current sensor board render


The current sensor breakout is a breadboard compatible breakout module for the INA139 series of high-side current sensor ICs. In addition to providing a mount point for the INA139 part and the shunt resistor, the module also includes a low-impedance output suitable for driving an analog-to-digital converter.


The potentially high-current pins - Vps and Vload - have two pins each dedicated to their functionality. It is not necessary to connect both pins.

Pin Number Pin Label Description
1 Vps Power supply pin 1 - connect to the incoming power supply
2 Vps Power supply pin 2 - connect to the incoming power supply
3 Vload Load pin 1 - connect to the load
4 Vload Load pin 2 - connect to the load
5 Vcc Logic-level Voltage Supply
6 Gnd Ground Pin
7 Vsns Sense voltage pin - leave unconnected in most applications unless filtering is desired
8 Vbuf Voltage buffer output - connect this to the ADC or other measurement device


Sustained Ratings

Each part is designed so that no more than 150mV is dropped across the part at the rated current. It is possible to run a multitude of settings on this part, but I have found that the most common combinations are targeted for 3.3V and 5V applications. Below you will find common configurations for measuring currents between 3mA to 3.0A.

Part Number Rated Current Transimpedance Volts Out @ Irated
ELAS00011100 3.0A 1.65V/A 4.95V
ELAS00011101 300mA 16.5V/A 4.95V
ELAS00011102 30mA 155.1V/A 4.95V
ELAS00011103 3mA 1551V/A 4.95V
ELAS00011104 3.0A 1.1V/A 3.3V
ELAS00011105 300mA 11V/A 3.3V
ELAS00011106 30mA 103.4V/A 3.3V
ELAS00011107 3mA 1034V/A 3.3V


These values are common to all part variants.

Parameter Value
Frequency 200kHz
Accuracy 2%
Recommended Minimum Vcc 3.0V
Recommended Maximum Vcc 5.0V
Recommended Minimum Vps 3.0V
Recommended Maximum Vps 35.0V

Absolute Maximum Ratings

Parameter Maximum
Vps to GND 40.0V
Vcc 5.5V


The schematic has three sections:

  1. Shunt Resistor
  2. High-Side Amplifier
  3. Voltage Follower

The shunt resistor is the resistor through which all current flows in order to create a differential voltage.

The high-side amplifier circuit is the circuit which measures the differential voltage across the shunt resistor and amplifies the signal to a more easily measured value.

The voltage follower takes the high-impedance output of the high-side amplifier and outputs a low-impedance voltage suitable for driving a multitude of input types, such as analog-to-digital converters.

Connection Diagrams

De-coupling capacitors are not necessary as they are integrated next to the part, although extra capacitance on the inputs of the pins would not compromise the performance of the part in any way.

Common Supply

In application in which the Vps is between 3.0V and 5.0V, Vcc and Vps may be connected. This is the simplest method of connection. It is possible that this method of connection may induce noise on the Vcc pin, depending on the load noise characteristics.

Common Supply

Split Supply

In application in which the Vps is to operate above 5.0V, Vcc should be supplied with its own voltage source between 3.0V and 5.0V.

Split Supply Connection


In some situations, it may be desireable to filter the output waveform, reducing the frequency content of the output signal while increasing the 'averaging' effect. When this is desired, a capacitor may be populated between Vsense and GND.

Split Supply with Filter

© by Jason R. Jones 2016
My thanks to the Pelican and Python Communities.