LTM4607 datasheet(9/26 Pages) AD

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LTM4712

Rev. 0

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OPERATION

The LTM4712 is a standalone nonisolated buck-boost

switching DC/DC power supply. The buck-boost topol-

ogy allows the LTM4712 to regulate its output voltage

for input voltages both above and below the magnitude of

the output. The maximum output current depends upon

the input voltage. Higher input voltages yield higher max-

imum output current.

This converter provides a precisely regulated output volt-

age programmable via an external resistor divider from

1V to 36V. The input voltage range is 5V to 36V. See the

Block Diagram (Figure 1).

The LTM4712 contains a constant frequency, peak current

mode controller, power switching elements, power induc-

tor and a modest amount of input and output capacitance.

The LTM4712 is a constant frequency PWM regulator.

The operating frequency can be adjusted from 100kHz to

600kHz by connecting the appropriate resistor value from

the FREQ pin to SGND. Alternatively, its frequency can be

synchronized by an input clock signal on the SYNC pin.

The typical switching frequency is 400kHz.

The output voltage of the LTM4712 is set by connecting

the FB pin to a resistor between FB pin and GND.

In addition to regulating output voltage, the LTM4712 is

equipped with average current control loops for either the

input or output. Add a current sense resistor to limit the

input or output current below maximum value. When the

resistor is present, the IMON pin reflects the current flow-

ing though the sense resistor between input or output.

The LTM4712 features an integrated compensation net-

work for most conditions. Some applications, however,

benefit from a different compensation network. In such

cases, apply an appropriate external compensation net-

work for optimal and proper operation.

If an external bias supply is applied on the EXTVCC pin,

then an efficiency improvement occurs due to the reduced

power loss in the internal linear regulator. This is espe-

cially true at the higher end of the input voltage range.

LTM4607 Datasheet(PDF) 9 Page - Analog Devices