Fairchild FAN5234 service manual

FAN5234

Dual Mobile-Friendly PWM / PFM Controller

FAN5234 — Dual Mobile-Friendly PWM / PFM Controller

November 2010

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

Under-Voltage Lockout

CC

 Power-Good Signal  Light-Load Hysteretic Mode Maximizes Efficiency  300KHz or 600KHz Operation  TSSOP16 Package

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

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

as a current-sense component.

DS(ON)

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 softstart sequence is completed. An adjustable over-current function monitors the output current by sensing the voltage drop across the lower MOSFET.

Ordering Information

Operating

Part Number

FAN5234MTCX -10 to +85°C 16-Lead, Thin-Shrink Small-Outline Package (TSSOP) Tape and Reel

Temperature

Range

Package Packing Method

A

Typical Application

FAN5234 — Dual Mobile-Friendly PWM / PFM Controller

VIN (B

TTERY)

= 2 to 24V

+5

C4

R5

C3

+5 9

R4

PGOOD

Block Diagram

VCC

ILIM

EN

SS1

FPWM

AGND

11

4

3

7

16

8

2

VIN

1

BO OT

FAN5234

14

13

Q1A

HDRV

SW

Q1B

LDRV

10

PGND

ISNS

12

VSEN

6

VOUT

5

Figure 1. 1.18V Output Regulator

C1

C5

R3

D1

L1

C2

+515

1.8V at 3.5A

C6

R1

R2

Figure 2. Block Diagram

Pin Configuration

FAN5234 — Dual Mobile-Friendly PWM / PFM Controller

VIN

PGOOD

EN

ILIM

VOUT

VSEN

SS

AGND

1

2

3

4

FA N5 23 4

5

6

7

8

16

15

14

13

12

11

10

FPWM

BOOT

HDRV

SW

ISNS

VCC

LDRV

PGND

9

Figure 3. Pin Configuration

Pin Definitions

Pin # Name Description

1 VIN

2 PGOOD

3 EN

4 ILIM

5 VOUT

6 VSEN

7 SS

8 AGND

9 PGND

10 LDRV

11 VCC

12 ISNS

13 SW

14 HDRV

15 BOOT

16 FPWM

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

is outside of a ±10%

SEN

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

is expected to exceed VCC, tie this pin to VCC.

OUT

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.

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 Parameter Min. Max. Unit

VCC VCC Supply Voltage 6.5 V

VIN V

BOOT, SW, ISNS, HDRV Pins 33 V BOOT to SW Pins 6.5 V

All Other Pins -0.3 VCC+0.3 V

TJ Junction Temperature -10 +150 ºC

T

Storage Temperature -65 +150 ºC

STG

TL Lead Soldering Temperature, 10 Seconds +300 ºC

Supply Voltage 27 V

IN

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 Parameter Min. Typ. Max. Unit

VCC VCC Supply Voltage 4.75 5.00 5.25 V

VIN V

TA Ambient Temperature -10 +85 °C

ΘJA Thermal Resistance, Junction to Ambient 112 °C/W

Supply Voltage 24 V

IN

Electrical Characteristics

Recommended operating conditions, unless otherwise noted.

Symbol Parameter Conditions Min. Typ. Max. Units

Power Supplies

LDRV, HDRV Open; V

Forced Above

I

VCC

V

CC

Current

SEN

Regulation Point

Shutdown (EN-0) 5 15 µA

I

SINK

I

SOURCE

V

Current, Sinking

IN

VIN Current, Sourcing VIN Pin = GND 7 15 20 µA

VIN Pin = Input Voltage Source

ISD VIN Current, Shutdown 1 µA

V

UVLO Threshold

UVLO

V

UVLO Hysteresis 0.1 0.5 V

UVLOH

Rising V

Falling 4.10 4.27 4.50

4.30 4.55 4.75

CC

Oscillator

> 5V 255 300 345

V

f

Frequency

osc

VPP Ramp Amplitude

V

Ramp Offset 0.5 V

RAMP

G Ramp / VIN Gain

IN

VIN = 0V 510 600 690

= 16V 2

V

IN

VIN > 5V 1.25

≥ 3V

V

IN

1V < VIN < 3V 250

Reference and Soft-Start

V

Internal Reference Voltage 0.891 0.900 0.909 V

REF

ISS Soft-Start Current At Startup 5 µA

VSS Soft-Start Complete Threshold 1.5 V

PWM Converter

I

from 0 to 3A,

Load Regulation

I

V

SEN

Bias Current 50 80 150 nA

SEN

OUT

V

from 2 to 24V

IN

VOUT Pin Input Impedance 40 55 65

UVLO

Under-Voltage Shutdown

TSD

I

Over-Current Threshold

SNS

UVLO Over-Voltage Threshold

% of Set Point, 2µs Noise Filter

R

= 68.5KΩ, Figure 6

ILIM

% of Set Point, 2µs Noise Filter

Output Drivers

HDRV Output Resistance

LDRV Output Resistance

Sourcing 8.0 15.0

Sinking 3.2 4.0

Sourcing 8.0 15.0

Sinking 1.5 2.4

850 1300 µA

10 20 30 µA

V

KHz

V

125

mV/V

-1 +1 %

KΩ

70 75 80 %

115 144 172 %

113 120 µA

Ω

FAN5234 — Dual Mobile-Friendly PWM / PFM Controller

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