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Gate Driver ICs Forum Discussions

RonnieRolfes
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Hi,

Page 15 Datasheet: Power dissipation, per input part is rated with 100mW and 12mW/°C derating above 65°C.

So the maximal ambient temperature could not be higher than 65+100/12 = 73.3°C ? but the device is rated for -40…125°.

Do I understand this rating in a wrong manner?

 

To calculate the losses, we need to now the internal RON/ROFF (Source/sink output resistance). Could you please let us know the values. (We tied it using Table 7, but it leads to different values)

 

We can only use one DESAT channel. What do we do with the unused DESDAT Pin?

 

Kind Regards

Rolf

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Guru_Prasad
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Hello @RonnieRolfes 

Yes, you can use 8 Ohms if Vincotech topology and input side driver voltage is 5V is used @25kHz

 

Cooling option for Driver IC:

The thermal coupling to the chips is given by the pins GND1 (for the primary) and VEE2LS&VEE2HS (for

the secondary) since these are also connected to the lead frame that is below the chip. In order to optimize

thermal performance, these pins should be connected to the bigger copper area (such as a polygon) with a

couple of vias.

Thanks

Guru

View solution in original post

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Guru_Prasad
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Hello @RonnieRolfes 

Thanks for posting your question in the Infineon community.

Q1 the maximal ambient temperature could not be higher than 65+100/12 = 73.3°C ? but the device is rated for -40…125°.Do I understand this rating in a wrong manner?

Ans: Yes your approach is not in the right direction. Your calculation represents internal temperature, not ambient temperature. The maximum ambient temperature can be calculated by using this formula 

Tamb_max=Tj-Ploss*Rth.

Q2To calculate the losses, we need to now the internal RON/ROFF (Source/sink output resistance). Could you please let us know the values? (We tied it using Table 7, but it leads to different values)

Ans: The RON and Roff are not fixed resistor they are nonlinear. 

 Ron=VCC_MAX/Source current(Given in Table-2)

 Roff=VEE_MAX/Sink current(Given in Table-2)

Q3 We can only use one DESAT channel. What do we do with the unused DESDAT Pin?

Ans: It is advisable to connect one capacitor to that pin the value of nearly 100pF.(no specific calculation is required. here just the DESAT pin  response will be slowly no effect in driver IC )

 

Thanks

Guru

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RonnieRolfes
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ANS/Q1:

Thank you for correcting me

 

ANS/Q2:   

I already thought that RON/ROFF will be the "Rdson" of the corresponding internal switch.  Will taking the Absolute Maximum Ratings in Table 2 be the "worst-case losses" for the RON/ROFF?  

e.g. RON = 20/2.4 = 8.33 Ohm and ROFF = 12/2.4 = 5 Ohm

Are the formulas fot the power dissiapation correct? (see attached picture)

 

ANS/Q3: 

 

We are using 100pF or 150pF for the desaturation at Pin 30 DESATHS.  Won't the desaturation detection at Pin 20 DESATLS react quicker than DESATHS if we use 100pF?

Would it make sense to use a capacitance e.g 100x higher than the one on DESATHS? So the blanking time is 100x longer and will not trigger a FAULT before  DESATHS 

See attached schematic

Best Regards

Rolf

 

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Guru_Prasad
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Hello @RonnieRolfes 

The Q2 answer is Correct.

I have some points for Q2 mentioned below.

Q1. By observing the schematic, I assume it is for driving the top & bottom IGBT Leg. If yes, then it is recommended to

use Desat for both the IGBTS to protect the system in fault events.

Q2. are you using R1701, R1703, R1706 & R1712, R1714, R1717 for both Turn ON & Turn OFF?


Q3. may I know what topology you are using here (IGBT connections)?


Q4. if you want to use Desat protection, then use calculation C = i*dt/dv where dt is the required saturation response

time, dv is (desat pin voltage) 9V typical given in datasheet and I is internal current 500uA given in datasheet to

charge the desat pin capacitor.


Q5. both the channels used the same power supply with the ground, so isolation has been bypassed. Please check

once again.

Could your share your application details

Thanks

Guru

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RonnieRolfes
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Hi Guru
See my answers below in green

Best Regards
Rolf

The Q2 answer is Correct.

I have some points for Q2 mentioned below.

Q1. By observing the schematic, I assume it is for driving the top & bottom IGBT Leg. If yes, then it is recommended to

use Desat for both the IGBTS to protect the system in fault events.

I know it, but the three-level module we like to use does not have an access to the common collector of the inner switches

[cid:image001.png@01D8563A.976B6780]


Q2. are you using R1701, R1703, R1706 & R1712, R1714, R1717 for both Turn ON & Turn OFF?

Only if the power dissipation of the 2ED is to high. But we would like to avoid the external booster if not necessary. That’s the main reason why I started this discussion 😊

Q3. may I know what topology you are using here (IGBT connections)?

3 phase three-level with active neutral point clamp (t-type). See picture above

Q4. if you want to use Desat protection, then use calculation C = i*dt/dv where dt is the required saturation response

time, dv is (desat pin voltage) 9V typical given in datasheet and I is internal current 500uA given in datasheet to

charge the desat pin capacitor.

That’s exactly how we did it for ONE channel of the 2ED. The question is hoe to “disable” the second one

Q5. both the channels used the same power supply with the ground, so isolation has been bypassed. Please check

once again.

You observed it well! But this is made on purpose. Guess the picture below will explain it

To reduce costs, some of the supplies and “Eice 2ED’s” needed to switch the IGBTs T1, T2, T3 and T4 are combined (as they share the same reference potential)

· 1 x Supply for all T1 and T2 Phase U

· 1 x Supply for all T1 and T2 Phase V

· 1 x Supply for all T1 and T2 Phase W

· [DC+] 1 x Supply for all T3

· 1 x Supply for all T4
[DC+][DC/2][Phase][cid:image014.png@01D8563F.7C665800][cid:image015.png@01D8563F.7C665800][cid:image016.png@01D8563F.7C665800][cid:image017.jpg@01D8563F.7C665800]





[T1 / T2 Phase U,T4 Phase U/V/W] [T1 / T2 Phase W,T1 / T2 Phase V,T3 Phase U/V/W]



[cid:image026.png@01D8563F.7C665800][2ED allows the needed 2mm Creepage between DC- and DC/2][cid:image029.png@01D8563F.7C665800]

Could your share your application details

The inverter shall be use for high speed (>120’000rpm) machines

Thanks

Guru
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Guru_Prasad
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Hello @RonnieRolfes 

Kindly  share the pictures again I am unable to see your pictures 

Thanks

Guru

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RonnieRolfes
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Hi Guru

Here are the pictures.

the next question is: Which Pins do have the least thermal path? Or in other words: To witch potential shall we attach a "cooling" plane? VCC2, GND2, VEE2 or OUT?

 

Best Regards$

Rolf

 

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Guru_Prasad
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Hello @RonnieRolfes 

I have reviewed your schematics and power supply connections looks all are correct. except below points 

are you using R1701, R1703, R1706 & R1712, R1714, R1717 for both Turn ON & Turn OFF?

Only if the power dissipation of the 2ED is to high. But we would like to avoid the external booster if not necessary. That’s the main reason why I started this discussion 

the next question is: Which Pins do have the least thermal path? Or in other words: To which potential shall we attach a "cooling" plane? VCC2, GND2, VEE2 or OUT?

Since you wanted to use only a driver instead of an external booster, need to evaluate the power loss and temperature rise of the Driver IC. To calculate the same can you provide IGBT details, and switching frequency?

 

Thanks

Guru

 

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RonnieRolfes
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Hello @Guru_Prasad 

Yes, we will use R1701, R1703, R1706 & R1712, R1714, R1717 for both Turn ON & Turn OFF. Having no option to set different switching speeds is fine for us

It will be a Semi-Custom 3 Phase 3 Level Module

- 1200V /40A  IGBT4 of Infineon, for the "outer" Switches T1/T4, together with a parallel SiC Diode

- 650V /40A Trenchstop 5 IGBT of Infineon, S5 for the "inner" Switches T2/T3

Our, and also your best Datasheet is Datasheet 10-PY12M3A040SH09-M749F38Y (vincotech.com)

 

The switching frequency is 25 to 50kHz, Ambient < 90°C

 

Best Regards

Rolf

 

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Guru_Prasad
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Hello @RonnieRolfes 

The power loss for Gate  driver IC was calculated based below formula

Guru_Prasad_2-1651140434048.png

 

Where 

2 is for two-channel 

∆Vge is Gate VCC_Max

Ipeak is the Peak current(Calculated based on VCC_max/Rg_total)

tr-Raise time of your IGBT

tf-Fall time of your IGBT 

fs is switching frequency

Iq_in is the Input Quiescent current of Gate Driver IC  

VCC1 is the input voltage of Driver IC 

Iq_Out is the Input Quiescent current of Gate Driver IC

VCC2 is the Out voltage of Driver IC

The losses for your case are given below

PIC-loss=2*(20*2.5A*(14.7ns+46.6ns)*25kHz)+(15*6mA)+(5*9mA)=153.2mW+90mW+45mW=288.2mW

The derating capacity of  IC at 90 deg  is 1000mW-300mW=700mW

Guru_Prasad_3-1651141631983.png

Note:

1)The peak current 2.5A is calculated from 20V/8ohm. The 8ohm considered from your Vincotech Datasheet

2)The tr,tf calculated from Vincotech Datasheet at your power supply conditions

3) switching frequency I have taken 25kHz from your given range 

Rg_total=Rg_on+Rg_int_Igbt(Rg_int_Igbt=0 in Vincotech Datasheet)

Conclusions:

1)The IC can drive rated current with Rg_total of  8 ohm. If you want to use of Rg_total <8ohm kindly use external booster.  

2)Desat disabling can be done by connecting resistor of 6kohm(3V/500uA) OR you can connect diode from Desat pin to ground in Forward direction.

 

I have one small question may  I know what is semi custom 3 Phase 3 Level Module topology? How are you connecting Vincotech module, IGBT4+Sic diode and Trench stop 5 IGBT for 3 level NPC?

Thanks

Guru

 

 

 

 

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RonnieRolfes
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Hi @Guru_Prasad 

So the fact is, that we can drive the module with 25kHz and 8Ohm without Booster. For lower Rgon/off or higher switching frequencies, we will need the booster. 

Thank you so far for that!

So would the best cooling option now be to connect the planes to  VCC2, GND2, VEE2 or OUT?

 

For disabling DESAT i'll connect a 3.3k (->  max 1.815@DESAT)  resistor just because it is already on the BoM

It will be a press-fit module. That is all I know

 

Greetings

Rolf

We will also start with 8Ohm.

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Guru_Prasad
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Hello @RonnieRolfes 

Yes, you can use 8 Ohms if Vincotech topology and input side driver voltage is 5V is used @25kHz

 

Cooling option for Driver IC:

The thermal coupling to the chips is given by the pins GND1 (for the primary) and VEE2LS&VEE2HS (for

the secondary) since these are also connected to the lead frame that is below the chip. In order to optimize

thermal performance, these pins should be connected to the bigger copper area (such as a polygon) with a

couple of vias.

Thanks

Guru