±0.25°C Accurate, 16-Bit Digital

Preliminary Technical Data

ADT7420

Rev. PrA

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FEATURES

Temperature accuracy: ±0.25°C from −20°C to +105°C

13- or 16-bit user selectable temperature-to-digital converter

Low drift silicon temperature sensor

No temperature calibration/correction required by user

Power saving 1 sample per second (SPS) mode

Fast first conversion on power-up of 6 ms

Operating temperature: −40°C to +150°C

Operating voltage: 2.7 V to 5.5 V

Critical overtemperature indicator

Programmable overtemperature/undertemperature interrupt

Low power consumption: 700 µW typical at 3.3 V

Shutdown mode for lower power: 7 µW typical at 3.3 V

16-lead RoHS-compliant LFCSP package

APPLICATIONS

RTD and thermistor replacement

Medical equipment

Cold junction compensation

Industrial control and test

Food transportation and storage

Environmental monitoring and HVAC

GENERAL DESCRIPTION

The ADT7420 is a high accuracy digital temperature sensor

offering breakthrough performance over a wide industrial

range, housed in an LFCSP package. It contains a band gap

temperature reference and a 13-bit ADC to monitor and digitize

the temperature to a 0.0625°C resolution. The ADC resolution,

by default, is set to 13 bits (0.0625°C). This can be changed to

16 bits (0.0078°C) by setting Bit 7 in the configuration register

to 1 (Register Address 0x03).

The ADT7420 is guaranteed to operate over supply voltages from

2.7 V to 5.5 V. Operating at 3.3 V, the average supply current is typi-

cally 210 μA. The ADT7420 has a shutdown mode that powers

down the device and offers a shutdown current of typically 2 μA.

The ADT7420 is rated for operation over the −40°C to +150°C

temperature range.

Pin A0 and Pin A1 are available for address selection, giving the

drain output that becomes active when the temperature exceeds

a programmable critical temperature limit. The default critical

temperature limit is 147°C. The INT pin is also an open-drain

output that becomes active when the temperature exceeds a

programmable limit. The INT and CT pins can operate in either

comparator or interrupt mode.

FUNCTIONAL BLOCK DIAGRAM

TEMPERATURE

VALUE

REGISTER

CONFIGURATION

REGISTER

REGISTER

REGISTER

REGISTER

REGISTER

POINTER

REGISTER

INTERNAL

REFERENCE

SOFTWARE

RESET

REGISTER

ID

REGISTER

STATUS

REGISTER

12

11

TEMPERATURE

SENSOR

INTERNAL

OSCILLATOR

FILTER

LOGIC

Σ-Δ

MODULATOR

GND

10

9

CT

INT

3

4

A0

A1

1

2

SCL

SDA

ADT7420

Figure 1.