PM6675AS datasheet(42/48 Pages) STMICROELECTRONICS

Nome de Peças	PM6675AS

Descrição Electrónicos	High efficiency step-down controller with embedded 2 A LDO regulator

PDF	48 Pages

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Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

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42 / 48 page

Application information

PM6675AS

42/48

where RDSon is the drain-source on-resistance low-side switch. Consider the temperature

effect and the worst case value in RDSon calculation (typically +0.4 %/°C).

The accuracy of the valley current also depends on the offset of the internal comparator

(±6 mV).

The negative valley-current limit (if the device works in forced-PWM mode) is given by:

Equation 47

8.1.7

All ceramic capacitors application

Design of external feedback network depends on the output voltage ripple across the output

capacitors ESR. If the ripple is great enough (at least 20 mV), the compensation network

simply consist of a CINT capacitor.

Figure 39.

Integrative compensation

The stability of the system depends firstly on the output capacitor zero frequency. It must be

verified that:

Equation 48

DSon

NEG

110

CFILT

CINT

RINT

Vr=0.6

VSNS

Ton One-shot

generator

VREF

PWM

Comparator

COMP

VOUT

Integrator

out

Zout

⋅

PM6675AS Folha de dados(PDF) 42 Page - STMicroelectronics