Boost converter design using TPS40210

SREC04,

 

SwitcherPro isn't going to allow this design because of a hard limit in the software on the allowable switch current.

While the TPS40210 controller can operate under these conditions, the decision was made to limit the switch current to a level that provided reasonably acceptable efficiency.  The TPS40210's 500mA driver is under-rated for the 100V 12A MOSFET, which will result in high switching losses and lower efficiency.

 

There are two possible solutions:

1) Select a lower switching frequency (100-250kHz) to reduce the switching losses and use the equations provided in the datasheet.

2) Select a TI MOSFET driver to drive the MOSFET, using the output of the TPS40210 controller as the input of the driver, and allow the driver's higher current capabilities to quickly turn the MOSFET ON and OFF.  This will allow a higher switching frequency despite the large gate charge of the MOSFET.

Thnx for ur idea but can you give brief solution to get this...?

SREC04,

 

I'm not sure what you're looking for.

TI offers a number of ground referened N-channel MOSFET drivers depending on your exact needs, price/size/performance requirements.

Inductor, capacitor and MOSFET selection as well as compensation design are all out-lined in the TPS40210 datasheet.

The schematic would be similar to the schematic provided in Switcher Pro for lower current designs, but would us a driver between the TPS40210 gate pin and the gate of the MOSFET.

 

You'll want to be very careful with MOSFET power dissipation as the MOSFET will be carrying about 12A of current 2/3s of the time for roughly 50Arms^2.

If you want, send me a private message with your name, e-mail contact, company name, regional location and end application and I can try to put you in contact with a regional TI support engineer who can help you. 

Dear Peter, Thnx for your response, I am from INDIA, working for Defense and Aerospace application, I have to design 28v to 80v,4A continous output boost converter which is going to drive Some actuator solenoid valve. TPS40210 has 500mA drive, but our MOSFET Drain or Swithching current is (80*4)/28 which is equal to 11.42 A. But my question is without using driver, TPS40210 o/p itself will not control MOSFET gate..? for any MOSFET , Gate drive current will be in some mA only know..?. Whether I need to use driver compulsary..? If so then for my exact requirement which TI driver will be the best..? and the important thing is how to simulate and verify the o/p, since Switchpro is not supporting for this requirement.I downloaded and tried with TINA software also.But could not get it. Operational point not found message is coming.

TPS40210 has 500mA drive, but our MOSFET Drain or Swithching current is (80*4)/28 which is equal to 11.42 A. But my question is without using driver, TPS40210 o/p itself will not control MOSFET gate..?

Yes, the TPS40210 can control the gate of a 100V MOSFET that would drive this kind of application, however the high gate charge of such a MOSFET would result in high switching losses, so I would normally recommend an alternate drive scheme.

For example, the Infineon BSC2050N10LS is a 20.5mOhm 100V Super SO8 MOSFET.  It's switching charge (the charge needed to turn the MOSFET ON) is 9nC and its total gate charge is 31nC.  This would take nearly 20ns to turn the MOSFET "ON" and over 60ns to fully drive the MOSFET gate due to the gate drive current.  If we consider the potential switching losses for 50kHz operation:  1/2 Vout * Isw * (t1+t2) * fsw = 1/2 80V * 12A * (40ns) * 50kHz = 0.96W and with an Rdson of 20.5mOhms, this MOSFET would generate 1.03W of conduction losses, for total losses of 2W (really pushing the power handling capabilities of the MOSFET)

By using an external driver, the switching time can be reduced significantly, reducing switching losses and allowing the use of a lower Rdson MOSFET or faster swithing frequencies.  with a 2-A driver like the TPS2829 (Also available in a Q-100 qualified version) a MOSFET like the BSC06N10NS3 could be selected.  This MOSFET's 13nC of switching charge and 6mOhm Rdson would only dissipate about 1W of power at 100kHz switching frequency when driven by the TPS2829 driver.

 

Can you send me a private message with your e-mail address please? 

Ya sure... My mail ID is rameshsrec04@gmail.com. I searched MOSFET which is given by you ( BSC06N10NS3 ). But couldnt get it.I mean there is no MOSFET in that Part number. If you dont mind, can you pls tel me correct part number. I mean manufacturer detail..

Dear peter, I got that MOSFET which is .BSC060N10NS3 G from infineon Technologies.. Thnx a lot for your great guidlines... Its really worth. I will proceed with this and let you know the result as soon as possible...