SC1112 Datasheet, PDF (1/21 Pages) Semtech Corporation – Triple Low Dropout Regulator Controllers

SC1112
Triple Low Dropout
Regulator Controllers
POWER MANAGEMENT
Description
.eatures
The SC1112 was designed for the latest high speed
motherboards. It includes three low dropout regulator con-
trollers. The controllers provide the power for the system
AGTL bus Termination Voltage, Chipset, and clock circuitry.
An adjustable controller with a 1.2V reference is available,
while two selectable outputs are provided for the VTT
(1.25 V or 1.5V, SC1112) or (1.2V or 1.5V, SC1112A)
and the AGP (1.5V or 3.3V). The SC1112 low dropout
regulators are designed to track the 3.3V power supply
as the VTTIN supply is cycled On and Off. A latched short
circuit protection is also available for the VTT output.
Other features include an integrated charge pump that
provides adequate gate drives for the external Mosfets,
and a capacitive programable delay for the power good
signal.
K Triple linear controllers
K Selectable and Adjustable Output Voltages
K LDOs track input voltage within 200mV (.unction of
the Mosfets used) until regulation
K Integrated Charge Pump
K Programmable Power Good delay Signal
K Latched Over Current Protection (VTT)
Applications
K Pentium^® III Motherboards
K Triple power supplies
Typical Application Circuit
+3.3V
VTT
+5V STBY
1K
C1
R1
10u
C6
330u
SC1112/A
C3
POWER GOOD
0.1u
Q2
5VSTBY
GND
ADJGATE AGPGATE
Q3
C14
330u
ADJ
0.1u C11
ADJSEN
CAP-
AGPSEN
VTTGATE
AGP
C2 C18
Q1
330u
C16 C17
RA
CAP+
VTTSEN
330u 0.1u
1u C10
FC
AGPSEL
VTT
RB
C13 C12
0.1u 330u
22n C5
DELAY
PWRGD
VTTSEL
VTTIN
C19
C8 C9
330u 330u 0.1u
VTT SELECT Signal
AGP SELECT Signal
Revision 7, October 2001
1
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