UCC3585M Datasheet, PDF (1/21 Pages) Texas Instruments – LOW-VOLTAGE SYNCHRONOUS BUCK CONTROLLER

UCC2585
UCC3585
SLUS304F − JULY 1999 − REVISED JANUARY 2005
LOWĆVOLTAGE SYNCHRONOUS
BUCK CONTROLLER
FEATURES
D VOUT Resistor Programmable Down to 0.9 V
D 3.3-V or 5.0-V Input Supply
D 1% DC Accuracy
D High Efficiency Synchronous Switching
D Drives P-Channel (High Side) and N-Channel
(Low Side) MOSFETs
D Lossless Programmable Current Limit
D Logic Compatible Shutdown
APPLICATIONS
D Local Microprocessor Core Voltage Power
Supplies for Desktop and Notebook
Computers
D DSP Core or I/O Powering
D High-Speed GTL Bus Regulation
DESCRIPTION
The UCC3585 synchronous buck controller
provides flexible high efficiency power conversion
for output voltages as low as 0.9 V with ensured
±1% dc accuracy. With an input voltage range of
3.0 V to 5.5 V, it is the ideal choice for 3.3 V only,
5.0 V only, or other low voltage systems. The fixed
frequency oscillator is capable of providing
practical PWM operation to 500 kHz.
The UCC3585 drives a complementary pair of
power MOSFET transistors. A P-channel on the
high side, and an N-channel on the low side step
down the input voltage at up to 90% efficiency.
A programmable two-level current limiting
function is provided by sensing the voltage drop
across the high side P-channel MOSFET. This
circuit can be configured to provide pulse-
by-pulse limiting, timed shutdown after seven
consecutive faults, or latch-off after fault detec-
tion, allowing maximum application flexibility. The
current limit threshold can be programmed over a
wide range with a single resistor.
VIN
ENABLE
+
C1
150 µ F
R1
10 kΩ
C7
0.47 µ F
UCC3585
15 VIN
CLSET 8
C2 5600 pF R2 10 kΩ
C3 47 pF
1 ENB
PDRV 12
2 COMP ISENSE 11
4 VFB
NDRV 14
R4
14 kΩ
Q1
SI4562DY
RTN
C4 0.47 µ F
10 SD
3 SS
C5 0.1 µ F
C6 470 pF
16 CT
7 ISET
R3 100 kΩ
N/C 6
N/C 9
PWRGND 13
GND 5
VIN = 3.3 V
VOUT = 1.8 V
IOUT = 3 A (max)
L1
3.7 µ H
VOUT
+
C8
150 µ F
+
C9
10 µ F
R5
2 kΩ
R6
2 kΩ
RTN
UDG−01127
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2001, Texas Instruments Incorporated
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