DESCRIPTION The LM2745/8 are high-speed synchronous buck regulator controllers with an accurate feedback voltage accuracy of ±1.5%. It can provide simple down conversion to output voltages as low as 0.6V. Though the control sections of the IC are rated for 3 to 6V, the driver sections are designed to accept input supply rails as high as 14V. The use of adaptive non-overlapping MOSFET gate drivers helps avoid potential shoot-through problems while maintaining high efficiency. The IC is designed for the more cost effective option of driving only N-channel MOSFETs in both the high-side and low-side positions. It senses the low-side switch voltage drop for providing a simple, adjustable current limit. The LM2745/8 features a fixed-frequency voltage-mode PWM control architecture which is adjustable from 50 kHz to 1 MHz with one external resistor. In addition, the LM2745 also allows the switching frequency to be synchronized to an external clock signal over the range of 250 kHz to 1 MHz. This wide range of switching frequency gives the power supply designer the flexibility to make better tradeoffs between component size, cost and efficiency.
FEATURES • Switching Frequency from 50 kHz to 1 MHz • Switching Frequency Synchronize Range 250 kHz to 1 MHz (LM2745 Only) • Startup with a Pre-biased Output Load • Power Stage Input Voltage from 1V to 14V • Control Stage Input Voltage from 3V to 6V • Output Voltage Adjustable Down to 0.6V • Power Good Flag and Shutdown • Output Overvoltage and Undervoltage Detection • ±1.5% Feedback Voltage Accuracy Over Temperature • Low-side Adjustable Current Sensing • Adjustable Soft-start • Tracking and Sequencing with Shutdown and Soft Start Pins • TSSOP-14 Package
APPLICATIONS • Down Conversion from 3.3V • Cable Modem, DSL and ADSL • Laser Jet and Ink Jet Printers • Low Voltage Power Modules • DSP, ASIC, Core and I/O