LT3640

PRODUCTION

Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer

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Overview

  • High Voltage Buck Regulator:
    • 4V to 35V Operating Range
    • 1.3A Output Current
  • OVLO Protects Input to 55V
  • Low Voltage Synchronous Buck Regulator:
    • 2.5V to 5.5V Input Voltage Range
    • 1.1A Output Current
  • Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency
  • Programmable Power-On Reset Timer
  • Programmable Window Mode Watchdog Timer
  • Typical Quiescent Current: 290μA
  • Short-Circuit Robust
  • Programmable Soft-Start
  • Low Shutdown Current: IQ < 1μA
  • Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and 28-Lead TSSOP Packages

The LT3640 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode® to maintain high efficiency and low output ripple.

The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 35V; a 36.5V OVLO protects the device to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high efficiency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs.

The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer flags when the μP pulses group too close together or too far apart.

The LT3640 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance.

Applications

  • Industrial Power Supplies
  • Automotive Electronic Control Units
LT3640
Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer
2MHz 3.3V/0.8A and 1.8V/0.8A Step Down Regulators HV Channel Efficiency, 2MHz, VOUT1 = 3.3V Product Package 1 Product Package 2 LV Channel Efficiency, 2MHz, VOUT2 = 1.8V
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Technical Articles 1

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LT3640
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Evaluation Kits

eval board
schematic 1
DC1359A

LT3640EFE Demo Board | 5V ≤ VIN ≤ 35V(55V Transients), VOUT1 = 1.2V @ 1A, VOUT2 = 3.3V @ 0.8A

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Product Details

Demonstration circuit 1359 is a Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer featuring the LT3640. The board operates from inputs ranging from 5V to to 35V and withstands transients up to 55V. The outputs are 3.3V @ 0.8A and 1.2V @ 1A.
DC1359A
LT3640EFE Demo Board | 5V ≤ VIN ≤ 35V(55V Transients), VOUT1 = 1.2V @ 1A, VOUT2 = 3.3V @ 0.8A
DC1359A - Schematic

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