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TELCOM SEMICONDUCTOR, INC.

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TC70/71

MICROMASTER™ – SYSTEM SUPERVISOR WITH POWER SUPPLY

MONITOR, WATCHDOG AND BATTERY BACKUP

VCC

VCCO

VBATT

TC70/71

CEI

(TC70)

∆V

DETECTOR

WATCHDOG

TIMER

WDD

(TC70)

CEO

(TC70)

TDO

(TC71)

VREF1

VREF2

VREF3

PF

(TC71)

TDI

(TC71)

RS

BATTERY

BACK-UP

CONTROL

DELAY

TIMER

GND

PIN CONFIGURATIONS (DIP and SOIC)

1

8

27

3

6

4

5

TC70

1

8

27

3

6

4

5

TC71

CEO

VCCO

GND

CEI

VCC

VCCO

GND

TDI

VCC

WDD

VBATT

RS

TDO

PF

VBATT

RS

ORDERING INFORMATION

Part No.

Package

Temp. Range

TC70COA

8-Pin SOIC

0

°C to +70°C

TC70CPA

8-Pin Plastic DIP

0

°C to +70°C

TC70EOA

8-Pin SOIC

– 40

°C to +85°C

TC70EPA

8-Pin Plastic DIP

– 40

°C to +85°C

TC71COA

8-Pin SOIC

0

°C to +70°C

TC71CPA

8-Pin Plastic DIP

0

°C to +70°C

TC71EOA

8-Pin SOIC

– 40

°C to +85°C

TC71EPA

8-Pin Plastic DIP

– 40

°C to +85°C

FUNCTIONAL BLOCK DIAGRAM

FEATURES

s

Maximum Functional Integration: Precision Power

Supply Monitor, Watchdog Timer, External RESET

Override, Threshold Detector and Battery Backup

Controller in an 8-Pin Package

s

Generates Power-on RESET and Guards Against

Unstable Processor Operation Resulting from

Power "Brown-out"

s

Automatically Halts and Restarts an Out-of-

Control Microprocessor

s

Output Can be Wire-ORed, or Hooked to Manual

RESET Pushbutton Switch

s

Watchdog Disable Pin for Easier Prototyping

(TC70)

s

Voltage Monitor for Power Fail or Low Battery

Warning (TC71)

s

Available in 8-Pin Plastic DIP or 8-Pin SOIC

Packages

s

Cost Effective

TYPICAL APPLICATIONS

s

All Microprocessor-based Systems

s

Test Equipment

s

Instrumentation

s

Set-Top Boxes

GENERAL DESCRIPTION

The TC70/71 is a fully-integrated power supply monitor,

watchdog and battery backup circuit in a space-saving

8-pin package.

When power is initially applied, the TC70/71 holds the

processor in its reset state for a minimum of 500msec after

start-up, processor sanity is monitored by the on-board

watchdog circuit. The processor must provide periodic high-

to-low level transitions to the TC70/71 to verify proper

execution. Should the processor fail to supply this signal

within the specified timeout period, an out-of-control proces-

sor is indicated and the TC70/71 issues a momentary

processor reset as a result. The TC70 also features a

watchdog disable pin to facilitate system test and debug.

The output of the TC70/71 can be wire-ORed to a push-

button switch (or electronic signal) to reset the processor.

When connected to a push-button switch, the TC70/71

provides contact debounce.

The integrated battery backup circuit on-board the TC70/

71 converts CMOS RAM into nonvolatile memory by first

to an external battery.

The TC71 incorporates an additional 1.3V threshold

detector for power fail warning, low battery detection or to

monitor power supply voltages other than +5V.

TC70/71-1 11/18/96