Re: Cooling of SO8
From: legg (legg_at_nospam.magma.ca)
Date: 12/07/04
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Date: Tue, 07 Dec 2004 18:26:37 GMT
On Tue, 7 Dec 2004 06:11:47 -0700, "Fritz Schlunder" <me@privacy.net>
wrote:
>
>"Heindorf" <heindorf@aeras.de> wrote in message
>news:41B58EDD.2B1D6C8D@aeras.de...
>> Hi,
>> I'm using a TC4420-SMD as a gate driver ( 15V, 100kHz, Qg=0.8µC, Rg=5
>> Ohm). Now the board is finished and the creature gets pretty hot despite
>> a little heatsink glued on top.Is there a pin-compatible IC available
>> with perhaps a higher power dissipation and/or lower output impedance?
>> Is there a better way to cool down the case ( no fan)?
>> Rolf
>
>
>The Microchip TC4422 is pin compatible and has somewhat lower output
>resistance. Some similar parts by IXYS are also pin compatible and have
>slightly better output resistance.
>
>http://ww1.microchip.com/downloads/en/DeviceDoc/21420d.pdf
>
>http://www.ixys.com/99054.pdf
>
>I assume you understand that total gate drive power is fixed for a given
>switching frequency, gate charge, and input voltage, irrespective of total
>gate resistance. All you can really expect to do is offload some of the
>heat away from the gate driver IC and into the gate resistor. You could
>keep the TC4420 part and just increase the gate resistance value, but then
>you would have slower switching performance. Alternatively you could
>replace the TC4420 with a lower resistance part like the TC4422 and then
>increase the gate resistor value a corresponding amount. In this way
>switching performance will not be altered (for the better or worse), but
>some of the heat will be offloaded from the driver IC and more into the gate
>resistor.
>
>Alternatively you could replace your MOSFET(s)/IGBT(s) with lower gate
>charge device(s), or decrease the switching frequency, or decrease the gate
>drive voltage...
>
10 out of 10.
RL
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