Key Difference between Logic level & Normal Level Mosfet

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kumarluc
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Hi 

I want to know the key difference between logic level & normal level Mosfet and also share the selection reason & criteria of both mosfet over the each other.

 

Regards

Lucky Kumar

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Abhilash_P
Moderator
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50 likes received 500 replies posted 250 solutions authored

Hi,

  Thank you for posting on the Infineon community.

The VGS maximum positive and negative voltage limits are found in the datasheet absolute maximum ratings.
These are given as +20 V and -20 V for most power MOSFETs. 

The turn-on voltage at the gate:

  • Logic: 2~4 V

  • Standard: 5~10 V

Standard MOSFETs: The VGS threshold VGS(TH) is typically between 2 and 4 V. The graph below shows that no drain current flows until VGS exceeds VGS(TH) and that a significantly higher voltage is needed to enable high current conduction at the drain. The device RDS(on) rating is typically given for a VGS of 10 V. Standard levels are typically driven with 10 to 15 V gate pulses.

Abhilash_P_1-1699339139773.png

Logic Level MOSFETs: The key difference with logic-level power MOSFETs is that VGS(TH) is much lower, typically between 1.2 and 2.2 V. The maximum VGS ratings are still +20 and -20 V. The advantage is that such devices can be driven with logic-level gate drive voltage, typically 5 V in applications where a higher voltage is not available.

Abhilash_P_2-1699339194151.png

 

Logic-level devices, however, have higher gate charge than standard-level parts of similar V(BR)DSS and RDS(on). This means that more gate charge is needed to switch the device on and off even though the drive voltage is lower. 
Low gate threshold also makes logic-level devices susceptible to induced turn-on caused by dVDS/dt in half bridge configurations, which creates shoot-through currents and increased switching losses.

For these reasons, standard-level devices are preferred for high-frequency switching applications.

 

Regards,
Abhilash P

 

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1 Reply
Abhilash_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 250 solutions authored

Hi,

  Thank you for posting on the Infineon community.

The VGS maximum positive and negative voltage limits are found in the datasheet absolute maximum ratings.
These are given as +20 V and -20 V for most power MOSFETs. 

The turn-on voltage at the gate:

  • Logic: 2~4 V

  • Standard: 5~10 V

Standard MOSFETs: The VGS threshold VGS(TH) is typically between 2 and 4 V. The graph below shows that no drain current flows until VGS exceeds VGS(TH) and that a significantly higher voltage is needed to enable high current conduction at the drain. The device RDS(on) rating is typically given for a VGS of 10 V. Standard levels are typically driven with 10 to 15 V gate pulses.

Abhilash_P_1-1699339139773.png

Logic Level MOSFETs: The key difference with logic-level power MOSFETs is that VGS(TH) is much lower, typically between 1.2 and 2.2 V. The maximum VGS ratings are still +20 and -20 V. The advantage is that such devices can be driven with logic-level gate drive voltage, typically 5 V in applications where a higher voltage is not available.

Abhilash_P_2-1699339194151.png

 

Logic-level devices, however, have higher gate charge than standard-level parts of similar V(BR)DSS and RDS(on). This means that more gate charge is needed to switch the device on and off even though the drive voltage is lower. 
Low gate threshold also makes logic-level devices susceptible to induced turn-on caused by dVDS/dt in half bridge configurations, which creates shoot-through currents and increased switching losses.

For these reasons, standard-level devices are preferred for high-frequency switching applications.

 

Regards,
Abhilash P