RT8113 Просмотр технического описания (PDF) - Richtek Technology

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производитель

RT8113

Single Phase VR11.1 PWM Controller with 7-bit VID

Richtek Technology 

RT8113

Output Current Sensing

The RT8113 provides a low input offset current-sense

amplifier (CSA) to monitor the output current. The output

current of CSA (IX) is used for load line control and over-

current protection. In this inductor current sensing

topology, RS and CS must be set according to the equation

below :

L

DCR

= RS

x CS

700nA is a typical value of the CSA input offset current.

VOFS-CSA is the input offset voltage of CSA. VOFS-CSA of

the RT8113 is smaller than +/- 1.5mV. Usually, “VOFS-CSA

+ 700n x (RCSP + RS - RCSN)” is negligible except at very

light load and the equation can be simplified as the equation

below :

IX

=

IL x DCR

RCSN

Then the output current of CSA will follow the equation

below :

IX

=

IL

x

DCR

-

VOFS-CSA + 700n x

RCSN

(RCSP

+ RS

-

RCSN )

BOOT

UGATE

PHASE

LGATE

CSA: Current Sense Amplifier

+

700nA

IX

VOFS_CSA

+

-

700nA

-

VIN

R1

C1

L

R2

RS

C2

ISP

RCSP

ISN

RCSN

DCR

CS

Figure 7. Circuit for Current Sensing

www.richtek.com

16

DS8113-02 April 2011

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