ZHCSDA8E January 2015 – May 2018 DRV10975
PRODUCTION DATA.
The BEMF constant, Kt[6:0] describes the motors phase-to-phase BEMF voltage as a function of the motor velocity.
The measured BEMF constant (Kt) needs to be converted to a 7-bit digital register value Kt[6:0] to program the BEMF constant value. The digital register value can be determined as follows:
The maximum Kt that can be programmed is 1330 mV/Hz. This represents a digital value of 1920 and an encoded Kt[6:0] value of 0x7Fh. The minimum Kt that can be programmed is 0.7 mV/Hz, which represents a digital value of 1 and an encoded Kt[6:0] value of 0x01h.
For convenience, the encoded value of Kt[6:0] may also be obtained from Table 3.
| Kt (mV/Hz) | Kt[6:0] | HEX | Kt (mV/Hz) | Kt [6:0] | HEX | Kt (mV/Hz) | Kt [6:0] | HEX | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 000 0000 | 00 | 22.3 | 010 1000 | 28 | 178 | 101 1000 | 58 | ||
| 0.7 | 000 0001 | 01 | 25.1 | 010 1001 | 29 | 200 | 101 1001 | 59 | ||
| 1.39 | 000 0010 | 02 | 27.8 | 010 1010 | 2A | 223 | 101 1010 | 5A | ||
| 2.09 | 000 0011 | 03 | 30.6 | 010 1011 | 2B | 245 | 101 1011 | 5B | ||
| 2.78 | 000 0100 | 04 | 33.4 | 010 1100 | 2C | 267 | 101 1100 | 5C | ||
| 3.48 | 000 0101 | 05 | 36.2 | 010 1101 | 2D | 290 | 101 1101 | 5D | ||
| 4.18 | 000 0110 | 06 | 39 | 010 1110 | 2E | 312 | 101 1110 | 5E | ||
| 4.88 | 000 0111 | 07 | 41.8 | 010 1111 | 2F | 334 | 101 1111 | 5F | ||
| 5.57 | 000 1000 | 08 | 44.6 | 011 1000 | 38 | 356 | 110 1000 | 68 | ||
| 6.27 | 000 1001 | 09 | 50.2 | 011 1001 | 39 | 401 | 110 1001 | 69 | ||
| 6.97 | 000 1010 | 0A | 55.7 | 011 1010 | 3A | 446 | 110 1010 | 6A | ||
| 7.66 | 000 1011 | 0B | 61.3 | 011 1011 | 3B | 490 | 110 1011 | 6B | ||
| 8.36 | 000 1100 | 0C | 66.9 | 011 1100 | 3C | 535 | 110 1100 | 6C | ||
| 9.06 | 000 1101 | 0D | 72.5 | 011 1101 | 3D | 580 | 110 1101 | 6D | ||
| 9.76 | 000 1110 | 0E | 78 | 011 1110 | 3E | 624 | 110 1110 | 6E | ||
| 10.4 | 000 1111 | 0F | 83.6 | 011 1111 | 3F | 669 | 110 1111 | 6F | ||
| 11.1 | 001 1000 | 18 | 89.2 | 100 1000 | 48 | 713 | 111 1000 | 78 | ||
| 12.5 | 001 1001 | 19 | 100 | 100 1001 | 49 | 803 | 111 1001 | 79 | ||
| 13.9 | 001 1010 | 1A | 111 | 100 1010 | 4A | 892 | 111 1010 | 7A | ||
| 15.3 | 001 1011 | 1B | 122 | 100 1011 | 4B | 981 | 111 1011 | 7B | ||
| 16.7 | 001 1100 | 1C | 133 | 100 1100 | 4C | 1070 | 111 1100 | 7C | ||
| 18.1 | 001 1101 | 1D | 145 | 100 1101 | 4D | 1160 | 111 1101 | 7D | ||
| 19.5 | 001 1110 | 1E | 156 | 100 1110 | 4E | 1240 | 111 1110 | 7E | ||
| 20.9 | 001 1111 | 1F | 167 | 100 1111 | 4F | 1330 | 111 1111 | 7F |