PM6685 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

PM6685

Dual step-down main supply controller with auxilary voltages for notebook system power

STMicroelectronics 

PM6685

Dual step-down main supply controller

with auxilary voltages for notebook system power

Features

■ 6V to 28V input voltage range

■ Fixed 5V - 3.3V output voltages

■ 5V and 3.3V voltage always available to deliver

100mA of peak current

■ 1.237V ±1% reference voltage available

■ Lossless current sensing using low side

■ MOSFETs' RDS(on)

■ Negative current limit

■ Soft-start internally fixed at 2ms

■ Soft output discharge

■ Latched OVP and UVP

■ Selectable pulse skipping at light loads

■ Selectable minimum frequency (33kHz) in

pulse skip mode

■ 4mW maximum quiescent power

■ Independent power good signals

■ Output voltage ripple compensation

Applications

■ Notebook computers

■ Tablet PC or slates

■ Mobile system power supply

■ 3 and -4 Cells Li+ battery-powered devices

VFQFPN-32 (5mm x 5mm)

Description

PM6685 is a dual step-down controller specifically

designed to provide extremely high efficiency

conversion with loss-less current sensing

technique. The constant on-time architecture

assures fast load transient response and the

embedded voltage feed-forward provides nearly

constant switching frequency operation.

An embedded integrator control loop

compensates the DC voltage error due to the

output ripple. The pulse skipping technique

increases efficiency for very light loads. Moreover,

a minimum switching frequency of 33kHz is

selectable in order to avoid audio noise issues.

The PM6685 provides a selectable switching

frequency, allowing either 200kHz/300kHz,

300kHz/400kHz, or 400kHz/500kHz operation of

the 5V/3.3V switching sections.

Table 1.

Device summary

Order code

PM6685

PM6685TR

Package

VFQFPN-32 (5mm x 5mm)

VFQFPN-32 (5mm x 5mm)

Packaging

Tube

Tape and Reel

October 2007

Rev 7

1/52

www.st.com

52

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