EL7571C Datasheet, PDF (1/23 Pages) Elantec Semiconductor – Programmable PWM Controller

EL7571C
Programmable PWM Controller
Features
General Description
• Pentium® II Compatible
• 5 bit DAC Controlled Output Voltage
• Greater than 90% Efficiency
• 4.5V to 12.6V Input Range
• Dual NMOS Power FET Drivers
• Fixed frequency, Current Mode
Control
• Adjustable Oscillator with External
Sync. Capability
• Synchronous Switching
• Internal Soft-Start
• User Adjustable Slope
Compensation
• Pulse by Pulse Current Limiting
• 1% Typical Output Accuracy
• Power Good Signal
• Output Power Down
• Over Voltage Protection
Applications
• Pentium® II Voltage Regulation
Modules (VRMs)
• PC Motherboards
• DC/DC Converters
• GTL Bus Termination
• Secondary Regulation
Ordering Information
Part No
EL7571C
Temp. Range
0°C to +70°C
Package
20-Pin SO
Outline #
MDP0027
The EL7571C is a flexible, high efficiency, current mode, PWM step
down controller. It incorporates five bit DAC adjustable output voltage
control which conforms to the Intel Voltage Regulation Module (VRM)
Specification for Pentium® II and Pentium® Pro class processors. The
controller employs synchronous rectification to deliver efficiencies
greater than 90% over a wide range of supply voltages and load condi-
tions. The on-board oscillator frequency is externally adjustable, or may
be slaved to a system clock, allowing optimization of RFI performance in
critical applications. In single supply operation, the high side FET driver
supports boot-strapped operation. For maximum flexibility, system oper-
ation is possible from either a 5V rail, a single 12V rail, or dual supply
rails with the controller operating from 12V and the power FETs from
5V.
Connection Diagram
ENABLE
1 OTEN
C3 240pF
2 CSLOPE
C3 240pF
3 COSC
1.4V _C3
0.1µF
4 REF
POWER
GOOD
5 PWRGD
6 VIDO
Voltage
I.D.
(VID
(0:4))
7 VID1
8 VID2
9 VID3
VH1 20
HSD 19
LX 18
VIN 17
VINP 16
LSD 15
GNDP 14
GND 13
CS 12
R2
5Ω
D1
C6 0.1µF
Q1
C8
1µF
L2
C1 1.5µH
1000µF
x3
4.5V
to
12.6V
VOUT
1.3V to
L1
R2 3.5V
C7
5.1µH _5Ω
1µF
Q2 D2
C2
1000µF
x6
10 VID4
FB 11
Q1, Q2: Siliconix, Si4410, x2
C1: Sanyo, 16MV 1000GX, 1000µF x3
C2: Sanyo, 6MV 1000GX, 1000µF x6
L1: Pulse Engineering, PE-53700, 5.1µH
L2: Micrometals, T30-26, 7T AWG #20, 1.5µH
R1: Dale, WSL-25-12, 15mΩ, x2
D1: BAV99
D2: IR, 32CTQ030
Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
© 2001 Elantec Semiconductor, Inc.