CS5231-3 Datasheet, PDF (1/11 Pages) Cherry Semiconductor Corporation – 500mA, 3.3V Linear Regulator with Auxiliary Control

CS5231-3
500mA, 3.3V Linear Regulator
with Auxiliary Control
Description
Features
The CS5231-3 combines a three-
terminal linear regulator with cir-
cuitry to control an external PFET
transistor with the intent of manag-
ing two input supplies. A 5V sup-
ply powers the regulator while an
auxiliary 3.3V supply is controlled
by the IC. The design has been opti-
mized to provide a “glitch-free”
transition between the two sup-
plies.
The CS5231-3 linear regulator pro-
vides a fixed 3.3V output @ 500mA
with an overall accuracy of ± 2%.
The NPN-PNP composite pass tran-
sistor provides a low dropout volt-
age and requires less supply cur-
rent than PNP designs. Full protec-
tion including current limit and
thermal shutdown is provided.
Also designed for low reverse cur-
rent, the IC prevents excessive cur-
rent from flowing from the output
to ground if the regulator input
voltage is lower than the output
voltage.
The CS5231-3 also controls an auxil-
iary supply that can provide power
to the regulator output when input
voltage for the regulator is not
available. The AuxDrv auxiliary
output is normally pulled up to the
regulator input voltage and drives
low whenever the input voltage
drops below 4.4V (nominal). It is
typically used to control a PFET
switch that connects a 3.3V auxil-
iary supply to the regulator output.
The CS5231-3 is available in a
5-lead D²PAK (TO-263) package.
Applications include Network
Interface Cards (NICs), modem
cards and power supplies with
multiple input sources.
Block Diagram
V_OUT
V_IN
Linear Regulator
s 3.3V ± 2% Output Voltage
s 3mA Quiescent Current
@ 500mA
s Fast Transient Response
s Current Limit
s Thermal Shutdown with
Hysteresis
s 450µA Reverse Output
Current
s Fast Transient Response
System Power Management
s Auxiliary Supply Control
Package Options
5 Lead D²PAK
10kΩ 50kΩ
Internal
Bias
AuxDrv
Gnd
V_IN UV
Comparator
Bandgap
Reference
Thermal
Shutdown
Current
Limit
Error
Amp
−
V_REF
Shutdown
1
1. No Connect
2. V_IN
3. Gnd
4. V_OUT
5. AuxDrv
Tab = Gnd
Consult factory for other package
options.
Rev. 3/31/99
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: [phone] Fax: [phone]
Email: [e-mail]
Web Site: www.cherry-semi.com
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