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Product description: Current sensor ACS709 -75A to + 75A - Pololu module
The module consists of a printed circuit board made for the AllegroACS709LLFTR-35BB-Tchip. The sensor works on the basis of the Hall effect. The system can be powered from the voltage range: 3.0 V to 5.5V. PinFAULT is set to high by default. It goes low when the measured current value exceeds the set threshold. The threshold value is selected by applying the appropriate voltage to the VOC pin. It depends on the value of the voltage divider resistors shown in the diagram below. By default, the threshold is set to 57 A but can be changed by adding an external resistor. Resetting the error flag (low state) on the FAULT pin is done by giving the low state to the FAULT_EN pin (by default pulled up to VCC). More details in thedocumentation.
Main features of the ACS709 current sensor -75A to + 75A
- The circuit is optimized for the current flowing in both directions from -37.5 A to 37.5 A with a linear measuring range from -75 to 75 A (please note the thermal limitsbelow).
- Due to the low resistance of the system (1.1 m Ohm) and the connections, the power losses are very small.
- Thanks to the use of the Hall effect, the current paths are isolated from the logical part.
- Bandwidth up to 120kHz with the possibility of reduction by adding an optional capacitor
- 2% precision at room temperature.
- Working temperature -40 ° C to 150 ° C.
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The maximum measured current depends on the duration of the measurement. For example: a current of 50 A can flow through the system for a maximum of 20 seconds without causing damage. After this time, the module reaches a temperature above 150 ° C. For the current above 30A, the manufacturer recommends the use of additional cooling. |
For proper operation of the sensor, it is enough to connect: the measured current(IP +andIP-), supply voltage 3V - 5.5V(VCCandGND) and the output(VIOUT). The remaining pins are optional, they are used to connect external capacitors, as shown in the picture above.
The output voltage is proportional to the strength of the measured current. The value is centered on VCC / 2. When powered by 5V the output voltage changes by 28mV to 1A of the measured current. The positive direction of the current increases the voltage value, while the negative direction decreases. The formula for the output voltage VOUT is as follows:
VIOUT = (0.028V / A * and + 2.5V) * VCC / 5V
TheVZCRpin is the voltage reference value for zero current flow (0 A). This value is approximately equal to VCC / 2, it allows you to precisely calculate the intensity of the measured current.
TheFILTpin allows you to connect an external Cf capacitor (between FILT and GND) to limit the bandwidth, by default set to 120kHz. For more information on external filtration, seeyour system documentation.
Specification
- Logic supply voltages: 3.0 V or 5.5 V
- Current consumption of the logical part: 11 mA
- Sensitivity for 3.3 V supply: 0.018 V / A
- Module weight 1.7 g
- Dimensions: 21 x 23 mm
