1FEATURES

2• Input Operating Voltage Range: 6V to 28V

• Absolute Maximum Input Rating: 30V

• Integrated 2A N-Channel Buck Switch

• Adjustable Current Limit Allows for Smaller

Inductor

• Adjustable Output Voltage from 2.51V

• Minimum Ripple Voltage at V OUT

• Power Good Output

• Switching Frequency Adjustable to 1MHz

• COT Topology Features:

– Switching Frequency Remains Nearly

Constant with Load Current and Input

Voltage Variations

– Ultra-Fast Transient Response

– No Loop Compensation Required

– Stable Operation with Ceramic Output

Capacitors lock–

Allows for Smaller Output Capacitor and

Current Sense Resistor

• Adjustable Soft-Start Timing

• Thermal Shutdown

• Precision 2% Feedback Reference

DESCRIPTION

The LM34922 Constant On-time Step-Down

Switching Regulator features all the functions needed

to implement a low cost, efficient, buck bias regulator

capable of supplying up to 2A of load current. This

voltage regulator contains an N-Channel Buck switch,

a startup regulator, current limit detection, and

internal ripple control. The constant on-time

regulation principle requires no loop compensation,

results in fast load transient response, and simplifies

circuit implementation. The operating frequency

remains constant with line and load. The adjustable

valley current limit detection results in a smooth

transition from constant voltage to constant current

mode when current limit is reached, without the use

of current limit foldback. The PGD output indicates

the output voltage has increased to within 5% of the

expected regulation value. Additional features

include: Low output ripple, VIN under-voltage lock–

out, adjustable soft-start timing, thermal shutdown,

gate drive pre-charge, gate drive under-voltage lockout,

and maximum duty cycle limit.