+

-

+

-

CONTROL

LOGIC

DRIVER

HS CURRENT

SENSE

LS CURRENT

SENSE

OSCILLATOR

PWM

COMP.

ERROR

AMPLIFIER

POWER GOOD

CONTROL

SW

VIN

PGND

FB

EN

INT. REG.

BIAS

VCC

BOOT

AGND

1.0V

Reference

ENABLE

LOGIC

PG

PFM MODE

CONTROL

9

LM60440, LM60430

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SNVSBN5A – FEBRUARY 2020 – REVISED JUNE 2020

Product Folder Links: LM60440 LM60430

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8 Detailed Description

8.1 Overview

The LM604x0 is a synchronous peak-current-mode buck regulator designed for a wide variety of applications.

Advanced high speed circuitry allows the device to regulate from an input voltage of 20 V, while providing an

output voltage of 3.3 V. The innovative architecture allows the device to regulate a 3.3-V output from an input of

only 3.8 V. The regulator automatically switches modes between PFM and PWM depending on load. At heavy

loads, the device operates in PWM at a constant switching frequency. At light loads, the mode changes to PFM

with diode emulation allowing DCM. This reduces the input supply current and keeps efficiency high. The device

features internal loop compensation which reduces design time and requires fewer external components than

externally compensated regulators.

The LM604x0 is available in an ultra-miniature WQFN package with wettable flanks. This enhanced QFN

package features extremely small parasitic inductance and resistance, enabling very high efficiency while

minimizing switch node ringing and dramatically reducing EMI. The VIN/PGND pin layout is symmetrical on either

side of the WQFN package. This allows the input current magnetic fields to partially cancel, resulting in reduce

EMI generation.

8.2 Functional Block Diagram