MC33341

http://onsemi.com

9

Load

R1

Battery or

Resistive

Load

Source

Return

Source

R2

R3

Comp

The above figure shows the MC33341 configured for source return low−side current sensing allowing a common power path between

Source + and Load +. This configuration is especially suited for negative output applications where a common ground path, Source + to

Load +, is desired. The Inverting Amplifier inputs, Pins 1 and 4, are used to sense the load induced voltage drop that appears across resistor

is required in applications where high peak levels of inrush current are possible. The resistor value should be chosen to limit the negative

substrate current to less than 20 mA. Excessively large values for R3 will degrade the current sensing accuracy.

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

Figure 16. Source Return Low−Side Current Sensing with

Internally Fixed Current and Voltage Thresholds

Vreg + Vth(V)

R2

R1

) 1

+ 1.2 R2

R1

) 1

Ireg +

V

th(ILS–)

R

S

+ –0.2

R

S

R3

+

I

pk

R

S

– 0.6

0.02