FAN5232 View Datasheet(PDF) - Fairchild Semiconductor
Part Name
Description
Manufacturer
FAN5232 Datasheet PDF : 9 Pages
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PRODUCT SPECIFICATION
Table 1. RC5232 Application Bill of Materials
Reference Manufacturer, Part #
Quantity Description
C1
SANYO
25SV47M
1
47µF, 25V
C2-5
Any
4
100nF, 50V
C6
AVX
1
220µF, 16V
TPSE227M016#0100
R1
Any
1
10KΩ, 1%
R2, R4
Any
2
4.7Ω, 1%
R3, R5
Any
2
1KΩ, 1%
R6
Any
1
715Ω, 1%
D1
Fairchild
MBR0540L
1
500mA, 40V Schottky
L1
Coiltronics
UP2B-1R5
1
1.5µH, 8.3A
Q1
Fairchild
FDS6690A
1
30V N-channel MOSFET
Q2
Fairchild
FDS6680S
1
30V N-channel MOSFET
with Integrated Schottky
U1
Fairchild FAN5232
1
Controller
FAN5232
Comments
OSCON, Irms = 3.5A
Ceramic
Tantalum, ESR=100mΩ
R < 8mΩ
R = 20mΩ @ VGS = 4.5V
R = 17mΩ @ VGS = 4.5V
Application Information
Overview
The FAN5232 is a high efficiency and high precision DC/DC
controller for LCD PCs and portable applications. It provides
a switcher controller capable of generating a voltage between
5V to 80% of Vin, and a 5V and a 3.3V linear regulator for
standby applications. The controller has a power good output
and an enable/soft start to permit proper system sequencing.
Initialization
The FAN5232 automatically initializes upon receipt of input
power. The Power-on Reset (POR) function continually
monitors the input supply voltage on the VCC pin and
initiates soft start operation after the input supply voltage
exceeds 4.5V. Should this voltage drop below 4.0V, POR
disables the chip.
Soft Start
When soft start is initiated by POR, and if the SDWN pin is
not held low, the voltage on the SDNADJ pin begins ramping
up, with the rate of rise set by the external capacitor on the
pin. Below 700mV, the output is off. Between 700mV and
1.6V, the output is allowed to linearly ramp up. Above 1.6V,
the output is fully enabled, and regulates.
Shutdown
There are two separate shutdown pins to provide output
power control – SDWN, and SDNADJ. Taking the SDNADJ
pin low will disable the switcher output and reset the output’s
internal latches for short circuit, under-voltage and over-volt-
age. Taking the SDWN pin low puts the entire chip in shut-
down. Each of the SDN pins has an internal
pull-up.
Switcher Architecture
Overview
The switcher output of the FAN5232 is generated from the
unregulated input (battery) voltage using a synchronous buck
converter. Both high-side and low-side MOSFETs are
N-channel.
The converter has pins for current sensing using the low-side
MOSFET RDS,on; a pin for voltage-sense feedback; a pin
that enables the converter and permits soft-start; a power
good pin; and a pin for generating the boost voltage to drive
the high-side MOSFET.
REV. 1.1.1 10/7/02
5
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