SMB117A Ver la hoja de datos (PDF) - Summit Microelectronics

Número de pieza

componentes Descripción

Fabricante

SMB117A

High-power, Four-channel Programmable DC-DC System Power Managers

Summit Microelectronics 

APPLICATIONS INFORMATION

High Voltage Operation:

While the SMB113A has a max input voltage of 6.0V

the controller can operate to0 much higher voltages by

using the circuit depicted below. By inserting a

capacitor, C1, in series with the HSDRV gate signal

the HSDRV pin is isolated from the 12V supply, and

the AC coupling capacitor acts as a level translator

transferring the 0-5V signal from the HSDRV pin to a

12V to 7V (12V-5V = 7V) signal at the gate of the

PFET. When the gate stops switching the capacitor

SMB113A/B/SMB117/A

Preliminary Information

becomes an open circuit and the gate will be pulled

high by R1 turning off the output. The schottky diode

and the pull-up resistor are used for DC restoration

and as a pull-up respectively.

Since the converter runs directly from the input supply

(12V in this instance) the efficiency is consistent with

that of a synchronous converter. Typical efficiency

curves are shown below.

12V

5V

7V

time

HSDRV

time

C1 0.1uF

Schottky

AC Coupling capacitor

R1

DC Restoration

1K

C28

22uF

LSDRV

All power comes directly from 12V supply

Q2(P)

+12V

Q6

C33

0.1uF

Q1(N)

FDNCP6420C

L1

3.3uH

C45

22uF

1

C51

0.1uF

Vout

Figure 7 – High-voltage operation

Summit Microelectronics, Inc

2111 2.6 9/16/2010

18

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