MC33341
http://onsemi.com
11
R3
Load
R1
Battery or
Resistive
Load
Source
Return
Source
R2
R
S
Comp
The above figure shows the MC33341 configured for load high−side current sensing allowing common paths for both power and ground
between the source and load. The Differential Amplifier inputs, Pins 1 and 6, are used to sense the load induced voltage drop that appear
across resistor R
S
. The internal voltage and current regulation thresholds are selected by the respective external connections of Pins 2 an
6. Resistor R3 is required in applications where high peak levels of load current are possible from the battery or load bypass capacitor. Th
resistor value should be chosen to limit the input current of the internal V
CC
clamp diode to less than 20 mA. Excessively large values fo
R3 ill degrade the current sensing accuracy.
V
reg
+ V
th(V)
ǒ
R2
R1
) 1
Ǔ
+ 1.2
ǒ
R2
R1
) 1
Ǔ
I
reg
+
V
th(IHS)
R
S
+
0.2
R
S
R3 +
ǒ
I
pk
R
S
Ǔ
–0.6
0.02
V
I
Load
8765
1234
R
R
R
R
R
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
0.4 V
1.2 V
R
0.2 V
V
CC
0.2 V 0.4 V 1.2 V
V
CC
1.2 V
V
CC
Inverting Amp
Transconductance
Amp
Differential Amp
Disable Logic
Differential Amp
Opto
Isolator
V
sen
V
th
I
sen
I
th
Reference
Figure 18. Load High−Side Current Sensing with
Internally Fixed Current and Voltage Thresholds
