CS5112
CS5112
1.4A Switching Regulator with 5V, 100mA Linear
Regulator with Watchdog, RESET and ENABLE
Description
The CS5112 is a dual output power sup-
ply integrated circuit. It contains a 5V
±2%, 100mA linear regulator, a watchdog
timer, a linear output voltage monitor to
provide a Power On Reset (POR) and a
1.4A current mode PWM switching reg-
ulator.
The 5V linear regulator is comprised of
an error amplifier, reference, and super-
visory functions. It has low internal sup-
ply current consumption and provides
1.2V (typical) dropout voltage at maxi-
mum load current.
The watchdog timer circuitry monitors
an input signal (WDI) from the micro-
processor. It responds to the falling
edge of this watchdog signal. If a correct
watchdog signal is not received within
the externally programmable time, a
reset signal is issued.
The externally programmable active
reset circuit operates correctly for an out-
put voltage (V
LIN
) as low as 1V. During
power up, or if the output voltage shifts
below the regulation limit, RESET tog-
gles low and remains low for the duration
of the delay after proper output voltage
regulation is restored. Additionally a reset
pulse is issued if the correct watchdog is
not received within the programmed
time. Reset pulses continue until the cor-
rect watchdog signal is received. The
reset pulse width and frequency, as well
as the Power On Reset delay, are set by
one external RC network.
The current mode PWM switching regu-
lator is comprised of an error amplifier
with selectable feedback inputs, a cur-
rent sense amplifier, an adjustable oscil-
lator, and a 1.4A output power switch
with anti-saturation control. The switch-
ing regulator can be configured in a
variety of topologies.
The CS5112 is load dump capable and
has protection circuitry which includes
current limit on the linear and switcher
outputs, and an overtemperature limiter.
Features
s
Linear Regulator
5V ± 2% @ 100mA
s
Switching Regulator
1.4A Peak Internal
Switch
120kHz Maximum
Switching Frequency
5V to 26V Operating
Supply Range
s
Smart Functions
Watchdog
RESET
ENABLE
s
Protection
Overtemperature
Current Limit
Block Diagram
V
FB1
V
FB2
SELECT
COMP
I
BIAS
C
OSC
Oscillator
Multiplexer
-
+
Switcher
Error Amplifier
COMP
V
IN
Logic
Base
Drive
+
-
Gnd
V
SW
1.4A
Package Options
24 Lead SO Wide
(Internally Fused Leads)
V
IN
NC
1
Current Sense Amplifier
ENABLE
V
REG
V
LIN
I
BIAS
Gnd
Gnd
Gnd
Gnd
RESET
C
Delay
WDI
C
OSC
+
-
Switcher Shutdown
ENABLE
V
REG
NC
V
SW
+
-
Current
Limit
Over
Temperature
Linear
Error Amplifier
V
LIN
Gnd
Gnd
Gnd
Gnd
V
FB1
V
FB2
1.25V
Bandgap
Reference
C
DELAY
WDI
RESET &
Watchdog Timer
RESET
SELECT
COMP
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. 4/22/99
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
