Synchronous Buck Switcher Drives 10-A Loads

Sep 27, 2006 2:53 PM

National Semiconductor’s 1-MHz synchronous buck switching controller is housed in a MSOP package and optimized for loads up to 10 A. The LM3743, which requires minimal external circuitry, also has programmable tracking and extensive protection features which make the controller well-suited for space-constrained designs.

The LM3743 voltage-mode PWM buck controller operates over the input range of 3 V to 5.5 V and drives external synchronous MOSFETs at either 300 KHz or 1 MHz, which generates output voltages as low as 0.8 V. It features an externally programmable soft start with tracking capability and external compensation. The device has an externally programmable current limit with low-side MOSFET current sensing that is ±15% accurate, as well as a hiccup mode of operation, which means that engineers do not need to over-design external components.

Additional protection features include under-voltage lockout and a fixed short-circuit, high-side current limit. Reference accuracy is ±1.75% over the temperature range of -40°C to +125°C. The device is offered in a 10-pin mini-SOIC package. Available now, the LM3743 is priced at $1.20 each in 1000-unit quantities.