CS8121
CS8121
5V, 1A Linear Regulator
with RESET and ENABLE
Description
The CS8121 is a 5V, 1A precision linear
regulator with two microprocessor
compatible control functions and pro-
tection circuitry included on chip. The
composite NPN-PNP output pass tran-
sistor assures a lower dropout voltage
(1.2V @ 1A) without requiring exces-
sive supply current (4mA).
The CS8121Õs two logic control func-
tions make this regulator well suited to
applications requiring microprocessor-
based control at the board or module
level.
ENABLE
controls the output
stage. A high voltage (>2.9V) on
the
ENABLE
lead turns off the regula-
torÕs pass transistor and sends the IC
into Sleep mode where it draws only
250µA.
RESET
sends a
RESET
signal
when the IC is powering up or when-
ever the output voltage falls out of reg-
ulation. The
RESET
signal is valid
down to V
OUT
= 1V.
The CS8121 design optimizes supply
rejection by switching the internal
bandgap reference from the supply
input to the regulator output as soon as
the nominal output voltage is achieved.
Additional on chip filtering enhances
rejection of high frequency transients
on all external leads.
The CS8121 is fault protected against
short circuit, over voltage and thermal
runaway conditions.
Features
s
5V ± 4% Output Voltage
s
Low Dropout Voltage
(1.2V @ 1A)
s
Low Quiescent Current
(4mA @ I
OUT
= 1A)
s
µP Compatible Control
Functions
RESET
ENABLE
s
Low Current Sleep Mode
I
Q
= 250µA
s
Fault Protection
Thermal Shutdown
Short Circuit
60V Peak Transient
Voltage
Block Diagram
Package Options
5 Lead TO-220
5 Lead TO-220
Overmolded
V
OUT
V
IN
Over
Voltage
Shutdown
ENABLE
Comparator
Bandgap
Supply
-
+
Error
Amplifier
5 Lead
TO-220
Output
Current
Limit
1 V
IN
V
OUT(SENSE)
VREF
RESET
Rev. 5/4/99
+
TO V
OUT
-
ENABLE
2
ENABLE
3 Gnd
1
Thermal
Shutdown
Bandgap
Reference
RESET
Comparator
+
-
Gnd
4 RESET
5 V
OUT
1 NC
2 V
IN
1
7 Lead D
2
PAK
3
ENABLE
4 Gnd
5 RESET
6 V
OUT
7 V
OUT(SENSE)
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
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
