MCT8316Z: MCT8316Z brake function not available

liu sq

Part Number: MCT8316Z
Other Parts Discussed in Thread: MCF8316A

I use MCT8316ZR to control the motor to lift and lower objects. At present, MCT8316ZR can control the rotation of the motor and drive the lifting of objects normally.

I am debugging the MCT8316ZR brake function, but I found that the brake function cannot maintain the motor hovering state.

I have made the following settings for MCT8316ZR:

Control_Register_1 = 0x03

Control_Register_2 = 0x66

Control_Register_3 = 0x46

Control_Register_6 = 0x01

Control_Register_8 = 0x03

Control_Register_7 = 0x03 (this reg set to 0x01 or 0x03 , I feel the same effect)

and set the brake pin to high , drvoff pin to low nsleep pin to low .

Other registers use default values.

When I need brake enable, the motor can be suspended. Pulling up the brake pin has a slight effect, but it is not very obvious. The braking force is very small.

May I ask what the reason is?

The attachment is a circuit schematic diagram.

Thank you.

over 2 years ago

0 Vishnu Balaraj over 2 years ago

TI__Mastermind 24415 points

I will get back to you shortly!

0 Vishnu Balaraj over 2 years ago

TI__Mastermind 24415 points

Hi Liu,

The motor braking torque in MCT8316Z is low because it applies passive braking. passive braking is achieved by tuning on all three low side FETs. This brake method does not generate high braking torque. We have align braking feature in MCF8316A (fully integrated Sensorless FOC solution) where the braking torque and braking angle can be controlled.

Regards,

Vishnu

0 liu sq over 2 years ago in reply to Vishnu Balaraj

Prodigy 30 points

The braking torque of MCT8316Z is low ,May I know the exact amount?

Can MCF8316A replace the MCT8316Z without repair my HW and SW?

If it is not ,which one chip can do that?

What is MCF8316A braking torque?

0 Vishnu Balaraj over 2 years ago in reply to liu sq

TI__Mastermind 24415 points

Liu,

Braking torque depends on the current flowing through the LS FETs. Current depends on the BEMF voltage of the motor and RdsON. Braking current is BEMF voltage divided by RdsON.

MCF8316A and MCT8316Z share the same package but not pin to pin compatible. So the schematic and layout will differ.

Regards,

Vishnu

0 liu sq over 2 years ago in reply to Vishnu Balaraj

Prodigy 30 points

Vishnu,

I just want to know how much greater the braking torque of MCF8316A than MCT8316Z under the same condition,so that I can evaluate whether replacing MCT8316Z with MCF8316A can solve the problem of my current use of MCT8316Z z-axis being unable to hover.

Or how to control the braking torque.

regards,

Liu.

0 Vishnu Balaraj over 2 years ago in reply to liu sq

TI__Mastermind 24415 points

Liu,

MCF8316A uses align braking in which DC current is applied to any two motor phases. This current can be configured by the user. Braking torque increases with the align current. Please refer to section 7.3.19.6 in MCF8316A Datasheet for more details on align braking. MCT8316Z applies brakes by tuning on all three low side FETs.

Regards,

Vishnu

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MCT8316Z: MCT8316Z brake function not available