TPS53355: About Qg of internal FET

ACGUY

Part Number: TPS53355

Hello E2E,

Please let me know how much the Qg of internal higf-side FET. I want to estimate the power loss for bootstrap resister tied to VBST-pin.

Regards,

ACGUY

over 5 years ago

0 Gerold Dhanabalan - Online Design Tools over 6 years ago

TI__Genius 14455 points

Hi,

The EVM uses a 2 ohm resistor 1/16W 0603 resistor which you can use as a reference. The datasheet does not have Qg information. Let me check if this information is available.

Regards,

Gerold

0 ACGUY over 5 years ago in reply to Gerold Dhanabalan - Online Design Tools

Guru 11170 points

Hello Gerold,

Did you have any update?

Regards,

ACGUY

0 Peter James Miller over 5 years ago in reply to ACGUY

TI__Guru 56925 points

AC Guy,

It took me some digging to get the details.

The high-side FET has about 10nC of gate charge.

There is an additional 1nC of dynamic charge inside the driver itself plus about 300uA of static load current from BOOT to SW.

At 1MHz switching frequency, the boot current is 10.5mA for 110uW of power dissipation per Ohm of BOOT resistance.

With the power dissipation of the boot resistor under 2mW for resistances upto 10-ohms, the power dissipation in the BOOT resistor is typically ignored.

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TPS53355: About Qg of internal FET