PM6680_08 Datasheet, PDF (1/49 Pages) STMicroelectronics – No Rsense dual step-down controller with adjustable voltages for notebook system power

PM6680
No Rsense dual step-down controller with adjustable voltages
for notebook system power
Features
■ 6 V to 28 V input voltage range
■ Adjustable output voltages
■ 5 V always voltage available deliver 100 mA
peak current
■ 1.237 V ± 1% reference voltage available
■ Lossless current sensing using low side
MOSFETs R_DS(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 (33 kHz) in
pulse skip mode
■ 4 mW maximum quiescent power
■ Independent power good signals
■ Output voltage ripple compensation
Applications
■ Notebook computers
■ Tablet PC or slates
■ Mobile system power supply
■ 3-4 cells Li+ battery powered devices
VFQFPN-32 5X5
Description
PM6680 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 33kHz is selectable to avoid audio
noise issues. The PM6680 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 5.5 V
and from 0.9 V to 3.3 V respectively.
Table 1. Device summary
Order codes
Package
PM6680
PM6680TR
VFQFPN-32 5mm x 5mm (Exposed pad)
Packaging
Tray
Tape and reel
January 2008
Rev 7
1/49
www.st.com
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