UCC3588 Datasheet, PDF (1/11 Pages) Texas Instruments – 5-Bit Programmable Output BiCMOS Power Supply Controller

UCC3588
PRELIMINARY
5-Bit Programmable Output BiCMOS Power Supply Controller
FEATURES
• 5-Bit Digital-to-Analog Converter
(DAC) supports Intel Pentium II
• Microprocessor VID Codes
• Compatible with 5V or 12V Systems
• 1% Output Voltage Accuracy
Guaranteed
• Drives 2 N-Channel MOSFETs
• Programmable Frequency to 800kHz
• Power Good OV / UV / OVP Voltage
Monitor
• Undervoltage Lockout and Softstart
Functions
• Short Circuit Protection
• Low Impedance MOSFET Drivers
• Chip Disable
APPLICATION DIAGRAM
DESCRIPTION
The UCC3588 synchronous step-down (Buck) regulator provides accurate
high efficiency power conversion. Using few external components, the
UCC1588 converts 5V to an adjustable output ranging from 3.5VDC to
2.1VDC in 100mV steps and 2.05VDC to 1.3VDC in 50mV steps with 1%
DC system accuracy. A high level of integration and novel design allow this
16-pin controller to provide a complete control solution for today’s
demanding microcontroller power requirements. Typical applications
include on board or VRM based power conversion for Intel Pentium II
microprocessors, as well as other processors from a variety of
manufacturers. High efficiency is obtained through the use of synchronous
rectification.
The softstart function provides a controlled ramp up of the system output
voltage. Overcurrent circuitry detects a hard (or soft) short on the system
output voltage and invokes a timed softstart/shutdown cycle to reduce the
PWM controller on time to 5%.
The oscillator frequency is externally programmed with RT and operates
over a range of 50kHz to 800kHz. The gate drivers are low impedance to-
tem pole output stages capable of driving large external MOSFETs. Cross
conduction is eliminated by fixed delay times between turn off and turn on
of the external high side and synchronous MOSFETs. The chip includes
undervoltage lockout circuitry which assures the correct logic states at the
outputs during power up and power down.
(continued)
12V IN
5V IN
C16
10µF
R1
10K
UCC3588
15 ^VCC
DRVHI ₁₃
++++
C1 C2 C3 C4 C1-C4 ^{11 PWRGOOD DRVLO 14}
D0
1500µF
4
D0
ISNS ₂
D1
5 ^D1
VSENSE ₁
D2
6 ^D2
VFB ₁₀
D3
7 ^D3
COMP ₉
D4
8 ^D4
3
C5
33nF
SS/ENBL
RT
16
GND ₁₂
R2
47k
RTN
R4
3Ω
R5
3Ω
R3
C6
200k 220pF
C7 22pF
D1 D2
R7
15k
R8
20k
C13
1nF
+
C15
150µF
Q1
IRL3103
L1
1.6µH
R6
0.003Ω
Q2
IRL3103
C8-C12 1500µF
VOUT
+
+
+
+
+
+
C8 C9 C10 C11 C12 C14
150µF
RTN
SLUS311 - JULY 1999
UDG-98158