PM6681A_08 Datasheet, PDF (1/47 Pages) STMicroelectronics – Dual synchronous step-down controller with adjustable LDO

PM6681A
Dual synchronous step-down controller with adjustable LDO
Features
■ 6 V to 36 V input voltage range
■ Adjustable output voltages
■ 0.9 - 3.3 V LDO adjustable delivers 100 mA
peak current
■ 5 V LDO delivers 100 mA peak current
■ 1.237 V ±1 % reference voltage available
■ No R_SENSE current sensing using low side
MOSFETs' R_DS(on)
■ Negative current limit
■ Soft-start internally fixed at 2 ms
■ Soft output discharge
■ Latched UVP
■ Not-latched OVP
■ Selectable pulse skipping at light loads
■ Selectable minimum frequency (33 kHz) in
pulse skip mode
■ 5 mW maximum quiescent power
■ Independent Power Good signals
■ Output voltage ripple compensation
Applications
■ Embedded computer system
■ FPGA system power
■ Industrial applications on 24 V
■ High performance and high density DC-DC
modules
■ Notebook computer
VFQFPN-32 (5 mm x 5 mm)
Description
PM6681A 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 33 kHz is selectable to avoid audio
noise issues. The PM6681A provides a selectable
switching frequency, allowing three different
values of switching frequencies for the two
switching sections. The output voltages OUT1
and OUT2 can be adjusted from 0.9 V to 5 V and
from 0.9 V to 3.3 V respectively. The device
provides also 2 LDOs, 5 V fixed and 0.9 V - 3.3 V
adjustable.
Table 1.
Order codes
Order codes
PM6681A
PM6681ATR
Package
VFQFPN-32 (5 mm x 5 mm)
exposed pad
Packaging
Tray
Tape and reel
June 2008
Rev 3
1/47
www.st.com
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