3

TC1023

TC1024

PRELIMINARY INFORMATION

TC1023/1024-05

6/12/97

PRECISION TEMPERATURE-TO-VOLTAGE

CONVERTERS WITH SHUTDOWN MODE

DETAILED DESCRIPTION

A plot of output voltage versus temperature for both the

TC1023 and TC1024 appears in Figure 5. The TC1023 can

be used with single power supply to measure temperatures

from 0

°C to 100°C. A pull-down resistor (R1 in Figure 1)

must be added from the output pin to the negative power

supply for measuring temperatures less than 0

°C. The

value of the resistor must be chosen to limit the maximum

current pulled from the output to the negative supply to

– 50

Figure 1. TC1023 Connections

Output Stage

Both devices have Class A output stages capable of

sourcing 1mA. These devices have a limited ability to drive

heavy capacitive loads. Loads of 50pF (to ground) can be

driven directly. For heavier loads, a 2k

Ω (or greater) resis-

tor should be placed in series with the output for decoupling.

If the TC1023/1024 is used in a noisy electrical environ-

ment, a 0.1

mended.

Shutdown/Calibrate Mode

The TC1023/1024 enters shutdown when the CE input

(typ) and the output to drop immediately to 0V through

approximately 100k

Ω. For applications where the TC1023/

1024 is connected to an external A/D converter, a refer-

shutdown for A/D calibration, as shown

in Figure 3. A

CMOS gate provides bias voltage to the bandgap refer-

limit current through the voltage reference to the desired

is the CMOS gate output high voltage at output current

Figure 2. TC1024 Connections

Figure 3. A/D Calibration

Multi-Zone Temperature Sensing

The CE input facilitates multi-zone temperature sens-

ing as shown in the example of Figure 4. In this example,

the processor addresses either of two sensors with a single

and routed to the processor's A/D converter, eliminating

the need for separate A/D input channels for each sensor.

Figure 4. TC1023/1024 Addressing

TC1023

GND

CE

V

OUT

TC102x

GND

CE

V

CC

TC102x

GND

Zone 1/Zone 2

Zone 1

Zone 2

CE

I/O Pin

MICROCONTROLLER

A/D

CONVERTER

TC102x

GND

R1

CE

V

CC

CAL

A/D

CONVERTER

CMOS

GATE

2.5V

REF

TC1024

GND

TC1024 (– 20

°C to +125°C)

CE