MP6614, How do VISEN react to sensed currents?

Motor Drivers/Sensors
1

VISEN is an analog voltage output from the MP6614, that according to the datasheet is proportional to the output current. But the two current sensors are on the lower side transistors of the H-bridge as seen in this block diagram taken from the datasheet:

MP6614 block diagram
MP6614 block diagram792×589 37.7 KB

Other similar block diagrams can be found for other similar MPS integrated circuits with an H-bridge. I am looking for H-bridge devices able to control a DC motor with four quadrant control and fast speed control including a PI control of current. So you can have both positive and negative power to the motor and both speed directions.

I like to know in more detail how VISEN react to different situations of current at these two sensors or possibly the current at the output. I was not able to find that information reading the datasheet, and therefore I hope for your help.

Assume that the two currents at the two sensors are positive when the currents flow downward in the two lower transistors. Then we call these currents Ileft and Iright. According to data sheet a current of 10000 times below the sense current are supplied to the resistor Rsense to GND on the Iset pin. Assume Rsense = 5000 Ohm. What is the expected VISEN voltage in these conditions?

Ileft = 0 A, Iright = 0 A
Ileft = 1 A, Iright = 0 A
Ileft = 0 A, Iright = 1 A
Ileft = -1 A, Iright = 0 A
Ileft = 0 A, Iright = -1 A
Ileft = 1 A, Iright = -1 A
Ileft = -1 A, Iright = 1 A

2

Hello viggo,

I will reach out to our team to get some clarification on this.

1 Like
3

Hello Viggo,

Looking through the datasheet more I think that for the same current in each branch the output will be the same. Since both LS-Fets use the same sense.

Only the positive current can be measured.

4

I now define IOUT1 to be the current going out of the chip on pin OUT1 to the motor.

If I understand your answer correctly, do you agree to this result?

Ileft = 0 A, Iright = 0 A, IOUT1 = anything, VISEN = 0 V
Ileft = 1 A, Iright = 0 A, IOUT1 = -1 A, VISEN = 1 V
Ileft = 0 A, Iright = 1 A, IOUT1 = 1 A, VISEN = 1 V
Ileft = -1 A, Iright = 0 A, IOUT1 = 1 A, VISEN = 0 V
Ileft = 0 A, Iright = -1 A, IOUT1 = -1 A, VISEN = 0 V
Ileft = 1 A, Iright = -1 A, IOUT1 = -1 A, VISEN = 1 V
Ileft = -1 A, Iright = 1 A, IOUT1 = 1 A, VISEN = 1 V

Therefore in the situation, where both upper transistors are on, the VISEN voltage will be zero regardless of the current.

I a situation where the motor provide return power to VIN, the VISEN will be zero regardless of the current.