L6997S Datasheet, PDF (1/30 Pages) STMicroelectronics – STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS

L6997S
STEP DOWN CONTROLLER
FOR LOW VOLTAGE OPERATIONS
1 Features
Figure 1. Package
■ FROM 3V TO 5.5V V_CC RANGE
■ MINIMUM OUTPUT VOLTAGE AS LOW AS
0.6V
■ 1V TO 35V INPUT VOLTAGE RANGE
■ CONSTANT ON TIME TOPOLOGY
■ VERY FAST LOAD TRANSIENTS
TSSOP20
Table 1. Order Codes
■ 0.6V, ±1% VREF
Part Number
Package
■ SELECTABLE SINKING MODE
■ LOSSLESS CURRENT LIMIT, AVAILABLE
ALSO IN SINKING MODE
L6997S
L6997STR
TSSOP20
Tape & Reel
■ REMOTE SENSING
■ OVP,UVP LATCHED PROTECTIONS
■ 600µA TYP QUIESCENT CURRENT
■ POWER GOOD AND OVP SIGNALS
■ PULSE SKIPPING AT LIGTH LOADS
■ 94% EFFICIENCY FROM 3.3V TO 2.5V
2 Applications
■ NETWORKING
■ DC/DC MODULES
■ DISTRIBUTED POWER
■ MOBILE APPLICATIONS
■ CHIP SET, CPU, DSP AND MEMORIES
SUPPLY
3 Description
The device is a high efficient solution for networking
dc/dc modules and mobile applications compatible
with 3.3V bus and 5V bus.
It's able to regulate an output voltage as low as 0.6V.
The constant on time topology assures fast load tran-
sient response. The embedded voltage feed-forward
provides nearly constant switching frequency opera-
tion in spite of a wide input voltage range.
An integrator can be introduced in the control loop to
reduce the static output voltage error.
The remote sensing improves the static and dynamic
regulation, recovering the wires voltage drop.
Pulse skipping technique reduces power consump-
tion at light loads. Drivers current capability allows
output currents in excess of 20A.
Figure 2. Minimum Component Count Application
3.3V
Rin2
Rin1
OSC
BOOT
HGATE
PGOOD
PHASE
OVP
LGATE
L6997S
ILIM
PGND
GND
Rilim
GNDSENSE
Cin
Dboot
HS
Cboot
L
LS
DS
0.6V
Ro1
Ro2
Cout
SS
Css
SHDN
VSENSE
INT
VFB
Vref
Cvref
June 2004
REV. 1
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