FAQ - CQ36 Series

A.
・An input current of 0A to the primary conductor ideally produces a data stream of 50% zeros of the time and 50% ones of the time. An input current of +INS(IP to IN) to the primary conductor produces a data stream of 8% zeros of the time and 92% ones of the time. An input current of -INS(IP to IN) to the primary conductor produces a data stream of 92% zeros of the time and 8% ones of the time. Full scale (F.S.) of output density is defined as 84%, which is the value between 8% and 92%(-INS to +INS) .
The relationship between the input current and the 16-bit code after Sinc3 filter is shown in Table 1.

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

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A.
・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-36xx 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-36xx is not damaged.

The linear sensing range is the current range in which the linearity of the current sensor output is guaranteed. When the current value exceeds the linear sensing range, the output saturates, but when the current value returns to within the linear sensing range, the output returns to normal.

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A.
・It is possible to flow current of up to 60Arms in CQ-36xx.

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A.
・CQ-36xx cannot detect unipolar current.

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A.
・ENOB depends on the OSR (oversampling ratio) and is as shown in the table below.

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A.
・The temperature drift of the primary conductor resistance of CQ-36xx is shown in Figure 2.

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A.
・The primary conductor resistance of CQ-36xx varies from 0.21 to 0.30mΩ (reference) at 25°C.

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A.
・The Primary Conductor Inductance of CQ-36xx is about 3nH (reference) at 25°C.

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A.
・This means that the output of the current sensor (Sensitivity and Zero-current output) is constant, even if the supply power voltage changed. CQ-36xx can detect without error, under the condition the supply power voltage is not stable.

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A.
・Figure 3 shows a recommended example of the power up sequence. In the power up sequence, if the time from AVDD=3.7V to AVDD=5V is less than 0.4msec, the output will be stabilized after 1.2msec (typ.) from the time VDD=3.7V.
DVDD can be input after AVDD go over 3.7V.
If it takes 0.4msec or more, it may take longer to stabilize the output. Please check the time needed to stabilize the output in that case.

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A.
・The response time of CQ-36xx is determined by the response time of the digital filter. The response time is defined as the time from the 90% arrival time of the input current change ΔIIN to the 90% arrival time of the output density change ΔDOUT.
Figure 4 (a) and (b) show the example response measurement results when OSR of Sinc3 filter is changed at CLK=20MHz for step current inputs of INS and -INS, respectively. The response time in Figure 4 (a) is calculated as the time from the 90% arrival point of the input current change ΔIIN = INS (+42%) to the 90% arrival point of ΔDOUT, i.e., the output density DOUT = 87.8% (= 50% + 42% * 0.9). The response time in Figure 4 (b) is calculated from the point where the input current change ΔIIN=-INS (-42%) reaches 90% to the point where ΔDOUT reaches 90%, i.e., the output density DOUT = 12.2% (= 50% - 42% * 0.9).

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A.
・Data delays occur and lead to inaccurate data capture.

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A.
・No, because CQ-36xx does not contain magnetic material.

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A.
・CQ-36xx is certified as IEC/UL 62368-1, UL 1577 by the international certification organization.

· IEC/UL 62368-1 Audio/video, information and communication technology equipment Part 1: Safety requirements Edition 2. (File No. E359197)
· CAN/CSA C22.2 No. 62368-1-14, 2nd Ed, Issued: 2014-12-01 (Audio/video, information and communication technology equipment Part 1: Safety requirements) (File No. E359197)
· UL1577 Non-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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A.
・The clearance distance and the creepage distance are both over 8.0mm.

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A.
・The Comparative Tracking Index (CTI) of the CQ-36xx package resin is 400V≦CTI<600 (PLC=1). The Material Group is Ⅱ.

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A.
・CQ-36xx can be used under the following conditions.

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A.
・No, it cannot be used under the conditions that exceed the isolation voltage. We cannot guarantee characteristics of the CQ-36xx. The device should be used under the recommended condition.

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A.
・The recommended land pattern is shown in Figure 5 and Table 5.

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A.
・Please see the application notes (2. Board Design Guidelines) here.

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A.
・Yes, please download from: Gerber Files.

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A.
・We show an example of the external circuit when using CQ-36xx in Figure 6. This is just an example and there are other possible circuits. Please evaluate your external circuit by yourself.

(a) Please place a 1μF bypass capacitor as close as possible to the AVDD, DVDD, and VSS pins of CQ-36xx.
(b) Insert a 1μF capacitor between the REFC pin and VSS for output stabilization.

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A.
・It is possible to flow current up to 60Arms (maximum primary current) in CQ-36xx, even larger current in case of transitional. When the CQ-36xx is used under the safety standard UL61800-5-1 conditions, please make sure the case temperature (Tc) does not exceed 130°C due to heat generated by primary current. Please refer to the Figure 7 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.

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A.
・CQ-36xx has the ESD tolerance which is more than 2000V at human body model (HBM) and more than 750V at Charged Device Model (CDM).

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A.
・There are two Hall elements inside CQ-36xx. Those Hall elements are connected in a differential manner. By detecting the difference of these two Hall elements' outputs, CQ-36xx 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 magnetic field and is reduced from the output of CQ-36xx 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 CQ-36xx, the output will have additional error of 0.01A = 10mA equivalent. 
- CQ-36x1: Sensitivity = 4%/A, Error = 10mA → Output error = 0.04%
- CQ-36x6: Sensitivity = 0.25%/A, Error = 10mA → Output error = 0.0025%

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 to the CQ-36xx may cause this. The extent of the error will depend on the layout of the current trace, actual current, distance from the CQ-36xx, and the part number (sensitivity). Figure 8 shows examples of nearby current paths. The current trace path IA has the least effect among these paths. Figure 9 shows some simulated examples of output error caused by nearby currents as shown in Figure 8.
Example: When a current carrying trace that runs close the CQ-36xx of 10A, the output will have additional error of 0.24%F.S. (IB) / 0.16%F.S. (IC).
- CQ-36x1: F.S. = ±10.5Apk, Error = 50mA (IB) / 34mA (IC)
- CQ-36x6: F.S. = ±168Apk, Error = 400mA (IB) / 270mA (IC)
*The current trace path IA has little effect on CQ-36xx.

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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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A.
・The following graphs show the changes in characteristics when the ambient temperature changes from 25°C to -40°C and 125°C.
Figure 10 shows the temperature drift of sensitivity, Figure 11 shows the temperature drift of zero-current output, and Figure 12 shows the temperature characteristics of total accuracy.
These graphs show “Average” and “Average ±3σ” of the actual result in a certain lot.

Please note that there is a difference between the definition of “Average” and that of “Typical” in the datasheet. “Typical” equals “Average” ±1σ.

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A.
・CQ-36xx are halogen-free/RoHS.

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A.
・CQ-36xx are Pb-free.

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A.
・The primary conductor is made from copper.

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A.
・The thermal resistance (θja) of CQ-36xx is 29°C/W when using the board shown in Figure 13.

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

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A.
・It is possible to provide the customized product, depending on quantity conditions and your requirement. Please contact us.

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A.
・The Zero-Current Output of the CQ-36xx may drift over time within the values defined in datasheet Section 15.
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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A.
・The CQ-36xx output can be affected by magnetic devices (mechanical relays, transformers, etc.) that are nearby.
In the case where magnetic devices must be placed close to the CQ-36xx, please check the effect on sensitivity or other characteristics and make sure any effects are understood and mitigated as much as possible.

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A.
・You can use the Sinc filter.

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A.
・There are two types of CLK: input and output.
CLK input type: CQ-360x (20MHz), CQ-362x (10MHz)
CLK output type: CQ-361x (20MHz), CQ-363x (10MHz)

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A.
・Please refer to Figure 14 below.
CQ-36xx DOUT changes at the rising edge of CLK.
Please perform data acquisition at the falling edge of CLK.

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