Product Summary

The MC34129P is a high performance current mode switching regulator specifically designed for use in low power digital telephone applications. The integrated circuit of the MC34129P features a unique internal fault timer that provides automatic restart for overload recovery. For enhanced system efficiency, a start/run comparator is included to implement bootstrapped operation of VCC. Other functions of the MC34129P contained are a temperature compensated reference, reference amplifier, fully accessible error amplifier, sawtooth oscillator with sync input, pulse width modulator comparator, and a high current totem pole driver ideally suited for driving a power MOSFET. Also included are protective features consisting of soft–start, undervoltage lockout, cycle–by–cycle current limiting, adjustable deadtime, and a latch for single pulse metering.

Parametrics

MC34129P maximum ratings: (1)VCC Zener Current IZ(VCC) 50 mA; (2)Start/Run Output Zener Current IZ(Start/Run) 50 mA; (3)Analog Inputs (Pins 3, 5, 9, 10, 11, 12) – –0.3 to 5.5 V; (4)Sync Input Voltage Vsync –0.3 to VCC V; (5)Drive Output Current, Source or Sink IDRV 1.0 A; (6)Current, Reference Outputs (Pins 6, 8) Iref 20 mA; (7)Operating Junction Temperature TJ +150 ℃; (8)Storage Temperature Range Tstg –65 to +150 ℃.

Features

MC34129P features: (1)Current Mode Operation to 300 kHz; (2)Automatic Feed Forward Compensation; (3)Latching PWM for Cycle-by-cycle Current Limiting; (4)Continuous Retry after Fault Timeout; (5)Soft-start with Maximum Peak Switch Current Clamp; (6)Internally Trimmed 2% Bandgap Reference; (7)High Current Totem Pole Driver; (8)Input Undervoltage Lockout; (9)Low Startup and Operating Current; (10)Direct Interface with Motorola SENSEFET Products.

Diagrams

MC34129P Simplified Block Diagram

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