FAN5234 Ver la hoja de datos (PDF) - Fairchild Semiconductor

Número de pieza

componentes Descripción

Lista de partido

FAN5234

Mobile-Friendly PWM/PFM Controller

Fairchild Semiconductor 

FAN5234

Mobile-Friendly PWM/PFM Controller

www.fairchildsemi.com

Features

• Wide input voltage range (2 to 24V) for Mobile systems

• Excellent dynamic response with Voltage Feed-Forward

and Average Current Mode control

• Lossless current sensing on low-side MOSFET or

precision over-current using sense resistor

• VCC Under-voltage Lockout

• Power-Good Signal

• Light load Hysteretic mode maximizes efficiency

• QSOP16, TSSOP16

• 300Khz or 600Khz operation

Applications

• Mobile PC regulator

• Hand-Held PC power

General Description

The FAN5234 PWM controller provides high efficiency and

regulation with an adjustable output from 0.9V to 5.5V that

are 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 even further enhanced by using

MOSFET’s RDS(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 go away. 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.

Typical Application

VIN (BATTERY)

= 2 to 24V

+5

VCC 11

C4

R5

ILIM 4

C3

+5

R4

EN 3

SS1 7

FPWM 16

AGND 8

PGOOD 2

VIN

1

FAN5234

15 BOOT

Q1A

14 HDRV

13 SW

Q1B

10 LDRV

9 PGND

12 ISNS

6 VSEN

5 VOUT

C1

C2

D1

+5

C5

L1

R3

1.8V@ 3.5A

C6

R1

R2

Figure 1. 1.8V Output Regulator (see Table 2, page 12 for BOM)

REV. 1.0.10 5/3/04

Share Link: