FAN5234 — Dual Mobile-Friendly PWM / PFM Controller
November 2010
FAN5234
Dual Mobile-Friendly PWM / PFM Controller
Features
Wide Input Voltage Range for Mobile Systems:
2V to 24V
Excellent Dynamic Response with Voltage Feed-
Forward and Average-Current-Mode Control
Lossless Current Sensing on Low-Side MOSFET or
Precision Over-Current via Sense Resistor
V
CC
Under-Voltage Lockout
Power-Good Signal
Light-Load Hysteretic Mode Maximizes Efficiency
300KHz or 600KHz Operation
TSSOP16 Package
Description
The FAN5234 PWM controller provides high efficiency
and regulation with an adjustable output from 0.9V to
5.5V required to power I/O, chip-sets, memory banks, or
peripherals in high-performance notebook computers,
PDAs,
and
internet
appliances.
Synchronous
rectification and hysteretic operation at light loads
contribute to a high efficiency over a wide range of
loads. The Hysteretic Mode of operation can be
disabled if PWM Mode is desired for all load levels.
Efficiency is further enhanced by using the MOSFET’s
R
DS(ON)
as a current-sense component.
Feed-forward ramp modulation, average current mode
control, and internal feedback compensation provide
fast response to load transients. The FAN5234 monitors
these outputs and generates a PGOOD (power-good)
signal when the soft-start is completed and the output is
within ±10% of its set point. A built-in over-voltage
protection prevents the output voltage from going above
120% of the set point. Normal operation is automatically
restored when the over-voltage conditions cease.
Under-voltage protection latches the chip off when the
output drops below 75% of its set value after the soft-
start sequence is completed. An adjustable over-current
function monitors the output current by sensing the
voltage drop across the lower MOSFET.
Applications
Mobile PC Regulator
Handheld PC Power
Related Resources
Application Note — AN-6002 Component
Calculations and Simulation Tools for FAN5234
or FAN5236
Application Note — AN-1029 Maximum Power
Enhancement Techniques for SO-8 Power
MOSFET
Ordering Information
Part Number
FAN5234MTCX
Operating
Temperature
Range
-10 to +85°C
Package
16-Lead, Thin-Shrink Small-Outline Package (TSSOP)
Packing Method
Tape and Reel
© 2004 Fairchild Semiconductor Corporation
FAN5234 • Rev. 2.0.0
www.fairchildsemi.com
FAN5234 — Dual Mobile-Friendly PWM / PFM Controller
Typical Application
VIN (BAT TERY)
= 2 to 24V
1
VIN
BO OT
C1
D1
C5
L1
Q1B
10
9
12
6
LDRV
PGND
ISNS
VSEN
VOUT
15
C2
+5
+5
C4
R5
VCC
11
FA N5 234
14
ILIM
EN
4
3
7
16
8
2
5
13
SW
Q1A
HDRV
1.8V at 3.5A
R1
C6
+5
C3
R4
SS1
FPWM
AGND
PGOOD
R3
R2
Figure 1. 1.18V Output Regulator
Block Diagram
Figure 2. Block Diagram
© 2004 Fairchild Semiconductor Corporation
FAN5234 • Rev. 2.0.0
www.fairchildsemi.com
2
FAN5234 — Dual Mobile-Friendly PWM / PFM Controller
Pin Configuration
VIN
PGOOD
EN
ILIM
VOUT
VSEN
SS
AGND
1
2
3
4
5
6
7
8
FA N5234
16
15
14
13
12
11
10
9
FPWM
BOOT
HDRV
SW
ISNS
VCC
LDRV
PGND
Figure 3. Pin Configuration
Pin Definitions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
VIN
PGOOD
EN
ILIM
VOUT
VSEN
SS
AGND
PGND
LDRV
VCC
ISNS
SW
HDRV
BOOT
FPWM
Description
Input Voltage.
Connect to main input power source (battery), also used to program
operating frequency for low input voltage operation
(see Table 1).
Power-Good Flag.
An open-drain output that pulls LOW when V
SEN
is outside of a ±10%
range of the 0.9V reference.
Enable.
Enables operation when pulled to logic HIGH. Toggling EN resets the regulator
after a latched fault condition. This is a CMOS input whose state is indeterminate if left open.
Current Limit.
A resistor from this pin to GND sets the current limit.
Output Voltage.
Connect to output voltage. Used for regulation to ensure a smooth
transition during mode changes. When V
OUT
is expected to exceed V
CC
, tie this pin to V
CC
.
Output Voltage Sense.
The feedback from the output. Used for regulation as well as
power-good, under-voltage, and over-voltage protection monitoring.
Soft-Start.
A capacitor from this pin to GND programs the slew rate of the converter during
initialization, when this pin is charged with a 5µA current source.
Analog Ground.
This is the signal ground reference for the IC. All voltage levels are
measured with respect to this pin.
Power Ground.
The return for the low-side MOSFET driver output. Connect to the gate of
the low-side MOSFET.
Low-Side Drive.
The low-side (lower) MOSFET driver output. Connect to the gate of the
low-side MOSFET.
Supply Voltage.
This pin powers the chip as well as the LDRV buffers. The IC starts to
operate when voltage on this pin exceeds 4.6V (UVLO rising) and shuts down when it drops
below 4.3V (UVLO falling).
Current-Sense Input.
Monitors the voltage drop across the lower MOSFET or external
sense resistor for current feedback.
Switching Node.
Return for the high-side MOSFET driver and a current-sense input.
Connect to source of high-side MOSFET and low-side MOSFET drain.
High-Side Drive.
High-side (upper) MOSFET driver output. Connect to the gate of the high-
side MOSFET.
BOOT.
Positive supply for the upper MOSFET driver. Connect as shown in Figure 2.
Forced PWM Mode.
When logic HIGH, inhibits the regulation from entering Hysteretic
Mode.
© 2004 Fairchild Semiconductor Corporation
FAN5234 • Rev. 2.0.0
www.fairchildsemi.com
3
FAN5234 — Dual Mobile-Friendly PWM / PFM Controller
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device
reliability. The absolute maximum ratings are stress ratings only.
Symbol
V
CC
V
IN
Parameter
V
CC
Supply Voltage
V
IN
Supply Voltage
BOOT, SW, ISNS, HDRV Pins
BOOT to SW Pins
All Other Pins
Min.
Max.
6.5
27
33
6.5
Unit
V
V
V
V
V
ºC
ºC
ºC
-0.3
-10
-65
V
CC
+0.3
+150
+150
+300
T
J
T
STG
T
L
Junction Temperature
Storage Temperature
Lead Soldering Temperature, 10 Seconds
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol
V
CC
V
IN
T
A
Θ
JA
Parameter
V
CC
Supply Voltage
V
IN
Supply Voltage
Ambient Temperature
Thermal Resistance, Junction to Ambient
Min.
4.75
-10
Typ.
5.00
Max.
5.25
24
+85
112
Unit
V
V
°C
°C/W
© 2004 Fairchild Semiconductor Corporation
FAN5234 • Rev. 2.0.0
www.fairchildsemi.com
4
FAN5234 — Dual Mobile-Friendly PWM / PFM Controller
Electrical Characteristics
Recommended operating conditions, unless otherwise noted.
Symbol
Power Supplies
Parameter
Conditions
LDRV, HDRV Open;
V
SEN
Forced Above
Regulation Point
Shutdown (EN-0)
VIN Pin = Input Voltage
Source
VIN Pin = GND
Rising V
CC
Falling
Min.
Typ.
Max.
Units
I
VCC
V
CC
Current
850
5
10
7
4.30
4.10
0.1
20
15
4.55
4.27
1300
15
30
20
1
4.75
4.50
0.5
µA
µA
µA
µA
µA
V
V
I
SINK
I
SOURCE
I
SD
V
UVLO
V
UVLOH
Oscillator
f
osc
V
PP
V
RAMP
G
V
IN
Current, Sinking
V
IN
Current, Sourcing
V
IN
Current, Shutdown
UVLO Threshold
UVLO Hysteresis
Frequency
Ramp Amplitude
Ramp Offset
Ramp / V
IN
Gain
V
IN
> 5V
V
IN
= 0V
V
IN
= 16V
V
IN
> 5V
V
IN
≥
3V
1V < V
IN
< 3V
255
510
300
600
2
1.25
0.5
125
250
345
690
KHz
V
V
mV/V
Reference and Soft-Start
V
REF
I
SS
V
SS
Internal Reference Voltage
Soft-Start Current
Soft-Start Complete Threshold
I
OUT
from 0 to 3A,
V
IN
from 2 to 24V
At Startup
0.891
0.900
5
1.5
0.909
V
µA
V
PWM Converter
Load Regulation
I
SEN
V
SEN
Bias Current
VOUT Pin Input Impedance
UVLO
TSD
Under-Voltage Shutdown
I
SNS
UVLO
Over-Current Threshold
Over-Voltage Threshold
% of Set Point,
2µs Noise Filter
R
ILIM
= 68.5KΩ, Figure 6
% of Set Point,
2µs Noise Filter
Sourcing
Sinking
Sourcing
Sinking
-1
50
40
70
115
113
80
55
75
144
+1
150
65
80
172
120
%
nA
KΩ
%
%
µA
Output Drivers
HDRV Output Resistance
LDRV Output Resistance
8.0
3.2
8.0
1.5
15.0
4.0
15.0
2.4
Ω
Ω
Continued on following page…
© 2004 Fairchild Semiconductor Corporation
FAN5234 • Rev. 2.0.0
www.fairchildsemi.com
5
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