0.47 2F

10 2H

Co

Cvcc

FB

EN

SS

Vin

Linear reg

RON

Timer

Css

Regulator IC

Internal

Passives

VOUT

GND

VIN

1

2

3

4

5

6

7

LMZ14202

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SNVS648J – JANUARY 2010 – REVISED OCTOBER 2015

7 Detailed Description

7.1 Overview

The LMZ14202 is a step-down DC-to-DC power module. It is typically used to convert a higher DC voltage to a

lower DC voltage with a maximum output current of 2 A.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Constant On-Time Control (COT) Circuit Overview

Constant on-time control (COT) control is based on a comparator and an ON-time one-shot, with the output

voltage feedback compared with an internal 0.8-V reference. If the feedback voltage is below the reference, the

main MOSFET remains off for a minimum of 260 ns. If the voltage on the feedback pin falls below the reference

level again the ON-time cycle is repeated. Regulation is achieved in this manner.

7.3.2 Output Overvoltage Comparator

The voltage at FB is compared to a 0.92-V internal reference. If FB rises above 0.92 V the ON-time is

immediately terminated. This condition is known as over-voltage protection (OVP). It can occur if the input

voltage is increased very suddenly or if the output load is decreased very suddenly. Once OVP is activated, the

top MOSFET ON-times are inhibited until the condition clears. Additionally, the synchronous MOSFET remains

on until the inductor current falls to zero.

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