allows the falling edges of SCLK to shift subsequent data bits out of the port. Note that if the MSB data bit is output and the SCLK signal is high, the first falling edge of SCLK will be ignored because the shifting mechanism has not become activated. After the first rising edge of SCLK, each subsequent falling edge will shift out the serial data . Once the LSB is prese nt, the falling edge of SCLK will cause the SDATA output to go to Hi-Z and DRDY to return high. The serial port register will be updated with a new data word upon the completion of another conversion if the serial port has been emptied, or if the CS is inactive (high).

CS can be operated asynchronously to the DRDY signal. The DRDY signal need not be monitored as long as the CS signal is taken low for at least two XIN clock cycles plus 200 ns prior to SCLK being toggled. This ensures that CS has gained control over the serial port.

Sleep Mode

The CS5505/6/7/8 devices offer two methods of putting the device into a SLEEP condition to conserve power. Calibration words will be retained in SRAM during either sleep condition. The M/SLP pin can be put into the SLEEP threshold to lower the operating power used by the device to about 1% of nominal. Alternately, the clock into the XIN pin can be stopped. This will lower the power consumed by the converter to about 30% of nominal. In both cases, the

converter must go through a wake-up sequence prior to conversions being initiated. This wakeup sequence includes the 10 msec. (typ.) power-on-reset delay, the start-up of the oscillator (unless an external clock is used), and the 1800 clock cycle wake-up delay after the clock begins. When coming out of the sleep condition, the converter will latch the A0 and A1 inputs.

Figure 13 illustrates how to use a gate and resistors to bias the M/SLP pin into the SLEEP threshold region when using the converter in the SSC mode. To use the SEC mode return resistor R1 to DGND instead of the supply. When in the SEC mode configuration the CS5505/6/7/8 will enter the SLEEP threshold when the logic control input is a logic 1 (VD+). Note that large resistors can be used to conserve power while in sleep. The input leakage of the pin is typically

less than 1 µA even at 125 °C, although the worst case specification tables indicate a leakage

VD+

Control

Input

’1’ = SSC Mode ’0’ = SLEEP

Tie R to DGND for SEC mode; control input

logic inverts.

R = 499k, V + = 5V; R = 590k, V + = 3.3V

1 1

Figure 13. Sleep Threshold Control

499k 1%

0.01µF

CS5505/6/7/8

M/SLP

of 10 µA maximum.

Power Supplies and Grounding

The analog and digital supply pins to the CS5505/6/7/8 are brought out on separate pins to minimize noise coupling between the analog and digital sections of the chip. Note that there is no

22 DS59F7

CS5505/6/7/8

DS59F7 23

CS5505/6/7/8

analog ground pin. No analog ground pin is required because the inputs for measurement and for the voltage reference are differential and require no ground. In the digital section of the chip the supply current flows into the VD+ pin and out of the DGND pin. As a CMOS device, the CS5505/6/7/8 requires that the supply voltage on the VA+ pin always be more positive than the voltage on any other pin of the device. If this requirement is not met, the device can latch-up or be damaged. In all circumstances the VA+ voltage must remain more positive than the

+5V Analog Supply

Calibration

Control

0.1

CAL

VD+ or DGND pins; VD+ must remain more positive than the DGND pin.

The following power supply options are possible:

VA+ = +5V to +10V, VA- = 0V, VD+ = +5V VA+ = +5V, VA- = -5V, VD+ = +5V VA+ = +5V , VA- = 0V to -5V, VD+ = +3.3V

The CS5505/6/7/8 cannot be operated with a

3.3V digital supply if VA+ is greater than +5.5V.

Ω

0.1

VA+

VD+

XIN

XOUT

Optional

Clock

Source

32.768 kHz

Analog*

Signal

Sources

Signal

Ground

Voltage

Reference

Note:

Bipolar/

Unipolar

Input Select

*Unused analog inputs should be tied to AIN-

To use the internal 2.5 volt reference see Figure 6.

10 12 13

BP/UP

CS5505/6

AIN1+ AIN2+ AIN3+

AIN4+

AIN-

VREF+

VREF-

VREFOUT

VA-

M/SLP

SCLK

SDATA

DRDY

A0 A1

CONV

DGND

23 2 1 24

Sleep Mode

Control

and

Output Mode

Select

Serial

Data

Interface

Control

Logic

Unused Logic

inputs must be

connected to

VD+ or DGND.

Figure 14. CS5505/6 System Connection Diagram Us ing External Reference, Single Supply

DS59F7 23

CS5505/6/7/8

24 DS59F7

CS5505/6/7/8

Figure 14 illustrates the System Connection Dia- gram for the CS5505/6 using a single +5V supply. Note that all supply pins are bypassed

with 0.1 µF capacitors and that the VD+ digital supply is derived from the VA+ supply.

Figure 15 illustrates the CS5505/6 using dual supplies of +5 and -5V.

+5V Analog Supply

Analog*

Signal

Sources

Signal

Ground

Voltage

Reference

-5V Analog Supply

Calibration

Control

Bipolar/

Unipolar

Input Select

*Unused analog inputs should be tied to AIN-

0.1

CAL

BP/UP

AIN1+

AIN2+

AIN3+

AIN4+

AIN-

VREF+

VREF-

VREFOUT

Figure 16 illustrates the CS5505/6 using dual supplies of +10V analog and +5V digital.

When using separate supplies for VA+ and VD+, VA+ must be established first. VD+ should never become more positive than VA+ under any operating condition. Remember to investigate transient power-up conditions, when one power supply may have a faster rise time.

Ω

0.1

VA+

CS5505/6

VA-

VD+

XIN

XOUT

M/SLP

SCLK

SDATA

DRDY

A0 A1

CONV

DGND

23 2 1

Optional

Clock

Source

32.768 kHz

Sleep Mode

Control

and

Output Mode

Select

Serial

Data

Interface

Control

Logic

Unused Logic

inputs must be

connected to

VD+ or DGND.

Note:

24 DS59F7

To use the internal 2.5 volt reference see Figure 6.

Figure 15. CS5505/6 System Connection Diagram Using External Reference, Dual Supplies

CS5505/6/7/8

DS59F7 25

CS5505/6/7/8

+10V Analog Supply

Analog*

Signal

Sources

Signal

Ground

Voltage

Reference

0.1

Calibration

Control

Bipolar/

Unipolar

Input Select

*Unused analog inputs should be tied to AIN-

(1)

10 12 13

CAL

BP/UP

CS5505/6

AIN1+ AIN2+ AIN3+

AIN4+

AIN-

VREF+

VREF-

VREFOUT

VA-

(2)

VD+VA+

XIN

XOUT

M/SLP

SCLK

SDATA

DRDY

A0 A1

CONV

DGND

0.1

32.768 kHz

23 2 1 24

Analog Supply

Optional

Clock

Source

Sleep Mode

Control

and

Output Mode

Select

Serial

Data

Interface

Control

Logic

Unused Logic

inputs must be

connected to

VD+ or DGND.

+5V

Note:

(1) To use the internal 2.5 volt reference see Figure 6. (2) VD+ must never exceed VA+. Examine power-up conditions.

Figure 16. CS5505/6 System Connection Diagram Using External Reference,

Dual Supply, +10V Analog, +5V Dig ital

Schematic & Layout Review Service

Confirm Optimum

Schematic & Layout

Before Building Your Board.

For Our Free Review Service

Call Applications Engineering.

Call: (512) 445-7222

DS59F4 25

PIN CONNECTIONS*

CS5505/6/7/8

26 DS59F7

CS5505/6

CS5505/6/7/8

MULTIPLEXER SELECTION INPUT A0 A1 MULTIPLEXER SELECTION INPUT

CHIP SELECT

CONVERT CONV SDATA SERIAL DATA OUTPUT

CALIBRATE CAL SCLK SERIAL CLOCK INPUT/OUTPUT

CRYSTAL IN XIN VD+ POSITIVE DIGITAL POWER

CRYSTAL OUT XOUT DGND DIGITAL GROUND

SE RIAL MODE/ SLEEP M/SLP VA- NEGATIVE ANALOG POWER

BIPOLAR/UNIPOLAR BP/

DIFFERENTIAL ANALOG INPUT AIN1+ VREFOUT VOLTAGE REFERENCE OUTPUT

DIFFERENTIAL ANALOG INPUT AIN2+ VREF- VOLTAGE REFERENCE INPUT

DIFFERENTIAL ANALOG RETURN AIN- VREF+ VOLTAGE REFERENCE INPUT

DIFFERENTIAL ANALOG INPUT AIN3+ AIN4+ DIFFERENTIAL ANALOG INPUT

CHIP SELECT

CS DRDY DATA READY

CONVERT CONV SDATA SERIAL DATA OUTPUT

CALIBRATE CAL SCLK SERIAL CLOCK INPUT/OUTPUT

CRYSTAL IN XIN VD+ POSITIVE DIGITAL POWER

CRYSTAL OUT XOUT DGND DIGITAL GROUND

SERIAL MODE/ SLEEP M/SLP VA- NEGATIVE ANALOG POWER

BIPOLAR/UNIPOLAR BP/

UP VA+ POSITIVE ANALOG POWER

DIFFERENTIAL ANALOG INPUT AIN+ VREFOUT VOLTAGE REFERENCE OUTPUT

NO CONNECTION NC VREF- VOLTAGE REFERENCE INPUT

DIFFERENTIAL ANALOG INPUT AIN- VREF+ VOLTAGE REFERENCE INPUT

CS DRDY DATA READY

UP VA+ POSITIVE ANALOG POWER

CS5507/8

*Pinout applies to both DIP and SOIC

26 DS59F4

PIN DESCRIPTIONS

CS5505/6/7/8

DS59F7 27

Pin numbers for four channel devices are in parentheses.

Clock Generator

XIN; XOUT - Crystal In; Crystal Out, Pins 4 (5) and 5 (6).

A gate inside the chip is connected to these pins and can be used with a crystal to provide the master clock for the device. Alternatively, an external (CMOS compatible) clock can be supplied into the XIN pin to provide the master clock for the device. Loss of clock will put the device into a lower powered state (approximately 70% power reduction).

Serial Output I/O

M/SLP - Serial Interfac e Mode Sele ct/ Sleep, Pin 6 (7).

Dual function pin which selects the operating mode of the serial port and provides a very low power sleep function. When M/SLP is tied to the VD+ pin the serial port will operate in the Synchronous Self-Clocking (SSC) mode. When M/SLP is tied to the DGND pin the serial port will operate in the Synchronous External Clocking (SEC) mode. When the M/SLP pin is tied half way between VD+ and DGND the chip will enter into a very low powered sleep mode in which its calibration data will be maintained.

CS5505/6/7/8

CS - Chip Select, Pin 1 (2).

This input allows an external device to access the serial port.

DRDY - Data Ready, Pin 20 (23)

Data Ready goes low at the end of a digital filter convolution cycle to indicate that a new output word has been placed into the serial port. DRDY will return high after all data bits are shifted out of the serial port or two master clock cycles before new data becomes available if the CS pin is inactive (high).

SDATA - Serial Data Output, Pin 19 (22).

SDATA is the output pin of the serial output port. Data from this pin will be output at a rate determined by SCLK and in a format determined by the M/SLP pin. Data is output MSB first and advances to the next data bit on the falling edges of SCLK. SDATA will be in a high impedance state when not transmitting data.

SCLK - Serial Clock Input/Output, Pin 18 (21).

A clock signal on this pin determines the output rate of the data from the SDATA pin. The M/SLP pin determines whether SCLK is an input or and output. When used as an input, it must not be allowed to float.

DS59F7 27

Control Input Pins

CS5505/6/7/8

28 DS59F7

CAL - Calibrate, Pin 3 (4).

When taken high the same time that the CONV pin is taken high the c onverter will perform a self-calibration which includes calibration of the offset and gain scale factors in the converter.

CONV - Convert, Pin 2 (3).

The CONV pin initiates a calibration cycle if it is taken from low to high while the CAL pin is high, or it initiates a conversion if it is taken from low to high with the CAL pin low. CONV latches the multiplexer selection when it transitions from low to high on the multiple channel devices. If CONV is held high (CAL low) the converter will do continuous conversions.

A0, A1 - Multiplexer Selection Inputs, Pins (1, 24).

A0 and A1 select the input channel for conversion on the multi-channel input devices. A0 and A1 are latched when CONV transitions from low to high. These two inputs have pull-down resistors internal to the chip.

BP/UP - Bipolar/Unipolar, Pin 7 (8).

The BP/UP pin selects the conversion mode of the converter. When high the converter will convert bipolar input signals; when low it will convert unipolar input signals.

CS5505/6/7/8

Measurement and Reference Inputs

AIN+, AIN-, (AIN1+, AIN2+, AIN3+, AIN4+, AIN-) - Differential Analog Inputs, Pins 8, 10 (9, 10, 12, 13, 11).

AIN- in the CS5505/6 is a common measurement node for AIN1+, AIN2+, AIN3+ and AIN4+.

VREF+, VREF- - Differential Voltage Reference Inputs, Pins 11, 12 (14, 15).

A differential voltage reference on these pins operates as the voltage reference for the converter. The voltage between these pins can be any voltage between 1.0 and 3.6 volts.

Voltage Reference

VREFOUT - Voltage Reference Output, Pin 13 (16).

The on-chip voltage reference is output from this pin. The voltage reference has a nominal magnitude of 2.5 volts and is referenced to the VA+ pin on the converter.

Power Supply Connections

VA+ - Positive Analog Power, Pin 14 (17).

Positive analog supply voltage. Nominally +5 volts.

VA- - Negative Analog Power, Pin 15 (18).

Negative analog supply voltage. Nominally -5 volts when using dual polarity supplies; or 0 volts (tied to system analog ground) when using single supply operation.

28 DS59F4

VD+ - Positive Digital Power, Pin 17 (20).

CS5505/6/7/8

DS59F7 29

Positive digital supply voltage. Nominally +5 volts or 3.3 volts.

DGND - Digital Ground, Pin 16 (19).

Digital Ground.

Other

NC - No Connection, Pin 9.

Pin should be left floating.

SPECIFICATION DEFINITIONS

Linearity Error

The deviation of a code from a straight line which connects the two endpoints of the A/D Converter transfer function. One endpoint is located 1/2 LSB below the first code transition and the other endpoint is located 1/2 LSB beyond the code transition to all ones. Units in percent of full-scale.

CS5505/6/7/8

Differential Nonlinearity

The deviation of a code’s width from the ideal width. Units in LSBs.

Full Scale Error

The deviation of the last code transition from the ideal [{(VREF+) - (VREF-)} - 3⁄2 LSB]. Units are in LSBs.

Unipolar Offset

The deviation of the first code transition from the ideal (1⁄2 LSB above the voltage on the AINpin.) when in unipolar mode (BP/UP low). Units are in LSBs.

Bipolar Offset

The deviation of the mid-scale transition (011...111 to 100...000) from the ideal (1⁄2 LSB below the voltage on the AIN- pin.) when in bipolar mode (BP/UP high). Units are in LSBs

DS59F7 29

ORDERING INFORMATION

Model Resolution

CS5505/6/7/8

Liearity

Error Channels Package Temperature

CS5505-ASZ (lead free) 16 Bits 0.0030%

4 24-pin SOIC

CS5506-BSZ (lead free) 20 Bits 0.0015%

CS5507-ASZ (lead free) 16 Bits 0.0030%

1 20-pin SOIC

CS5508-BSZ (lead free) 20 Bits 0.0015%

ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION

Model Number Peak Reflow Temp MSL Rating* Max Floor Life

CS5505-ASZ (lead free)

CS5506-BSZ (lead free)

260 °C 3 7 Days

CS5507-ASZ (lead free)

CS5508-BSZ (lead free)

* MSL (Moisture Sensitivity Level) as specified by IPC/JEDEC J-STD-020.

-40 to +85 °C

30 DS59F7

REVISION HISTORY

Contacting Cirrus Logic Support

For all product questions and inquiries contact a Cirrus Logic Sales Representative. To find the one nearest to you go to www.cirrus.com

IMPORTANT NOTICE

Cirrus Logic, Inc. and its subsidiaries (“Cirrus”) believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided “AS IS” without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third parties. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. Cirrus owns the copyrights associated with the information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Cirrus integrated circuits or other products of Cirrus. This consent does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE IN PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DEVICES, LIFE SUPPORT PRODUCTS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF CIRRUS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK AND CIRRUS DISCLAIMS AND MAKES NO WARRANTY, EXPRESS, STATUTORY OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR PARTICULAR PURPOSE, WITH REGARD TO ANY CIRRUS PRODUCT THAT IS USED IN SUCH A MANNER. IF THE CUSTOMER OR CUSTOMER'S CUSTOMER USES OR PERMITS THE USE OF CIRRUS PRODUCTS IN CRITICAL APPLICATIONS, CUSTOMER AGREES, BY SUCH USE, TO FULLY INDEMNIFY CIRRUS, ITS OFFICERS, DIRECTORS, EMPLOYEES, DISTRIBUTORS AND OTHER AGENTS FROM ANY AND ALL LIABILITY, INCLUDING ATTORNEYS' FEES AND COSTS, THAT MAY RESULT FROM OR ARISE IN CONNECTION WITH THESE USES.

Cirrus Logic, Cirrus, and the Cirrus Logic logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks or service marks of their respective owners.

Revision Date Changes

F4 MAR 1995 First Final Release

F5 AUG 2005 Updated device ordering info. Updated legal notice. Added MSL data..

F7 OCT 2009 Increased minimum Vdiff voltage from 4.5 to 4.75 V.

CS5505/6/7/8

DS59F7 31

- NOTES -

CS5505/6/7/8

32 DS59F7

CDB5505/6/7/8

http://www.cirrus.com

CDB5505/6/7/8

Evaluation Board for CS5505/6/7/8 Series of ADCs

JUN ‘09

DS59DB4

CDB No Longer Available

For Reference Only

Evaluation Board for CS5505/6/7/8 Series of ADC’s

Features

Operation with on-board 32.768 kHz crystal or off-board clock source

Jumper selectable:

- SSC mode; SEC mode; Sleep

DIP Switch Selectable:

- BP/UP mode; A0, & A1 channel selection

On-board precision voltage reference

Access to all digital control pins

On-board patch area

AIN4+

AIN3+

AIN2+

Description

The CDB5505/ 5506/5507/5508 is a ci rcuit boa rd d esigned to provide quick evaluation of the CS5505/6/7/8 series of A/D converters. The board can be configured to evaluate the CS5505/6/7/8 in either SSC (Synchronous Self-Clocking) or SEC (Synchronous External-Clocking) serial port mode.

The board allows access to all of the digital interface pins of the CS5505/6/7/8 chip.

ORDERING INFORMATION

CDB5505 Evaluation Board CDB5506 Evaluation Board CDB5507 Evaluation Board CDB5508 Evaluation Board

CS5505/6/7/8

E A D E

AIN1+

AIN-

VREF

+5V

GND

Cirrus Logic, Inc. Crystal Semiconductor Products Division

P.O. Box 17847, Austin, Texas 78760 (512) 445 7222 FAX: (512) 445 7581 http://www.crystal.com

-5V

CLKI

MAR ‘95

DS59DB2

Introduction

CDB5505/6/7/8

34 DS59DB4

CDB No Longer Available

For Reference Only

CS5505/6/7/8

The CDB5505/6/7/8 evaluation board provides a quick means of testing the CS5505/6/7/8 series A/D converters. The CS5505/6/7/8 converters require a minimal amount of external circuitry. The evaluation board comes configured with the A/D converter chip operating from a 32.768 kHz crystal and with an off-chip precision 2.5 volt reference. The board provides access to all of the digital interface pins of the CS5505/6/7/8 chip.

The board is configured for operation from +5 and -5 volt power supplies, but can be operated from a single +5 volt supply if the -5V binding post is shorted to the GND binding post.

Evaluation Board Overview

The board provides a complete means of making the CS5505/6/7/8 A/D converter chip function. The user must provide a means of taking the output data from the board in serial format and using it in his system.

Figure 1 illustrates the schematic for the board. The board comes configured for the A/D converter chip to operate from the 32.768 kHz watch crystal. A BNC connector for an external clock is provided on the board. To connect the external BNC source to the converter chip, a circuit trace must be cut. Then a jumper must be inserted in the proper holes to connect the XIN pin of the converter to the input line from the

BNC. The BNC input is terminated with a 50Ω resistor. Remove this resistor if driving from a logic gate. See the schematic in Figure 1.

The board comes with the A/D converter VREF+ and VREF- pins hard-wired to the

2.5 volt bandgap voltage reference IC on the board. The VREF+ and VREF- pins can be connected to either the on chip reference or an

off-board reference if the connections (2A and 2B) to the bandgap IC are cut.

Note that the pin-out of the CS5505/6/7/8 series chips allows the 20-pin single channel devices to be plugged into the 24-pin, four channel footprint. See Figure 2 which illustrates the footprint compatib ility.

Prior to powering up the board, select the serial port operating mode with the appropriate jumper on the M/SLP header. The device can be operated in either the SSC (Synchronous Self-Clocking) or the SEC (Synchronous External Clocking) mode. See the device data sheet for an explanation of these modes.

All of the control pins of the CS5505/6/7/8 are available at the J1 header connector. Buffer ICs U2 and U3 are used to buffer the converter for interface to off-board circuits. The buffers are used on the evaluation board only because the exact loading and off-board circuitry is unknown. Most applications will not require the buffer ICs for proper operation.

To put the board in operation, select either bipolar or unipolar mode with DIP switch S2. Then press the CAL pushbutton after the board is powered up. This initiates calibration of the converter which is required before measurements can be taken.

To select an input channel on the four channel devices, use DIP switch S2 to select the inputs

A1 A0 Channel addressed

00 AIN1

01 AIN2

10 AIN3

11 AIN4

Table 1. Multiplexer Truth Table

34 DS59DB2

CDB5505/6/7/8

DS59DB4 35

CDB No Longer Available

For Reference Only

DRDY

SCLKI

SCLKO

SDATA

DRDY

CONV

SCLK

SDATA

CAL

BP/UP

CS5505/6/7/8

R22

C16

U2F

C18

0.1 2

U3A

VD+

U3B

VD+

100k

R24

R25

100k

TP13

SCLK

AIN3+

AIN4+

TP4

TP5

402

100k

R28

R29

100k

AIN4+

AIN3+

R11

100k

R10 20k

CAL

C11

0.01

C10

0.1

VD+

0.1

AGND

0.1

6.8V

VD+

R18

47k

R17

VD+

U2A

VD+

C17

TP10

CAL

VD+

VA+

VREFOUT

R27

0.1

DGND

0.1

6.8V

U2B

0.1

TP9

CONV

VREF+

VREF-

C19

C20

10nF

R26

- 5

R19

TP8

10nF

R20

100k

VD+

U2D

U2C

TP11

TP7

CS5506

CS5507

CS5505

0.1

25k

-2.5 V

LT1019

0.1

U2E

R23

100k

TP12

DRDY

SDATA

CS5508

TP3

402

VREF

External

100k

R16

U3D

TP14

BP/UP

AIN2+

AIN1+

TP6

402

100k

R30

AIN2+

AIN1+

U2 74HC4050

VD+

R31

R21

R15

TP15

C15

C14

C13

C12

402

100k

U3 74HC125

U3C

47k

VD+

100k

R14

100k

M/SLP

AIN-

0.01 F

0.01

R13

AIN-

R12 100k

XIN XOUT

VA- DGND

SLEEP

BP/UP

CONV

SSC

SEC

kHz

32.768

-5

0.1

200

CLKIN

Figure 1. ADC Connections

+5V

GND

-5V

DS59DB2 35

CDB5505/6/7/8

36 DS59DB4

CDB No Longer Available

For Reference Only

CS5505/6/7/8

A0 A1

CS DRDY

CONV SDATA

CAL SCLK

XIN VD+

XOUT DGND

M/SLP VA-

BU/UP VA+

AIN1+ VREFOUT

AIN2+/NC VREF-

AIN- VREF+

AIN3+ AIN4+

Figure 2. CS5505/6 and CS5507/8 Pin Layouts

CS5505/6

2/1

CS5507/8

3/2

4/3

5/4

6/5

7/6

8/7

9/8

10/9

11/10

12 13

for A0 and A1 (see Table 1). Once A0 and A1 are selected, the CONV switch (S2-3) must be switched on (closed) and then open to cause the CONV signal to transition low to high. This latches the A0 and A1 channel selection into the converter. With CONV high (S2-3 open) the converter will convert continuously.

20/23

19/22

18/21

17/20

16/19

15/18

14/17

13/16

12/15

11/14

Figures 3 and 4 illustrate the evaluation board layout while Figure 5 illustrates the component placement (silkscreen) of the evaluation board.

36 DS59DB2

CDB5505/6/7/8

DS59DB4 37

CDB No Longer Available

For Reference Only

CS5505/6/7/8

Figure 3. Top Ground Plane Layer (NOT TO SCALE)

DS59DB2 37

CDB5505/6/7/8

38 DS59DB4

CDB No Longer Available

For Reference Only

CS5505/6/7/8

Figure 4. Bottom Trace Layer (NOT TO SCALE)

38 DS59DB2

CDB5505/6/7/8

DS59DB4 39

CDB No Longer Available

For Reference Only

CS5505/6/7/8

Figure 5. Silk Screen Layer (NOT TO SCALE)

DS59DB2 39

CDB5505/6/7/8

40 DS59DB4

REVISION HISTORY

Revision Date Changes

DB2 MAR 1995 First Release

F5 AUG 2005 Updated legal notice.

DB4 JUN 2009 Removed re

ferences to part numbers for devices containing lead (Pb).

Contacting Cirrus Logic Support

For all product questions and inquiries contact a Cirrus Logic Sales Representative. To find the one nearest to you go to www.cirrus.com

IMPORTANT NOTICE

Cirrus Logic, Inc. and its subsidiaries (“Cirrus”) believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided “AS IS” without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third parties. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. Cirrus owns the copyrights associated with the information contained herein and gives con- sent for copies to be made of the information only for use within your organization with respect to Cirrus integrated circuits or other products of Cirrus. This consent does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROP- ERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE IN PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DEVICES, LIFE SUPPORT PRODUCTS OR OTHER CRIT- ICAL APPLICATIONS. INCLUSION OF CIRRUS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK AND CIR- RUS DISCLAIMS AND MAKES NO WARRANTY, EXPRESS, STATUTORY OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR PARTICULAR PURPOSE, WITH REGARD TO ANY CIRRUS PRODUCT THAT IS USED IN SUCH A MANNER. IF THE CUSTOMER OR CUSTOM- ER'S CUSTOMER USES OR PERMITS THE USE OF CIRRUS PRODUCTS IN CRITICAL APPLICATIONS, CUSTOMER AGREES, BY SUCH USE, TO FULLY INDEMNIFY CIRRUS, ITS OFFICERS, DIRECTORS, EMPLOYEES, DISTRIBUTORS AND OTHER AGENTS FROM ANY AND ALL LIABILITY, INCLUDING AT- TORNEYS' FEES AND COSTS, THAT MAY RESULT FROM OR ARISE IN CONNECTION WITH THESE USES.

CDB No Longer Available

For Reference Only

Cirrus Logic CS5508 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual