LTC1553L Datasheet, PDF (1/20 Pages) Linear Technology – 5-Bit Programmable Synchronous Switching Regulator Controller for Pentium II Processor

LTC1553L
5-Bit Programmable
Synchronous Switching
Regulator Controller for
Pentium^® II Processor
FEATURES
s _{5-Bit Digitally Programmable 1.8V to 3.5V Fixed}
Output Voltage
s _{Provides All Features Required by the Intel}
Pentium^® II Processor VRM 8.2 DC/DC
Converter Specification
s _{Flags for Power Good, Over-Temperature and}
Overvoltage Fault
s _{19A Output Current Capability from a 5V Supply}
s _{Dual N-Channel MOSFET Synchronous Driver}
s _{Initial Output Accuracy: ±1.5%}
s _{Excellent Output Accuracy: ±2% Typ Over Line,}
Load and Temperature Variations
s _{High Efficiency: Over 95% Possible}
s _{Adjustable Current Limit Without External Sense}
Resistors
s _{Fast Transient Response}
s _{Available in 2O-Lead SSOP and SW Packages}
U
APPLICATIONS
s _{Power Supply for Pentium II, SPARC, ALPHA and}
PA-RISC Microprocessors
s _{High Power 5V to 1.8V-3.5V Regulators}
DESCRIPTION
The LTC^®1553L is a high power, high efficiency switching
regulator controller optimized for a 5V input to 1.8V-3.5V
output applications. It features a digitally programmable
output voltage, a precision internal reference and an internal
feedback system that provides output accuracy of ±1.5% at
room temperature and typically ±2% over-temperature, load
current and line voltage shifts. The LTC1553L uses a syn-
chronous switching architecture with two external N-channel
output devices, providing high efficiency and eliminating the
need for a high power, high cost P-channel device. Addition-
ally, it senses the output current across the on-resistance of
the upper N-channel FET, providing an adjustable current
limit without an external low value sense resistor.
The LTC1553L free-runs at 300kHz and can be synchronized
to a faster external clock if desired. It includes all the inputs
and outputs required to implement a power supply conform-
ing to the Intel Pentium^® II Processor VRM 8.2 DC/DC
Converter Specification.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
TYPICAL APPLICATION
PV_CC
12V
V_IN
5V
PENTIUM^® II
SYSTEM
+
0.1µF
10µF
2.7k
5.6k 5.6k 5.6k
0.1µF
10µF
+ C_IN**
1200µF
×4
5
C1
150pF
R_C
8.2k
C_C
0.01µF
PWRGD
V_CC I_MAX
FAULT
OT
VID0 TO VID4
LTC1553L
OUTEN
COMP _{SS SGND GND}
C_SS
0.1µF
PV_CC
G1
I_FB
G2
SENSE
0.1µF
Q1*
L_O^†
2µH
20Ω
18A
+ COUT^††
Q2*
330µF
×7
*SILICONIX SUD50N03-10
**SANYO 10MV1200GX
†_{COILTRONICS CTX02-13198 OR}
PANASONIC 12TS-2R5SP
††_{AVX TPSE337M006R0100}
Figure 1. 5V to 1.8V-3.5V Supply Application
V_OUT
1.8V TO
3.5V
14A
1553L F01
1