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General => General Technical Chat => Topic started by: rckanta on June 16, 2018, 01:06:44 pm

Title: MOSFET become hot
Post by: rckanta on June 16, 2018, 01:06:44 pm

why MOSFET become hot? what are the reason of MOSFET become hot?

Title: Re: MOSFET become hot
Post by: firewalker on June 16, 2018, 01:14:39 pm

Because the current passing through it is exceeding the maximum value, or the transistor is operating inside it's linear (ohmic) region. The main reason for it to be inside it's ohmic region is "poor" or incorrect gate driving.

Alexander.

Title: Re: MOSFET become hot
Post by: madires on June 16, 2018, 01:48:21 pm

Resistance ;) When the MOSFET is fully turned on it's R_DS_on. And if not fully turned on it's a much higher resistance value as firewalker has already pointed out. The power loss is P = R * I^2.

Title: Re: MOSFET become hot
Post by: daqq on June 16, 2018, 02:22:38 pm

P = V * I

Title: Re: MOSFET become hot
Post by: ogden on June 16, 2018, 04:06:13 pm

Besides mentioned static dissipation, there are switching losses as well - in case mosfet is switched fast, >= 50KHz or so.

You can get loads of "why MOSFET become hot" information here (http://lmgtfy.com/?q=mosfet+dissipation).

Title: Re: MOSFET become hot
Post by: CopperCone on June 17, 2018, 12:37:38 am

because it matured and features began to set in?

Title: Re: MOSFET become hot
Post by: Miyuki on June 17, 2018, 08:32:09 pm

Be careful
Pressure of magic smoke increase and can leak

Title: Re: MOSFET become hot
Post by: NiHaoMike on June 17, 2018, 08:44:24 pm

Quote from: CopperCone on June 17, 2018, 12:37:38 am

because it matured and features began to set in?

For a given voltage rating, new MOSFETs tend to have a lower on resistance for a given gate charge.