LINEAR TECHNOLOGY LTC1873 User's Manual
Summary
The LTC1873 is a high-performance dual switching regulator controller designed for sophisticated, low-voltage power delivery applications. This IC integrates two independent, synchronous 2-Phase PWM regulators on one chip, ensuring maximum efficiency and fast transient response crucial for modern CPUs and I/O core supplies. Featuring Intel Desktop VID compliance (5-Bit voltage adjustment), it maintains stable performance at a fixed 550kHz frequency without relying on external current sense resistors. Ideal for power supply designers creating complex electronics requiring highly regulated, multi-rail power within constrained space and strict efficiency guidelines.
Page 1 Text Content
LTC1873
Dual 550k Hz Synchronous 2-Phase Switching Regulator Controller with 5-Bit VID
FEATURES DESCRIPTIO Two Independent PWM Controllers in One Package The LTC®1873 is a dual switching regulator controller opti- Side 1 Output Is Compliant with Intel Desktop mized for high efficiency with low input voltages. It includes VRM 8.4 Specifications (Includes 5-Bit VID DAC) two complete, on-chip, independent switching regulator con-
1.3V to 3.5V Output Voltage with 50m V/100m V Steps trollers. Each is designed to drive a pair of external Two Sides Run Out-of-Phase to Minimize CIN N-channel MOSFETs in a voltage mode feedback, synchro- All N-Channel External MOSFET Architecture nous buck configuration. The LTC1873 includes digital out- No External Current Sense Resistors Required put voltage adjustment on side 1 that conforms to the Intel Precison Internal 0.8V ±1% Reference Desktop VID specification. A constant-frequency, true PWM 550k Hz Switching Frequency Minimizes External design minimizes external component size and cost and Component Size optimizes load transient performance. The synchronous buck Very Fast Transient Response architecture automatically shifts to discontinuous and then to Up to 25A Output Current per Channel Burst Mode TM operation as the output load decreases, ensur-
Low Shutdown Current: < 100µA ing maximum efficiency over a wide range of load currents. Small 28-Pin SSOP Package
The LTC1873 features an onboard reference trimmed to 1% and delivers better than 1.5% regulation at the converter APPLICATIO S outputs over all combinations of line, load and temperature. Each channel can be enabled independently; with both chan-
Microprocessor Core and I/O Supplies
nels disabled, the LTC1873 shuts down and supply current
Multiple Logic Supply Generator
drops below 100µA.
High Efficiency Power Conversion
, LTC and LT are registered trademarks of Linear Technology Corporation.
Chipset Power Supply Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
Low Cost Desktop CPU Supply with RDRAM Keepalive
4.5V TO 5.5V IN OUT 1µF LT1761
10Ω CIN 16.2k
GND ADJ 0.1%
MBR0530T
VCC PVCC
FB2 BOOST2 16.9k
TG2 QT2 1µF L2
COMP2 VRDRAM SW2 2.5V/7A 2.45V/100m A STANDBY
1k RUN/SS2 BG2 QB2
COUT2
RUN/SS1 47k
0.1µF IMAX2
STBY/ON 1k QSS2
LTC1873 FAULT MBR0530T SENSE BOOST1
QT1B 1µF
220p F TG1 QT1A L1
56k 39p F VCORE COMP1 SW1 1.3V TO 3.5V
BG1 QB1A
FCB COUT1 CIN = SANYO 10MV1200GX (6 IN PARALLEL)
33k COUT1 = SANYO 6MV1500GX (8 IN PARALLEL) 5-BIT VID VID4:0 IMAX1 COUT2 = SANYO 6MV1500GX (3 IN PARALLEL) L1: 1µH SUMIDA CEP125-1R0MC-H
SGND PGND
L2: 2.2µH COILTRONICS UP2B-2R2 QSS1, QSS2: MOTOROLA MMBT3904LT1 QT1A, QT1B, QB1A, QB1B: FAIRCHILD FDS6670A 1873 TA01 QT2, QB2: 1/2 SILICONIX Si4966
Page Summary Contents For LINEAR TECHNOLOGY LTC1873 User's Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 32 |
| File Size | 314.14 KB |
| Published | June 18, 2026 |
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Frequently Asked Questions
What is the maximum output current per channel?
The device can provide up to 25A Output Current per Channel.
Does the LTC1873 require external resistors for sensing?
No External Current Sense Resistors Required, simplifying the design.
What kind of multiple supplies does this chip support?
It is designed for Microprocessor Core and I/O Supplies (e.g., desktop CPU supply).
What is the operating temperature range for the LTC1873?
The operational temperature range is specified as –40°C to 85°C.