FAQ - CZ3A Series

CZ3A Series

[Q0463]
・Is it possible to sense both DC current and AC current?
A.
・It is possible to sense both DC current and AC current.
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[Q0515]
・What is the difference between maximum primary current and linear sensing range?
A.
・Maximum primary current indicates the current value which can be flown for a long time in a current sensor and depends on the cross-sectional area of the primary conductor.
CZ-3Axx can be damaged when it has 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, CZ-3Axx will not be damaged.
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[Q0516]
・How much current can be flown in CZ-3Axx?
A.
・It is possible to flow current of up to 50Arms(maximum primary current)  in CZ-3Axx.
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[Q0517]
・Can CZ-3Axx detect unipolar current? (ex. Current detection of 0 to 21A)
A.
・CZ-3Axx can not detect only unipolar current. In that case, please consider CZ-372x.
Click here for details
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[Q0518]
・How much current resolution can the CZ-3Axx achieve?
A.
・Output noise affects the resolution of the measured current. It is possible to reduce the output noise by filter, and to increase the resolution depending on the filter characteristic.
Figure 1. External Circuits Example
Figure 1. External Circuits Example
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[Q0519]
・How big is the primary conductor resistance temperature drift of CZ-3Axx?
A.
・The primary conductor resistance temperature drift of CZ-3Axx is shown in Figure 2.
Figure 2. CZ-3Axx Temperature Drift of the Primary Conductor Resistance  (normalized at 25℃)
Figure 2. CZ-3Axx Temperature Drift of the Primary Conductor Resistance (normalized at 25℃)
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[Q0520]
・How big is the production tolerance in primary conductor resistance?
A.
・The production tolerance in primary conductor resistance is from 0.21 to 0.30mΩ at 25°C(reference value) .
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[Q0521]
・How big is the primary conductor inductance?
A.
・The Primary Conductor Inductance of CZ-3Axx is about 3nH (reference) at 25°C.
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[Q0522]
・What does "non-ratiometric" mean?
A.
・This means that the output of the current sensor(Sensitivity and Zero-current voltage) is constant, even if the supply power voltage changed.  CZ-3Axx can detect without error , under the condition the supply power voltage is not stable.
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[Q0523]
・How fast is the power-on time ?
A.
・Figure 3. shows a recommended example of the power up sequence.
In the power up sequence of CZ-3A0x, if the time from VDD=2.75V to VDD=3.3V is less than 0.87msec, the output will be stabilized after 0.87msec(typ.) from the time VDD=2.75V. If it takes 0.87msec or more, it may take longer to stabilize the output.
In the power up sequence of CZ-3AGx, if the time from VDD=2.75V to VDD=5.0V is less than 0.79msec, the output will be stabilized after 0.79msec(typ.) from the time VDD=2.75V. If it takes 0.79msec or more, it may take longer to stabilize the output.
Please check the time needed to stabilize the output in that case.
Figure 3. Recommended example of the power up sequence
Figure 3. Recommended example of the power up sequence
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[Q0524]
・How fast is the response time?
A.
・The response time of the CZ-3Axx is typically 1μs with 1000pF load capacitance. Figure 4 and  Figure 5 shows the pulse response waveform(N=1).
Figure 4. Rise response waveform (left), fall response waveform (right). CZ-3A04(Vh=48mV/A), Input current =25A.
Figure 4. Rise response waveform (left), fall response waveform (right). CZ-3A04(Vh=48mV/A), Input current =25A.
Figure 5. Rise response waveform (left), fall response waveform (right). CZ-3AG4(Vh=48mV/A), Input current =25A.
Figure 5. Rise response waveform (left), fall response waveform (right). CZ-3AG4(Vh=48mV/A), Input current =25A.
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[Q0525]
・What is the recovery time from a fully saturated output?
A.
・Figure 5 shows the transient response waveform of CZ-3Axx(N=1). The time from saturation to normal is about 2.5μs.
Figure 5. The CZ-3Axx Transient Response Waveform from the VOUT Deep Saturation. Test conditions:for saturation, IIN=25A; for linear VOUT, IIN=0A.
Figure 5. The CZ-3Axx Transient Response Waveform from the VOUT Deep Saturation. Test conditions:for saturation, IIN=25A; for linear VOUT, IIN=0A.
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[Q0526]
・What happens if a load capacitance over 1000pF is inserted to the CZ-3Axx VOUT?
A.
・CZ-3Axx does not output the correct value because of the oscillation of output.
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[Q0527]
・What happens if a load current over +/-2mA is applied to CZ-3Axx VOUT?
A.
・The CZ-3Axx does not output the correct value. Please use under the recommended operating conditions.
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[Q0528]
・Does CZ-3Axx show magnetic hysteresis?
A.
・No, because CZ-3Axx does not contain magnetic material.
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[Q0529]
・What safety standards CZ-3Axx have?
A.
・The CZ-3Axx has been certified with IEC/UL-62368 and UL-1577 by the international certification association.

・IEC/UL 62368-1, 2nd Ed, 2014-12-01 (Audio/video, information and communication technology equipment Part 1: Safety requirements) (File No. E359197)
・CAN/CSA C22.2 No. 62368-1-14, 2nd Ed-(Audio/video, information and communication technology equipment Part 1: Safety requirements) (File No. E359197)
・UL1577-Optical Isolators-Edition 5.(File No. E499004)
・CSA Component Acceptance Service No. 5A-Component Acceptance Service for Optocouplers and Related Devices (File No. E499004)
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[Q0530]
・What is the clearance distance and the creepage distance?
A.
・The clearance distance and the creepage distance are both over 8.0mm.
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[Q0531]
・What is the CTI of the package?
A.
・The Comparative Tracking Index (CTI) of the CZ-3Axx package resin is 600V. The Material Group is I.
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[Q0532]
・How much is the working voltage of CZ-3Axx?
A.
・CZ-3Axx can be used under the following conditions.
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[Q0533]
・Is it allowable to use this device over the rating isolation voltage of the data-sheet?
A.
・No, it cannot be used under the conditions that exceed the isolation voltage. We cannot guarantee characteristics of the CZ-3Axx. The device should be used under the recommended condition.
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[Q0534]
・What is the voltage noise rejection ratio?
A.
・The voltage noise rejection ratio of the primary conductor is calculated by measuring the output while a high frequency sine wave voltage is applied as the input noise to the primary conductor.
Table 4 shows the CZ-3Axx series having a good voltage noise rejection ratio.
Figure 6. shows the frequency dependency of the voltage noise rejection ratio.
Table 4. Voltage Noise Rejection Ratio when high frequency sine wave voltage
Table 4. Voltage Noise Rejection Ratio when high frequency sine wave voltage
Figure 6. CZ-3Axx Noise Frequency vs Voltage Noise Rejection Ratio
Figure 6. CZ-3Axx Noise Frequency vs Voltage Noise Rejection Ratio
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[Q0535]
・How do I decide the time constant value RC ?
A.
・Please decide the time constant value considering the requirement of output resolution and response time (Please refer to [Q0518]).
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[Q0536]
・How should I solder the CZ-3Axx to the board?
A.
・Please refer to "Soldering condition" described in Important notices page.
Click here for details
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[Q0537]
・Can I get the recommended land pattern?
A.
・Yes. The recommended land pattern is shown in Figure 7 & Table 5.
Figure 7. CZ-3Axx recommended land pattern
Figure 7. CZ-3Axx recommended land pattern
Table 5. CZ-3Axx recommended land pattern dimensions
Table 5. CZ-3Axx recommended land pattern dimensions
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[Q0538]
・Can I get the board layout guidelines of CZ-3Axx?
A.
・Please see the application notes (2. Board Design Guidelines) here.
Click here for details
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[Q0539]
・Can I get the gerber file of the evaluation board?
A.
・Yes, please download from: Gerber Files.
Click here for details
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[Q0540]
・Can I get the recommended circuit diagram to use the CZ-3Axx?
A.
・In this subsection, we show two examples of the external circuit when using CZ-3Axx. These are just examples and there are other possible circuits. Please evaluate your external circuit by yourself. 

Case1) Connecting a 3V A/D converter in the subsequent stage
Case2) Connecting an amplifier to change the reference voltage of the output or to change the sensitivity

Case1) CZ-3Axx+ADC(3V)
(a)0.1μF bypass capacitor should be placed close to VDD and VSS pins of CZ-3Axx.
(b)Add a low-pass filter to the VOUT pins if necessary. The R1 and C1 values should befixed in consideration of the time constant of the filter and load conditions.
(c)3.3V should be applied in case of CZ-3A0x. 5V should be applied in case of CZ-3AGx.

Case2) CZ-3Axx+Amplifier
(a)0.1μF bypass capacitor should be placed close to VDD and VSS pins of CZ-3Axx.
(b)R1 and R2 are resistors that decides the gain. The R0 value should be fixed inconsideration of the load condition. The R1 and R2 values should be fixed in consideration of the gain.
(c)3.3V should be applied in case of CZ-3A0x. 5V should be applied in case of CZ-3AGx.
Figure 8. External Circuit Example
Figure 8. External Circuit Example
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[Q0541]
・Can I get the recommended condition to use CZ-3Axx considering less heat generation?
A.
・It is possible to flow current up to 50Arms(maximum primary current) in CZ-3Axx, even larger current in case of transitional. When the CZ-3Axx is used under conditions compliant with the safety standard, please make sure the case temperature (Tc) does not exeed 130℃ due to heat generated by primary current. Please refer to the Figure 9. for the position to measure Tc. 
If the heat dissipation is not enough, using pad on vias may help. They can suppress heat generation without increasing the trace area, by thermally connecting the primary conductors to an inner or outer thermal layer directly.
Figure 9. Position to measure package case temperature
Figure 9. Position to measure package case temperature
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[Q0542]
・How big ESD does CZ-3Axx endure?
A.
・CZ-3Axx has the ESD tolerance which is more than 2000V at human body model (HBM) and more than 200V at machine model (MM). (Both are reference values.)
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[Q0543]
・What should I take care of the other current lines(stray magnetic field)?
A.
・There are two Hall elements inside CZ-3Axx connected in a differential manner. By detecting the difference of these two Hall elements’ outputs, CZ-3Axx reduces the effects of stray magnetic fields as a built-in common-mode rejection function. When the same magnetic field is applied to both Hall elements, this magnetic field is deemed to be the stray and is reduced from the output of CZ-3Axx by the ratio of Stray Magnetic Field Reduction (Ebc: 0.01A/mT Typ.).

Example: When a stray magnetic field of 1mT is applied to the CZ-3Axx, the output will have additional error of 0.01A=10mA equivalent.
-CZ-3A01: Sensitivity=120mV/A, Error=10mA → Output error=1.2mV
-CZ-3A07: Sensitivity=12mV/A, Error=10mA → Output error=0.12mV

On the other hand, when different magnetic fields are applied to each Hall element, this will appear as output error.
For example, a current carrying trace that runs close the CZ-3Axx may cause this. The extent of the error will depend on the layout of the current trace, actual current, distance from the CZ-3Axx, and the part number (sensitivity). Figure 11 shows some simulated examples of output error by the nearby current.
Figure 10. Examples of nearby current lines
Figure 10. Examples of nearby current lines
Figure 11. Output Error by nearby current
Figure 11. Output Error by nearby current
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[Q0544]
・Can I get a way to estimate the temperature inside CZ-3Axx?
A.
・The temperature of the primary current lead frame and the sensor inside the package are almost the same, the best estimated temperature would be of the primary current lead frame.
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[Q0545]
・How much effect does CZ-3Axx have on the electrical characteristics with respect to temperature drift?
A.
・The graphs below show the change in characteristics when the ambient temperature is changed from -40 ° C to 85 ° C.
Figure 12 shows temperature drift of sensitivity, Figure 13 shows temperature drift of zero-current output, and Figure 14 shows total accuracy.
All graphs show “Average” and “Average ±3σ” of the actual result in a certain lot.
Figure12. Temperature Drift of Sensitibity  (left), Figure 14. Temperature dependency of Total Accuracy  (right)
Figure12. Temperature Drift of Sensitibity (left), Figure 14. Temperature dependency of Total Accuracy (right)
Figure 13. Temperature Drift of Zero-current Output
Figure 13. Temperature Drift of Zero-current Output
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[Q0546]
・What kind of impact does CZ-3Axx's output have, when the sudden step voltage or the sudden pulse current are applied to the primary current pins?(dV/dt, dI/dt)
A.
・Figure 15. shows the dV/dt noise property of CZ-3Axx output voltage (VOUT), when 1kV is applied to the primary conductor at the rise time of 1μs. The yellow line shows the input voltage waveform and the green line shows the output voltage waveform. The convergence time of CZ-3A0x is as short as 2μs. The convergence time of CZ-3AGx is as short as 3μs. Please avoid this noise by adjusting the capture timing.

Figure 16(a). shows the output voltage (VOUT) of CZ-3A0x, when a 10A pulse is applied to the primary conductor with a pulse width of 1μs.
Figure 16(b). shows the output voltage (VOUT) of CZ-3AGx, when a 10A pulse is applied to the primary conductor with a pulse width of 2μs.
The yellow line shows the input current waveform and the green line shows the output voltage waveform.
The convergence time of CZ-3A0x is as short as 2μs.
The convergence time of CZ-3AGx is as short as 3μs.
Figure 15. dV/dt noise waveform (left: rise waveform, right: fall waveform)
Figure 15. dV/dt noise waveform (left: rise waveform, right: fall waveform)
Figure 16. dI/dt noise waveform
Figure 16. dI/dt noise waveform
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[Q0547]
・Is CZ-3Axx halogen-free?
A.
・CZ-3Axx is halogen-free.
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[Q0548]
・Are CZ-3Axx Pb-free?
A.
・CZ-3Axx are Pb-free.
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[Q0549]
・What is the primary conductor made from?
A.
・The primary conductor is made from copper.
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[Q0550]
・What is the thermal resistance of the package?
A.
・The thermal resistance (θja) of CZ-3Axx is 32°C/W when using the board shown in Figure 17.
Table 5. Thermal Resistance measurement board
Table 5. Thermal Resistance measurement board
Figure 17. Thermal Resistance measurement board
Figure 17. Thermal Resistance measurement board
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[Q0551]
・Is it possible to use the internal EEPROM?
A.
・Sorry, internal EEPROM is not available.
Products will be shipped after the adjustment of EEPROM at factory test.
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[Q0552]
・Is it possible to order the customized products?
A.
・It is possible to provide the customized product, depending on quantity conditions and your requirement. Please contact us.
Click here for details
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[Q0553]
・Can I get the recommended way to use the CZ-3Axx?
A.
・The Zero-Current Output of the CZ-3Axx may drift over time within the values defined in datasheet Section 14.
Therefore, in order to minimize this drift, we recommend calibrating the Zero-Current Output by software after the power-up time of the system when the measured current is zero.
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[Q0554]
・Can I get the recommended way to use the CZ-3Axx nearby the stray magnetic field components?
A.
・The CZ-3Axx output can be affected by devices including magnetic materials(mechanical relays, transformers, etc.)  nearby.
In the case those devices must be placed close to the CZ-3Axx, please check the effect on the CZ-3Axx current sensitivity or other characteristics. And please make sure that any bad characteristics are understood, and that your system does not have any critical effects.
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[Q0601]
・Is CZ-3Axx compliant with RoHS?
A.
・CZ-3Axx is compliant with RoHS.
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[Q0602]
・What is the overcurrent detection function?
A.
・When the primary current exceeds overcurrent detection threshold which you can set, OCD pin outputs an overcurrent detection digital signal. (Normal output: "H", Over current detection: "L")
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[Q0603]
・How do I use the overcurrent detection function?
A.
・Please see application note Appendix.
Click here for details
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[Q0604]
・How fast is the response time of overcurrent detection output?
A.
・Table 6 shows the  response time of overcurrent detection output of CZ-3A0x.  Table 7 shows the  response time of overcurrent detection output of CZ-3AGx.
Table 6.  Response time of overcurrent detection output of CZ-3A0x
Table 6. Response time of overcurrent detection output of CZ-3A0x
Table 7.  Response time of overcurrent detection output of CZ-3AGx
Table 7. Response time of overcurrent detection output of CZ-3AGx
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