LTC3738

Features:

3-Phase Controller with Onboard MOSFET Drivers
Programmable Active Voltage Positioning (AVP)with True Current Sensing
Programmable External Thermal Detection or Internal Thermal Sensing
Precise Output Current Matching Optimizes
Thermal Performance and Solution Size
Supports Starting into Precharged VOUTS
Differential Amplifier Accurately Senses VOUT
PWM, Pulse Skip and Stage SheddingTM Operation
Synchronizable
210kHz to 530kHz Per Phase, Fixed Frequency
Output Power Good Indicator with Adaptive Blanking
Adjustable Soft-Start Current Ramping
Short-Circuit Shutdown Timer with Defeat Option
OPTI-LOOP® Compensation Minimizes COUT
38-Lead (5mm × 7mm) QFN Package


Application

High Performance Notebook Computers
Servers, Desktop Computers and Workstations


Specifications

Topside Driver Voltages (BOOSTN) ........................ 38V to 0.3V
Switch Voltage (SWN)............................................ 32V to 5V
Boosted Driver Voltage (BOOSTN SWN) ............ 7V to 0.3V
Peak Output Current <1ms (TGN, BGN) ................ 5A
Supply Voltage (VCC), PGOOD, VR_HOTB
Pin Voltages .......................................................... 7V to 0.3V
OUTEN, SS, PLLFLTR,
FCB/SYNC Voltages ............................................... VCC to 0.3V
ITH Voltage ........................................................... 2.4V to 0.3V
IN+, IN, VID0-VID5, TSNS ................................... 5V to 0V
AVP, SENSE+, SENSE ......................................... 1.9V to 0V
Operating Ambient Temperature Range ............... 0°C to 85°C
Junction Temperature (Note 2) ............................. 125°C
Storage Temperature Range ..................................65°C to 125°C


Description

The LTC®3738 is a 3-phase synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable, fixed frequency architecture. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each controller at an optimal frequency for efficiency and ease of thermal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Pulse Skip mode technology.
The LTC3738 also allows users to program load slope via a resistor for AVP control. Both external and internal thermal sensing are available from the on-chip thermal detector and comparator.
A differential amplifier of LTC3738 provides sensing of both the high and low sides of the output voltage.
Soft-start and a defeatable, timed short-circuit shutdown protect the MOSFETs and the load. A foldback current circuit also provides protection for the external MOSFETs under short-circuit or overload conditions. An all- "1" VID detector turns off the regulator after a 1µs timeout.