Hall Current 3 click
PID: MIKROE‐3118
Weight: 28 g
Hall current 3 click is a very accurate current measurement Click board™,
which utilizes the Hall effect to provide a precise and reliable measurement
of reasonably high current. Its most distinctive feature is a very low series
resistance of only 0.7mΩ, making this device a nearly-perfect ammeter. The
maximum current which can be measured by the MLX91210 integrated Hall
sensor IC goes up to ±30A, but in respect to the nominal current
measurement rating of the sensor, the current measurement is limited to
about ±10A. The measurement is thermally compensated and conditioned
by the high-speed integrated analog front-end sections of the Hall sensor IC.
The current measurement value can be obtained from the onboard 12bit A/D
converter, via the I2C interface.
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, this 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 it work?
Hall current 3 click 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 overvoltage, 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.
SPECIAL CARE SHOULD BE TAKEN IF WORKING WITH THE HIGH VOLTAGE!
Note: Since the MLX91210 provides up to 2.5 kV AC and 390 V DC, a special care should be
taken if working with the high voltage. The Click board™ contains exposed areas which can
be lethal if touched, while operated at high voltages.
Specifications
Type
Current sensor
Applications
Audio applications, telecommunication applications, smart current
metering, servers/motherboards current monitoring, and similar
application which require reliable and accurate current
measurement
On-board
modules
MLX91210, a linear Hall current sensor by Melexis; MCP3221, a
12-bit A/C converter with I2C interface by Microchip; PCA9306
Dual Bidirectional I2C voltage level translator, from Texas
Instruments
Key Features
Very low series resistance, which makes this sensor an ideal
ammeter. Wide current input range, great accuracy, low thermal
drift, immunity to EMI or other magnetic interferences, low count
of external components
Interface
I2C
Input
Voltage
3.3V,5V
Click board
size
L (57.15 x 25.4 mm)
Pinout diagram
This table shows how the pinout on Hall current 3 click 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
Hall current 3 click specifications
Description
Thermal drift
Sensitivity
Nominal sensor range
Min
Typ
Max
Unit
-
± 0.06
± 0.12
A
78.8
80
81.2
mV/A
-
±10
-
A
Onboard Jumpers and Settings
Label
Name
Default
LD1
PWR
-
VCC
SEL
VCC SEL
Left
TB1
IP+, IP‐
-
Description
Power LED indicator
Logic voltage level selection: left position 3.3v, right
position 5V
Current input connector
Software support
We provide a library for the HallCurrent3 Click on our LibStock page, as well
as a demo application (example), developed using MikroElektronika
compilers. The demo can run on all the main MikroElektronika development
boards.
Library Description
This library provides basic functionality for reading the current value and
controlling the click board.
Key functions:
float hallcurrent3_getCurrent()- Reads current in mA
uint16_t hallcurrent3_readData(uint8_t reg) - Reads current data
Example description
The application is composed of three sections :
System Initialization - Initialization of the I2C module
Application Initialization - Driver initialization
Application Task - (code snippet) - Reads the current from a bipolar current sensor and logs to
USBUART every 1 second.
void applicationTask()
{
Current_data = hallcurrent3_getCurrent();
FloatToStr(Current_data, demoText);
mikrobus_logWrite("Current : ", _LOG_TEXT);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" mA", _LOG_LINE);
Delay_ms( 1000 );
}
The full application code, and ready to use projects can be found on
our Libstock page.
Other MikroElektronika libraries used in the example:
I2C
Conversions
Additional notes and information
Depending on the development board you are using, you may need USB UART
click, USB UART 2 click or RS232 click to connect to your PC, for development
systems with no UART to USB interface available on the board. The terminal
available in all MikroElektronika compilers, or any other terminal application
of your choice, can be used to read the message.
mikroSDK
This click board is supported with mikroSDK - MikroElektronika Software
Development Kit. To ensure proper operation of mikroSDK compliant click
board demo applications, mikroSDK should be downloaded from
the LibStock and installed for the compiler you are using.
For more information about mikroSDK, visit the official page.
https://www.mikroe.com/hall‐current‐3‐click?search_query=MIKROE‐3118&results=1 9‐19‐18
