General Description

The MAX17497A/MAX17497B include both a current mode fixed-frequency flyback converter and a synchronous step-down regulator. They contain all the control circuitry required to design wide input-voltage nonisolated power supplies to supply multiple output rails for smart meters, industrial control, and other similar applications. The MAX17497A has its rising/falling undervoltage lockout (UVLO) thresholds optimized for universal offline (85V AC to 265V AC) applications, while the MAX17497B supports undervoltage lockout (UVLO) thresholds suitable to low-voltage DC-DC applications. Both devices also include a 3.3V fixed-output synchronous step-down regulator that delivers up to 600mA load current.

Benefits and Features

♦ Reduced Component Count and Board Space

   ◇ Flyback/Boost with Integrated Internally

      Compensated Step-Down Regulator

   ◇ No Current-Sense Resistor

   ◇ Space-Saving 16-Pin (3mm x 3mm) TQFN

      Package

♦ Minimal Radio Interference

   ◇ 250kHz Switching in Offline Version

      Minimizes Interference with Radio Receivers

      in Smart Meter Applications

♦ Reduced Inrush Current

   ◇ Programmable Flyback/Boost Soft-Start

   ◇ Internal Digital Soft-Start for Step-Down

      Regulator

♦ Reduced Power Dissipation Under Fault

   ◇ Hiccup Mode Overcurrent Protection

   ◇ Thermal Shutdown with Hysteresis

♦ Robust Protection Features

   ◇ Flyback/Boost Programmable Current Limit

   ◇ Input Overvoltage Protection

♦ Optimized Loop Performance

   ◇ Programmable Slope Compensation for

      Flyback/Boost Maximizes Obtainable Phase

      Margin

♦ High Efficiency

   ◇ Low RDSON, 150mI, 65V-Rated Internal

      nMOSFET

   ◇ 3.3V Step-Down Regulator Efficiency Greater

      Than 90

♦ Optional Spread Spectrum

Applications

   AC-DC Power Supplies for Smart Meter Applications

   Universal-Input Offline AC-DC Power Supplies

   Wide-Range DC Input Flyback/Boost Industrial Power Supplies