SC1109 Datasheet, PDF (1/17 Pages) Semtech Corporation – SYNCHRONOUS PWM CONTROLLER WITH DUAL LOW DROPOUT REGULATOR CONTROLLERS

SYNCHRONOUS PWM CONTROLLER WITH
DUAL LOW DROPOUT REGULATOR
CONTROLLERS
SC1109
PRELIMINARY - October 16, 2000
DESCRIPTION
The SC1109 was designed for the latest high
speed motherboards. It combines a synchronous
voltage mode controller (switching section) with
two low-dropout linear regulator controllers. The
voltage mode controller provides the power
supply for the system AGTL bus. The 1.8V and
2.5V linear controllers power the Chipset and
clock circuitry.
The SC1109 switching section features lossless
current sensing and latched driver outputs for
enhanced noise immunity. It operates at a fixed
frequency of 200kHz, the output voltage is
internally fixed at 1.2V
The SC1109 linear sections are low dropout
regulators designed to track the 3.3V power
supply when it turns on or off.
TYPICAL APPLICATION CIRCUIT
FEATURES
• 1.8V, 2.5V linear controllers
• LDOs track input voltage within 200mV until
regulation
• Integrated drivers
• Power Good Signal
• Soft Start
• Lossless Current Sense
APPLICATIONS
• Pentium^® III Motherboards
• Triple power supplies
ORDERING INFORMATION
Part Number⁽¹⁾
SC1109CSTR
Package
Linear
Voltage
Temp.
Range (T_J)
SO-16 1.8V/2.5V 0° to 125°C
SC1109EVB
Evaluation Board
Note:
(1) Only available in tape and reel packaging. A reel
contains 1000 devices.
12V IN
5V STBY
5V IN
POWER GOOD
C2
C3
2x1500uF + 0.1uF
C9
0.1uF
C5
0.1uF
U4 SC1109CS
11 _VCC
STBY ³
4 _BCAP+
BST ¹⁰
C6
0.1uF
5 _BCAP-
9
DH
PHASE ⁷
14
SS/EN
12
PWRGD
8
DL
13
VOSENSE
GND ⁶
15 _GATE2
2
GATE1
16 _LDOS2
1
LDOS1
R1 2.2
R2 2.2
C4
0.1uF
C1
0.1uF
Q1
L1 4uH
C7
Q2
3x1500uF +
1.2V 6A
C8
0.1uF
VTT
3.3V IN
+ C10
330uF
Q3
+ C11
330uF
2.5V
Q4
+ C12
330uF
1.8V
© 2000 SEMTECH CORP.
Pentium is a registered trademark of Intel Corporation
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