DRV10975ZPWPR datasheet(18/65 Pages) TI1

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Phase U

Phase V

Phase W

Center

Tap

RPH_PH

Phase U

Phase V

Phase W

Center

Tap

PH_CT

RPH_CT

DRV10975, DRV10975Z

SLVSCP2E – JANUARY 2015 – REVISED MAY 2018

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Product Folder Links: DRV10975

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Device Functional Modes (continued)

Figure 8. Wye-Connected Motor Phase Resistance

For a delta-connected motor, the motor phase resistance refers to the equivalent phase to center tap in the wye

configuration, which is represented as RY. RPH_CT = RY (see Figure 9).

For both the delta-connected motor and the wye-connected motor, calculating the equivalent RPH_CT is easy by

measuring the resistance between two phase terminals (RPH_PH), and then dividing this value by two as shown in

Equation 1.

RPH_CT = ½RPH_PH

(1)

Figure 9. Delta-Connected Motor and the Equivalent Wye Connections

The motor phase resistance (RPH_CT) must be converted to a 7-bit digital register value Rm[6:0] to program the

motor phase resistance value. The digital register value can be determined as follows:

1. Convert the motor phase resistance (RPH_CT) to a digital value where the LSB is weighted to represent 7.35

mΩ: Rmdig = RPH_CT / 0.00735.

2. Encode the digital value such that Rmdig = Rm[3:0] << Rm[6:4].

The maximum resistor value, RPH_CT, that can be programmed for the DRV10975 is 14.1 Ω, which represents

Rmdig = 1920 and an encoded Rm[6:0] value of 0x7Fh. The minimum resistor the DRV10975 supports is

0.0294 Ω, RPH_CT, which represents Rmdig = 4.

DRV10975ZPWPR Datasheet(PDF) 18 Page - Texas Instruments