CS8151
CS8151
5V, 100mA Low Dropout Linear Regulator
with WATCHDOG, RESET, & WAKE UP
Description
The CS8151 is a precision 5V, 100mA
micro-power voltage regulator with
very low quiescent current (400µA
typical at 200µA load). The 5V output
is accurate within ±2% 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 CS8151 ideal for use in
battery operated, microprocessor con-
trolled equipment.
The CS8151 WAKE UP function brings
the microprocessor out of Sleep mode.
The microprocessor in turn, signals its
WAKE UP status back to the CS8151
by issuing a WATCHDOG signal.
The WATCHDOG logic function mon-
itors an input signal (WDI) from the
microprocessor. The CS8151 responds
to the falling edge of the WATCH-
DOG signal which it expects at least
once during each wake-up period.
When the correct 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
signal 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 ±2% / 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
16 Lead PDIP
16 Lead SOIC Wide*
(Internally Fused)
N/C
N/C
N/C
1
Delay
______
RESET
WAKE UP
Gnd
Gnd
WDI
N/C
V
IN
Block Diagram
V
OUT
V
IN
Current Source
(Circuit Bias)
Over
Voltage
Shutdown
V
OUT
Current Limit
Sense
internally
connected on
TO-220 and
D
2
PAK
Gnd
Gnd
*N/C
Sense
V
OUT
WAKE UP
* For SO Wide package, pin # 6 is Gnd
Delay
Timing
Circuit
WAKE UP
Circuit
Sense
7 Lead TO-220
Tab (Gnd)
7 Lead D
2
PAK
Tab (Gnd)
+
-
Error
Amplifier
WDI
Falling Edge
Detector
V
OUT
WATCHDOG
Circuit
Thermal
Shutdown
Bandgap
Reference
RESET
RESET
Circuit
Gnd
1. V
OUT
2. V
IN
3. WDI
1
4. Gnd
5. WAKE UP
6. RESET
7. Delay
1
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. 5/4/99
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
