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Aug 30, 2016
05:30 AM
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Aug 30, 2016
05:30 AM
Hello Everyone!
This is my very first post at Infineon Forums.
I am using BTN8982TA Half Bridge to drive a 12V 250W DC motor. I have used the schematic given in the application note of BTN8982TA (Attached Below). A PWM of frequency 490Hz is used to vary the speed.
When I drive the motor with the circuit, the circuit draws more current than what the motor draws at full 12V. I have tried varying the slew rate resistor from 5 Ohms to 51K Ohms. But it did not change the current. I am guessing a cross conduction between the PMOS and the NMOS.
Will increasing the PWM frequency help?
Kindly provide a solution for this problem.
Thank you.
This is my very first post at Infineon Forums.
I am using BTN8982TA Half Bridge to drive a 12V 250W DC motor. I have used the schematic given in the application note of BTN8982TA (Attached Below). A PWM of frequency 490Hz is used to vary the speed.
When I drive the motor with the circuit, the circuit draws more current than what the motor draws at full 12V. I have tried varying the slew rate resistor from 5 Ohms to 51K Ohms. But it did not change the current. I am guessing a cross conduction between the PMOS and the NMOS.
Will increasing the PWM frequency help?
Kindly provide a solution for this problem.
Thank you.
Solved! Go to Solution.
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1 Solution
Oct 24, 2018
02:20 AM
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Oct 24, 2018
02:20 AM
Cross current protection is integrated into BTN8982TA. It means we have a voltage comparator being used to check the Vgs voltage of the MOSFET which is switched for the moment. Only if the Vgs is lower than the threshold voltage, the other MOSFET can be switched on. Therefore this active cross current protection feature can avoid the cross conduction between PMOS and NMOS.
Could you please clarify how you measured the current? Did you measure the current at Vs pin? Or you convert the current at IS pin to voltage?
If you measure the current at IS pin, you will see offset current when the output current is 0A. Please use the following way to calculate the load current: IL = dKILIS * (IIS - IIS(offset))
Please find the detailed explanation in Chapter 4.2 and Chapter 4.5.1.1 in our application note:
https://www.infineon.com/dgdl/Infineon-NovalithIC_BTN89x0-x2-AN-v00_06-EN.pdf?fileId=db3a30433fa9412...
Could you please clarify how you measured the current? Did you measure the current at Vs pin? Or you convert the current at IS pin to voltage?
If you measure the current at IS pin, you will see offset current when the output current is 0A. Please use the following way to calculate the load current: IL = dKILIS * (IIS - IIS(offset))
Please find the detailed explanation in Chapter 4.2 and Chapter 4.5.1.1 in our application note:
https://www.infineon.com/dgdl/Infineon-NovalithIC_BTN89x0-x2-AN-v00_06-EN.pdf?fileId=db3a30433fa9412...
1 Reply
Oct 24, 2018
02:20 AM
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Oct 24, 2018
02:20 AM
Cross current protection is integrated into BTN8982TA. It means we have a voltage comparator being used to check the Vgs voltage of the MOSFET which is switched for the moment. Only if the Vgs is lower than the threshold voltage, the other MOSFET can be switched on. Therefore this active cross current protection feature can avoid the cross conduction between PMOS and NMOS.
Could you please clarify how you measured the current? Did you measure the current at Vs pin? Or you convert the current at IS pin to voltage?
If you measure the current at IS pin, you will see offset current when the output current is 0A. Please use the following way to calculate the load current: IL = dKILIS * (IIS - IIS(offset))
Please find the detailed explanation in Chapter 4.2 and Chapter 4.5.1.1 in our application note:
https://www.infineon.com/dgdl/Infineon-NovalithIC_BTN89x0-x2-AN-v00_06-EN.pdf?fileId=db3a30433fa9412...
Could you please clarify how you measured the current? Did you measure the current at Vs pin? Or you convert the current at IS pin to voltage?
If you measure the current at IS pin, you will see offset current when the output current is 0A. Please use the following way to calculate the load current: IL = dKILIS * (IIS - IIS(offset))
Please find the detailed explanation in Chapter 4.2 and Chapter 4.5.1.1 in our application note:
https://www.infineon.com/dgdl/Infineon-NovalithIC_BTN89x0-x2-AN-v00_06-EN.pdf?fileId=db3a30433fa9412...