説明

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The MAX22256/MAX22258 integrated primary-side controllers and H-bridge drivers for isolated power-supply circuits feature a precision on-board oscillator, protection circuitry, and internal MOSFETs to provide up to 650mARMS of current to the primary winding of a transformer. These devices feature an internal 450kHz (typ) oscillator and can also be driven by an external clock to synchronize multiple devices and control EMI. An internal flip-flop stage guarantees a fixed 50% duty-cycle to prevent DC current flow in the transformer as long as the clock period is constant.

The MAX22256/MAX22258 operate from a wide single-supply voltage range from 5V to 36V and include undervoltage lockout for controlled startup. Break-before-make switching is integrated to prevent cross-conduction of the H-bridge MOSFETs. A resistor-adjustable overcurrent limit allows primary-side limiting of load currents on the transformer’s secondary side and thermal shutdown circuitry provides additional protection against excessive power dissipation.

The MAX22256A features a 30ns (typ) dead time for conventional H-bridge switching topologies. The MAX22256B/C feature a fixed dead time of 60ns (typ) and 100ns (typ), respectively, and are optimized for the zero-voltage switching of an LLC topology. The MAX22258 features a resistor-programmable dead time and a synchronized clock output (CLKO).

主な特長

• Simple, Flexible Design
  • 5V to 36V Supply Range
  • Up to 91% Efficiency
  • Provides over 15W to Transformer
  • Undervoltage Lockout
  • Internal or External Clock Source
  • Synchronous Clock Output (MAX22258)
  • Programmable Overcurrent Threshold
  • 30ns to 200ns Adjustable Deadtime (MAX22258)
• Robust Integrated System Protection
  • Fault Detection and Indication
  • Overcurrent Limiting up to 1A
  • Overtemperature Protection
  • Precision Internal Clock Source (±6%) Prevents Excessive Transformer Core Losses Due to Frequency Shift
  • Wide Temperature Range: -40°C to +125°C
• Space Savings
  • Small 3mm x 3mm 10-Pin TDFN Package (MAX22256A/B/C) with 0.5mm Pitch
  • Small 4mm x 5mm 14-Pin TSSOP Package (MAX22258) with 0.65mm Pitch

アプリケーション/用途

• 絶縁型モータ駆動ゲート電源
• 絶縁型+24V PLCフィールド電源