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YuTa_4942221
Level 5
Level 5
Distributor - Macnica (Japan)
50 replies posted 50 questions asked 100 sign-ins

Customers are considering PFC controllers (ICE2PCS01G, ICE2PCS05G).
Checking the data sheet and AN, it says that the Min AC voltage is 85VAC, but is there any problem with an input AC voltage smaller than this?
I think there is no problem, but if there is a problem, please let me know.

 

Best Regards.

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1 Solution
Abhilash_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 250 solutions authored

Hi,

 

    The ratings of the MOSFET and passive components depends on the  converter specs. 

The Rsense value and VINS has to be redesigned carefully based on the max and min limits of the IC. If you have designed the converter lets say for a minimum input voltage of 85Vin, then going below that value might cause higher input current flowing through the circuit. Which might damage the MOSFET,  passive components and trigger the IBOP.

But you can always redesign the converter based on your requirements, but the input to the IC has to be taken care of. 

You cannot reduce the input voltage once it has been designed for a particular condition. If the application requires this , then the whole converter has to be redesigned, 

I hope the above explanation has helped you in answering your query. 

 

Regards,

Abhilash P

 

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6 Replies
Abhilash_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 250 solutions authored

Hi,

 

  The PFC IC ICE2PCS01G has an input protection feature called as AC-Brownout shutdown. 

Brown-out occurs when the input voltage VAC falls below the minimum input voltage of the design (i.e. 85V for universal input voltage range) and the VCC has not entered into the VCCUVLO level yet. For a system without input brown out protection (IBOP), the boost converter will increasingly draw a higher current from the mains at a given output power which may exceed the maximum design values of the input current and lead to over heat of MOSFET and boost diode. ICE2PCS02 provides a new IBOP feature whereby it senses directly the input voltage for Input Brown-Out condition via an external resistor/capacitor/diode network as shown in the following figure. This network provides a filtered value of VIN which turns the IC on when the voltage at Pin 4 (VINS) is more than 1.5V. The IC enters into the standby mode and gate is off when VINS goes below 0.7V. The hysteresis prevents the system to oscillate between normal and standby mode.

Abhilash_P_0-1644498673689.png

One more reason for not going below 85Vac is as explained below, 

In order to obtain 300W output power at 85 V minimum AC input voltage, the maximum input RMS current and the sinusoidal peak value of AC currents are calculated as follows,

Abhilash_P_1-1644498881918.png

Abhilash_P_2-1644498936853.png

The peak current through the inductor is given by, 

Abhilash_P_3-1644498981026.png

The current sense resistance is calculated based on the IC soft over current control threshold and peak
current carried by boost choke. When the Isense signal reaches the soft over control threshold, IC will reduce the internal control voltage and accordingly the duty cycle is reduced in the following cycles. Finally the boost choke current is limited. According to IC datasheet, soft over current control threshold is -0.68V maximum. So the current sense resistor should be, 

Abhilash_P_4-1644499036095.png

Since this Rsense is calculated based on the choke current which in-turn depends on the input voltage, operating the IC below 85V may lead to soft over current control .

 

I hope from the above explanation it is clear that why we shouldnt operate the IC below 85Vac.

 

 

Regards,

Abhilash P

 

 

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YuTa_4942221
Level 5
Level 5
Distributor - Macnica (Japan)
50 replies posted 50 questions asked 100 sign-ins

Abhilash P --san

Thank you very much for contacting me.
Since ICE2PCS02 has a VINS terminal, it has an IBOP function, so I thought it could not be used, but since ICE2PCS01G does not have a VIN terminal, I thought that there would be no problem in terms of IBOP function.

Regarding the calculation of Rsence resistance, I think that there is no problem if Rsence is calculated assuming AC24V input in advance, but is it wrong?
【Calculation result】
Rsence ≤ 0.033Ω
* When the output power is 300W

If the input AC voltage is low, soft overcurrent control will not be applied if Rsence is reduced, but does it mean that AC85V or less is not recommended for ICs?
If you make a mistake, we would appreciate it if you could give us some advice.

 

Best Regards.

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Abhilash_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 250 solutions authored

Hi,

 

   Can you please provide your desired operating conditions?

 

Regards,

Abhilash P 

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YuTa_4942221
Level 5
Level 5
Distributor - Macnica (Japan)
50 replies posted 50 questions asked 100 sign-ins

Abhilash P -san


The operating conditions are as follows.
Input voltage: AC19.2 to 26.4V
Output voltage: 37V (± 5%)
Rated current: 8A
Peak output current: 11A

Is there any problem with this information?

Best Regards.

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Abhilash_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 250 solutions authored

Hi,

 

    The ratings of the MOSFET and passive components depends on the  converter specs. 

The Rsense value and VINS has to be redesigned carefully based on the max and min limits of the IC. If you have designed the converter lets say for a minimum input voltage of 85Vin, then going below that value might cause higher input current flowing through the circuit. Which might damage the MOSFET,  passive components and trigger the IBOP.

But you can always redesign the converter based on your requirements, but the input to the IC has to be taken care of. 

You cannot reduce the input voltage once it has been designed for a particular condition. If the application requires this , then the whole converter has to be redesigned, 

I hope the above explanation has helped you in answering your query. 

 

Regards,

Abhilash P

 

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YuTa_4942221
Level 5
Level 5
Distributor - Macnica (Japan)
50 replies posted 50 questions asked 100 sign-ins

Abhilash P --san

I'm sorry I couldn't reply.
I understand that it can be used if the customer pays attention to the design (especially the converter).

I would like to make a proposal to our customers.

Thank you very much.

Best Regards.

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