L5981_08 Datasheet, PDF (1/37 Pages) STMicroelectronics – 1 A step-down switching regulator

L5981
1 A step-down switching regulator
Features
■ 1 A DC output current
■ 2.9 V to 18 V input voltage
■ Output voltage adjustable from 0.6 V
■ 250 kHz switching frequency, programmable
up to 1 MHz
■ Internal soft-start and inhibit
■ Low dropout operation: 100 % duty cycle
■ Voltage feed-forward
■ Zero load current operation
■ Over current and thermal protection
■ VFQFPN8 3 mm x 3 mm package
Applications
■ Consumer: STB, DVD, DVD recorder, car
audio, LCD TV and monitors
■ Industrial: Chargers, PLD, PLA, FPGA
■ Networking: XDSL, modems, DC-DC modules
■ Computer: Optical storage, hard disk drive,
printers, audio/graphic cards
■ LED driving
Figure 1. Application circuit
VFQFPN8 3 mm x 3 mm
Description
The L5981 is step down switching regulator with
1.5 A (min.) current limited embedded power
MOSFET, so it is able to deliver in excess of 1 A
DC current to the load depending on the
application condition.
The input voltage can range from 2.9 V to 18 V,
while the output voltage can be set starting from
0.6 V to V_IN. Having a minimum input voltage of
2.9 V, the device is suitable also for 3.3 V bus.
Requiring a minimum set of external components,
the device includes an internal 250 kHz switching
frequency oscillator that can be externally
adjusted up to 1 MHz.
The VFQFPN8 package with exposed pad allows
reducing the R_thJA down to approximately
60 °C/W.
September 2008
Rev 4
1/37
www.st.com
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