MIC2131 datasheet(8/20 Pages) MICREL

8 / 20 page

Micrel, Inc.

MIC2130/1

April 2008

M9999-042108-C

Functional Diagram

Figure 1. MIC2130/1 Block Diagram

Functional Description

The MIC2130/31 is a voltage mode synchronous buck

controller built for optimum speed and efficiency. It is

designed for wide input voltage range and for high

output power buck converters. Figure 1 shows the block

diagram.

The control loop has two stages of regulation. During

steady-state to medium output disturbances, the loop

operates in fixed frequency, PWM mode while (gm loop),

during a large output voltage disturbance (~±6%

nominal), the loop becomes hysteretic; meaning that for

a short period, the switching MOSFETs are switched on

and off continuously until the output voltage returns to

it’s nominal level. This maximizes transient response for

large load steps, while nominally operating in fixed

frequency PWM mode. Voltage mode control is used to

allow for maximum flexibility and maintains good

transient regulation. The operating input voltage range is

8V to 40V and output can be set from 0.7V up to

0.85*VIN. Start-up surges are prevented using built in

soft start circuitry as well as resistor-less (LSD RDSON is

used to sense load current) current sensing for overload

protection. Other protection features include UVLO, over

voltage latch off protection, Power good signal.

MIC2131 Datasheet(PDF) 8 Page - Micrel Semiconductor