UCC256303: 3kW output use how to connect to UCC27714

Hi Doi-san,

I have asked the system engineer for the UCC256303 to help answer your post. I think there may be an issue as the UCC25630 needs to sense the switch node voltage for the adaptive timing.

Regards

Peter

Yalong-san,

Do you mean an additional drive transformer is required?

What is turn ratio  pri. vs sec. ?

Is there another solution which reduce their board space?

Best Regards,

H.DOI

Hi Doi-San,

Yes. You will need an additional drive transformer. The reason is that UCC25630 needs to detects the switching node for adaptive deadtime function. HO will be high voltage, so it cannot direct connect to HI in UCC27714. Turn ratio of 1 will be ok. This looks like the simplest method for this application.
Best regards,

Yalong

Yalong-san,

One more connection.
Is this right?
UCC25630 RVCC to UCC27714 VDD direct connection without resistor.

Best Regards,
H.DOI

Hi all,

My customer tried, but over 2kW, it does not work well, noisy or minus voltage.

This is because 4 x MOSFET use, I think.   Two SiC 40mohm is better.

Please let me know the connection such as,

UCC256303  + two UCC5310MC  drive-> two 40mohm SiC

My customer have isolated +/- voltage cct. for UCC5310MC outputs.

And  my customer want to another plan for Input 700V DC  output 4kW 60V.

Is there any method to use UCC256303  with bus voltage 700VDC?

Depletion mode small FET can be used for this case?

If yes, give me the recommended cct. 

Thank you.

Hi Doi-san,

1. How to connect UCC256303 to two UCC5310MC. (If you can use non-isolated gate driver, I think that will be ok as well)

Low side:

UCC256303 LO connects to UCC5310MC IN+

UCC256303 GND connects to UCC5310MC GND1

UCC256303 RVCC connects to UCC5310MC Vcc1

UCC5310MC GND1 connects to UCC5310MC Vee2

UCC5310MC Vcc2 connects to UCC5310MC Vcc1

High side:

UCC256303 HO connects to UCC5310MC IN+

UCC256303 HS connects to UCC5310MC GND1

UCC256303 HB connects to UCC5310MC Vcc1

UCC5310MC GND1 connects to UCC5310MC Vee2

UCC5310MC Vcc2 connects to UCC5310MC Vcc1

2. Can UCC256303 used for bus voltage 700VDC?

It is possible but need some extra circuits.

The maximum voltage for HB (HS) is 640V. So HS pin cannot directly connect to the switching node. A high voltage resistor divider can be used to scale the switching node voltage to below 50V.

HB pin cannot be supplied from a bootstrap diode, but instead need to supply from a isolated power supply.

An isolated gate driver is needed as well.  Use UCC5310MC as an example, the connection (high side) will be:

UCC256303 HO connects to UCC5310MC IN+

UCC256303 HS connects to UCC5310MC GND1, and also connect to the middle point of a resistor divider from switching node

UCC256303 HB connects to UCC5310MC Vcc1, and also connect to a isolated power supply output

UCC5310MC Vee2 connects to switching node

UCC5310MC Vcc2 connects to another isolated power supply output

Please let me know if you have any further questions.

Best regards,

Yalong

Yalong-san,

Thank you for your advice.

For bus voltage DC700V
I understand another isolated power is needed for high-side of UCC25603.
Another two questions I have for UCC25603 HS from switching node resistor divided.
1. Pulse Amplitude should be more than ? v .
2. Maximum Impedance of HS bottom to UCC25603 GND (or low side FET Source).

Best Regards,
H.DOI

Doi-san,

Let's me check with our designer and I will get back to you.

Best regards,

Yalong

Yalong-san,

Thank you for your support.

When can you advice ?

Customer will stop evaluation within few days if no answer from you.

Best Regards,

H.DOI

Hi Doi-San,

Sorry for the delayed reply.

1. Pulse Amplitude should be more than ? v .

Suggest to have a resistor divide to make the peak voltage of HS pin between 50V and 100V

2. Maximum Impedance of HS bottom to UCC25603 GND (or low side FET Source).

The leakage current for HS node at dc voltage 160V is 2.5uA, and 4uA for HS node at dc voltage 640V. You can use this to choose the resistor divider values.

Best regards,

Yalong

Yalong-san,

I think the peak voltage should be between 500V to 600V.
When the resistance value on the upper side is large, a CR delay occurs between the upper resistor and the parallel stray capacitance of the lower resistor.
It is better that the resistance value on the upper side is smaller.

How do you think about?

Best Regards,
H.DOI

Doi-san,

It is ok to have the peak voltage between 500V to 600V. In terms of the time delay, you are right that smaller upper resistor will make the delay time smaller. The importance of this will depend on how large the parasitic capacitance is.

However, the reason I suggest to have the peak voltage between 50V to 100V is because slew rate detector for adaptive deadtime control works better for a smaller HS node voltage.

Best regards,

Yalong