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FAN5235QSC

P1-P3P4-P6P7-P9P10-P12P13-P15
www.fairchildsemi.com
REV. 1.3.3 1/3/02
Features
• Synchronous rectification
• ±1% precision internal reference
• >90% efficiency
• Input and output voltage feedback
• 5.4V to 24V input voltage range
• Internally set 300kHz ±15% oscillator
• 5V and 3.3V Main outputs switch out of phase
• 5V-ALWAYS and 3.3V-ALWAYS outputs
• Adjustable boost converter for 12V
• Boost converter slaved to 5V Main
• Input UVLO
• Outputs OVP of Buck Converters
• Precision current limit option for 5V, 3.3V Main
• Power Good Voltage Monitor
Applications
• Notebook PCs and PDAs
• Hand-held portable instruments
Description
The FAN5235 is a high efficiency and high precision
DC/DC controller for notebook converters. Utilization of
both input and output voltage feedback in a current-mode
control allows for fast and stable loop response over a wide
range of input and output voltage variations. The two main
regulators switch out of phase to minimize input ripple
current.
Current sense based on MOSFET Rdson gives maximum
efficiency, while also permitting use of a sense resistor for
high accuracy. An externally adjustable boost converter can
be set to generate 12V.
The FAN5235 is available in a 24-pin QSOP package, and in
a 24-pin TSSOP package.
Typical Application
1 VIN
2 3.3 ALW
3 CPUMP3.3
4 HSD3.3
5 SW3.3
6 5V-ALW
7 LSD3.3
8 GND3.3
9 ISEN3.3
10 VFB3.3
11 SDN3.3
12 PGOOD
CPUMP5 24
HSD5 23
SW5 22
ISEN5 21
LSD5 20
GND5 19
VFB5 18
SDN5 17
SW12 16
VFB12 15
SGND 14
SDWN 13
FAN5235
Vin = 5.4-24V
12V @ 120mA
3.3V-ALWAYS@50mA
5V @ 5A
SDN5
SDWN
PGOOD
3.3V @ 5A
+
SDN3.3
+
+
5V-ALWAYS@ 50mA
5V-ALWAYS
5V-ALWAYS
VFB12
FAN5235
System Electronics Regulator for Mobile PCs
FAN5235
2
REV. 1.3.3 1/3/02
Pin Assignments
Pin Description
Pin Name Pin Number Pin Function Description
VIN 1
Input power.
3.3V-ALWAYS 2
3.3V Always on linear regulator.
Load current on pins 2 and 6 must not exceed
50mA total.
CPUMP3.3 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
HSD3.3 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".
SW3.3 5
High side FET Source and Low Side FET Drain Switching Node.
Switching
node for 3.3V.
5V-ALWAYS 6
5V Always on linear regulator output.
The sum of the load currents on pins 2
and 6 must not exceed 50mA total.
LSD3.3 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".
GND3.3 8
Ground for 3.3V MOSFET.
ISEN3.3 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.
VFB3.3 10
Voltage feedback for 3.3V.
SDN3.3
11
Soft Start and ON/OFF for 3.3V.
OFF=GND. ON=open with SDWN=High. Use
open collector device for control.
PGOOD 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.
SDWN
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.
SGND 14
Signal ground.
VFB12 15
Voltage feedback for 12V.
SW12 16
FET driver for 12V Boost.
SDN5
17
Enable/Soft Start for 5V and 12V.
Soft start and ON/OFF for 5V & 12V.
OFF=Grounded. ON=open with SDWN
=High.
VFB5 18
Voltage feedback for 5V.
GND5 19
Ground for 5V MOSFET.
LSD5 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".
1
Top View
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VIN
3.3V-ALWAYS
5V-ALWAYS
CPUMP3.3
HSD3.3
SW3.3
ISEN3.3
LSD3.3
GND3.3
VFB3.3
SDN3.3
PGOOD
CPUMP5
HSD5
SW5
ISEN5
LSD5
GND5
VFB5
SDN5
SW12
VFB12
SGND
SDWN
FAN5235
REV. 1.3.3 1/3/02
3
Absolute Maximum Ratings
1
Note:
1. Stresses beyond "Absolute Maximum Ratings" may cause permanent device damage. Continuous exposure to absolute
maximum rating conditions may affect device reliability. Functional operation of the device at these or any other conditions
beyond those indicated in the operational sections of the specification is not implied.
Recommended Operating Conditions
Thermal Information
ISEN5 21
Current Sense for 5V.
This pin should be connected to the drain of the bottom
Mosfet using appropriate resistor and RC filter. See Application Section.
SW5 22
High Side Driver Source and Low Side Driver Drain Switching Node.
Switching node for 5V.
HSD5 23
High 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".
CPUMP5 24
Charge Pump 5V.
High side Gate drive voltage for 5V. High side Gate drive
voltage for 5V. This pin is to be connected to SW5 through a 100nF cap. and to
5V-ALWAYS through a diode.
Parameter Conditions Min. Typ. Max. Units
V
IN
-0.3 27 V
SW, ISEN Pins,SDWN Pin -0.3 27 V
CPUMP, HSD Pins -0.3 33 V
SDN, VFB, V_always pins -0.3 6.5 V
CPUMP to SW pins, and all other pins -0.3 6.5 V
The sum of the load currents on pins 2 and 6 must not exceed 60mA total
Input Voltage, V
IN
+5.4V to 24V
Ambient Temperature, T
A
-20°C to 85°C
Thermal Resistance,
θ
JA
88°C/W
Thermal Resistance,
θ
JC
QSOP 28.5°C/W
TSSOP 16°C/W
Maximum Junction Temperature 150°C
Storage Temperature Range -65°C to 150°C
Maximum Lead Temperature, Soldering 10 Sec 300°C
Pin Description
(Continued)
Pin Name Pin Number Pin Function Description
P1-P3P4-P6P7-P9P10-P12P13-P15

FAN5235QSC

Mfr. #:
Buy FAN5235QSC
Manufacturer:
ON Semiconductor
Description:
IC REG CONV MOBILE 5OUT 24QSOP
Lifecycle:
New from this manufacturer.
Delivery:
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