CQ-330x Series Current Sensors Frequently Asked Questions


【About Measuring Current】

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

It is possible to sense both DC current and AC current.

2. What is the difference between maximum primary current and linear sensing range?

Maximum primary current indicates the current value which can be applied for a long time in a current sensor and depends on the cross-sectional area of the primary conductor. CQ-330x 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 order, such as an over current, CQ-330x is not damaged (see also Question 3).
Linear sensing range is the 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 a normal operation when the current value returns within the linear sensing range.

3. How much pulse current can be flown in CQ-330x?

It has been confirmed by an experiment in AKM labo that CQ-330x did not break under pulse current conditions of Table 1.

 

 Table 1. Sustainable Pulse Current Condition*

Current Amplitude[A] 

Pulse Duration[ms] 

Duty Cycle[%] 

Maximum Quantity
of Pulses Allowed 

 60

 1000

 10

Unlimited

 110

 20

 10

Unlimited

 260

 6

 1

Unlimited

 *The data in this table is valid at Ta = 25°C only, and were obtained using one sample mounted on the AKM CQ-330x evaluation board.

 

4. How much current can be flown in CQ-330x?

It is possible to flow current of up to 20Arms in CQ-330x.

5. Can CQ-330x detect unipolar current? (e.x. current detection of 0 to 21A)

Please contact us if you require a unipolar detection version.
Please access here to contact us.

 

6. How small  current can the CQ-330x resolve?

The current resolution is determined by its output noise voltage. The current resolution can be increased by applying a noise filtering circuit.
Examples of current resolution with filtering circuits are provided in table 2. 

 

 Table 2. CQ-3301(Vh=195mV/A) Current Resolution
versus Filter Bandwidth*

 Pk-Pk Noise [mV]

 Current Resolution [mA]

 CF [nF]

R[kΩ] 

BW [kHz] 

 9.6

 49 

1000 

 7.5

38

0.47 

 1 

339 

 5.2

27

4.7

1

34

 3.6

18

4.7

10

3

*N=1


 

【About Primary Conductor】

7. How much is the temperature drift of the primary conductor resistance of CQ-330x?

The temperature drift of the primary conductor resistance of CQ-330x is shown in Figure 1.

 

 

Figure 1. The Temperature Drift of the Primary Conductor Resistance with Reference to the Resistance at 25°C

 

【About Sensor Output】

8. 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 offset voltage of AKM current sensors have the ratiometric characteristics.
Recommended circuit is shown in Figure 2.

 

Figure 2. Recommended external circuits of CQ-330x

 

 

9. How soon after power-on will a valid signal be available from the CQ-330x?

The typical time when CQ-330x reach to valid output is given in Table 3 and in Figure 3 (Iin = 0 A, VDD = 5 V) and Figure4 (Iin = 21 A, VDD = 5 V).
We recommend a 3X to 5X safety margin to account for power-on time variation over process and temperature ranges.

Table 3. CQ-330x Input Current versus Power-On Time

  Iin (A)  

Ton (μs)

 0

 21

 21

 21

 

 

Figure 3. Startup Waveform of CQ-330x with (IIN = 0 A) .

 

Figure 4. Startup Waveform of CQ-330x (IIN = 21 A).

 

 

10. What is the frequency characteristics of CQ-330x?

The graph in Figure 5 shows the typical frequency characteristics of the CQ-330x.
The plot on the top shows the amplitude and the plot on the bottom shows the phase delay.


Figure 5. Frequency Characteristics of the CQ-330x

 

 

11. What is the response time?

Response time is TYP 0.5μs.(In the case of load capacity of 100pF)

 

12. What is the response time of VOUT from deep saturation?

The VOUT response time of CQ-3300 from deep saturation was less than 1 µs by AKM measurement. Figure 6 shows the transient response waveform of CQ-3300.


Figure 6  The CQ-3300 Transient Response Waveform from the VOUT Deep Saturation.
 

 

13. What happens if a load capacitance over 100pF is inserted to the CQ-330x VOUT?

CQ-330x do not output the correct value because of the oscillation of output. It is no problem if resistance is inserted between the output and load capacitance, such as a low-pass filter.

 

14. What happens if a load current over +/-0.5mA is applied to CQ-330x VOUT?

CQ-330x do not output the correct value because output of CQ-330x cannot drive the load.

 

【About Insulation Performance】

15. What safety standards CQ-330x have?

CQ-330x have been certified with IEC/UL-60950 and UL-508 by the international certification association.

 

16. How much are the clearance distance and the creepage distance?

The clearance distance and the creepage distance are both over 5.0mm.

 

17. What is the CTI of the package?
The CTI value of the package of CQ-330x is 600V (under the condition of sample thickness = 3.0mm).

 

18. How much is the isolation voltage of CQ-330x?

CQ-330x can be used under the following conditions.


System
Voltage
Overvoltage category
Basic
Isolation
1000600300150(Vrms)
Reinforced
Isolation
600300150100

Working
Voltage
Pollution Degree
12

3
Basic
Isolation
14501000400 (Vrms)
Reinforced
Isolation
828500200


19. Is it allowable to use this device over the rating isolation voltage of the data-sheet?
The device should be used within a recommended condition.


20. How will capacitive coupling between the primary conductor in the CQ-330x and the Hall sensor affect the sensor output?
The current path noise rejection ratio test is conducted by injecting a high-frequency sinusoidal signal onto the primary conductor.
The signal coupling onto the output of the Hall-effect device is then measured.
The CQ-330x have a high noise rejection ratio as shown in Table 4.
Figure 7 shows frequency characteristics of noise rejection ratio.

 

Table 4. Typical Capacitive Coupling of 20 Vp-p Signal on the Sensed Current Path

   Frequency (MHz)   

  Vout (mVpp)  

   Noise Rejection (dB)   

 5

 54

 -51

 10

88

 -47

 15

166

 -42

 20

388

 -34

  

 

Figure 7. CQ-330x Noise Rejection Ratio versus Noise Frequency

 

 


【About Board / Circuit design】

21. How do I connect thermal radiation pin(TAB1, TAB2)?

Please layout the thermal radiation pattern to be larger , while ensuring the necessary creepage distance and clearance distance between the primary side.
The recommended circuit shown in Figure 8 (Please refer to Question 24).

 

Figure 8 CQ-330x Recommended Circuit Diagram 

 

 

22. What are the constant parameters of RC?
Please decide the parameters considering the requirement of output resolution and response time (Please refer to Question 6).


23. How should I solder the CQ-330x to the board?

Please refer to "Soldering condition".

 

24. Is there the recommended land pattern?

Yes.The recommended land pattern is shown in Figure 9.

 

 Figure 9. Recommended Land Pattern of CQ-330x

 

25. Are there any other board layout guidelines of CQ-330x?

Please see the application notes (board layout guide) here.

 

26. Is gerber file of the evaluation board provided?

Yes, please download from: Gerber Files.


【About Various Tolerances】

27. What is the ESD tolerance?

CQ-330x have the ESD tolerance which is more than 2000V by human body model (HBM) and more than 200V by machine model (MM).

 

28. How much does CQ-330x have influenced from the other current line?
The influence from other current lines, as shown in Figure 10, depends on the applied current of the other current lines and the distance between the CQ-330x and the other current lines.
For example, if you want to reduce the error within 400mA caused by the other line where 20A current flows, you need to  separate the other current line to the distance of 6mm or more as a distance A, 5mm or more as a distance B. Please do not place magnetic materials near the CQ-330x to avoid their influences.

 

 

Figure 10 Influence from other Current Line of CQ-330x

 

 

29. Is there a way to estimate the temperature of CQ-330x?

It is possible to estimate the internal temperature measuring the diode characteristics of the IC. (Technical Resource:Estimated method of the CQ-330x IC internal temperature)

【About Package】

30. Are CQ-330x halogen-free/RoHS?

CQ-330x are halogen-free/RoHS. 

 

31. Are CQ-330x Pb-free?

CQ-330x are Pb-free.

 

32. What is the primary conductor made from?

The primary conductor is made from copper.

【Others】

33. Is it possible to use the internal EEPROM?

Sorry, internal EEPROM is not available.
Products will be shipped after the adjustment of EEPROM at factory test.

34. Is it possible to order the customized products?

It is possible to customize depending on quantity conditions and requirement.

 

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