Linear Technology LTC1605-2, LTC1605-1 Datasheet

1

LTC1605-1/LTC1605-2

Single Supply 16-Bit, 100ksps,

Sampling ADCs

The LTC®1605-1/LTC1605-2 are 100ksps, sampling
16-bit A/D converters that draw only 55mW (typical) from
a single 5V supply. These easy-to-use devices include a
sample-and-hold, precision reference, switched capacitor
successive approximation A/D and trimmed internal clock.

The LTC1605-1’s input range is 0V to 4V while the
LTC1605-2’s input range is ±4V. An external reference
can be used if greater accuracy over temperature is
needed.

The ADC has a microprocessor compatible, 16-bit or two
byte parallel output port. A convert start input and a data
ready signal (BUSY) ease connections to FIFOs, DSPs and
microprocessors.

■

Sample Rate: 100ksps

■

Complete 16-Bit Solution on a Single 5V Supply

■

Unipolar Input Range: 0V to 4V (LTC1605-1)

■

Bipolar Input Range: ±4V (LTC1605-2)

■

Power Dissipation: 55mW Typ

■

Signal-to-Noise Ratio: 86dB Typ

■

Operates with Internal or External Reference

■

Internal Synchronized Clock

■

28-Pin 0.3" PDIP and SSOP Packages

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Industrial Process Control

■

Multiplexed Data Acquisition Systems

■

High Speed Data Acquisition for PCs

■

Digital Signal Processing

LTC1605-1 Low Power, 100kHz, 16-Bit Sampling ADC on 5V Supply

4k

4k

200Ω

2.5V

REFERENCE

20k 10k

16-BIT

SAMPLING ADC

D15 TO D0

33.2k

2.2µF

2.5V

2.5V

10µF 0.1µF

2.2µF

0V TO 4V

INPUT

V

IN

CAP

REF

AGND1

1

4

2

AGND25DGND

14

CONTROL

LOGIC AND

TIMING

BUSY

BYTE

CS

R/C

28 27

6 TO 13

15 TO 22

26

25

24

23

DIGITAL
CONTROL
SIGNALS

1605-1/2 TA01

16-BIT
OR 2 BYTE
PARALLEL
BUS

5V

V

DIGVANA

BUFFER

3

CODE

0

INL (LSBs)

65535

1605-1/2 TA02/G04

16384

32768

49152

2.0

1.5

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

Typical INL Curve

FEATURES

DESCRIPTIO

U

APPLICATIO S

U

TYPICAL APPLICATIO

U

2

LTC1605-1/LTC1605-2

(Notes 1, 2)

V

ANA

.......................................................................... 7V

V

DIG

to V

ANA

........................................................... 0.3V

V

DIG

........................................................................... 7V

Ground Voltage Difference

DGND, AGND1 and AGND2 .............................. ±0.3V

Analog Inputs (Note 3)

VIN..................................................................... ±25V

CAP ............................ V

ANA

+ 0.3V to AGND2 – 0.3V

REF....................................Indefinite Short to AGND2

Momentary Short to V

ANA

Digital Input Voltage (Note 4) ........ V

DGND

– 0.3V to 10V

Digital Output Voltage........ V

DGND

– 0.3V to V

DIG

+ 0.3V

Power Dissipation.............................................. 500mW

Operating Ambient Temperature Range

LTC1605-1C/LTC1605-2C ....................... 0°C to 70°C

LTC1605-1I/LTC1605-2I .................... – 40°C to 85°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

Consult factory for Military grade parts.

ORDER PART

NUMBER

LTC1605-1CG
LTC1605-1IG
LTC1605-2CG
LTC1605-2IG
LTC1605-1CN
LTC1605-1IN
LTC1605-2CN
LTC1605-2IN

T

JMAX

= 125°C, θJA = 95°C/W (G)

T

JMAX

= 125°C, θJA = 130°C/W (N)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

Analog Input Range (Note 9) 4.75V ≤ V

ANA

≤ 5.25V, 4.75V ≤ V

DIG

≤ 5.25V

LTC1605-1 ● 0 to 4 V

LTC1605-2

● ±4V

C

IN

Analog Input Capacitance 10 pF

R

IN

Analog Input Impedance 10 kΩ

The ● denotes the specifications which apply over the full operating temperature range, otherwise

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution ● 16 Bits
No Missing Codes ● 15 Bits
Transition Noise 1 LSB

RMS

Integral Linearity Error (Note 7) ● ±3LSB
Zero Error Ext. Reference = 2.5V (Note 8) ● ±10 mV
Zero Error Drift ±2 ppm/°C
Full-Scale Error Drift ±7 ppm/°C
Full-Scale Error Ext. Reference = 2.5V (Notes 12, 13) ● ±0.50 %
Full-Scale Error Drift Ext. Reference = 2.5V ±2 ppm/°C
Power Supply Sensitivity

V

ANA

= V

DIG

= V

DD

VDD = 5V ±5% (Note 9) ±8LSB

The ● denotes the specifications which apply over the full operating

CO VERTER CHARACTERISTICS

U

A ALOG I PUT

UU

ABSOLUTE AXI U RATI GS

W

WW

U

PACKAGE/ORDER I FOR ATIO

UUW

1
2
3
4
5
6
7
8

9
10
11
12
13
14

28
27
26
25
24
23
22
21
20
19
18
17
16
15

V

IN

AGND1

REF

CAP

AGND2

D15 (MSB)

D14
D13
D12
D11
D10

D9
D8

DGND

V

DIG

V

ANA

BUSY
CS
R/C
BYTE
D0
D1
D2
D3
D4
D5
D6
D7

G PACKAGE

28-LEAD PLASTIC SSOP

N PACKAGE

28-LEAD PDIP

TOP VIEW

temperature range, otherwise specifications are at TA = 25°C. With external reference (Notes 5, 6).

specifications are at TA = 25°C. (Note 5)

3

LTC1605-1/LTC1605-2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

S/(N + D) Signal-to-(Noise + Distortion) Ratio 1kHz Input Signal (Note 14) 87 dB

10kHz Input Signal 85 dB
20kHz, –60dB Input Signal 30 dB

THD Total Harmonic Distortion 1kHz Input Signal, First 5 Harmonics – 101 dB

10kHz Input Signal, First 5 Harmonics – 92 dB

Peak Harmonic or Spurious Noise 1kHz Input Signal –101 dB

10kHz Input Signal –92 dB
Full-Power Bandwidth (Note 15) 275 kHz
Aperture Delay 40 ns
Aperture Jitter Sufficient to Meet AC Specs
Transient Response Full-Scale Step (Note 9) 2 µs
Overvoltage Recovery (Note 16) 150 ns

The ● denotes the specifications which apply over the full operating temperature range,

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

REF

Output Voltage I

OUT

= 0 ● 2.470 2.500 2.520 V

V

REF

Output Tempco I

OUT

= 0 ±5 ppm/°C

Internal Reference Source Current 1 µA
External Reference Voltage for Specified Linearity (Notes 9, 10) 2.30 2.50 2.70 V
External Reference Current Drain Ext. Reference = 2.5V (Note 9) ● 100 µA
CAP Output Voltage I

OUT

= 0 2.50 V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

High Level Input Voltage VDD = 5.25V ● 2.4 V

V

IL

Low Level Input Voltage VDD = 4.75V ● 0.8 V

I

IN

Digital Input Current VIN = 0V to V

DD

● ±10 µA

C

IN

Digital Input Capacitance 5pF

V

OH

High Level Output Voltage VDD = 4.75V IO = –10µA 4.5 V

IO = –200µA ● 4.0 V

V

OL

Low Level Output Voltage VDD = 4.75V IO = 160µA 0.05 V

IO = 1.6mA ● 0.10 0.4 V

I

OZ

Hi-Z Output Leakage D15 to D0 V

OUT

= 0V to VDD, CS High ● ±10 µA

C

OZ

Hi-Z Output Capacitance D15 to D0 CS High (Note 9) ● 15 pF

I

SOURCE

Output Source Current V

OUT

= 0V –10 mA

I

SINK

Output Sink Current V

OUT

= V

DD

10 mA

The ● denotes the specifications which apply over the

The ● denotes the specifications which apply over the

DY A IC ACCURACY

UW

I TER AL REFERE CE CHARACTERISTICS

UU U

DIGITAL I PUTS A D DIGITAL OUTPUTS

UU

otherwise specifications are at TA = 25°C. (Notes 5, 14)

full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)

full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)

4

LTC1605-1/LTC1605-2

The ● denotes the specifications which apply over the full operating temperature

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

SAMPLE(MAX)

Maximum Sampling Frequency ● 100 kHz

t

CONV

Conversion Time ● 8 µs

t

ACQ

Acquisition Time ● 2 µs

t

1

Convert Pulse Width (Note 11) ● 40 ns

t

2

Data Valid Delay After R/C↓ (Note 9) ● 8 µs

t

3

BUSY Delay from R/C↓ CL = 50pF ● 65 ns

t

4

BUSY Low 8 µs

t

5

BUSY Delay After End of Conversion 220 ns

t

6

Aperture Delay 40 ns

t

7

Bus Relinquish Time ● 10 35 83 ns

t

8

BUSY Delay After Data Valid ● 50 200 ns

t

9

Previous Data Valid After R/C↓ 7.4 µs

t

10

R/C to CS Setup Time (Notes 9, 10) 10 ns

t

11

Time Between Conversions 10 µs

t

12

Bus Access and Byte Delay (Notes 9, 10) 10 83 ns

The ● denotes the specifications which apply over the full operating temperature

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

DD

Positive Supply Voltage (Notes 9, 10) 4.75 5.25 V

I

DD

Positive Supply Current ● 11 16 mA

P

DIS

Power Dissipation 55 80 mW

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: All voltage values are with respect to ground with DGND, AGND1
and AGND2 wired together (unless otherwise noted).

Note 3: When these pin voltages are taken below ground or above V

ANA

=

V

DIG

= VDD, they will be clamped by internal diodes. This product can

handle input currents of greater than 100mA below ground or above V

DD

without latch-up.
Note 4: When these pin voltages are taken below ground, they will be

clamped by internal diodes. This product can handle input currents of
90mA below ground without latchup. These pins are not clamped to V

DD

.

Note 5: VDD = 5V, f

SAMPLE

= 100kHz, tr = tf = 5ns unless otherwise

specified.
Note 6: Linearity, offset and full-scale specifications apply for a V

IN

input

with respect to ground.
Note 7: Integral nonlinearity is defined as the deviation of a code from a

straight line passing through the actual end points of the transfer curve.
The deviation is measured from the center of the quantization band.

Note 8: Zero error for the LTC1605-1 is the voltage measured from

0.5LSB when the output code flickers between 0000 0000 0000 0000
and 0000 0000 0000 0001. Zero error for the LTC1605-2 is the voltage
measured from –0.5LSB when the output code flickers between 0000
0000 0000 0000 and 1111 1111 1111 1111.

Note 9: Guaranteed by design, not subject to test.
Note 10: Recommended operating conditions.
Note 11: With CS low the falling R/C edge starts a conversion. If R/C

returns high at a critical point during the conversion it can create small
errors. For best results ensure that R/C returns high within 3µs after the
start of the conversion.

Note 12: As measured with fixed resistors shown in Figure 4. Adjustable to
zero with external potentiometer.

Note 13: Full-scale error is the untrimmed deviation from ideal last code
transition, divided by the full-scale range and includes the effect of offset
error.

Note 14: All specifications in dB are referred to a full-scale 4V input for the
LTC1605-1 and to ±4V input for the LTC1605-2.

Note 15: Full-power bandwidth is defined as full-scale input frequency at
which a signal-to-(noise + distortion) degrades to 60dB or 10 bits of
accuracy.

Note 16: Recovers to specified performance after (±20V) input
overvoltage for the LTC1605-1 and ±15V for the LTC1605-2.

TI I G CHARACTERISTICS

WU

POWER REQUIRE E TS

WU

range, otherwise specifications are at TA = 25°C. (Note 5)

range, otherwise specifications are at TA = 25°C. (Note 5)

5

LTC1605-1/LTC1605-2

TYPICAL PERFOR A CE CHARACTERISTICS

UW

SUPPLY VOLTAGE (V)

4.50

9.5

SUPPLY CURRENT (mA)

10.0

10.5

11.0

11.5

12.0

12.5

4.75 5.00 5.25 5.50

1605-1/2 G01

f

SAMPLE

= 100kHz

TEMPERATURE (°C)

–50

10.0

POWER SUPPLY CURRENT (mA)

10.5

11.0

11.5

12.0

–25 0 25 50

1605-1/2 G02

75 100

f

SAMPLE

= 100kHz

LOAD CURRENT (mA)

CHANGE IN CAP VOLTAGE (V)

0.04

0.02

0

–0.02

–0.04

–0.06

–0.08

–0.10

–60 –40 –20 0

1605-1/2 G03

–70–80 –50 –30 –10 10

LTC1605-1

LTC1605-2

CODE

0

DNL (LSB)

65535

1605-1/2 G05

16384

32768

49152

2.0

1.5

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

FREQUENCY (kHz)

0

MAGNITUDE (dB)

1605-1/2 G07/F11

5 10 15 20 25 30 35 40 45 50

0
–10
–20
–30
–40
–50
–60
–70
–80
–90

–100
–110
–120
–130

f

SAMPLE

= 100kHz

f

IN

= 1kHz
SINAD = 87dB
THD = 101.1dB
SNR = 87.2dB

INPUT FREQUENCY (kHz)

1

SINAD (dB)

90

88

86

84

82

80

10 100

1605-1/2 G08

INPUT FREQUENCY (kHz)

1

TOTAL HARMONIC DISTORTION (dB)

–70

–80

–90

–100

–110

10 100

1605-1/2 G09

Supply Current vs Supply Voltage Supply Current vs Temperature

Change in CAP Voltage vs
Load Current

Typical INL Curve Typical DNL Curve

Power Supply Feedthrough
vs Ripple Frequency

LTC1605-2 Nonaveraged
4096-Point FFT Plot

SINAD vs Input Frequency
(LTC1605-2)

Total Harmonic Distortion vs
Input Frequency (LTC1605-2)

CODE

0

INL (LSBs)

65535

1605-1/2 TA02/G04

16384

32768

49152

2.0

1.5

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

RIPPLE FREQUENCY (Hz)

POWER SUPPLY FEEDTHROUGH (dB)

–20

–30

–40

–50

–60

–70

–80

100 10k 100k 1M

LTXXXX GXX

1k

LTC1605-2

LTC1605-1

6

LTC1605-1/LTC1605-2

16-BIT CAPACITIVE DAC

COMPREF BUF

2.5V REF

CAP

(2.5V)

C

SAMPLE

C

SAMPLE

•

•

•

D15

D0

BUSY

CONTROL LOGIC

R/C BYTE

INTERNAL

CLOCK

CS

ZEROING SWITCHES

V

DIG

V

ANA

V

IN

REF

AGND1
AGND2

DGND

16

1605-1/2 BD

+

–

SUCCESSIVE APPROXIMATION

REGISTER

OUTPUT LATCHES

4k

4k

6K*

20k

3.75k*

10k
OPEN*

*RESISTOR VALUES FOR THE LTC1605-2

VIN (Pin 1): Analog Input. Connect through a 200Ω
resistor to the analog input. Full-scale input range is 0V
to 4V for the LTC1605-1 and ±4V for the LTC1605-2.

AGND1 (Pin 2): Analog Ground. Tie to analog ground
plane.

REF (Pin 3): 2.5V Reference Output. Bypass with 2.2µF
tantalum capacitor. Can be driven with an external refer­ence.

CAP (Pin 4): Reference Buffer Output. Bypass with 2.2µF
tantalum capacitor.

AGND2 (Pin 5): Analog Ground. Tie to analog ground
plane.

D15 to D8 (Pins 6 to 13): Three-State Data Outputs.
Hi-Z state when CS is high or when R/C is low.

DGND (Pin 14): Digital Ground.
D7 to D0 (Pins 15 to 22): Three-State Data Outputs.

Hi-Z state when CS is high or when R/C is low.
BYTE (Pin 23): Byte Select. With BYTE low, data will be

output with Pin 6 (D15) being the MSB and Pin 22 (D0)

PIN FUNCTIONS

UUU

being the LSB. With BYTE high the upper eight bits and
the lower eight bits will be switched. The MSB is output
on Pin 15 and bit 8 is output on Pin 22. Bit 7 is output on
Pin 6 and the LSB is output on Pin 13.

R/C (Pin 24): Read/Convert Input. With CS low, a falling
edge on R/C puts the internal sample-and-hold into the
hold state and starts a conversion. With CS low, a rising
edge on R/C enables the output data bits.

CS (Pin 25): Chip Select. Internally OR’d with R/C. With
R/C low, a falling edge on CS will initiate a conversion.
With R/C high, a falling edge on CS will enable the output
data.

BUSY (Pin 26): Output Shows Converter Status. It is low
when a conversion is in progress. Data valid on the rising
edge of BUSY. CS or R/C must be high when BUSY rises
or another conversion will start without time for signal
acquisition.

V

ANA

(Pin 27): 5V Analog Supply. Bypass to ground with

a 0.1µF ceramic and a 10µF tantalum capacitor.

V

DIG

(Pin 28): 5V Digital Supply. Connect directly to

Pin␣ 27.

FU CTIO AL BLOCK DIAGRA

UU

W