LINEAR TECHNOLOGY LTC2482 Technical data

LTC2482

16-Bit ∆Σ ADC with

FEATURES

■

Easy Drive Technology Enables Rail-to-Rail Inputs
with Zero Differential Input Current

■

Directly Digitizes High Impedance Sensors with
Full Accuracy

■

600nV RMS Noise, Independent of V

■

Operates with a Reference as Low as 100mV with

REF

16-Bit Resolution

■

GND to VCC Input/Reference Common Mode Range

■

Simultaneous 50Hz/60Hz Rejection Mode

■

2ppm INL, No Missing Codes

■

1ppm Offset and 15ppm Total Unadjusted Error

■

No Latency: Digital Filter Settles in a Single Cycle

■

Single Supply 2.7V to 5.5V Operation

■

Internal Oscillator

■

Available in a Tiny (3mm × 3mm) 10-Lead
DFN Package

U

APPLICATIO S

■

Direct Sensor Digitizer

■

Weight Scales

■

Direct Temperature Measurement

■

Strain Gauge Transducers

■

Instrumentation

■

Industrial Process Control

■

DVMs and Meters

Easy Drive Input

Current

Cancellation

U

DESCRIPTIO

The LTC®2482 combines a 16-bit plus sign No Latency
∆Σ™ analog-to-digital converter with patented Easy Drive™
technology. The patented sampling scheme eliminates
dynamic input current errors and the shortcomings of on­chip buffering through automatic cancellation of differen­tial input current. This allows large external source
impedances and input signals with rail-to-rail input range
to be directly digitized while maintaining exceptional DC
accuracy.

The LTC2482 allows a wide common mode input range
(0V to V
reference can be as low as 100mV or can be tied directly
to VCC. The noise level is 600nV RMS independent of V
This allows direct digitization of low level signals with 16­bit accuracy. The LTC2482 includes an on-chip trimmed
oscillator, eliminating the need for external crystals or
oscillators and provides 87dB rejection of 50Hz and 60Hz
line frequency noise. Absolute accuracy and low drift are
automatically maintained through continuous, transpar­ent, offset and full-scale calibration.

, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ and Easy Drive are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patent pending.

) independent of the reference voltage. The

CC

REF

.

TYPICAL APPLICATIO

V

CC

SENSE

10k

10k

I

DIFF

= 0

1µF

V

IN

V

IN

V

REF

+

LTC2482

–

GND F

U

+FS Error vs R

80

VCC = 5V

= 5V

V

REF

60

+

= 3.75V

V

IN

–

= 1.25V

V

IN

1µF

V

CC

SDO

SCK

3-WIRE
SPI INTERFACE

CS

O

2482 TA01

40

= GND

F

O

= 25°C

T

A

20

0

–20

+FS ERROR (ppm)

–40

–60

–80

10 100 10k

1

SOURCE

R

SOURCE

at IN+ and IN

CIN = 1µF

1k

(Ω)

–

100k

2482 TA02

2482f

1

LTC2482

PACKAGE/ORDER I FOR ATIO

UU

W

TOP VIEW

11

DD PACKAGE

10-LEAD (3mm × 3mm) PLASTIC DFN

10

9

6

7

8

4

5

3

2

1

F

O

SCK

GND

SDO

CS

*GND

V

CC

V

REF

IN

+

IN

–

WWWU

ABSOLUTE AXI U RATI GS

(Notes 1, 2)

Supply Voltage (VCC) to GND...................... – 0.3V to 6V

Analog Input Voltage to GND ....... –0.3V to (V

+ 0.3V)

CC

ORDER PART

NUMBER

Reference Input Voltage to GND .. –0.3V to (VCC + 0.3V)

Digital Input Voltage to GND ........ –0.3V to (V

Digital Output Voltage to GND ..... –0.3V to (V

+ 0.3V)

CC

+ 0.3V)

CC

LTC2482CDD
LTC2482IDD

Operating Temperature Range

LTC2482C ................................................... 0°C to 70°C

LTC2482I ................................................ –40°C to 85°C

Storage Temperature Range ................ –65°C to 125°C

T

= 125°C, θJA = 43°C/ W

JMAX

EXPOSED PAD (PIN 11) IS GND

MUST BE SOLDERED TO PCB

*PIN 1 MAY BE DRIVEN WITH A DIGITAL

SIGNAL IN ORDER TO REMAIN PIN

COMPATIBLE WITH THE LTC2480/LTC2484

Consult LTC Marketing for parts specified with wider operating temperature ranges.
**The temperature grade is indicated by a label on the shipping container.

DD PART MARKING**

LBSQ

UW

ELECTRICAL CHARACTERISTICS ( OR AL SPEED)

over the full operating temperature range, otherwise specifications are TA = 25°C. (Notes 3, 4)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution (No Missing Codes) 0.1 ≤ V
Integral Nonlinearity 5V ≤ VCC ≤ 5.5V, V

2.7V ≤ VCC ≤ 5.5V, V
Offset Error 2.5V ≤ V
Offset Error Drift 2.5V ≤ V
Positive Full-Scale Error 2.5V ≤ V
Positive Full-Scale Error Drift 2.5V ≤ V

Negative Full-Scale Error 2.5V ≤ V
Negative Full-Scale Error Drift 2.5V ≤ V

Total Unadjusted Error 5V ≤ VCC ≤ 5.5V, V

5V ≤ VCC ≤ 5.5V, V

2.7V ≤ VCC ≤ 5.5V, V
Output Noise 5V ≤ VCC ≤ 5.5V, V

≤ VCC, –FS ≤ VIN ≤ +FS (Note 5) ● 16 Bits

REF

= 5V, V

REF

= 2.5V, V

REF

≤ VCC, GND ≤ IN+ = IN– ≤ VCC (Note 14) ● 0.5 5 µV

REF

≤ VCC, GND ≤ IN+ = IN– ≤ V

REF

≤ VCC, IN+ = 0.75V

REF

≤ VCC, IN+ = 0.75V

REF

≤ VCC, IN+ = 0.75V

REF

≤ VCC, IN+ = 0.75V

REF

= 2.5V, V

REF

= 5V, V

REF

= 2.5V, V

REF

= 5V, GND ≤ IN– = IN+ ≤ VCC (Note 13) 0.6 µV

REF

= 2.5V (Note 6) ● 2 20 ppm of V

IN(CM)

IN(CM)

= 1.25V (Note 6) 1 ppm of V

IN(CM)

CC

, IN– = 0.25V

REF

, IN– = 0.25V

REF

, IN– = 0.25V

REF

, IN– = 0.25V

REF

= 1.25V 15 ppm of V

IN(CM)

REF

REF

REF

REF

= 2.5V ppm of V

= 1.25V ppm of V

IN(CM)

The ● denotes specifications which apply

REF
REF

10 nV/°C

● 32 ppm of V

0.1 ppm of

● 32 ppm of V

0.1 ppm of

REF

V

/°C

REF

REF

/°C

V

REF

REF
REF
REF

RMS

2

2482f

LTC2482

U

CO VERTER CHARACTERISTICS

temperature range, otherwise specifications are at T

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Common Mode Rejection DC 2.5V ≤ V
Input Common Mode Rejection 2.5V ≤ V

50Hz ±2%
Input Common Mode Rejection 2.5V ≤ V

60Hz ±2%
Input Normal Mode Rejection 2.5V ≤ V

50Hz ±2%
Input Normal Mode Rejection 2.5V ≤ V

60Hz ±2%
Input Normal Mode Rejection 2.5V ≤ V

50Hz/60Hz ±2%
Reference Common Mode 2.5V ≤ V

Rejection DC

Power Supply Rejection DC V

Power Supply Rejection, 50Hz ±2% V

Power Supply Rejection, 60Hz ±2% V

REF

REF

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

≤ VCC, GND ≤ IN– = IN+ ≤ V

REF

= 2.5V, IN– = IN+ = GND 120 dB

= 2.5V, IN– = IN+ = GND (Note 7) 120 dB

= 2.5V, IN– = IN+ = GND (Note 8) 120 dB

The ● denotes specifications which apply over the full operating

= 25°C. (Notes 3, 4)

A

(Note 5) ● 140 dB

CC

(Note 5) ● 140 dB

CC

(Note 5) ● 140 dB

CC

(Notes 5, 7) ● 110 120 dB

CC

(Notes 5, 8) ● 110 120 dB

CC

(Notes 5, 9) ● 87 dB

CC

(Note 5) ● 120 140 dB

CC

UUU

A ALOG I PUT AUD REFERE CE

temperature range, otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

+

IN

–

IN

FS Full Scale of the Differential Input (IN+ – IN–) ● 0.5V

LSB Least Significant Bit of the Output Code ● FS/2

V

IN

V

REF

CS (IN+)IN

CS (IN–)IN

CS (V

)V

REF

I

(IN+)IN+ DC Leakage Current Sleep Mode, IN+ = GND ● –10 1 10 nA

DC_LEAK

I

(IN–)IN– DC Leakage Current Sleep Mode, IN– = GND ● –10 1 10 nA

DC_LEAK

I

(V

DC_LEAK

Absolute/Common Mode IN+ Voltage GND – 0.3V VCC + 0.3V V

Absolute/Common Mode IN– Voltage GND – 0.3V VCC + 0.3V V

Input Differential Voltage Range (IN+ – IN–) ● –FS +FS V

Reference Voltage Range ● 0.1 V

+

Sampling Capacitance 11 pF

–

Sampling Capacitance 11 pF

Sampling Capacitance 11 pF

REF

)V

REF

Leakage Current Sleep Mode, V

REF

The ● denotes specifications which apply over the full operating

REF

16

CC

REF

= V

CC

● –100 1 100 nA

V

V

2482f

3

LTC2482

UU

DIGITAL I PUTS A D DIGITAL OUTPUTS

operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

V

IL

V

IH

V

IL

I

IN

I

IN

C

IN

C

IN

V

OH

V

OL

V

OH

V

OL

I

OZ

High Level Input Voltage 2.7V ≤ VCC ≤ 5.5V ● VCC – 0.5 V
CS, F

O

Low Level Input Voltage 2.7V ≤ VCC ≤ 5.5V ● 0.5 V
CS, F

O

High Level Input Voltage 2.7V ≤ VCC ≤ 5.5V (Note 10) ● VCC – 0.5 V
SCK

Low Level Input Voltage 2.7V ≤ VCC ≤ 5.5V (Note 10) ● 0.5 V
SCK

Digital Input Current 0V ≤ VIN ≤ V
CS, F

O

Digital Input Current 0V ≤ VIN ≤ VCC (Note 10) ● –10 10 µA
SCK

Digital Input Capacitance 10 pF
CS, F

O

Digital Input Capacitance 10 pF
SCK

High Level Output Voltage IO = –800µA ● VCC – 0.5 V
SDO

Low Level Output Voltage IO = 1.6mA ● 0.4 V
SDO

High Level Output Voltage IO = –800µA ● VCC – 0.5 V
SCK

Low Level Output Voltage IO = 1.6mA ● 0.4 V
SCK

Hi-Z Output Leakage ● –10 10 µA
SDO

CC

The ● denotes specifications which apply over the full

● –10 10 µA

WU

POWER REQUIRE E TS

otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CC

I

CC

Supply Voltage ● 2.7 5.5 V

Supply Current Conversion Mode (Note 12) ● 160 250 µA

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

Sleep Mode (Note 12)

● 12 µA

2482f

4

LTC2482

WU

TI I G CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

EOSC

t

HEO

t

LEO

t

CONV_1

f

ISCK

D

ISCK

f

ESCK

t

LESCK

t

HESCK

t

DOUT_ISCK

t

DOUT_ESCK

t

1

t2 CS↑ to SDO High Z ● 0 200 ns
t3 CS↓ to SCK↓ (Note 10) ● 0 200 ns
t4 CS↓ to SCK↑ (Note 10) ● 50 ns

t

KQMAX

t

KQMIN

t

5

t

6

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

Note 2: All voltage values are with respect to GND.
Note 3: V

V

REFCM

VIN = IN+ – IN–, V

Note 4: Use internal conversion clock or external conversion clock source
with f

EOSC

Note 5: Guaranteed by design, not subject to test.
Note 6: Integral nonlinearity is defined as the deviation of a code from a

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

Note 7: f

EOSC

Note 8: f

EOSC

External Oscillator Frequency Range (Note 15) ● 10 4000 kHz

External Oscillator High Period ● 0.125 100 µs

External Oscillator Low Period ● 0.125 100 µs

Conversion Time Simultaneous 50Hz/60Hz ● 144.1 146.9 149.9 ms

Internal SCK Frequency Internal Oscillator (Note 10) 38.4 kHz

Internal SCK Duty Cycle (Note 10) ● 45 55 %

External SCK Frequency Range (Note 10) ● 4000 kHz

External SCK Low Period (Note 10) ● 125 ns

External SCK High Period (Note 10) ● 125 ns

Internal SCK 24-Bit Data Output Time Internal Oscillator (Notes 10, 12) ● 0.61 0.625 0.64 ms

External SCK 24-Bit Data Output Time (Note 10) ● 24/f
CS↓ to SDO Low ● 0 200 ns

SCK↓ to SDO Valid ● 200 ns
SDO Hold After SCK↓ (Note 5) ● 15 ns
SCK Set-Up Before CS↓ ● 50 ns
SCK Hold After CS↓ ● 50 ns

= 2.7V to 5.5V unless otherwise specified.

CC

= V

/2, FS = 0.5V

REF

IN(CM)

REF

= (IN+ + IN–)/2

= 307.2kHz unless otherwise specified.

= 256kHz ±2% (external oscillator).
= 307.2kHz ±2% (external oscillator).

The ● denotes specifications which apply over the full operating temperature

External Oscillator

● 41036/f

External Oscillator (Notes 10, 11) f

External Oscillator (Notes 10, 11)

● 192/f

Note 9: Simultaneous 50Hz/60Hz rejection (internal oscillator) or

= 280kHz ±2% (external oscillator).

f

EOSC

Note 10: The SCK can be configured in external SCK mode or internal SCK
mode. In external SCK mode, the SCK pin is used as digital input and the
driving clock is f

. In internal SCK mode, the SCK pin is used as digital

ESCK

output and the output clock signal during the data output is f
Note 11: The external oscillator is connected to the FO pin. The external

oscillator frequency, f

, is expressed in kHz.

EOSC

Note 12: The converter uses the internal oscillator.
Note 13: The output noise includes the contribution of the internal

calibration operations.

Note 14: Guaranteed by design and test correlation.
Note 15: Refer to Applications Information section for performance vs

data rate graphs.

(in kHz) ms

EOSC

/8 kHz

EOSC

(in kHz) ms

EOSC

(in kHz) ms

ESCK

ISCK

.

2482f

5

LTC2482

INPUT VOLTAGE (V)

–3

INL (ppm OF V

REF

)

–1

1

3

–2

0

2

–0.75 –0.25 0.25 0.75

2482 G03

1.25–1.25

VCC = 2.7V
V

REF

= 2.5V

V

IN(CM)

= 1.25V

F

O

= GND

–45°C, 25°C, 90°C

INPUT VOLTAGE (V)

–12

TUE (ppm OF V

REF

)

–4

4

12

–8

0

8

–0.75 –0.25 0.25 0.75

2482 G06

1.25–1.25

VCC = 2.7V
V

REF

= 2.5V

V

IN(CM)

= 1.25V

F

O

= GND

85°C

25°C

–45°C

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Integral Nonlinearity
(VCC = 5V, V

3

VCC = 5V
V

REF

2

V

IN(CM)

= GND

F

O

)

–45°C

1

REF

0

85°C

–1

INL (ppm OF V

–2

–3

= 5V

REF

= 2.5V

–1.5 –0.5 0.5 1.5

INPUT VOLTAGE (V)

Total Unadjusted Error
(VCC = 5V, V

12

VCC = 5V
V

8

V
F

)

4

REF

0

= 5V

REF
IN(CM)

= GND

O

REF

= 2.5V

25°C

= 5V)

= 5V)

25°C

85°C

–45°C

2482 G01

Integral Nonlinearity
(VCC = 5V, V

3

VCC = 5V

= 2.5V

V

REF

2

)

1

REF

0

–1

INL (ppm OF V

–2

2.5–2–2.5 –1 0 1 2

–3

= 1.25V

V

IN(CM)

= GND

F

O

–0.75 –0.25 0.25 0.75

= 2.5V)

REF

–45°C, 25°C, 90°C

INPUT VOLTAGE (V)

1.25–1.25

2482 G02

Total Unadjusted Error
(VCC = 5V, V

12

VCC = 5V
V

8

V
F

)

4

REF

0

REF
IN(CM)

= GND

O

= 5V

= 1.25V

= 2.5V)

REF

85°C

25°C

–45°C

Integral Nonlinearity
(VCC = 2.7V, V

= 2.5V)

REF

Total Unadjusted Error
(VCC = 2.7V, V

= 2.5V)

REF

–4

TUE (ppm OF V

–8

–12

–1.5 –0.5 0.5 1.5

INPUT VOLTAGE (V)

Offset Error vs V

0.3
VCC = 5V

= 5V

V

REF

)

REF

OFFSET ERROR (ppm OF V

0.2

0.1

–0.1

–0.2

–0.3

V
T

0

–1

= 0V

IN

= 25°C

A

01

–4

TUE (ppm OF V

–8

2.5–2–2.5 –1 0 1 2

2482 G04

–12

IN(CM)

356

24

V

(V)

IN(CM)

2482 G07

–0.75 –0.25 0.25 0.75

INPUT VOLTAGE (V)

0.3

0.2

)

REF

0.1

0

–0.1

OFFSET ERROR (ppm OF V

–0.2

–0.3

1.25–1.25

2482 G05

Offset Error vs Temperature

VCC = 5V

= 5V

V

REF

= 0V

V

IN

= GND

V

IN(CM)

= GND

F

O

–30 0

–45

–15

TEMPERATURE (°C)

30 90

45

15

60

75

2482 G08

6

2482f

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC2482

Offset Error vs V

0.3
REF+ = 2.5V

–

= GND

REF

)

REF

OFFSET ERROR (ppm OF V

–0.3

0.2

0.1

–0.1

–0.2

0

2.7

= 0V

V

IN

V

IN(CM)

= 25°C

T

A

3.1 3.5

= GND

CC

4.3 5.1 5.5

3.9 4.7
VCC (V)

On-Chip Oscillator Frequency
vs Temperature

310

308

306

2482 G09

Offset Error vs V

0.3

0.2

)

REF

0.1

0

–0.1

OFFSET ERROR (ppm OF V

–0.2

–0.3

0

1234

REF

V

(V)

REF

On-Chip Oscillator Frequency
vs V

CC

310

308

306

VCC = 5V

–

= GND

REF

= 0V

V

IN

V

IN(CM)

= 25°C

T

A

V

= 2.5V

REF

= 0V

V

IN

V

IN(CM)

= GND

F

O

= GND

5

2482 G10

= GND

304

FREQUENCY (kHz)

VCC = 4.1V

= 2.5V

V

REF

302

= 0V

V

IN

= GND

V

IN(CM)

= GND

F

O

300

–45 –30

–15

TEMPERATURE (°C)

PSRR vs Frequency at V

0

VCC = 4.1V DC

= 2.5V

V

REF

–20

+

= GND

IN

–

= GND

IN

–40

= GND

F

O

= 25°C

T

A

–60

–80

REJECTION (dB)

–100

–120

–140

0

10 100

FREQUENCY AT VCC (Hz)

30

150

45

CC

10k 1M

1k 100k

60 75

2482 G11

2482 G13

304

FREQUENCY (kHz)

302

300

90

2.5

3.5 4.0 4.5

3.0
VCC (V)

PSRR vs Frequency at V

0

VCC = 4.1V DC ±1.4V

= 2.5V

V

REF

–20

+

= GND

IN

–

= GND

IN

–40

= GND

F

O

= 25°C

T

A

–60

–80

REJECTION (dB)

–100

–120

–140

0

60

80

40

20

FREQUENCY AT VCC (Hz)

100

120 160

140

CC

5.0 5.5

2482 G12

180

2482 G14

220200

2482f

7

LTC2482

UW

TYPICAL PERFOR A CE CHARACTERISTICS

PSRR vs Frequency at V

0

VCC = 4.1V DC ±0.7V

= 2.5V

V

REF

–20

+

= GND

IN

–

= GND

IN

–40

= GND

F

O

= 25°C

T

A

–60

–80

REJECTION (dB)

–100

–120

CC

200

180

160

140

CONVERSION CURRENT (µA)

120

Conversion Current
vs Temperature

FO = GND
CS = GND
SCK = NC
SDO = NC

VCC = 5V

VCC = 2.7V

–140

30600

30650 30700 30800

FREQUENCY AT VCC (Hz)

Sleep Mode Current
vs Temperature

2.0
FO = GND

1.8

CS = V

CC

SCK = NC

1.6
SDO = NC

1.4

1.2

1.0

0.8

0.6

SLEEP MODE CURRENT (µA)

0.4

0.2

0

–30 0

–45

–15

VCC = 5V

VCC = 2.7V

30 90

45

15

TEMPERATURE (°C)

30750

2482 G15

100

–45

–30 0

–15

TEMPERATURE (°C)

15

60

30 90

75

45

2482 G16

Conversion Current
vs Data Output Rate

500

V

= V

REF

CC

IN+ = GND

450

–

= GND

IN
SCK = NC

400

SDO = NC
CS = GND

350

= EXT OSC

F

O

= 25°C

T

A

300

250

SUPPLY CURRENT (µA)

200

150

100

0

60

75

2482 G17

20 40 60 1007010 30 50 90

OUTPUT DATA RATE (READINGS/SEC)

VCC = 5V

VCC = 3V

80

2482 G18

8

2482f

LTC2482

U

UU

PI FU CTIO S

GND (Pin 1): Ground. This pin should be tied to ground;
however, in order to remain pin compatible with the
LTC2480/LTC2484, this pin may be driven HIGH or LOW.

VCC (Pin 2): Positive Supply Voltage. Bypass to GND
(Pin 8) with a 1µF tantalum capacitor in parallel with 0.1µF
ceramic capacitor as close to the part as possible.

V

(Pin 3): Positive Reference Input. The voltage on this

REF

pin can have any value between 0.1V and V
reference input is GND (Pin 8).

+

IN

(Pin 4), IN– (Pin 5): Differential Analog Inputs.

The voltage on these pins can have any value between GND
– 0.3V and VCC + 0.3V. Within these limits the converter
bipolar input range (VIN = IN+ – IN–) extends from
–0.5 • V
converter produces unique overrange and underrange
output codes.

CS (Pin 6): Active LOW Chip Select. A LOW on this pin
enables the digital input/output and wakes up the ADC.
Following each conversion the ADC automatically enters
the Sleep mode and remains in this low power state as long
as CS is HIGH. A LOW-to-HIGH transition on CS during the
Data Output transfer aborts the data transfer and starts a
new conversion.

to 0.5 • V

REF

. Outside this input range the

REF

. The negative

CC

GND (Pin 8): Ground. Shared pin for analog ground,
digital ground and reference ground. Should be connected
directly to a ground plane through a minimum impedance.

SCK (Pin 9): Bidirectional Digital Clock Pin. In Internal
Serial Clock Operation mode, SCK is used as the digital
output for the internal serial interface clock during the Data
Output period. In External Serial Clock Operation mode,
SCK is used as the digital input for the external serial inter­face clock during the Data Output period. A weak internal
pull-up is automatically activated in Internal Serial Clock
Operation mode. The Serial Clock Operation mode is de­termined by the logic level applied to the SCK pin at power
up or during the most recent falling edge of CS.

FO (Pin 10): Frequency Control Pin. Digital input that
controls the conversion clock. When FO is connected to
GND the converter uses its internal oscillator running at

307.2kHz. The conversion clock may also be overridden
by driving the FO pin with an external clock in order to
change the output rate or the digital filter rejection null.

Exposed Pad (Pin 11): This pin is ground and should be
soldered to the PCB, GND plane. For prototyping purposes
this pin may remain floating.

SDO (Pin 7): Three-State Digital Output. During the Data
Output period, this pin is used as the serial data output.
When the chip select CS is HIGH (CS = VCC), the SDO pin
is in a high impedance state. During the Conversion and
Sleep periods, this pin is used as the conversion status
output. The conversion status can be observed by pulling
CS LOW.

2482f

9

LTC2482

1.69k

SDO

2482 TC02

Hi-Z TO V

OL

VOH TO V

OL

VOL TO Hi-Z

C

LOAD

= 20pF

V

CC

UU

W

FU CTIO AL BLOCK DIAGRA

V

REF

3

+

IN

4

–

IN

5

GND

+

IN

3RD ORDER

∆Σ ADC

–

IN

–

REF

AUTOCALIBRATION

AND CONTROL

8

REF

2

V

CC

1

+

SERIAL

INTERFACE

INTERNAL

OSCILLATOR

GND

SCK

SD0

CS

F

2482 FD

9

7

6

O

10

TEST CIRCUITS

SDO

1.69k

Hi-Z TO V
VOL TO V

OH

VOH TO Hi-Z

= 20pF

C

LOAD

OH

2482 TC01

10

2482f