10μA-10mA Low-Side Current Sensor

Rajkumar Sharma
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SKU: EL145610
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This single-supply, low-side, current-sensing solution accurately detects load current between 10μΑ and 10mA. A unique yet simple gain-switching network was implemented to measure the three-decade load current range accurately. The linear range of the output is from 100mV to 4.90V. INA326 instrumentation amplifier is used since low-side sensing is desirable because the common-mode voltage is near the ground. Therefore, the current sensing solution is independent of bus voltage, which allows for using single-supply, rail-to-rail input/output (RRIO) amplifiers. Low-side current sensing places a shunt resistor between the system load and the ground. The current drawn by the load generates a voltage across the shunt resistor. The output voltage of the circuit is equal to the current sense across the shunt resistor and the gain of the amplifier. A high-value resistor is used as a shunt for accurate current sense. It is advisable to use 0.1% tolerance shunt resistor R2.

Credits: Circuit is from Texas Instruments Application Note

Features

Supply 5V DC
Input Current Range 10uA to 10mA
Output 100mV(0,1V) to 4.90V
On Board Power LED
Very Small Board
PCB Dimensions 28.10 x 17.30 mm

Connections

CN1L Pin 1 = VCC 5V DC, Pin 2 = GND, Pin 3 = GND, Pin 4 = Output 100mV to 5V
CN2: Pin 1 = Current Input, Pin 2 = GND
D1: Power LED
J1: Gain Set

Schematic

Parts List

NO	QNTY.	REF.	DESC.	MANUFACTURER	SUPPLIER	SUPPLIER PART NO
1	1	CN1	4 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5317-ND
2	1	CN2	2 PIN SCREW TERMINAL PITCH 5.08MM	PHOENIX	DIGIKEY	277-1247-ND
3	1	C1	1uF/25V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
4	1	C2	194PF/25V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
5	1	C3	10PF/50V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
6	1	C4	100nF/50V CERAMIC SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
7	1	C5	10uF/25V CERAMCIS SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
8	1	D1	LED SMD SIZE 0805	OSRAM	DIGIKEY	475-1278-1-ND
9	1	J1	2 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5315-ND
10	1	R1	50K 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
11	1	R2	25E 0.1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
12	1	R3	100E 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
13	1	R4	100K 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
14	1	R5	1K 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
15	1	R6	511K 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
16	1	R7	10M 1% SMD SIZE 0805	YAGEO/MURATA	DIGIKEY
17	1	U1	INA326	TI	DIGIKEY	INA326EA/2K5CT-ND
18	1	J1	SHUNT FOR JUMPER	SULINS CONNECT	DIGIKEY	S9001-ND