FAN5235 Datasheet, PDF (2/15 Pages) Fairchild Semiconductor – System Electronics Regulator for Mobile PCs

FAN5235
Pin Assignments
VIN
3.3V-ALWAYS
CPUMP3.3
HSD3.3
SW3.3
5V-ALWAYS
LSD3.3
GND3.3
ISEN3.3
VFB3.3
SDN3.3
PGOOD
Top View
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
CPUMP5
HSD5
SW5
ISEN5
LSD5
GND5
VFB5
SDN5
SW12
VFB12
SGND
SDWN
Pin Description
Pin Name
VIN
3.3V-ALWAYS
CPUMP3.3
HSD3.3
SW3.3
5V-ALWAYS
LSD3.3
GND3.3
ISEN3.3
VFB3.3
SDN3.3
PGOOD
SDWN
SGND
VFB12
SW12
SDN5
VFB5
GND5
LSD5
Pin Number Pin Function Description
1
Input power.
2
3.3V Always on linear regulator. Load current on pins 2 and 6 must not exceed
50mA total.
3
Charge Pump 3.3V. High side Gate drive voltage for 3.3V. This pin is to be
connected to SW3.3 through a 100nF cap. and to 5V-ALWAYS through a diode
4
High-side gate driver for 3.3V. Connect this pin directly to the gate of an
N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1".
5
High side FET Source and Low Side FET Drain Switching Node. Switching
node for 3.3V.
6
5V Always on linear regulator output. The sum of the load currents on pins 2
and 6 must not exceed 50mA total.
7
Low-side gate driver for 3.3V. Connect this pin directly to the gate of an
N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1".
8
Ground for 3.3V MOSFET.
9
Current sense for 3.3V. This pin should be connected to the Drain of the bottom
Mosfet with an appropriate resistor and an RC filter. See Application Section.
10
Voltage feedback for 3.3V.
11
Soft Start and ON/OFF for 3.3V. OFF=GND. ON=open with SDWN=High. Use
open collector device for control.
12
Power Good Flag. An open collector output that will be logic low if any output
voltage is not above 89% of the nominal output voltage.
13
Master Shutdown. Shutdown for all power. Off when low. When high
5V/3.3V-ALWAYS are ON while 5V/3.3V-Main are ready to turn on if SDN5,
SDN3.3 go open.
14
Signal ground.
15
Voltage feedback for 12V.
16
FET driver for 12V Boost.
17
Enable/Soft Start for 5V and 12V. Soft start and ON/OFF for 5V & 12V.
OFF=Grounded. ON=open with SDWN=High.
18
Voltage feedback for 5V.
19
Ground for 5V MOSFET.
20
Low side FET driver for 5V. Connect this pin directly to the gate of an N-channel
MOSFET. The trace from this pin to the MOSFET gate should be < 1".
2
REV. 1.3.3 1/3/02