TC70 Datasheet, PDF (1/7 Pages) TelCom Semiconductor, Inc – MICROMASTER - SYSTEM SUPERVISOR WITH POWER SUPPLY MONITOR, WATCHDOG AND BATTERY BACKUP

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TC70/71
MICROMASTER™ – SYSTEM SUPERVISOR WITH POWER SUPPLY
MONITOR, WATCHDOG AND BATTERY BACKUP
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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
FUNCTIONAL BLOCK DIAGRAM
VCC
CEI
(TC70)
VBATT
BATTERY
BACK-UP
CONTROL
VCCO
CEO
(TC70)
PF
(TC71)
WDD
(TC70)
GND
TDI
(TC71)
WATCHDOG
TIMER
VREF1
∆V
DETECTOR
VREF3
VREF2
DELAY
TIMER
TC70/71
RS
TDO
(TC71)
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
3 ^{processor in its reset state for a minimum of 500msec after}
V_CC is in tolerance to ensure stable system start-up. 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
4 ^{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
5 ^{write-protecting, then switching the VCC line of the RAM over}
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.
ORDERING INFORMATION
Part No.
TC70COA
TC70CPA
TC70EOA
TC70EPA
TC71COA
TC71CPA
TC71EOA
TC71EPA
Package
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
8-Pin Plastic DIP
6 Temp. Range
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
– 40°C to +85°C
0°C to +70°C
0°C to +70°C
7 ^{– 40°C to +85°C}
– 40°C to +85°C
PIN CONFIGURATIONS (DIP and SOIC)
VCCO 1
VCC ₂
GND 3
CEI 4
TC70
8 VBATT ^VCCO 1
7 RS
VCC 2
6 WDD
GND 3
5 CEO
TDI 4
TC71
8 ^VBATT
7 RS
6 PF
5 TDO
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TELCOM SEMICONDUCTOR, INC.
TC70/71-1 11/18/96
5-7