PM6675 Datasheet, PDF (1/47 Pages) STMicroelectronics – Very fast load transient response using constant on-time control loop

PM6675
High efficiency step-down controller
with embedded 2A LDO regulator
Preliminary Data
Features switching
■ Switching section
– 4.5V to 28V input voltage range
– 0.6V, ±1% voltage reference
– Selectable 1.5V fixed output voltage
– Adjustable 0.6V to 3.3V output voltage
– 1.237V ±1% reference voltage available
VFQFPN-24 4x4
– Very fast load transient response using
constant on-time control loop
t(s) – No RSENSE current sensing using low side
MOSFETs' R_DS(ON)
uc ^{– Negative current limit}
d _{– Latched OVP and UVP}
ro _{– Soft start internally fixed at 3ms}
P _{– Selectable pulse skipping at light load}
te ^{– Selectable No-Audible (33KHz) pulse skip}
le ^mode
o _{– Ceramic output capacitors supported}
bs ^{– Output voltage ripple compensation}
O ^{– Output soft-end}
- _{■ LDO regulator section}
t(s) ^{– Adjustable 0.6V to 3.3V output voltage}
– Selectable ±1Apk or ±2Apk current limit
uc ^{– Dedicated Power-Good signal}
d _{– Ceramic output capacitors supported}
ro – Output soft-end
te ^{P Applications}
le _{■ Notebook computers}
so _{■ Graphic cards}
Ob^{■ Embedded computers}
Description
The PM6675 device consists of a single high
efficiency step-down controller and an
independent Low Drop-Out (LDO) linear
regulator.
The Constant On-Time (COT) architecture
assures fast transient response supporting both
electrolytic and ceramic output capacitors. An
embedded integrator control loop compensates
the DC voltage error due to the output ripple.
A selectable low-consumption mode allows the
highest efficiency over a wide range of load
conditions. The low-noise mode sets the minimum
switching frequency to 33kHz for audio-sensitive
applications.
The LDO linear regulator can sink and source up
to 2Apk. Two fixed current limits (±1A-±2A) can be
chosen.
An active Soft-End is independently performed on
both the switching and the linear regulators
outputs when disabled.
Order codes
Part number
PM6675
Package
VFQFPN-24 4x4 (Exposed Pad)
Packaging
Tube
January 2007
Rev 1
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.
1/47
www.st.com
47