CS8151C
CS8151C
5V, 100mA Low Dropout Linear Regulator
with Watchdog, RESET, & Wake Up
Description
The CS8151C is a precision 5V, 100mA
micro-power voltage regulator with
very low quiescent current (400µA typ-
ical at 200µA load). The 5V output is
accurate within ±1% and supplies 100
mA of load current with a typical
dropout voltage of 400mV.
Microprocessor control logic includes
Watchdog, Wake Up and RESET . This
unique combination of low quiescent
current and full microprocessor con-
trol makes the CS8151C ideal for use in
battery operated, microprocessor con-
trolled equipment.
The CS8151C Wake Up function brings
the microprocessor out of Sleep mode.
The microprocessor in turn, signals its
Wake Up status back to the CS8151C
by issuing a Watchdog signal.
The Watchdog logic function monitors
an input signal (WDI) from the micro-
processor. The CS8151C responds to
the falling edge of the Watchdog signal
which it expects at least once during
each wake-up period. When the cor-
rect Watchdog signal is received, a
falling edge is issued on the wake-up
signal line.
RESET is independent of V
IN
and
operates correctly to an output voltage
as low as 1V. A RESET signal is issued
in any of three situations. During
power up the RESET is held low until
the output voltage is in regulation.
During operation if the output voltage
shifts below the regulation limits, the
RESET toggles low and remains low
until proper output voltage regulation
is restored. And finally, a RESET signal
is issued if the regulator does not
receive a Watchdog signal within the
Wake Up period.
The RESET pulse width, Wake Up sig-
nal frequency, and Wake Up delay
time are all set by one external capaci-
tor C
Delay
.
The regulator is protected against
short circuit, over voltage, and thermal
runaway conditions. The device can
withstand 74 volt load dump tran-
sients, making it suitable for use in
automotive environments.
Features
s
5V ±1% / 100 mA Output
Voltage
s
Micropower Compatible
Control Functions:
Wake Up
Watchdog
RESET
s
Low Dropout Voltage:
400mV @ 100mA
s
Low Sleep Mode Quiescent
Current (400µA typ)
s
Protection Features:
Thermal Shutdown
Short Circuit
74V Load Dump
Reverse Transient (-50V)
Package Options
8 Lead PDIP
V
IN
WDI
WAKE UP
RESET
1
Block Diagram
V
OUT
V
IN
Current Source
(Circuit Bias)
Over
Voltage
Shutdown
V
OUT
Current Limit
Sense
V
OUT
Gnd
N/C
Delay
WAKE UP
Delay
Timing
Circuit
WAKE UP
Circuit
Sense
+
-
Error
Amplifier
WDI
Falling Edge
Detector
V
OUT
WATCHDOG
Circuit
Thermal
Shutdown
Bandgap
Reference
RESET
RESET
Circuit
Gnd
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 3/17/99
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
