cq-330x/cq-320x application note · 7/16/2020 · (a) a 0.1μf bypass capacitor should be placed...

CQ-330x/CQ-320x Application Note (rev.5) -1/28-

CQ-330x/CQ-320x Application Note

September 11, 2020


Table of Contents

0. Overview..................................................................................................................................... 3

0.1. CQ-330x/CQ-320x ............................................................................................................. 3

1.1. Temperature drift characteristics .................................................................................... 6

1.2. Temperature Drift of Sensitivity ...................................................................................... 7

1.3. Temperature Drift of Zero-current Output .................................................................... 7

1.4. Temperature dependency of Total Accuracy ................................................................. 7

1.5. Resolution of measured current (Output Noise) .......................................................... 8

1.6. Voltage Noise Rejection Ratio .......................................................................................... 9

1.7. Temperature Drift of the Primary Conductor Resistance .......................................... 10

1.8. Variation of the Primary Conductor Resistance .......................................................... 10

1.9. Inductance of the Primary Conductor .......................................................................... 10

1.10. Evaluation board ............................................................................................................ 10

1.11. Response Time................................................................................................................ 11

1.12. Frequency Characteristic .............................................................................................. 12

1.13. dV/dt, dI/dt .................................................................................................................... 13

2. Board Design Guidelines ........................................................................................................ 14

2.1. External Circuits Example .............................................................................................. 14

2.2. Trace of the Primary Current ......................................................................................... 16

2.3. Trace of the signal paths ................................................................................................ 17

2.4. Thermal design ................................................................................................................ 19

2.5. Stray Magnetic Field Reduction Function ..................................................................... 20

3. Useful Tips ................................................................................................................................ 23

3.1. Supply Voltage ................................................................................................................. 23

3.2. Calibration of Zero-Current Output in initialization .................................................... 23

3.3. Startup............................................................................................................................... 23

3.4. Magnetic parts around .................................................................................................... 24

3.5. Heat Generation ............................................................................................................... 24

3.6. Sensitivity variation by internal heating ...................................................................... 24

3.7. Storage Environment ...................................................................................................... 25

3.8. Sensitivity and Zero-Current Output Drift by Reflow ................................................ 25

3.9. Maximum Primary Current and Linear Sensing Range ............................................. 26

3.10. Safety Standard ............................................................................................................. 27

3.11. Other information .......................................................................................................... 27

Disclaimer...................................................................................................................................... 28


0. Overview

This document is an application note to help use AKM’s current sensor

CQ-330x/CQ-320x series effectively.

This document consists of three sections;

1. Electric characteristics of the current sensor

2. Board design guideline

3. Useful tips

Figure1. A trademark of AKM coreless current sensor ＝ Currentier

0.1. CQ-330x/CQ-320x

Part number CQ-330x: VDD=5V CQ-320x: VDD=3.3V

Features Small-size Coreless Current Sensor

Applications Appliance, AC Motors, DC Motors.

Best fit for the applications that need isolation,

low heat and small size.

Market trend

CQ-330x/CQ-320x series are the coreless current sensor with small-size and high

galvanic isolation, especially designed for the currents range from 4.5A to ±44A. By

packaging the sensitive and the fast response Hall-effect sensor along with primary

current conductor in small VSOP package, the sensor shows good performance in small

sized inverter application. Further more, the product meets IEC/UL compliance, so it

can be used for industrial application.


1. Small Package

The CQ-330x/CQ-320x series has a small package（7.9×7.6×1.15mm） due to

AKM’s unique packaging. It enables us to achieve more than 5mm creepage and

clearance in a small configuration.

2. Ultra-fast High Response

CQ-330x/CQ-320x series has an ultra-fast high response 0.5μsec. It is suitable for

overcurrent applications.

3. Low heat generation, 20Arms, ±4.5～±44App

The CQ-330x/CQ-320x series has primary conductor resistance as low as 1.6mΩ due

to AKM’s unique packaging. This will reduce the heat generated by primary current

significantly compared to a shunt resistor, while allowing a continuous current flow of

20Arms.

Table1. CQ-330x series (VDD=5V)

Part # Pole Linear Sensing

Range(A)

Sensitivity

(mV/A)

Total

Accuracy

(%F.S.) *1

Response

time

(μs)

CQ-330G

Bi

polar

−4.5 4.5 450 ±2.2

0.5

CQ-3300 −6.4 6.4 325 ±1.3

CQ-3301 −10.7 10.7 195 ±1.3

CQ-3302 −21.0 21.0 100.0 ±1.3

CQ-330A −31.8 31.8 66.0 ±1.3

CQ-3303 −35.0 35.0 60.0 ±1.3

CQ-330H −42 42 50 ±1.3

CQ-330E

Uni

polar

0 20.5 200 ±2.2

CQ-330B 0 21.0 195 ±2.6

CQ-330J −2 42 82.7 ±2.6

CQ-330F −2 42 80.0 ±2.6

*1 Defined as the average value ±1 of the actual measurement results within a certain

lot at Ta=-40～90℃.


Table2. CQ-320x series(VDD=3.3V)


Range(A)

Sensitivity

(mV/A)

Total

Accuracy

(%F.S.) *1

Response

time

(μs)

CQ-3200

Bipolar

−8.5 8.5 155.0 ±1.3

0.5

CQ-3201 −10.1 10.1 130.0 ±1.3

CQ-3202 −21.1 21.1 62.5 ±1.2

CQ-320A −29.3 29.3 45.0 ±1.2

CQ-3203 −35.7 35.7 37.0 ±1.2

CQ-3204 −44.0 44.0 30.0 ±1.2

CQ-320B Unipolar -1.1 20.9 120.0 ±1.9


lot at Ta=-40～90℃.


1. Electrical Characteristics of the current sensor

1.1. Temperature drift characteristics

Figure 3. and Figure 4. show the temperature drift characteristics (Sensitivity, Zero-

current output, Total accuracy) of CQ-330x/CQ-320x series. The definitions of

characteristic are shown in section 1.2~1.4.

Table 3. Temperature drift characteristics CQ-330x (VDD=5V)


Range(A)

Temperature drift characteristics

Sensitivity

(％) *1

Zero-

current

output

(mV) *1

Total

Accuracy

(％F.S.) *1

CQ-330G

Bipolar

-4.5 4.5 ±2.2 ±38 ±2.2

CQ-3300 -6.4 6.4 ±1.4 ±26 ±1.3

CQ-3301 -10.7 10.7 ±1.4 ±16 ±1.3

CQ-3302 -21.0 21.0 ±1.4 ±10 ±1.3

CQ-330A -31.8 31.8 ±1.4 ±10 ±1.3

CQ-3303 -35.0 35.0 ±1.4 ±10 ±1.3

CQ-330H -42 42 ±2.3 ±10 ±1.3

CQ-330E

Unipolar

0 20.5 ±1.6 ±23 ±2.2

CQ-330B 0 21.0 ±2.1 ±19 ±2.6

CQ-330J -2 42 ±2.3 ±10 ±2.6

CQ-330F -2 42 ±2.3 ±10 ±2.6


lot at Ta=-40～90℃.


Table 4. Temperature drift characteristics CQ-320x (VDD=3.3V)


Range(A)

Temperature drift characteristics

Sensitivity

(％) *1

Zero-

current

output

(mV) *1

Total

Accuracy

(％F.S.) *1

CQ-3200

Bipolar

-8.5 8.5

±0.7

±10 ±1.3

CQ-3201 -10.1 10.1 ±9 ±1.3

CQ-3202 -21.1 21.1 ±7 ±1.2

CQ-320A -29.3 29.3 ±7 ±1.2

CQ-3203 -35.7 35.7 ±7 ±1.2

CQ-3204 -44.0 44.0 ±7 ±1.2

CQ-320B Unipolar -1.1 20.9 ±9 ±1.9


lot at Ta=-40～90℃.

1.2. Temperature Drift of Sensitivity

Temperature Drift of Sensitivity (Vh-d [%]) is defined as the change rate of Sensitivity

(Vh [mV/A]) when Operating Ambient Temperature (Ta [°C]) changes from 35°C to

Ta1(−40°C ≤ Ta1 ≤ 90°C);

1.3. Temperature Drift of Zero-current Output

Temperature Drift of Zero-current Output (Vof-d [mV]) is defined as the change of Zero-

current Output (Vof [V]) when Operating Ambient Temperature (Ta [°C]) changes from

25°C to Ta1(−40°C ≤ Ta1 ≤ 90°C);

Vof-d = Vof(Ta= Ta1) – Vof(Ta =35°C)

1.4. Temperature dependency of Total Accuracy

Total Accuracy (Etotal) is defined as follows;

𝐸𝑡𝑜𝑡𝑎𝑙 = 100 ×𝑉𝑒𝑟𝑟𝐹. 𝑆.

𝑉𝑒𝑟𝑟 = |𝑉ℎ−𝑚𝑒𝑎𝑠 − 𝑉ℎ| × |𝐼𝑁𝑆| + |𝑉𝑜𝑓−𝑑| + |𝜌𝑚𝑒𝑎𝑠| × 𝐹. 𝑆.

𝑉ℎ−𝑚𝑒𝑎𝑠 ：Measured Sensitivity [mV/A]

𝑉ℎ ：Typical Sensitivity [mV/A]

𝑉𝑜𝑓−𝑑 ：Measured Drift of Zero-current Output [mV]

𝜌𝑚𝑒𝑎𝑠 ：Measured Linearity Error [%F.S.]

𝑉ℎ−𝑑 = 100 × (𝑉ℎ(𝑇𝑎 = 𝑇𝑎1)

𝑉ℎ(𝑇𝑎 = 35℃)− 1)


1.5. Resolution of measured current (Output Noise)

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.

Table 5. Current resolution of CQ-330x (without filter, typical datasheet values)

Table 6. Current resolution of CQ-320x (without filter, typical datasheet values)

Part # Pole Sensitivity

[mV/A]

Linear

Sensing

Range

[A]

Output

noise

[mVpp]

Output

noise

[mVrms]

Input

Current

Equivalent

Noise

[mArms]

ENOB

[Bits]

CQ-330G

Bipolar

450 -4.5 4.5 24.4 3.7 8 8.3

CQ-3300 325 -6.4 6.4 17.8 2.7 8 8.8

CQ-3301 195 -10.7 10.7 10.6 1.6 8 9.6

CQ-3302 100 -21 21 7.3 1.1 11 10.1

CQ-330A 66 -31.8 31.8 5.3 0.8 12 10.6

CQ-3303 60 -35 35 4.6 0.7 12 10.8

CQ-330H 50 -42 42 4.6 0.7 14 10.8

CQ-330E

Unipolar

200 0 20.5 11.2 1.7 9 9.4

CQ-330B 195 0 21 11.2 1.7 9 9.4

CQ-330J 82.7 -2 42 5.9 0.9 11 10.2

CQ-330F 80 -2 42 5.9 0.9 11 10.1

Part # Pole Sensitivity

[mV/A]

Linear

Sensing

Range

[A]

Output

noise

[mVpp]

Output

noise

[mVrms]

Input

Current

Equivalent

Noise

[mArms]

ENOB

[Bits]

CQ-3200

Bipolar

155 -8.5 8.5 9.2 1.4 9 9.1

CQ-3201 130 -10.1 10.1 7.9 1.2 9 9.3

CQ-3202 62.5 -21.1 21.1 5.3 0.8 13 9.9

CQ-320A 45 -29.3 29.3 4.6 0.7 16 10.1

CQ-3203 37 -35.7 35.7 4.0 0.6 16 10.3

CQ-3204 30 -44 44 4.0 0.6 20 10.3

CQ-320B Unipolar 120 -1.1 20.9 7.92 1.2 10 9.3


Figure 2. External Circuits Example

(a) A 0.1μF bypass capacitor should be placed close to VDD and VSS pins of the device.

(b) Add a low-pass filter to VOUT pin if it is necessary. The RF and CF values should be

fixed in consideration of the time constant of the filter and load conditions.

1.6. Voltage Noise Rejection Ratio

The Voltage Noise Rejection Ratio of the Primary Conductor was calculated by measuring

the output while a high frequency sine wave voltage was applied as the input noise to

the primary conductor. Table 7. shows the CQ-330x/CQ-320x series having a strong

voltage noise rejection ratio. Figure 3. shows the frequency dependency of the voltage

noise rejection ratio.

Table 7. Voltage Noise Rejection Ratio when high frequency sine wave voltage

Frequency (MHz) VOUT (mVpp) Noise Rejection (dB)

5 54 -51

10 88 -47

15 166 -42

20 388 -34

Figure 3. CQ-330x/CQ-320x Noise Frequency vs Voltage Noise Rejection Ratio

-80

-70

-60

-50

-40

-30

-20

-10

0

5 10 15 20

Nois

e R

eje

cti

on

[d

B]

Noise Frequency [MHz]


1.7. Temperature Drift of the Primary Conductor Resistance

Figure 4. shows the temperature drift of the primary conductor resistance of

CQ-330x/CQ-320x. (reference)

Figure 4. CQ-330x/CQ-320x Temperature Drift of the Primary Conductor

Resistance

(normalized at 25℃)

1.8. Variation of the Primary Conductor Resistance

The primary conductor resistance of CQ-330x/CQ-320x varies from 1.2mΩ to 2.1mΩ

(reference) at 25°C.

1.9. Inductance of the Primary Conductor

The Primary Conductor Inductance of CQ-330x/CQ-320x is about 2.7nH (reference) at

25°C.

1.10. Evaluation board

Figure 5. shows the evaluation board which is used for derating curve of

CQ-330x/CQ-320x shown in Chapter “3.5 Heat Generation”. Table 8. shows the condition

of CQ-330x/CQ-320x evaluation board.

Table 8. Evaluation board

Board size 42.0mm×35.5mm

Number of layer 2 layers

Copperlayer thickness 70μm /layer

Board thickness 1.6mm


・Face(1st layer) ・Tail(2nd layer)

Figure 5. CQ-330x/CQ-320x evaluation board

1.11. Response Time

The response time of CQ-330x/ CQ-320x is typically 0.5μs with a load capacitance of

100pF. Figure 6. shows the typical pulse response waveform of CQ-330x.

Part #：CQ-330H Vh=50mV/A

IIN=25A, Rise and fall response time is about 0.5µs.

Figure 6. CQ-330H Rise response waveform (left), fall response waveform(right).

Figure 7. shows the typical pulse response waveform of CQ-320x.

Part #：CQ-3204 Vh=30mV/A

IIN=25A, Rise and fall response time is about 0.5µs.

Figure 7. CQ-3204 Rise response waveform (left), fall response waveform(right).

IIN

VOUT

1us

IIN

VOUT

1us

IIN

VOUT

1μs

IIN

VOUT

1μs


1.12. Frequency Characteristic

The graph in Figure 8. shows the typical frequency characteristics of

the CQ-330x/CQ-320x(N=1).

(a)Gain Characteristic

(b) Phase Characteristic

Figure 8. Frequency Response of the CQ-330x/CQ-320x

-10

-5

0

5

1K 10K 100K 1M

Gain

[d

B]

Frequency [Hz]

-135

-90

-45

0

1K 10K 100K 1M

Ph

ase [

deg]

Frequency [Hz]


1.13. dV/dt, dI/dt

Figure 9. shows the dV/dt noise property of CQ-330x/CQ-320x output voltage (VOUT),

when 1kV is applied to the primary conductor at the rise time of 1.5μs. The yellow line

shows the input voltage waveform and the green line shows the output voltage waveform.

The convergence time is as short as 1.5μs. Please avoid this noise by adjusting the

capture timing.

Figure 9. dV/dt noise waveform (left: rise waveform, right: fall waveform)

Figure 10. shows the output voltage (VOUT) of CQ-330x/CQ-320x, when a 4.5A pulse is

applied to the primary conductor with a pulse width of 1μs. The yellow line shows the

input current waveform and the green line shows the output voltage waveform. The

convergence time is as short as 1.5μs.

Figure 10. dI/dt noise waveform


2. Board Design Guidelines

2.1. External Circuits Example

In this subsection, we show three examples of the external circuit when using CQ-

330x/CQ-320x. These are just examples and there are other possible circuits. Please

evaluate your external circuit by yourself.

Case1) Connecting a 5V A/D converter in the subsequent stage (CQ-330x:VDD=5V)

Case2) Connecting a 3.3V A/D converter in the subsequent stage (CQ-320x:VDD=3.3V)

Case3) Connecting an amplifier to change the reference voltage of the output or to

change the sensitivity

Case1) CQ-330x + ADC(5V)

Figure 11. External Circuit Example 1

(a) 0.1μF bypass capacitor should be placed close to VDD and VSS pins of CQ-330x.

(b) Add a low-pass filter to VOUT pin if it is necessary. The RF and CF values should be fixed

in consideration of the time constant of the filter.


Case2) CQ-320x+ADC(3.3V)


(a) 0.1μF bypass capacitor should be placed close to VDD and VSS pins of CQ-320x.

(b) Add a low-pass filter to VOUT pin if it is necessary. The RF and CF values should be fixed

in consideration of the time constant of the filter.

Case3) CQ-330x/CQ-320x+Amplifier


(a) 0.1μF bypass capacitor should be placed close to VDD and VSS pins of CQ-330x/CQ-320x.

(b) R1 and R2 are resistors that decides the gain. The R0 value should be fixed in consideration

of the load condition. The R1 and R2 values should be fixed in consideration of the gain.


2.2. Trace of the Primary Current

2.2.1. Width and Length of the Primary Current Trace

Please design the trace of the primary current for CQ-330x/CQ-320x wider in the width

and shorter in the length to make the trace resistance small and to prevent overheating.

And, please refer to Figure14. and Table 9. for the recommended footprint.

Figure 14. CQ-330x/CQ-320x recommended land pattern

Table 9. CQ-330x/CQ-320x recommended land pattern dimensions

L 1.42

E 7.62

W1 3.60

W2 1.65

W3 0.35

C 0.30

P 0.65

Unit：mm

2.2.2. The Configuration of the Trace

The traces of primary conductors are recommended to be drawn left to right straightly

(See Figure. 15a). When the traces cannot be drawn left to right because of the restriction

of the board layout, the traces should be drawn toward the opposite side of signal pins

(Figure. 15b). Please be aware that sensitivity is slightly different by ~1% between Figure.

15a and Figure.15b. If the traces are drawn toward the signal pins, the sensitivity of the

current sensor will change by ~8% at worst because of the interference of the curved

traces (Figure.15c). This layout is also not recommended from a viewpoint of the

interference to the signal paths.


Figure 15. How to trace the primary conductor of CQ-330x/CQ-320x

2.2.3. Direction of the primary current

The user needs to know the direction of the current flow in the primary conductor to

detect the correct output. In case of the trace shown in the

Figure 6, the output of the CQ-330x/CQ-320x decreases as current flows from right to

left and increases from left to right.

Figure 16. The relationship between the output of CQ-330x/CQ-320x

and the direction of the primary current

2.3 Trace of the signal paths

Please refer to the followings for pin names of CQ-330x/CQ-320x.

Figure 17. CQ-330x/CQ-320x Pin configuration

(a) VOUT > Vof (b) VOUT < Vof

CQ-3xxx CQ-3xxx

CQ-3xxx

320x

CQ-3xxx

320x

CQ-3xxx

(a)Straight

(recommended)

(b) Away from the

signal paths

(recommended)

(c) Toward the signal paths

(Not recommended)


Table 10. Pin functions of CQ-330x/CQ-320x

No. ピン名 I/O 機能

1 TAB1 - Thermal radiation pin, recommended to connect to GND

2 TEST1 - Test pin, recommended to connect to GND

3 VDD PWR Power supply pin, 5V:CQ-330x / 3.3V:CQ-320x

4 TEST2 - Test pin, recommended to connect to VDD

5 VSS GND Ground pin (GND)

6 VOUT O Analog output pin

7 TEST3 - Test pin, recommended to connect to VDD

8 TAB2 - Thermal radiation pin, recommended to connect to GND

9 N I Primary conductor pin(+)

10 P I Primary conductor pin(-)

2.3.1. Length and width of the signal paths

We recommend making the traces of VDD and VOUT signals as wide and short as possible

to avoid electrical noise from external capacitive coupling.

2.3.2. Noise filtering

In order to reduce the noise superimposed on the power line, we recommend placing a

0.1µF by-pass capacitor between VDD and VSS pins as close to those pins as possible. By

adding an electrolytic capacitor with larger capacitance in parallel, it will reduce the

effect of the instant voltage drop of the power supply.

In case that large noise is superimposed on the output, adding a low pass filter to the

VOUT pin may provide improvement. When adding a low pass filter, please consider the

time constant to meet the required response time.

2.3.3. Connection to GND

Generally, in an inverter circuit board, GND of power line and that of signal line are

isolated from each other in order to avoid malfunction of the MCU due to noise. Please

connect the VSS pin of CQ-330x/CQ-320x to the GND of signal line.

2.3.4. Insulation design

The clearance and creepage between the primary conductor and the signal paths are

more than 5mm. The Comparative Tracking Index (CTI) of the CQ-330x/CQ-320x

package resin is 600V, The Material Group is I. Table 11. shows the Working Voltage of

CQ-330x/CQ-320x.

In order to maximize the insulation withstanding voltage of CQ-330x/CQ-320x, please

keep enough distance between traces of the primary conductor and the signal paths. In

case that there is a specific standard required for the system, please design the


clearance and creepage to meet that requirement.

If the creepage is shorter than the requirement, it is possible to increase to more than

5mm by adding a slit in the board as shown in Figure 18.

Table11. Working Voltage

Figure 18. Example to increase the creepage

2.4. Thermal design

2.4.1. Thermal design

The CQ-330x/CQ-320x is capable of 20Arms continuous current, even larger current in

case of transitional. When CQ-330x/CQ-320x is used under conditions compliant with

safety standard, please ensure the case temperature (Tc) is kept lower than 130℃ from

heating by the primary current. Please refer to the Figure19. for the position to measure

Tc.

Figure 19. Position to measure package case temperature

2.4.2. Junction temperature (Tj) estimation

Working

Voltage

Pollution Degree

1 2 3

Basic

Isolation

1450 1000 400 (Vrms)

Reinforced

Isolation

825 500 200

Slit in the board


25

50

75

100

125

150

0 100 200 300 400 500 600Case

Tem

pera

ture

Tc[℃

]

Time[s]

25

50

75

100

125

150

0 50 100 150 200 250Case

Tem

pera

ture

Tc[℃

]

Time[s]

42A

Tj can be estimated the temperature from CQ-330x/CQ-320x’s lead frame. Because it

nearly equals to the temperature of the sensor inside the package. Please ensure the

junction temperature (Tj) is kept lower than 125℃.

2.4.3. Improvement of heat dissipation

These can increase heat dissipation without increasing the trace area by thermally

connecting the primary conductors to an inner or outer thermal layer directly. If the

heat dissipation is not enough, using thermal vias may help.

2.4.4. Heating Measurement(reference)

Figure 20. show the results of Tc measurement used by figure 5.”Evaluation board”.

This result is a reference data. Tc is changed much by the board layout and the heat

dissipation. Please confirm it in your evaluation environment.

Measurement Condition

Measurement Temperature：at RT.（about 25℃）

Position to measure Tc：Refer to Figure 19.

Maximum operation temperature ：Tc<130℃

The size of wire which is connected to the board is selected according to the standard

of the amount of current.

14sq., AWG5.8, Diameter:4.2mm

Figure 20. Relationship between CQ-330x/CQ-320x Case temperature and

amount of input current (left: 10~35A, right: 42A)

2.5. Stray Magnetic Field Reduction Function

10A

20A

35A

Tc<130℃


CQ-330x/CQ-320x can be detected the primary current by detecting the magnetic flux

density of primary current. Therefore, CQ-330x/CQ-320x is affected by external magnetic

field, and this will appear as output error. In this section, we show about the situation

affected by nearby current lines.

Figure 21. defines the distance from nearby current lines.

Figure 22. shows the relationship between “output error” and “distance A/B”.

Example:

In case of the nearby current is 20A and its output error keep less than 400mA,

CQ-330x/CQ-320x keeps the clearance more than 6mm (Distance A) and

5mm (Distance B).

*Distance B is not only defined as the line on the left of CQ330x package but also the line

on the right of CQ330x package.

Figure 21. The definition of Distance

Distance A

Distance B

Distance A ... Distance from the edge of lead frame

Distance B ... Distance from the edge of mold


(a) Distance A

(b) Distance B

Figure 22. The relationship between output error and distance

0

100

200

300

400

500

600

700

800

0 10 20 30 40

Ou

tpu

t E

rro

r(m

A)

distance A（mm）

20A

15A

10A

5A

Other current line's current value

0

100

200

300

400

500

600

700

800

0 10 20 30 40

Ou

tpu

t E

rro

r(m

A)

distance B（mm）

20A

15A

10A

5A

Other current line's current value


3. Useful Tips

3.1. Supply Voltage

The CQ-330x/CQ-320x has a ratiometric output. This means that the output of the

current sensor changes proportionally to the supply power voltage. A ratiometric output

is suitable for applications where the output is converted to digital using an A/D converter

and where fluctuation of the power supply voltage causes reference error of the A/D

converter. Figure11. shows an example of the external circuit where a 5V A/D converter

is connected. Figure12. shows the case where a 3.3V A/D converter is used. The supply

voltage of the CQ-330x/CQ-320x and the reference voltage of the A/D converter fluctuate

at the same ratio. This will avoid the effects of the fluctuation of the power supply to the

A/D converter output.

Figure 23. Shows the output voltage of CQ-3302 (Sensitivity Vh=100mV/A) and

CQ-3202 (Sensitivity Vh=62.5mV/A) as an example ratiometric output.

(a) CQ-3302(100mV/A) (b) CQ-3202(62.5mV/A)

Figure 23. Output voltage of the CQ-330x/CQ-320x

vs Input Current with different VDD.

3.2. Calibration of Zero-Current Output in initialization

The Zero-Current Output of the CQ-330x/CQ-320x may drift over time within the values

defined in datasheet Section 14. Therefore, in order to minimize this drift, we strongly

recommend calibrating the Zero-Current Output by software after the power-up time of

the system when the measured current is zero.

3.3. Startup

The power-on time is 21 μs. We recommend a 3X to 5X safety margin to account for

power-on time variation over process and temperature ranges.


3.4. Magnetic parts around

The CQ-330x/CQ-320x output can be affected by magnetic devices (mechanical, lays,

transformers, etc.) that are nearby. In the case where magnetic devices must be placed

close to the CQ-330x/CQ-320x, please check the effect on sensitivity or other

characteristics and make sure any effects are understood and mitigated as much as

possible.

3.5. Heat Generation

CQ-330x/CQ-320x must be used under the condition within the derating curve shown

in Figure 24. If CQ-330x/CQ-320x are placed near the electric parts which produce much

heat such as IPM, confirm that the ambient temperature does not exceed beyond the

derating curve. (e.g. if the maximum primary current is 10A, the ambient temperature

must not exceed 90°C)

Figure 24. Derating curve of CQ-330x/CQ-320x

3.6. Sensitivity variation by internal heating

Sensitivity of CQ-330x/CQ-320x series drift by internal heating of primary conductor.

Figure 25 shows variation of sensitivity by internal heating. In Figure 25, the x axis is

applied current [Arms], the y axis is sensitivity variation from without internal heating.

Each current applied 5sec. Sensitivity of CQ-330x/CQ-320x series can drift 3% when

20Arms is applied. The result of Figure 25 is evaluated by using AKM’s recommend board

layout, and sensitivity variation by internal heating is depend on board size and heating

radiation. Please confirm the effect of internal heating by using actual board layout.


Figure 25. Sensitivity variation by internal heating

3.7. Storage Environment

CQ-330x/CQ-320x is the condition of MSL2a (JEDEC J-STD-020).

Please store under the following conditions.

[Storage term]

Within 1 year after delivery (Before and after unpacking the moisture-proof packing.)

[Before unpacking the moisture-proof packing]

5~40°C, less than 90%RH

[After unpacking the moisture-proof packing]

5~30°C, 60%RH or less, less than 168hours (1week).

3.8. Sensitivity and Zero-Current Output Drift by Reflow

Solder reflow can cause the Sensitivity and Zero-Current Output of CQ-330x/CQ-320x

to drift. Section 9 of the datasheet shows the variation of the shipment test results by

AKM. The reflow process can induce drift within the values defined in Section 14 of the

datasheet. Regarding Zero-Current Output drift, we recommend calibrating according to

Section 3.2 of this document.

Figure 26. and Table.12 show the recommended reflow temperature profile. AKM

recommends subjecting the CQ-330x/CQ-320x to a reflow process a maximum of three

(3) times.


Table 12. Reflow Conditions

Figure 26. Reflow profile

3.9. Maximum Primary Current and Linear Sensing Range

Maximum Primary Current (IRMSmax) is the maximum current that can be flowed through

the primary conductor continuously. It depends on the cross-sectional area of the primary

conductor. CQ-330x/CQ-320x can be damaged if it is used in conditions where the DC

current or the root-mean-square value of AC current exceeds IRMSmax for an extended

period of time. In the case of pulsed current, it is possible to apply currents larger than

IRMSmax.

Linear Sensing Range (INS) is the current range where we guarantee the linearity of

CQ-330x/CQ-320x output. If the primary current is beyond INS, the output will saturate.

However, it will return to normal once the primary current is back within INS.


3.10. Safety Standard

CQ-330x/CQ-320x is certified as UL508 and IEC/UL62368-1, by the international

certification organization.

・UL 508 – Industrial Control Equipment – Edition 17.

(File No. E353882)

・IEC/UL62368-1 -Audio/video, Information and Communication Technology Equipment-

2nd Edition(File No.E359197)

・CAN/CSA C22.2 No.62368-1-14 -Audio/video, Information and Communication

Technology Equipment- 2nd Ed,(File No.E359197)

3.11. Other information

Please check our website akm.com for datasheets, selection guide, and more.

http://www.akm.com

akm.com


Disclaimer

All information included in this document are provided only to illustrate the operation

and application examples of AKM Products. You are fully responsible for use of such

information contained in this document in your product design or applications. AKM

ASSUMES NO LIABILITY FOR ANY LOSSES INCURRED BY YOU OR THIRD PARTIES

ARISING FROM THE USE OF SUCH INFORMATION IN YOUR PRODUCT DESIGN OR

APPLICATIONS.

cq-330x/cq-320x application note · 7/16/2020 · (a) a 0.1μf bypass capacitor should be placed...

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