DESCRIPTION

The LTM4676A is a dual 13A or single 26A step-down µModule (micromodule) DC/DC regulator with 40msturn-on time. It features remote configurability and telemetry-monitoring of power management parameters over PMBus—an open standard I²C-based digital interface protocol . The LTM4676A is comprised of fast analog control loops, precision mixed-signal circuitry, EEPROM, power MOSFETs, inductors and supporting components.The LTM4676A’s 2-wire serial interface allows outputs to be margined, tuned and ramped up and down at programmable slew rates with sequencing delay times. Input and output currents and voltages, output power, temperatures, uptime and peak values are readable. At start-up, output voltages, switching frequency, and channel phase angle assignments can be set by pin-strapping resistors. The LTpowerPlay GUI and DC1613 USB-to-PMBus converter and demo kits are available.

 

FEATURES

  • Dual, Fast, Analog Loops with Digital Interface for Control and Monitoring
  • Wide Input Voltage Range: 4.5V to 26.5V
  • Output Voltage Range: 0.5V to 5.5V
  • ±0.5% Maximum DC Output Error Over Temperature
  • ±2.5% Current Readback Accuracy at 10A Load
  • 400kHz PMBus-Compliant I²C Serial Interface
  • Integrated 16-Bit ∆Σ ADC
  • Supports Telemetry Polling Rates Up to 125Hz
  • Constant Frequency Current Mode Control
  • Parallel and Current Share Multiple Modules
  • All 7-Bit Slave Addresses Supported
  • Pin-Compatible to Dual 18A LTM4677
  • 16mm × 16mm × 5.01mm BGA Package

    Readable Data:

    • Input and Output Voltages, Currents, and Temperatures
    • Running Peak Values, Uptime, Faults and Warnings
    • Onboard EEPROM Fault Log Record with ECC

    Writable Data and Configurable Parameters:

    • Output Voltage, Voltage Sequencing and Margining
    • Digital Soft-Start/Stop Ramp
    • OV/UV/OT, UVLO, Frequency and Phasing

       

      POWER MODULE INTRODUCTION

      The LTM4676A is a highly configurable dual 13A output standalone nonisolated switching mode step-down DC/DC power supply with built-in EEPROM NVM (nonvolatile memory) with ECC and I²C-based PMBus/SMBus 2-wire serial communication interface capable of 400kHzSCL bus speed. Two output voltages can be regulated (Vout0, Vout1—collectively, Voutn) with a few external input and output capacitors and pull-up resistors. Readback telemetry data of average input and output voltages and currents, Channel PWM duty cycles, and module temperatures are continually digitized cyclically by an integrated 16-bit ADC (analog-to-digital converter). Many fault thresholds and responses are customizable. Data can be autonomously saved to EEPROM when a fault occurs, and the resulting fault log can be retrieved over I²C at a later time, for analysis.The LTM4676A provides precisely regulated output voltages between 0.6VDC to 5.5VDC (±0.5% above 1VDC, ±5mV below 1VDC). The target output voltage can be set according to pin-strapping resistors (VOUTnCFG and VTRIMnCFG pins), NVM/register settings, and altered on the fly via the I²C interface. The output voltage can be modified by the user at any time with a write to PMBus VOUT_COMMAND. Executing this command has a typical latency less than 10ms. Writes to PMBus OPERATION have a typical latency less than 1ms. The NVM factory-default switching frequency is 500kHz and the phase-interleaving angle between its two channels is 180°. Channel switching frequency, phase angle, and phase relationship with respect to the falling edge of the SYNC pin waveform can be configured according to a pin-strap resistor (FSWPHCFGpin) and NVM/register settings—though, not on the fly during regulation. The 7-bit I²C slave address of the module defaults to the value retrieved from MFR_ADDRESS[6:0] at power-up (factory default: 0x4F), but the least significant four bits of the address are set by resistor pin-strapping the ASEL pin. Bits[6:4] of MFR_ADDRESS can be written and stored to EEPROM. Between the ASEL resistor pin-strap and user-configurable MFS_ADDRESS[6:4], the LTM4676A can take on any 7-bit slave address desired. With the exception of the ASEL pin, the module can be configured to ignore all pin-strap resistors, if desired (seeMFR_CONFIG_ALL[6]).