Features • 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 Description 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 VIN• 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. Applications • Embedded computer systems • High end gaming systems • Set-top boxes • WebPAD

Also Recommended LM2647 Dual Sub-Bandgap Synchronous Controller LM5642▲ Has Clock Synchronization Capability And Wider Input Voltage Range LM2645▲ Has Additional Linear Regulator Controller And 3.3V Output Rail MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application *click for larger image	Block Diagram *click for larger image
Typical Performance *click for larger image Channel 1 Efficiency at 5Vout

Datasheet

Title		Size	Date	Other Language
	LM2642 Two-Phase Synchronous Step-Down Switching Controller	1032 Kbytes	15-Feb-06	日本語

Featured Application Notes

Title		Size	Date	Other Language
	AN-1239: Application Note 1239 LM2642 Evaluation Board	1018 Kbytes	23-Mar-06	日本語 中文

More Application Notes

Title		Size	Date	Other Language
	AN-1973: Application Note 1973 Benefits and Challenges of High-Frequency Regulators	348 Kbytes	25-Jun-09
	AN-1870: Application Note 1870 LM26420 Evaluation Board	429 Kbytes	14-Apr-09

Design Tools

Reference Design

LM2642 Reference Design - Sychronous Buck Triple Output Converter: 18-21V Input, 2.5V @ 0.9A; 3.3V @ 1.75A; 1.5V @ 3.7A Outputs

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2642MTC	ABCD150	0	34175	0	0	4234000	1	1201409060
LM2642MTCX	ABCD150	0	34175	0	0	4234000	1	1201409060

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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