CQ-209x Series Current Sensors Frequently Asked Questions

How much current can be flown in CQ-2 series?

It is possible to flow current of up to 20Arms in CQ-209x.

How much pulse current can be flown in CQ-2 series?

It has been confirmed by an experiment in AKM labo that CQ-2 series did not break at a pulse current of 500A, 100us.

What is the difference of maximum primary current and linear sensing range?

Maximum primary current indicates the current value which can be applied for a long time in current sensor and depends on the cross-sectional area of the primary conductor. CQ-2 series can be damaged when they have been used for a long time over the maximum effective current value. If current flows at a short period within msec, such as an over current, CQ-2 series is not damaged.
Linear sensing range is a current range where linear output of the current sensor is guaranteed. Output will be saturated when the current value exceeds the linear sensing range, and will return to normal output when the current value returns within the linear sensing range.

What is the difference between the lineups of CQ-2 series?

Please refer to the selection guide here.

What kind of packages does AKM use?

CQ-2 series use AKM's original package called AI-Shell which has a simple structure with case, the Hall sensor, magnetic core, and primary conductor.

Can CQ-2 series detect unipolar current? (e.x. current detection of 0 to 40A)

CQ-2 series can detect unipolar current. Moreover, there are product lineups which are specialized in unipolar detection such as CQ-206B and CQ-209B. Please select the product which is most suited to your requirements.

How small is a current resolution?

Current resolution of each product is shown in here.

What safety standards CQ-2 series have?

CQ-209x series are compliant with IEC-60950, but there is no plan to certificate them.

Are CQ-2 series compliant with halogen-free/RoHS?

CQ-2 series are compliant with halogen-free/RoHS.

Is it possible to sense both DC current and AC current?

They can sense both DC current and AC current.

What does "ratiometric" mean?

Ratiometric output means the output characteristic which varies in proportional to the power supply voltage. In the case that the output of a current sensor is captured by an A/D converter, ratiometric output can reduce the A/D conversion error due to variations of the reference voltage of A/D converter, by maiking reference voltage from the same power source as the current sensor. Both sensitivity and output voltage of AKM current sensors have the ratiometric characteristics.
Recommended circuit is shown in Figure 1.

Figure 1. Recommended external circuits of CQ-2 series

What is the ESD tolerance?

CQ-2 series have the ESD tolerance which is more than 2000V by human body model and more than 200V by machine model.

Do CQ-2 series support the Pb-free product?

CQ-2 series are compliant with Pb-free.

What happens if a load capacitance over 100pF is applied to CQ-2 series?

CQ-2 series do not output the correct value because of the oscillation of output. It is no problem to add a low-pass filter.

What happens if a load current over +/-0.5mA is applied to CQ-2 series?

CQ-2 series do not output the correct value because output of CQ-2 series cannot drive the load.

How should the board be soldered?

Please refer to "Soldering condition".

Is there the recommended land pattern?

Yes.The recommended land pattern is shown in the figure 2.

 Figure 2. Recommended Land Pattern of CQ-209x

Is gerber file of the evaluation board given?

Yes, download from: Gerber Files.

How is the die temperature taken?

The die temperature is estimated by using the direction characteristic of the diode in the IC.(Technical Resource:Estimated method of the CQ-2 series IC internal temperature)

Are there any other board layout guidelines of CQ-2 series?

With reference to a board layout guide, inductance and impedance of current course, please minimize them.

Does the lead include lead?

No, CQ-209x is Pb-free. And terminals are plated with tin of 100%.

What is the primary conductor made from?

The primary conductor is made from copper.

How soon after power-on will a valid signal be available from the CQ209x?

The typical time to valid output is given in table 1 and in figure 3 (Iin = 0 A, VDD = 5 V) and figure4 (Iin = 21 A, VDD = 5 V).
However, we recommend a 3X to 5X safety margin to account for power-on time variation over process and temperature ranges.

 Table 1. CQ209x Input Current versus Power-On Time

  Iin (A)  

Ton (µs)





 Figure 3. Startup of CQ209x with 0 A applied, then a VDD step from 0 to 5 V.


 Figure 4. Startup of CQ209x with 21 A applied, then a VDD step from 0 to 5 V.



How will capacitive coupling between the primary conductor in the CQ209x and the Hall sensor affect the sensor output?

The current path noise rejection test is conducted by injecting a high-frequency sinusoidal frequency onto the primary conductor. The signal coupling onto the output of the Hall-effect device is then measured.
The CQ209x family devices exhibit a high level of current path noise rejection as table 2 reveals.
In addition, figure 5 indicates performance as a function of frequency.

 Table 2. Typical Capacitive Coupling of 20 Vp-p Signal on the Sensed Current Path

  Frequency (MHz)  

Vout (mVpp)

  Noise Rejection (dB)  













 Figure 5. CQ209x noise rejection versus noise frequency



What is the frequency response of CQ209x?

The graph in figure 6 shows the results of the typical frequency response of the CQ209x.
The plot on the top is the amplitude response and the plot on the bottom is the phase response.

 Figure 6. Frequency response of the CQ209x



What does the characterization data look like at the sensor IC full linear sensing range?

Please see the graphs below for Temperature Drift of Sensitivity in figure 7, Temperature Drift of Offset Voltage in figure 8 and Total Error in figure 9.

 Figure 7. CQ209x Temperature Drift of Sensitivity to the sensitivity at 35°C (for reference, n=1)



 Figure 8. CQ2092 Temperature Drift of Offset Voltage from the offset voltage at 35°C (for reference, n=3)



 Figure 9. CQ209x Total Error



How much are clearance distance and the creepage distance?

Clearance distance and the creepage distance are all 2.0mm.

How much is the temperature drift of the primary conductor resistance of CQ209x?

The temperature drift of the primary conductor resistance of CQ209x are shown in figure 10.

 Figure 10. The temperature drift of the primary conductor resistance to the resistance at 25°C



Is the device used more than the rating isolation voltage of the data-sheet?

The device should be used with a recommended condition.

What is the response time?

Response time is 1μs.(In the case of load capacity of 100pF)

How many is the CTI of the package?

CQ-209x has Anti-tracking resistance of CTI200.

How many is constant number of R and C?

Add a low-pass filter (R and C) if it is necessary.

Is the data communication pin used?

The data communication pin is not used. The product is adjusted before shipment in AKM. Please contact us because there is possibility to be able to accommodate depending on volume.

What are materials of the cores?

Ferite core is used in CQ209x.


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