LTC1753_15 Datasheet, PDF (1/24 Pages) Linear Technology – 5-Bit Programmable Synchronous Switching Regulator Controller for Pentium III Processor

FEATURES
s _{5-Bit Digitally Programmable 1.3V to 3.5V Fixed}
Output Voltage, VRM 8.4 Compliant
s _{Fast Transient Response: 0% to 100% Duty Cycle}
s _{Phase Lead Compensation for Remote Sensing}
s _{Overtemperature Protection}
s _{Flags for Power Good 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 _{Available in 2O-Lead SSOP and SW Packages}
U
APPLICATIO S
s _{Power Supply for Pentium}^® _{III, AMD-K6}^®_{-2, SPARC,}
ALPHA and PA-RISC Microprocessors
s _{High Power 5V to 1.3V-3.5V Regulators}
LTC1753
5-Bit Programmable
Synchronous Switching
Regulator Controller for
Pentium^® III Processor
DESCRIPTIO
The LTC^®1753 is a high power, high efficiency switching
regulator controller optimized for 5V input to a digitally
programmable 1.3V-3.5V output. The internal 5-bit DAC
programs the output voltage from 1.3V to 2.05V in 50mV
increments and from 2.1V to 3.5V in 100mV increments. The
precision internal reference and an internal feedback system
provide an output accuracy of ±1.5% at room temperature
and typically ±2% over temperature, load current and line
voltage shifts. The LTC1753 uses a synchronous 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. Additionally, 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 LTC1753 free-runs at 300kHz and can be synchronized
to a faster external clock if desired. It provides a phase lead
compensation scheme and under harsh loading conditions,
the PWM duty cycle can be momentarily forced to 0% or
100% to reduce the output voltage recovery time.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
AMD-K6 is a registered trademark of Advanced Micro Devices, Inc.
TYPICAL APPLICATIO
PV_CC
12V
V_IN
5V
5.6k
5.6k
+
0.1µF
10µF
600Ω ^0.1µF
10µF
C_IN**
1200µF
×4
Q1A*
PWRGD
V_CC
I_MAX
PV_CC
G1
Q1* ^LO^†
1.3µH
FAULT
CPU
5
20Ω
18A
I_FB
VID0 TO VID4
OUTEN
LTC1753
Q2A*
+ COUT^††
2700µF
G2
Q2*
×5
C1
150pF
R_C
15k
C_C
4700pF
COMP _SS
C_SS
0.1µF
SGND GND SENSE ^VFB
1µF
NC
* SILICONIX SUD50N03-10
** SANYO 10MV1200GX
† _{PANASONIC ETQP 6FIR3LFA}
†† _{SANYO 6MV2700GX}
Figure 1. 5V to 1.3V-3.5V Supply Application
V_OUT
1.3V TO
3.5V
14A
1753 F01
1753fa
1