MC33341D 查看數據表（PDF） - ON Semiconductor

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MC33341D

Power Supply Battery Charger Regulation Control Circuit

ON Semiconductor 

MC33341

Pin 8 to ground. This configuration is shown for ease of

understanding and would normally be used to provide an

isolated control signal to a primary side switching regulator

controller. In non−isolated, primary or secondary side

applications, a load resistor can be placed from Pin 8 to

ground. This resistor will convert the Drive Output current

to a voltage for direct control of a regulator.

In applications where excessively high peak currents are

possible from the source or load, the load induced voltage

drop across RS could exceed 1.6 V. Depending upon the

current sensing configuration used, this will result in

forward biasing of either the internal VCC clamp diode,

Pin 6, or the device substrate, Pin 1. Under these conditions,

input series resistor R3 is required. The peak input current

should be limited to 20 mA. Excessively large values for R3

will degrade the current sensing accuracy. Figure 22 shows

a method of bounding the voltage drop across RS without

sacrificing current sensing accuracy.

Source

RS

Load

R3

R2

Opto

Isolator

8

7

6

5

VCC

VCC

VCC

VCC

1.2 V Differential Amp

R1

Disable Logic 0.4 V

1.2 V

VCC

Differential Amp

R

R

RR

R

R

VCC

VCC

Inverting Amp

Vsen

Transconductance

Vth

V

Amp

Isen

Ith

I

VCC

Reference

0.2 V 0.4 V 1.2 V

VCC

0.2 V

1

2

3

4

Battery or

Resistive

Load

Source

Return

Comp

Load

The above figure shows the MC33341 configured for source high−side current sensing allowing a common ground path between Load − and

Source Return −. The Differential Amplifier inputs, Pins 1 and 6, are used to sense the load induced voltage drop that appears across resistor

RS. The internal voltage and current regulation thresholds are selected by the respective external connections of Pins 2 and 6. Resistor R3

is required in applications where a high peak level of reverse current is possible if the source inputs are shorted. The resistor value should

be chosen to limit the input current of the internal VCC clamp diode to less than 20 mA. Excessively large values for R3 will degrade the

current sensing accuracy.

ǒ Ǔ Vreg + Vth(V)

R2

R1

)

1

Ireg

+

Vth(I HS)

RS

ǒ Ǔ Ipk RS – 0.6

R3 +

0.02

ǒ Ǔ + 1.2

R2

R1

)

1

+

0.2

RS

Figure 14. Source High−Side Current Sensing with

Internally Fixed Voltage and Current Thresholds

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