MC33341

http://onsemi.com

13

R3

Load

R1

Battery or

Resistive

Load

Source

Return

Source

R2

Comp

The above figure shows the MC33341 configured for load low−side current sensing allowing common paths for both power and ground,

between the source and load. The Noninverting input paths, Pins 1 and 4, are used to sense the load induced voltage drop that appears

6. Resistor R3 is required in applications where high peak levels of load current are possible from the battery or load bypass capacitor. The

resistor value should be chosen to limit the negative substratecurrent to less than 20 mA. Excessively large values for R3 will degrade the

current sensing accuracy.

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

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 20. Load Low−Side Current Sensing with

Internally Fixed Current and Voltage Thresholds