Q67006-A9341 Просмотр технического описания (PDF) - Infineon Technologies

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Q67006-A9341

Voltage-Current Regulator

Infineon Technologies 

TLE 4305

Current Control Loop

Current Loop TLE 4305

from Voltage Loop

VREF

RI1

25 kΩ

Control

Logic

Driver

1 kΩ OUT

D2

CSE RI1

C-OTA

RSense

25 kΩ

CRE

RCC CCO

1 kΩ

CCCO

10 nF

AES02880

Figure 7 Current Control Loop

To detect the current a sense resistor Rsense is placed in the current back-path to the

transformer (see Figure 4 and Figure 7).

The control operational amplifier compares the voltage at pin CRE to the voltage at the

inverting input of the OTA. In an overcurrent condition, the overall closed loop through

current loop, opto isolator, primary regulator, transformer and the application reduces the

PWM duty cycle to meet the closed loop condition.

VCSE - VCRE is typical 200 mV.

The current limit is defined by

IQmax = 200 mV / Rsense

(6)

To compensate the overall closed current loop a 10 nF capacitor should be connected

to pin VCO. With the internal 1 kΩ resistor it reduces the voltage loop’s bandwidth.

As already explained for the voltage loop, the capacitor can be modified according to the

overall loop’s bandwidth.

To further improve the current control in addition a compensation can be added at pin

CRE as shown in Figure 8.

Data Sheet

12

Rev. 2.2, 2008-11-17

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