FEATURES

2• 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 cost•

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 pre•

Cable Modem, DSL and ADSL

• Laser Jet and Ink Jet Printers

• Low Voltage Power Modules

• DSP, ASIC, Core and I/O

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 include the ability to startup with a pre•

biased load on the output, soft-start, input

undervoltage lockout (UVLO) and Power Good (based on both undervoltage and overvoltage

detection). In addition, the shutdown pin of the IC can

be used for providing startup delay, and the soft-start

pin can be used for implementing precise tracking, for

the purpose of sequencing with respect to an external

rail.