HOW DOES IT WORK?

Current 5 Click as its foundation uses the INA381, a zero-drift topology, a current-sensing amplifier with an integrated comparator that can be used in both low-side and high-side current-sensing and protection applications from Texas Instruments. This current-sensing amplifier accurately measures voltages developed across the current-sensing resistor (also known as current-shunt resistors) on common-mode voltages that far exceed the device supply voltage. Current is measured on IN load connection terminal withstanding the full common-mode voltages from –0.2V to +26V at the input pins when the supply voltage is removed without causing damage.

The INA381 also uses a reference input from an onboard REF potentiometer that simplifies setting the corresponding current threshold level to use for out-of-range comparison. Combining the precision measurement of the current-sense amplifier and the onboard comparator enables an all-in-one overcurrent detection device. This combination creates a highly-accurate design that quickly detects out-of-range conditions and allows the system to take corrective actions to prevent potential component or system-wide damage.

The amplified output voltage of the INA381 is developed across the onboard current-sensing resistor, which is the input voltage across the IN terminal (IN+ and IN– pins) multiplied by the gain of the amplifier (200V/V). The output voltage of the INA381 is then converted to a digital value using the ADC121S021, a low-power, single-channel 12-bit analog to digital converter (ADC), with a high-speed SPI interface also from Texas Instruments.

The INA381's integrated comparator is designed to quickly detect when the sense current is out-of-range, and provide an interrupt alert signal, routed to the INT pin of the mikroBUS™ socket, for quicker and faster responses. This alert output can be configured to operate in two modes, transparent or latched, selectable according to the logic state on the RST pin of the mikroBUS™ socket. In transparent mode, the output status follows the input state, while in the latched mode, the alert output is cleared only when the latch is reset.

The onboard comparator in the INA381 is designed to reduce the possibility of oscillations in the alert output when the measured signal level is near the over-limit threshold level due to noise, with a hysteresis 50mV. When the voltage on the comparator input exceeds the voltage developed at the comparator reference input, the alert signal sets to a low logic state. The output voltage then must drop to less than the reference input threshold voltage by the hysteresis level of 50mV so that the alert pin de-asserts and returns to the nominal high state. Also, this board allows the user to change the hysteresis from a preset value of 50mV via an onboard Hyst potentiometer. The user can also bring external signals such as REF and HYST on the eponymous onboard headers.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.