LM2642  Product Folder

The LM2642 consists of two current mode synchronous buck regulator controllers with a switching frequency of 300kHz.

The two switching regulator controllers operate 180° out of phase. This feature reduces the input ripple RMS current, thereby significantly reducing the required input capacitance. The two switching regulator outputs can also be paralleled to operate as a dual-phase single output regulator.

The output of each channel can be independently adjusted from 1.3 to V_IN• maximum duty cycle. An internal 5V rail is also available externally for driving bootstrap circuitry.

Current-mode feedback control assures excellent line and load regulation and a wide loop bandwidth for excellent response to fast load transients. Current is sensed across either the Vds of the top FET or across an external current-sense resistor connected in series with the drain of the top FET. Current limit is independently adjustable for each channel.

The LM2642 features analog soft-start circuitry that is independent of the output load and output capacitance. This makes the soft-start behavior more predictable and controllable than traditional soft-start circuits.

A PGOOD1 pin is provided to monitor the dc output of channel 1. Over-voltage protection is available for both outputs. A UV-Delay pin is also available to allow delayed shut off time for the IC during an output under-voltage event.

• Two synchronous buck regulators
• 180° out of phase operation
• 4.5V to 30V input range
• Power good function monitors Ch.1
• 37µA Shutdown current
• 0.04% (typical) line and load regulation error
• Current mode control with or without a sense resistor
• Independent enable/soft-start pins allow simple sequential startup configuration.
• Configurable for single output parallel operation. (See ).
• Adjustable cycle-by-cycle current limit
• Input under-voltage lockout
• Output over-voltage latch protection
• Output under-voltage protection with delay
• Thermal shutdown
• Self discharge of output capacitors when the regulator is OFF
• TSSOP package

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