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UCC27212A-Q1: gate driver with single input and dual output

Karthik karri
Prodigy 195 points
Part Number: UCC27212A-Q1
Other Parts Discussed in Thread: TPS28225-Q1, , UCC27712-Q1, UCC27714, UCC2897A, UCC57108-Q1, UCC27444-Q1, UCC21551-Q1, UCC21551, UCC23525, UCC28C53-Q1, UCC21530-Q1, UCC21530, UCC21330

Tool/software:

 Hello Ti Team,

I am looking for half bridge gate driver with single input(IN) and two outputs (OUTA,OUTB)..I will be using for two switch forward converter which drives the two MOSFETS at the same time .

So single input and two outputs (OUTA,OUTB) which drives the high and low side MOSFETS.

and the driver should be AEC-Q automotive qualified....

Please check and let me know suitable gate driver

Thanks,

karthik

  • 0
    TI__Genius 9985 points

    Hey Karthik,

    Thank you for reaching out to TI with your question regarding our half-bridge gate driver portfolio.

    The only Automotive qualified half-bridge driver that is in our portfolio currently is the TPS28225-Q1. It is a 4A driver and is 27V rated. What is your bus voltage?

    Another option is to use a product like the UCC27212A-Q1 and implement an inverter circuit to use 1 PWM signal for both the HI and LI inputs.

    Let me know if you have any questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Hi William,

    Ok then i will use controller+  UCC27212A-Q1 half bridge driver which drives the two switch forward converter.

    Your statement  "implement an inverter circuit to use 1 PWM signal for both the HI and LI inputs"  ==> invert circuit is not necessary William because both MOSFETS of two switch forward converter should turn -on at the same time.

    So 1 PWM signal to diive Hi,Li  inputs of the driver sufficient i think so..like below picture.

    I will go like above picture shown i think it could be ok..what is your opinion william??

    Thanks,

    Karthik

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    Thank you for the explanation and diagram. I better understand your use case now. Yes, you can use the UCC27212A-Q1 with a single input on HI and LI.

    With your current setup, the HO FET does not have the reference that it needs for Vgs that it would typically have with HS in a typical half-bridge circuit. Also, there is not a way to supply and recharge the bootstrap capacitor. I have made a quick model to show how this could be implemented. There is an example of this shown in the UCC27714 datasheet in Section 7.4.3 Operation with HO and LO Outputs High Simultaneously in Figure 49. This is not the same as how you would implement it with the UCC27712A-Q1. The UCC27712-Q1 has an integrated bootstrap diode and the MOSFET labeled M3 below is not connected to HB.

    As a disclaimer, this does not include all required components such as gate resistors and support circuitry. This shows the main components that are needed.

    Let me know if there are any questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Thanks William for drawing  the the circuit.i got your point now ..as both switches of two switch  forward converter operating at the same time cboot cannot be charged without the external bootstrap circuit which you mentioned in the diagram and i have the ucc27714 datasheet figure 49.i understood you point.

    But i did'nt understood the bootstrap circuit operation...can you explain me in detail..

    question 1:

    can you explain me how the M3,M4 MOSFET and D3 diode will operate with respect to two switch forward converter (M1,M2 MOSFETS ,D1,D2,Diodes L1)

    or is there any application note for this please let me know i will go trough it..

    question 2:

    Also seen one of the comment in the TI forum for two switch forward converter bootstrap circuit..can you explain me that ..

    Actually i dont want to add too many switches for bootstrap  in the two switch forward converter topology so let me know  1s consideration in the above picture will work out without above M3,M4, D3  circuit..

    (or) let me know any option without adding many components like M3,M4 D3 circuit  which i can drive high side MOSFET .

    waiting for your early  reply  William !!!

    thanks in advance !!

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    1. This circuitry with R1, M3, M4, and D3 is for biasing the high-side as you mentioned. So, when the HO/LO is off, M4 is now off which turns on M3 due to the gate no longer being connected to ground via M4. When this is the case with M3 on and M4 off, D3 now clamps the HS node to ground through M3 which allows the bootstrap capacitor Cboot to be charged and then it will be discharged when HO/LO is turned back on to drive the gate of M1.

    2. I am not sure which E2E thread that comment from Richard came from, but it appears that they are switching HO and LO independently and at opposite times, not at the same time. This would perform the normal bootstrapping operation with the exception of the charging path would include the inductor.

    For an alternative solution, you must find a way to bias the high side due to the typical bootstrapping operation will not work in this scenario. An isolated bias for HB-HS would be a possible solution that would no involve adding too many extra components. Check out this FAQ outlining some high side biasing solutions.

    [FAQ] How to bias the high side of a half-bridge gate driver and why

    Let me know if there are any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Ok thanks you so much William for the great explanation.I had one more query ,need your suggestion on it!

    After doing some tradestudy on two switch forward and active clamp forward converter .I observed Active clamp forward gives better efficiency .

     Active clamp forward converter suits my application and gives better efficiency compared to two switch forward converter.So i am considering  active clamp forward converter in my design.

     We have to use only Automotive qualified AEC-Q components in our designs or projects  due to some constraints.

    UCC2897A fits my requirement but it is not AEC-Q qualified and i have checked there is no AEC-Q  qualified  active clamp forward converter  controller in TI.

    So my doubt is now,

    is there any option to go with Ti normal  PWM Controller + Ti Half bridge driver which can drive the active clamp highside forward converter operation.

    As two MOSFETS operate complimentary in active clamp forward converter ,with  general Half bridge driver can we drive it or is there any limitation to Active clamp forward converter?

    is there any Ti normal  PWM Controller + Ti Half bridge driver,  what is your suggestion please check and let me know William.

    Waiting for your reply!! Thanks in Advance!

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    I'm glad to hear that your design and converter are working effectively.

    As for a controller, I am the Applications Engineer for gate drivers so I am not the expert to comment on the best controller for you. In order to find that, it would be best if you started a thread with our controllers team.

    For using a half-bridge gate driver in the topology shown in that schematic, that is the intended operation for half-bridge gate drivers where Q2 and Q1 operate complimentary of each other (with some deadtime). This allows for the bootstrapping to occur and doesn't create a shoot through condition.

    For the circled waveforms, When Q2 gate is given a high signal (Q1 gate will get a low signal), the drain of Q1 will then be connected to the high voltage bus and Vds will be high. Then, when Q2 is low and Q1 is high in the complimentary portion of the waveform, Q1 Vds will now be low. This is expected operation for a typical half bridge setup.

    Let me know if you have any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Hello Willam,

    Thanks for explaining the circuit.

    Question 1:

    As you said UCC27212A-Q1 will not have interlock cross conduction feature which supports two switch forward converter operation .But my two -switch forward  converter input voltage is 280V but the UCC27212A-Q1 HB pin voltage is  120V only.So i cannot use UCC27212A-Q1.

    Can you suggest any AEC-Q automotive qualified similar driver like UCC27212A-Q1 with high side HB pin withstand voltage of 300V and without interlock  feature for two switch forward converter opeartion

    Question 2:

    Also Is there any any limitation to the bootstrap capacitor charging when i go for high frequency operation of the converter around 250khz ?

    Is there any application note for the calculation 

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    1. You are correct. You cannot use the UCC27212A-Q1 with a 280V bus voltage. For a driver that can withstand a 300V bus and does not have interlock, the only thing in our portfolio is the UCC27714. It is not automotive qualified as you have requested though. Another option is to use a low-side driver with a pulse transformer to withstand the high voltage and avoid the interlock requirement. Please take a look at this Application Note regarding pulse transformers.

    Why use a Gate Drive Transformer?

    2. For charging the bootstrap capacitor initially on startup, there will be a delay before the high-side (HO) outputs because HB UVLO must be satisfied. This charging occurs while the low-side LO is on and so it may take multiple LO pulses to charge the bootstrap capacitor initially. During steady state operation, LO will have to pulse enough to keep the capacitor charged to continue driving the high-side. Bootstrap capacitor sizing is calculated with this table to help optimize this process.

    [FAQ] UCC27282: How to Correctly Size the Bootstrap Capacitor for Half-Bridge Gate Drivers

    Let me know if there are any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Hello William,

    Thanks for  confirming it as there is non-AEC  driver for 300V.

    Also thanks for suggesting  solution to it with recommending low-side driver with a pulse transformer.

    I have some doubts in it..

    Question 1:

    But i checked the shared application note,INA,INB signals are vice-versa and M1 and M2 will operate complementary (means both M1,M2 will not operate at same time) which does not satisfy to avoid interlock requirement i think so right

     

    But two switch forward converter both mosfet will operate same time know..

    Can you kindly explain how  i can use Low-side driver with a pulse transformer for two -switch forward converter. With some diagram or operation explanation in the picture below by editing it with pulse transformer circuit so that i can understand better..

    Question 2:

    One more doubt is ,for high input voltage of 300V,the power mosfet gate charge Qg is high and require high source and sink current .How pulse transformer can deliver it ?

    Question 3:

    I just came across this hi-low driver which is slightly different from half -bridge driver as High MOSFET source is not connected with drain of low side mosfet.

    Does it helps me to  give solution ??      and if , then any TI AEC-Q component is available.

    Waiting for your reply William,Thank you.

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    1. Yes, I see how this may not work for your application. There are ways to use a low-side driver as a high-side driver using some methods of isolation. These are discussed in the FAQ below. We offer a variety of low-side drivers that are automotive rated such as the UCC57108-Q1 single channel driver or the UCC27444-Q1 dual channel driver. Another option would be to use a dual channel isolated gate driver like the UCC21551-Q1.

    [FAQ] UCC27624: Can I use a Low Side driver as a High Side driver?

    2. The pulse transformer current is dependent on the gate driver current output. With our low-side portfolio, we have source and sink current ratings of up to 10A. We have higher current isolated gate drivers as well.

    3. With this diagram that you have shown, there is no path to ground shown for charging the bootstrap capacitor. For this to work, something on the "TO LOAD" side would need to provide a path to ground for the bootstrap capacitor to charge. So as shown, this will not work for your application.

    With the requirement for an Automotive rated component without interlock and at least 300V rated, either an isolated gate driver or a low-side driver with the isolated supply solution as seen in the linked FAQ seems to be your best option.

    Let me know if there are any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Hello William,

    Thanks for your lovely suggestion,

    I checked the UCC21551-Q1 it suits my requirement i think, but some doubts to confirm it.

    Question 1:

    I checked the datasheet ,if DT pin left open or floating overloap is allowed which i can use for two-switch forward converter for both mosfets driving same time. can you confirm it it is ok?

    Question 2:

    As  input voltage is 280V and VSSA pin will see my input voltage when high side MOSFET( M1) in picture is on, but VSSA pin  withstand voltage is not given in electrical characteristics of datasheet.But functional isolation voltage is given 1850V.So VSSA pin can support upto 1850V. it is my understanding ,correct me if i am wrong and let what is the VSSA pin withstand voltage. 

    Question 3:

    Can i power-up VDDA,VDDB with the same power supply (12v supply ) which has common ground GND??

    (OR) VDDA,VDDB should be powered-up with two different power supply which has two separate grounds isolated(GND1,GND2 in picture below) 

    Thanks in advance William!!

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    As a note, I realized that for the pulse transformer solution you can flip the polarity of the low-side secondary winding to achieve both outputs operating at the same time. See the image below:

    For your questions regarding the UCC21551-Q1, I am going to connect you with one of our isolated gate drivers applications engineers as they are the experts on that product.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    TI__Genius 17666 points

    Hi Karthik, 

    1. Yes, you can disable the deadtime function by tying DT to VCC. This will allow the outputs to overlap.

    2. Your understanding is about right. The UCC21551 has an internal DC working voltage of Viowm=2121V. However, the channel to channel spacing will set a limit to the voltage that can be applied between them in open air without arching. The 3.2mm distance according to IEC60664 is only safe for 1000Vrms, when the pollution degree is 1 and the material grade is 1, as for this device. You can boost this by using a conformal coating, but for higher voltages it is usually recommended to use two, single channel drivers such as UCC23525.

    Best regards,

    Sean

  • 0 in reply to William Moore
    Prodigy 195 points

    Hello William,

    Thankyou,correct, we can do like below,

  • 0 in reply to Karthik karri
    TI__Genius 9985 points

    Hey Karthik,

    As it appears you have two potential solutions with either an isolated gate driver or the pulse transformer for your two-switch forward converter. I am going to mark this thread as resolved.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Hello William,

    For the below question, Sean cashin not replied yet.can he clarify this query also

    Question :

    Can i power-up VDDA,VDDB with the same power supply (12v supply ) which has common ground GND??

    (OR) VDDA,VDDB should be powered-up with two different power supply which has two separate grounds isolated(GND1,GND2 in picture below) 

    Also if i give isolated supply like above, bootstrap circuit Cboot  is not required know ???

    isolated supply will drive high side MOSFET with constant supply to VDDA.

    question 2:

    I dont want primary to secondary isolation, can i connect GND pin to VSSB pin like mentioned below,. Is there any problem can you check and tell me..

    please clarify this  both query, thank you.

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Hi Karthik,

    1. You usually cannot power both the output A and output B channels with the same 12V supply, since in a forward converter you need to drive a half-bridge. The high-side channel will require a bootstrap circuit or its own isolated supply, like in your second image. Could you maybe provide an overall power supply schematic? I am confused.

    2. You can connect GND and VSSB if you do not need isolation, but this should not be necessary if you have an isolated power supply on the output side. Isolation is usually a system-level benefit.

    Best regards,

    Sean

  • 0 in reply to Sean Cashin
    Prodigy 195 points

    Hi Sean,

    This is my architecture block diagram where my controller, gate driver of the two switch forward converter are same as PFC_GND(GND1).

    My point is like.. as you mentioned, if we use isolated supply to high side , Cboot and bootstrap circuit  are not required .can you confirm this??

    point2:

    The below picture is from UCC21551-Q1 datasheet first page.In the diagram they used same VDD supply to high side and low side which means they referred to same ground.

    so when output A and output B channels are powered up with the same VDD supply,Cboot and bootstrap circuit is required. Can you confirm this??

    Anyways i will use below mentioned external circuit to charge the cboot capacitor in two switch forward converter as both MOSFETS will turn-on at the same time.

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Hi Karthik,

    1. Yes, you can use an isolated supply instead of a bootstrap circuit.

    2. This datasheet image shows a "bootstrap" circuit. It might not work in your circuit if the low-side switch is open. Your external circuit is a good idea if you do not use an isolated bias supply.

    Best regards,

    Sean 

  • 0 in reply to Sean Cashin
    TI__Genius 9985 points

    Hey Karthik,

    As Sean mentioned, for the UCC27714 datasheet image, the thermal and current spikes through the bootstrap resistor would be very large due to the small nature of that resistance. So adding another larger resistor for that path would be advised as seen by the below image.

    Let us know if there are any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 195 points

    Dear William and Sean,

    Thank you so much for your suggestions for the doubts which i asked.

    I am going to select the UCC21551-Q1 isolated half bridge driver. For further points or doubts in any i will contact you during design.Please share your both email id's in personal chat and also wanted to connect with you due the nice suggestion and discussion which you given. 

     Thanks,

    Karthik

  • 0 in reply to Karthik karri
    Prodigy 195 points

    Hello William ,

    Good day!!

    We are planning likely to use SIC MOSFET for better efficiency in two switch forward converter.UCC21551-Q1 gate driver  will support SIC Mosfet also right as mentioned in the datasheet.

    Can you confirm it..

  • 0 in reply to Karthik karri
    TI__Expert 4616 points

    Hi Karthik,

    Hope you are doing well. I am the applications engineer for our dual channel isolated gate drivers.

    I can confirm UCC21551-Q1 will be able to drive a SiC MOSFET load.

    If you have any further questions on this device, feel free to ask below!

    Regards,

    Hiroki

  • 0 in reply to Hiroki Honda
    Prodigy 195 points

    Hi William and Honda and Sean ,

    It will be good option to go with  UCC28C53-Q1 controller + UCC21551x-Q1 gate driver previously we discussed for two switch forward converter( two -switch forward converter operation requirement: by disabling the deadtime function by tying DT to VCC which will allow the outputs to overlap).

    But the UCC28C53-Q1 controller need minimum of 10V to 12V for VDD supply which to give UCC28C53-Q1 controller output (OUT) of 12V .So i cannot give 12V to  PWM INA and INB pins of the UCC21551x-Q1 as they support max only 6V.

    So there  is any alternative isolated gate driver with same features(overlap feature) and AEC-Q qualification and support INA,INB  logic input pins with a voltage of 10 to 12V  ??

    Can you please check and let me know...

  • 0 in reply to Karthik karri
    Prodigy 195 points

    Hi William and Honda and Sean ,

    UCC21320 -Q1 or UCC21530-Q1 will suit my application i think ( if DT pin pulled to VCCI then overlap is allowed ) can you check and confirm it 

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Hi Karthik,

    You can simply use a resistor divider near the UCC21551 input to limit voltage to 5V. This allows your signal line to still have 12V logic and be more immune to noise.

    You should use the UCC21551 which is an update to the UCC21530. While the function is the same according to the datasheet, there are many improvements in the design and production of the UCC21551 that will lower the failure rate.

    Best regards,

    Sean 

  • 0 in reply to Sean Cashin
    Prodigy 195 points

    Ok Sean.

    what about UCC21320 -Q1  .can i use it ?

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Can you try to use UCC21330 instead? If you use the older versions of this family, just make sure to use a VCC of 5V or less, in case you want to replace with the new device versions later.

    Best regards,

    Sean

  • 0 in reply to Sean Cashin
    Prodigy 195 points

    Hello Sean,

    Ok

    But as discussed  i will be using  UCC28C53-Q1 controller, so UCC28C53-Q1 controller need minimum of 10V to 12V for VDD supply which to give UCC28C53-Q1 controller output (OUT) of 12V.

    I understood one of your solution recommendation for resistor divider near the UCC21551 input to limit voltage to 5V.

    But is there any other solution like using AEC-Q isolated gate driver  which supports 12V VCCI excluding ( UCC21320 -Q1 or UCC21530-Q1).

    Thanks,

    Karthik.

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    You could use a diode input gate driver such as UCC23525 as long as you limit the current from 12V into the diode sufficiently. 

  • 0 in reply to Sean Cashin
    Prodigy 195 points

    Hello Sean,

    Then it is better to go with UCC21551-Q1 by adding resister divider as shown in  below picture,

    I will be operating at 100khz switching  frequency, resistor R1 ,R2 1% tolerance could be ok i think, what is your opinion ??

    Do you recommend any other components Sean for  better noise immunity ?? like capacitor across R2 resister.

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Hi Karthik,

    It sounds like a resistor divider is all that you need to resolve this issue. 1% tolerance will work great. You should add a ~100pF capacitor to filter noise, since  these resistors will make the IN node have a higher impedance.

    Best regards,

    Sean

  • 0 in reply to Sean Cashin
    Prodigy 195 points

    Hi Sean and honda,

    I am performing simulation for UCC21551 in the PSICE for TI, i am facing an issue when DT pin it is connected to VCCI and simulation is error.For two switch forward converter you know according to our previous discussion both MOSFET should on at the same time and for that i should connect DT pin to VCCI which is recommended in the datasheet.

    1str problem :

    If i connect DT to VCCI or Left open i am getting simulation error.which is required for my application to have overlap of outA and outB

    2nd problem observed :

    IF i keep INA,INB with same logic high, as i need one same logic high input to both switches and connected DT with 100M resistance  to make it as floating.Still it is not working .I am getting simulation error .can you check what is the issue from your side.

    But  when i am connecting DT to GND with  resistance(example 20k).it is working .

    Requesting Sean and Honda to please check the issue from your side at the earliest and give the response.

    Thanks,

    Karthik

  • 0 in reply to Karthik karri
    TI__Genius 17666 points

    Hi Karthik,

    Can you share your simulation? 

    Can you make sure that this is the .lib file that you are using: 2260.UCC21551.lib

    Best regards,

    Sean