MC33341

http://onsemi.com

7

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

current sensing configuration used, this will result in

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

sacrificing current sensing accuracy.

Figure 14. Source High−Side Current Sensing with

Internally Fixed Voltage and Current Thresholds

Load

R1

Battery or

Resistive

Load

Source

Return

Source

R2

R3

Comp

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

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

current sensing accuracy.

Vreg + Vth(V)

R2

R1

) 1

+ 1.2 R2

R1

) 1

Ireg +

V

th(IHS)

R

S

+ 0.2

R

S

R3

+

I

pk

R

S

– 0.6

0.02

V

I

Load

87

6

5

12

3

4

R

R

R

R

R

0.4 V

1.2 V

R

0.2 V

0.2 V 0.4 V 1.2 V

1.2 V

Inverting Amp

Transconductance

Amp

Differential Amp

Disable Logic

Differential Amp

Opto

Isolator

Reference