Hall Current 3 Click Board™

Featuring a reasonably high current range that can be measured, extremely low series resistance, a differential current sensing by two integrated Hall plates, offering robustness and resistance towards external magnetic interferences, high isolation voltage of the IC itself, very low thermal drift, and fast response time with no hysteresis, the Hall Current 3 Click Board™ can be used for a wide range of measuring and monitoring applications in audio applications, telecommunication applications, white goods applications, and basically in every application which requires reasonably high current measurement or monitoring.

How Does The Hall Current 3 Click Board™ Work?

The Hall Current 3 Click Board™ utilizes the MLX91210, a linear Hall current sensor, from Melexis. This sensor utilizes the Hall effect phenomenon to measure the current passing through the input pins of the IC. This allows the series resistance to stay very low, in magnitudes of μΩ, reducing dissipation and losses in the main current flow. The main current flow through the input rails of the IC generates a magnetic field, which causes the Hall effect on two integrated Hall plates. These two plates are connected differentially, preventing foreign magnetic interferences to influence the measurement. A front-end section conditions and amplifies the signal, canceling out interferences. The conditioned signal is then available at the VOUT pin of the MLX91210, with a linear dependency of the input current. It is further routed to an A/D converter. The VOUT voltage is very stable and has a very low sensitivity drift over temperature (±1.5 % with nominal current).

The VOUT pin of the MLX91210 stays at 50% of VDD (5V), at 0A of current. This allows to measure both polarities: positive current polarity will pull the VOUT above half of the VDD, while negative current polarity will draw the VOUT pin below the VDD voltage. The MLX91210 also features fault reporting if over-voltage, undervoltage, or calibration data CRC error occurs. It will set the VOUT pin to a high impedance mode (Hi-Z). The datasheet offers an explanation about Hi-Z timings for each type of error. The resolution of the MLX91210 IC can be determined from the full IC label: MLX91210KDF-CAS-101-SP, where CAS-101 means that it has the analog voltage resolution of 80mV/A or ±25A for the full scale (FS) measurement.

The output voltage is also routed to the MCP3221, a 12 Bit SAR type ADC with the I2C interface, from Microchip. This ADC is used in several different Click Board™ designs, as it yields accurate conversions, it requires a low count of external components, and has a reasonably good signal to noise ratio (SNR). It can achieve up to 22.3ksps, which allows good measurement resolution for the most purposes. After the VOUT measurement voltage has been converted to a digital value, it can be read via the I2C bus of the MCP3221 ADC.

Since the ADC IC works only with 3.3V communication voltage levels, the Click Board™ is equipped with the PCA9306, a bi-directional I2C level translator. This IC accepts two voltage levels: one reference voltage for the input signal, and other reference voltage for the output signal. The output reference signal can be selected with the VCC SEL jumper, allowing communication with both 3.3V and 5V MCUs. The I2C bus already contains pull-up resistors included, so no further configuration is needed, it can be used right out of the box.

The input terminal has the cross section of 2.5mm, so it can accept a high input current, more than 10A. It has two input poles: IP+ and IP-. Conductors with the current that needs to be measured can be connected to this terminal.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout on Hall current 3 Click Board™ corresponds to the pinout on the mikroBUS socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	+3V3	7	3.3V	5V	10	+5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

SPECIFICATIONS

ONBOARD JUMPERS AND SETTINGS