LTC2472CDDPBF datasheet(6/20 Pages) LINER

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LTC2470/LTC2472

24702f

PIN FUNCTIONS

REFOUT (Pin 1): Reference Output Pin. Nominally 1.25V,

this voltage sets the full-scale input range of the ADC. For

noise and reference stability connect to a 0.1μF capacitor

tied to GND. This capacitor value must be less than or

equal to the capacitor tied to the reference compensation

pin (COMP). REFOUT cannot be overdriven by an external

reference.

COMP (Pin 2): Internal Reference Compensation Pin. For

low noise and reference stability, tie a 0.1μF capacitor

to GND.

CS (Pin 3): Chip Select (Active LOW) Digital Input. A LOW

on this pin enables the SDO output. A HIGH on this pin

places the SDO output pin in a high impedance state and

any inputs on SDI and SCK will be ignored.

SDI (Pin 4): Serial Data Input Pin. This pin is used to pro-

gram the sleep mode and the 250sps/1ksps output rate.

SCK (Pin 5): Serial Clock Input. SCK synchronizes the

serial data input/output. Once the conversion is complete,

a new data bit is produced at the SDO pin following each

SCK falling edge. Data is shifted into the SDI pin on each

rising edge of SCK.

SDO (Pin 6): Three-State Serial Data Output. SDO is used

for serial data output during the DATA INPUT/OUTPUT

state. This pin goes Hi-Z when CS is high.

GND (Pins 7, 11, Exposed Pad Pin 13 – DFN Package):

Ground. Connect directly to the ground plane through a

low impedance connection.

REF– (Pin 8):

Negative Reference Input to the ADC. The

voltage on this pin sets the zero input to the ADC. This

pin should be tied directly to ground or the ground sense

of the input sensor.

IN+ (LTC2472), IN (LTC2470) (Pin 9):

Positive input volt-

age for the LTC2472 differential device. ADC input for the

LTC2470 single-ended device.

IN– (LTC2472), GND (LTC2470) (Pin 10):

Negative input

voltage for the LTC2472 differential device. GND for the

LTC2470 single-ended device.

VCC (Pin 12): Positive Supply Voltage. Bypass to GND

with a 10μF capacitor in parallel with a low-series-induc-

tance 0.1μF capacitor located as close to the device as

possible.

TYPICAL PERFORMANCE CHARACTERISTICS (T

A = 25°C, unless otherwise noted)

Power Supply Rejection

vs Frequency Applied to VCC

Conversion Time vs Temperature

100

100k

10k

10M

FREQUENCY AT VCC (Hz)

24702 G010

–120

–100

–80

–60

–40

–20

TA = 25°C

TEMPERATURE (°C)

–50

24702 G11

4.4

4.0

4.1

4.2

4.3

3.9

3.8

–25

100

VCC = 2.7V

VCC = 4.1V

VCC = 5.5V

VREF vs VCC

2.0

3.5

2.5

4.0

3.0

5.0

5.5

4.5

6.0

VCC (V)

1.250345

1.250340

24702 G12

1.250305

1.250310

1.250315

1.250320

1.250325

1.250330

1.250335

TA = 25°C

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