Current 2 Click
PID: MIKROE‐3292
Weight: 28 g
Current 2 click is an accurate current sensing Click board™ suitable for a very
accurate measurement of the current through the load. It utilizes the highside current sensing approach, which has a few advantages over the lowside current sensing. Current 2 click is equipped with an integrated
transimpedance amplifying circuit, designed specifically for low-power
current sensing applications. Designed to be used with a common mode
voltage up to 6V, this Click board™ is a perfect solution for the battery
charging monitoring, various battery gauges, and other similar low voltage
applications that require simple and reliable current monitoring.
It comes in the package which also includes the mikroSDK™ software and a
library with all the functions. The Click board™ comes as a fully tested and
approved prototype, making it a reliable device ready to use on the
development board.
Current 2 click features a very low error margin of less than 0.2%, a very
low offset and quiescent current, allowing the voltage across the sense
resistor as high as 2.5V. The output current is converted to voltage and fed
to the 10-bit A/D converter, which uses a voltage reference IC, for improved
accuracy. Thanks to the external sense resistor, Current 2 click is able to
provide readings for quite a large current through the connected load. Due
to the high-side sensing configuration, Current 2 click does not disturb the
GND potential of the connected load and allows the detection of the shortcircuit condition at the input. The A/D converter allows reading the
measured current via the SPI interface.
How does it work
The Current click 2 is based on the FAN4010, a high-side current sensor
by ON Semiconductor (formerly Fairchild). This integrated circuit is a
transimpedance amplifier suitable for the current sensing through the shunt
resistor on the high side, between the power supply and the connected load.
This allows the short circuit on the load to be sensed and will not disturb the
GND reference of the connected load since the shunt resistor between the
load negative connection terminal and the GND is avoided. These
advantages are especially useful for battery charging applications and
battery gauges since the short circuit detection is very important in such
applications. Also, the negative terminal of the battery has to stay on the
same potential as the GND for the temperature output to be accurate, which
is impossible with the low-side shunt resistor.
The similar schematic could be designed using only operational amplifiers,
however due to a high inaccuracy of such design (as the offset voltage of a
typical operational amplifier can greatly affect the output current, especially
after the amplification is applied), and the low common mode voltage that
typical operational amplifier can withstand, specialized current sensing
amplifier ICs (CSA) such as the FAN4010, are used instead.
The FAN4010 features an extremely low current offset of only 2 µA, which
allows very accurate measurement within the 0.2% margin. The
transconductance ratio at the output of the FAN4010 is 10 mA/V, where V
represents the voltage across the shunt resistor. The current at the output
linearly depends on the current through the load. By using the appropriate
resistor between the output and the GND, this current can be scaled to an
appropriate voltage level that can be used as the input for the A/D
converter.
The MCP3001, a 10-bit A/D converter (ADC) with SPI interface, from
Microchip. It is a high-performance, low-noise single-supply ADC, which can
deliver up to 200,000 samples per second (200 ksps). This makes it well
suited for fast monitoring applications. It is also equipped with the reference
input pin, allowing it to use an accurate voltage reference, which ensures
very high sampling accuracy. Combined with the MCP1501-20 IC, a highprecision, buffered voltage reference of 2.048V, it is used with enough
headroom to sample load current up to 4 A (4 A = 2 V at the ADC input).
The calculation formulas can derived from the datasheet of the FAN4010.
However, it is not necessary to perform any calculations if using mikroSDK
compatible functions, provided for this Click board™. These functions already
contain all the necessary calculations and output the current through the
connected load directly in physical units [mA]. The included example
demonstrates their practical usage.
Specifications
Type
Current sensor
Applications
This Click board™ is a perfect solution for the battery charging
monitoring, various battery gauges, and other similar low
voltage applications that require simple and reliable current
monitoring.
On-board
modules
FAN4010, a high-side current sensor by ON Semiconductor
(formerly Fairchild); MCP3001, a 10-bit A/D converter (ADC)
with SPI interface; MCP1501-20 IC, a high-precision, buffered
voltage reference of 2.048V, both from Microchip.
Key Features
A very low series resistance, high-side sensing approach with no
shunt resistor that disturbs the GND reference, highly accurate
10-bit A/D converter, combined with the precise voltage
reference source.e
Interface
SPI
Input
Voltage
5V
Pinout diagram
This table shows how the pinout on Current 2 Click corresponds to the pinout
on the mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
NC
1
AN
PWM
16
NC
NC
2
RST
INT
15
NC
NC
3
CS
RX
14
NC
CS
4
SCK
TX
13
NC
SPI Data OUT
SDO
5
MISO
SCL
12
NC
SPI Data IN
SDI
6
MOSI
SDA
11
NC
SPI Chip Select
Notes
Ground
NC
7
3.3V
5V
10
5V
GND
8
GND
GND
9
GND
Power Supply
Ground
Onboard settings and indicators
Label
Name
Default
Description
LD1
PWR
-
Power LED indicator
TB1
-
-
Load connector
Software support
We provide a library for the Current 2 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
Library offers a choice to get 10bit result from the AD converter as one
sample result or averaged result with desired number of samples. Result
from the ADC can be calculated to get current in a proper value [mA],
depending on the RSENSE, ROUT and VREF on the Current 2 Click board. For
more details check documentation.
Key functions:
uint16_t current2_getADC( void ) - Function returns 10-bit digital value from the AD
uint16_t current2_getAverageADC( uint8_t nSamp ) - Function returns averaged result from
uint16_t current2_getCurrent( uint8_t nSample ) - Function reads averaged result from the
converter.
the AD converter.
ADC and performs a calculations to get current in proper value [mA].
Examples description
The application is composed of the three sections :
System Initialization - Initializes peripherals and pins.
Application Initialization - Initializes SPI interface in Mode 0.
Application Task - (code snippet) - Reads the current averaged result of 20 samples and gets
this result in a proper value [mA]. Repeats the current reading every 500ms.
void applicationTask()
{
current = current2_getCurrent( 20 );
WordToStr( current, text );
mikrobus_logWrite( "Current : ", _LOG_TEXT );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( " mA", _LOG_LINE );
Delay_ms( 500 );
}
The full application code, and ready to use projects can be found on
our LibStock page.
Other mikroE Libraries used in the example:
Conversions
SPI
UART
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/current‐2‐click/1‐15‐19