RC5057 Datasheet, PDF (1/20 Pages) Fairchild Semiconductor – High Performance Programmable Synchronous DC-DC Controller for Low Voltage Microprocessors

www.fairchildsemi.com
RC5057
High Performance Programmable Synchronous
DC-DC Controller for Low Voltage Microprocessors
Features
• Programmable output from 1.3V to 3.5V using an
integrated 5-bit DAC
• Remote sense
• Active Droop
• 85% efficiency typical at full load
• Integrated Power Good and Enable/Soft Start functions
• Drives N-channel MOSFETs
• Overcurrent protection using MOSFET sensing
• 16 pin SOIC package
• Meets Intel Pentium II & III specifications using
minimum number of external components
Applications
• Power supply for Pentium^® II & III
• VRM for Pentium II & III processor
• Telecom line cards
• Routers, switches & hubs
• Programmable step-down power supply
Description
The RC5057 is a synchronous mode DC-DC controller IC
which provides a highly accurate, programmable output voltage
for all Pentium II & III CPU applications and other high-perfor-
mance processors. The RC5057 features remote voltage
sensing, adjustable current limit, and active droop for optimal
converter transient response. The RC5057 uses a 5-bit D/A
converter to program the output voltage from 1.3V to 3.5V.
The RC5057 uses a high level of integration to deliver load cur-
rents in excess of 16A from a 5V source with minimal exter-
nal circuitry. Synchronous-mode operation offers optimum
efficiency over the entire specified output voltage range. An
on-board precision low TC reference achieves tight tolerance
voltage regulation without expensive external components,
while active droop permits exact tailoring of voltage for the
most demanding load transients. The RC5057 also offers
integrated functions including Power Good, Output Enable/
Soft Start and current limiting, and is available in a 16 pin
SOIC package.
Block Diagram
OSC
+5V
VCCA ₅
-
+
-
+
Digital
Control
-
-
+
+
5-Bit
DAC
16 15141312
VID0 VID2 VID4
VID1 VID3
1.24V
Reference
11
GNDA
1
ENABLE/SS
Power
Good
+12V
3 ^RS
+5V
10
4
8 VCCP
9 HIDRV
7 ^LODRV
6
GNDP
2
PWRGD
Pentium is a registered trademark of Intel Corporation
VO
Rev. 1.2.0