This board is a simple carrier of Allegro’s CT220BMV-HS5 TMR-based, contactless current sensor, which measures the magnetic field of the current flowing through a nearby conductor without needing to be connected in series with the circuit.
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CT220 Contactless Current Sensor Carrier, bottom view with dimensions.
We are offering these breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their CT220 tunneling magnetoresistance (TMR), contactless current sensors; we therefore recommend careful reading of the CT220 datasheet (2MB pdf) before using this product. The following list details some of the sensors’ key features:
CT220BMV-HS5 Contactless Current Sensor Carrier ±1.5mT/15G. (1)
This carrier board features the CT220BMV-HS5, which has a magnetic field range of ±1.5 mT (±15 G). Its output sensitivity is 1500 mV/mT when VDD is 5 V (or 990 mV/mT when VDD is 3.3 V). This version can be visually distinguished from the other versions by a marking that starts with AC printed on the sensor IC, as shown in the picture above (the silkscreen also has a blank white box that can be used for adding customised identifying markings).
| IC Part Number | Range | Supply Voltage | Sensitivity @ 5V | Zero Point @ 5V | Size |
|---|---|---|---|---|---|
| CT220BMV-HS5 | ±1.5 mT (bidirectional) | 2.7 V to 5.5 V | 1500 mV/mT | 2.5 V | 0.4″×0.62″ |
The sensor’s current range and current sensitivity depend on its distance from the conductor, along with other parameters like the conductor’s geometry and angle relative to the board. When the board is tied to a round wire as pictured below, the overall diameter of the wire (with insulation) will be the main factor, and these graphs can help you estimate the sensor’s range and sensitivity for wires of different thicknesses. However, you should calibrate the sensor in your particular setup for best results (see Converting the sensor output into a current reading below).
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This CT220 carrier board is designed to measure a current running parallel to the long axis of the board, which generates a magnetic field forming concentric circles around the current conductor. Two pairs of slots along the sides of the board provide a good way to attach the board to a wire with small zip ties (cable ties) or similar fasteners.
CT220 Contactless Current Sensor Carrier attached to a wire with zip ties and connected with a 4-pin JST SH-style cable. |
Direction of magnetic field and current measured by a CT220 Contactless Current Sensor Carrier. |
The sensor requires a supply voltage of 2.7 V to 5.5 V to be connected across VDD and GND. The sensor outputs a ratiometric analogue voltage on OUT that is centred at VDD/2 and changes according to the magnetic field it senses.
When measuring current in a conductor on the same side of the board as the sensor (over the IC, such as with the sensor tied to a wire as shown above), current flowing in the direction of the red arrow in the picture above increases the output voltage, while current flowing in the opposite direction decreases the output voltage. If the conductor is instead on the opposite side of the board from the sensor (under the IC), these directions are flipped.
The FLAG pin is normally high and drives low when the magnetic field is above 90% or below 10% of the full field range.
These connections can be made through the board’s JST SH-style 4-pin connector, which works with our 4-pin JST SH-style cables, or with a set of through-holes that are spaced with a 0.1″ (2.54 mm) pitch and compatible with 0.1″ male headers and solderless breadboards.
Pinout of the CT220 Contactless Current Sensor Carrier.
To get accurate current readings from the CT220, it is necessary to calibrate it in your application setup. A simple way to do this involves the following two steps:
Then, given a voltage VOUT measured from the sensor, you can calculate the corresponding current with the gain a and offset b:
``\text {Current} = \frac {V_\text {OUT} – b} {a}``
To illustrate this with an example, let’s say you measure your sensor with no current flowing in the wire and get 2.5 V. Next, you put 10 A through your wire and measure the sensor voltage again, this time getting 2.8 V. That means the output voltage changed by 0.3 V for 10 A, so the sensitivity is 0.03 V/A, or 30 mV per A.
For better accuracy in bidirectional current applications, Allegro recommends a slightly more thorough calibration procedure that involves applying a known current in both directions; see the CT220 datasheet (2MB pdf) for details.
Schematic diagram of the CT220 Contactless Current Sensor Carrier.
The dimension diagram is available as a downloadable PDF (301k pdf).
We have a variety of current sensors available with different ranges, sensitivities, and features. The table below summarizes our selection of active and preferred options:
| CT220 ContactlessCurrent SensorCarriers | ACS3704xCurrent SensorMicro Carriers | ACS3704xCurrent SensorCompact Carriers | ACS711 CurrentSensor Carriers | ACS71240 CurrentSensor Carriers | ACS724 CurrentSensor Carriers | ACS37030Current SensorCompact Carriers | ACS37220Current SensorCompact Carriers | |
|---|---|---|---|---|---|---|---|---|
| Allegro Sensor | CT220xMV-HS5 | ACS3704x | ACS711KEXT | ACS71240 | ACS724LLCTR | ACS37220 | ACS37030 | |
| Sensing technology | XtremeSense™ TMR (tunneling magnetoresistance) |
Hall effect | Hall effect | Hall effect | Hall effect | Hall effect + inductive coil | Hall effect | |
| Logic voltage range | 2.7–5.5 V | 3.3V versions: 3.0–3.6 V 5V versions: 4.75–5.5 V |
3.0–5.5 V | 3.3V ver: 3.0–3.6 V 5V ver: 4.5–5.5 V |
4.5–5.5 V | 3.0–3.6 V | 3.3V ver: 3.15–3.45 V 5V ver: 4.5–5.5 V |
|
| Family current range | 10–800 A | 10–30 A | 15.5–31 A | 10–50 A | 2.5–50 A | 20–65 A | 100–200 A | |
| Range/sensitivity of individual versions | (2) ±1.5 mT / 1500 mV/mT ±15 mT / 150 mV/mT |
ACS37041: 3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A 5V Bidirectional: ±10 A / 200 mV/A ±30 A / 66.7 mV/A ACS37042: 3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A 5V Bidirectional: ±10 A / 200 mV/A ±30 A / 66.7 mV/A |
ACS37041: 3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A 5V Bidirectional: ±10 A / 200 mV/A ±30 A / 66.7 mV/A ACS37042: 3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A 5V Bidirectional: ±10 A / 200 mV/A ±30 A / 66.7 mV/A |
Bidirectional:(1) ±15.5 A / 90 mV/A ±31 A / 45 mV/A |
3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A ±50 A / 26.4 mV/A 5V Bidirectional: ±10 A / 200 mV/A ±30 A / 66 mV/A ±50 A / 40 mV/A 5V Unidirectional: 0–50 A / 80 mv/A |
5V Bidirectional:(2) ±2.5 A / 800 mV/A ±5 A / 400 mV/A ±10 A / 200 mV/A ±20 A / 100 mV/A ±30 A / 66 mV/A ±50 A / 40 mV/A 5V Unidirectional:(2) 0–5 A / 800 mv/A 0–10 A / 400 mv/A 0–20 A / 200 mv/A 0–30 A / 133 mV/A |
3.3V Bidirectional: ±20 A / 66 mV/A ±40 A / 33 mV/A ±65 A / 20.3 mV/A |
3.3V Bidirectional: ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A 5V Bidirectional: ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A |
| IC current path resistance | N/A | 1.6 mΩ | 0.6 mΩ | 0.6 mΩ | 0.6 mΩ | 0.7 mΩ | 0.1 mΩ | |
| PCB | N/A | 2 layers, 1-oz copper |
2 layers, 2-oz copper |
2 layers, 2-oz copper |
2 layers, 2-oz copper |
2 layers, 2- or 4-oz copper(3) |
2 layers, 2-oz copper |
2 layers, 2-oz copper |
| Max bandwidth | 30 kHz | 150 kHz | 100 kHz | 120 kHz | 120 kHz(4) | 5 MHz | 150 kHz | |
| Size | 0.4″ × 0.62″ | 0.3″ × 0.4″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ |
| Overcurrent fault output |
User-configurable threshold | |||||||
| Common-mode field rejection | ||||||||
| Nonratiometric output | ||||||||
| 1-piece price | $4.95 | $4.15 – $4.69 | $4.45 – $4.99 | $4.85 | $5.25 | $9.95 – $11.49 | $11.95 | $6.95 |
Note 1: Sensitivity when Vcc = 3.3 V; actual sensitivity is ratiometric (i.e. it is proportional to Vcc).
Note 2: Sensitivity when Vcc = 5 V; actual sensitivity is ratiometric (i.e. it is proportional to Vcc).
Note 3: 50A version of this carrier uses 4-oz copper PCB; all other versions of this carrier use 2-oz copper.
Note 4: Bandwidth can be reduced by adding a filter capacitor.
| ACS37030Current SensorCompact Carriers | ACS37030Current SensorLarge Carriers | CT432/CT433 TMRCurrent SensorCompact Carriers | CT432/CT433 TMRCurrent SensorLarge Carriers | ACS72981Current SensorCompact Carriers | ACS72981Current SensorLarge Carriers | ACS37220Current SensorCompact Carriers | ACS37220Current SensorLarge Carriers | |
|---|---|---|---|---|---|---|---|---|
| Allegro Sensor | ACS37030 | CT432/CT433 | ACS72981xLR | ACS37220 | ||||
| Sensing technology | Hall effect + inductive coil | XtremeSense™ TMR (tunneling magnetoresistance) |
Hall effect | Hall effect | ||||
| Logic voltage range | 3.0–3.6 V | 3.3V versions: 3.0–3.6 V 5V versions: 4.75–5.5 V |
3.3V versions: 3.0–3.6 V 5V versions: 4.5–5.5 V |
3.3V versions: 3.15–3.45 V 5V versions: 4.5–5.5 V |
||||
| Family current range | 20–65 A | 20–70 A | 50–200 A | 100–200 A | ||||
| Range/sensitivity of individual versions | 3.3V Bidirectional: ±20 A / 66 mV/A ±40 A / 33 mV/A ±65 A / 20.3 mV/A |
3.3V Bidirectional: ±40 A / 33 mV/A ±65 A / 20.3 mV/A |
3.3V Bidirectional: ±20 A / 50 mV/A ±30 A / 33.3 mV/A ±50 A / 20 mV/A ±70 A / 14.3 mV/A 3.3V Unidirectional: 0–20 A / 100 mv/A 0–30 A / 66.7 mv/A 0–50 A / 40 mv/A 0–65 A / 30.8 mv/A 5V Bidirectional: ±20 A / 100 mV/A ±30 A / 66.7 mV/A ±50 A / 40 mV/A ±65 A / 30.8 mV/A 5V Unidirectional: 0–20 A / 200 mv/A 0–30 A / 133.3 mv/A 0–50 A / 80 mv/A 0–70 A / 57.1 mv/A |
3.3V Bidirectional: ±50 A / 20 mV/A ±70 A / 14.3 mV/A 3.3V Unidirectional: 0–50 A / 40 mv/A 0–65 A / 30.8 mv/A 5V Bidirectional: ±50 A / 40 mV/A ±65 A / 30.8 mV/A 5V Unidirectional: 0–50 A / 80 mv/A 0–70 A / 57.1 mv/A |
3.3V Bidirectional:(1) ±50 A / 26.4 mV/A ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A ±200 A / 6.6 mV/A 3.3V Unidirectional:(1) 0–50 A / 52.8 mv/A 0–100 A / 26.4 mv/A 0–150 A / 17.6 mv/A 0–200 A / 13.2 mv/A 5V Bidirectional:(2) ±50 A / 40 mV/A ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A 5V Unidirectional:(2) 0–50 A / 80 mv/A 0–100 A / 40 mv/A 0–150 A / 26.7 mv/A |
3.3V Bidirectional:(1) ±50 A / 26.4 mV/A ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A ±200 A / 6.6 mV/A 3.3V Unidirectional:(1) 0–50 A / 52.8 mv/A 0–100 A / 26.4 mv/A 0–150 A / 17.6 mv/A 0–200 A / 13.2 mv/A 5V Bidirectional:(2) ±50 A / 40 mV/A ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A 5V Unidirectional:(2) 0–50 A / 80 mv/A 0–100 A / 40 mv/A 0–150 A / 26.7 mv/A |
3.3V Bidirectional: ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A 5V Bidirectional: ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A |
3.3V Bidirectional: ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A 5V Bidirectional: ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A |
| IC current path resistance | 0.7 mΩ | 1 mΩ | 0.2 mΩ | 0.1 mΩ | ||||
| PCB | 2 layers, 2-oz copper |
6 layers, 2-oz copper |
2 or 4 layers(3), 2-oz copper |
6 layers, 2-oz copper |
6 layers, 2-oz copper |
6 layers, 2-oz copper |
2 layers, 2-oz copper |
6 layers, 2-oz copper |
| Max bandwidth | 5 MHz | 1 MHz | 250 kHz | 150 kHz | ||||
| Size | 0.7″ × 0.8″ | 1.4″ × 1.2″ | 0.8″ × 1.1″ | 1.4″ × 1.2″ | 0.7″ × 0.8″ | 1.4″ × 1.2″ | 0.7″ × 0.8″ | 1.4″ × 1.2″ |
| Overcurrent fault output |
User-configurable threshold | |||||||
| Common-mode field rejection | ||||||||
| Nonratiometric output | ||||||||
| 1-piece price | $11.95 | $14.95 | $12.95 | $16.95 | $13.95 | $16.95 | $6.95 | $10.95 |
Note 1: Sensitivity when Vcc = 3.3 V; actual sensitivity is ratiometric (i.e. it is proportional to Vcc).
Note 2: Sensitivity when Vcc = 5 V; actual sensitivity is ratiometric (i.e. it is proportional to Vcc).
Note 3: 50A and higher versions of this carrier use a 4-layer PCB; all other versions of this carrier use a 2-layer PCB.
You can also use the following selection box to see these options sorted by current range:
Alternatives available with variations in these parameter(s): current range Select variant…
| Size: | 0.4″ × 0.62″ × 0.2″ |
|---|---|
| Weight: | 0.4 g |
| Magnetic field sensitivity: | 1500 mV/mT1 |
|---|---|
| Minimum logic voltage: | 2.7 V |
| Maximum logic voltage: | 5.5 V |
| Supply current: | 1.2 mA2 |
| Magnetic field range: | -1.5mT to +1.5mT |
| Current sensor: | Allegro CT220BMV-HS5 |
| PCB dev codes: | cs11a |
|---|---|
| Other PCB markings: | 0J15332 |
This DXF drawing shows the locations of all of the board’s holes.
Allegro product page for the CT220, where you can find application notes and other resources.
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