TL7770-5, TL7770-12
DUAL POWER-SUPPLY SUPERVISORS
SLVS019F – OCTOBER 1987 – REVISED JULY 1999
DW OR N PACKAGE
(TOP VIEW)
Power-On Reset Generator
Automatic Reset Generation After Voltage
Drop
V
1RESIN
1CT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CC
RESET Defined When V
Exceeds 1 V
2RESIN
CC
2CT
1RESET
1RESET
1VSU
Wide Supply-Voltage Range . . . 3.5 V
to 18 V
2RESET
2RESET
2VSU
Precision Overvoltage and Undervoltage
Sensing
1VSO
2VSO
2SCR DRIVE
1SCR DRIVE
GND
250-mA Peak Output Current for Driving
SCR Gates
2-mA Active-Low SCR Gate Drive for
False-Trigger Protection
Temperature-Compensated Voltage
Reference
True and Complementary Reset Outputs
Externally Adjustable Output Pulse
Duration
description
The TL7770 is an integrated-circuit system supervisor designed for use as a reset controller in microcomputer
and microprocessor power-supply systems. This device contains two independent supply-voltage supervisors
that monitor the supplies for overvoltage and undervoltage conditions at the VSO and VSU terminals,
respectively. When V attains the minimum voltage of 1 V during power up, the RESET output becomes active
CC
(low). As V approaches 3.5 V, the time-delay function activates, latching RESET and RESET active (high and
CC
low, respectively) for a time delay (t ) after system voltages have achieved normal levels. Above V
= 3.5 V,
d
CC
taking RESIN low activates the time-delay function during normal system-voltage levels. To ensure that the
microcomputer system has reset, the outputs remain active until the voltage at VSU exceeds the threshold
value, V , for a time delay, which is determined by an external timing capacitor such that:
IT+
td
20 103 capacitance
where t is in seconds and capacitance is in farads.
d
Theovervoltage-detectioncircuitisprogrammableforawiderangeofdesigns. Duringanovervoltagecondition,
an internal silicon-controlled rectifier (SCR) is triggered, providing 250-mA peak instantaneous current and
25-mA continuous current to the SCR gate drive terminal, which can drive an external high-current SCR gate
or an overvoltage-warning circuit.
The TL7770C series is characterized for operation from 0°C to 70°C. The TL7770I series is characterized for
operation from –40°C to 85°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 1999, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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