PM6685 Datasheet, PDF (1/16 Pages) STMicroelectronics – DUAL STEP-DOWN CONTROLLER WITH AUXILARY VOLTAGES FOR NOTEBOOK SYSTEM POWER

PM6685
DUAL STEP-DOWN CONTROLLER WITH AUXILARY VOLTAGES
FOR NOTEBOOK SYSTEM POWER
Preliminary Data
Features
■ CONSTANT ON TIME TOPOLOGY ALLOWS
VERY FAST LOAD TRANSIENTS
■ 6V TO 28V INPUT VOLTAGE RANGE
■ FIXED 5V-3.3V OUTPUT VOLTAGES
■ 5V AND 3.3V ALWAYS VOLTAGES
AVAILABLE DELIVER 100mA PEAK
CURRENT
■ 1.23V ± 1% REFERENCE VOLTAGE
AVAILABLE
■ NO R_SENSE CURRENT SENSING USING
LOW SIDE MOSFETs’ R_DS(on)
■ ACCURATE CURRENT SENSE WITH
R_SENSE
■ NEGATIVE CURRENT LIMIT
■ SOFT START INTERNALLY FIXED AT 2ms
■ SOFT OFF FOR OUTPUT DISCHARGE
■ LATCHED OVP AND UVP
■ SELECTABLE PULSE SKIPPING AT LIGHT
LOADS
■ SELECTABLE MINIMUM FREQUECY
(25kHz) IN PULSE SKIP MODE
■ 4 mW MAXIMUM QUIESCENT POWER
■ INDIPENDENT POWER GOOD SIGNALs
■ OUTPUT VOLTAGE RIPPLE
COMPENSATION
VFQFPN-32 5X5
Description
PM6685 is a dual step-down controller
specifically designed to provide extremely high
efficiency conversion, with lossless 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.
Pulse skipping technique increases efficiency at
very light load. Moreover a minimum switching
frequency of 25kHz is selectable 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...
Applications
■ NOTEBOOK COMPUTERS
■ TABLET PC OR SLATES
■ MOBILE SYSTEM POWER SUPPLY
■ 3-4 CELLS Li+ BATTERY POWERED
DEVICES
Order codes
Part number
PM6685
Marking
PM6685
Package
VFQFPN-32 5X5
September 2005
This is preliminary information on a new product now in development or undergoing evaluation.
Details are subject to change without notice.
Packing
TAPE & REEL
Rev 1
1/16
www.st.com
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