JAJSN65A October 2019 – October 2021 DRV10982-Q1
PRODUCTION DATA
The BEMF constant, Kt[6:0] describes the phase-to-phase BEMF voltage of the motor as a function of the motor velocity.
#SLVSCP28809 shows the measurement technique for this constant as used in the DRV10982-Q1 device.
With the motor coasting, use an oscilloscope to capture the differential voltage waveform between any two phases. Derive the BEMF constant used by the DRV10982-Q1 device as shown in #SLVSCP28476.
where
The measured BEMF constant (KtPH) must be converted to a 7-bit digital register value Kt[6:0] (combination of KtShift[2:0] and KtValue[3:0]) to program the BEMF constant value. The digital register value can be determined as follows:
The maximum KtPH that can be programmed is 1760 mV/Hz. This represents a digital value of 1920 and an encoded Kt[6:0] value of 0x7Fh. The minimum KtPH that can be programmed is 0.92 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 8-4.
Kt[6:0] {KtShift[2:0], KtValue[3:0]} | KtPH (mV/Hz) | Kt [6:0] {KtShift[2:0], KtValue[3:0]} | KtPH (mV/Hz) | Kt [6:0] {KtShift[2:0], KtValue[3:0]} | KtPH (mV/Hz) | |||||
---|---|---|---|---|---|---|---|---|---|---|
BINARY | HEX | BINARY | HEX | BINARY | HEX | |||||
000 0000 | 0x00 | 0 | 010 1000 | 0x28 | 29.44 | 101 1000 | 0x58 | 235.52 | ||
000 0001 | 0x01 | 0.92 | 010 1001 | 0x29 | 33.12 | 101 1001 | 0x59 | 264.96 | ||
000 0010 | 0x02 | 1.84 | 010 1010 | 0x2A | 36.8 | 101 1010 | 0x5A | 294.4 | ||
000 0011 | 0x03 | 2.76 | 010 1011 | 0x2B | 40.48 | 101 1011 | 0x5B | 323.84 | ||
000 0100 | 0x04 | 3.68 | 010 1100 | 0x2C | 44.16 | 101 1100 | 0x5C | 353.28 | ||
000 0101 | 0x05 | 4.6 | 010 1101 | 0x2D | 47.84 | 101 1101 | 0x5D | 382.72 | ||
000 0110 | 0x06 | 5.52 | 010 1110 | 0x2E | 51.52 | 101 1110 | 0x5E | 412.16 | ||
000 0111 | 0x07 | 6.44 | 010 1111 | 0x2F | 55.2 | 101 1111 | 0x5F | 441.6 | ||
000 1000 | 0x08 | 7.36 | 011 1000 | 0x38 | 58.88 | 110 1000 | 0x68 | 471.04 | ||
000 1001 | 0x09 | 8.28 | 011 1001 | 0x39 | 66.24 | 110 1001 | 0x69 | 529.92 | ||
000 1010 | 0x0A | 9.2 | 011 1010 | 0x3A | 73.6 | 110 1010 | 0x6A | 588.8 | ||
000 1011 | 0x0B | 10.12 | 011 1011 | 0x3B | 80.96 | 110 1011 | 0x6B | 647.68 | ||
000 1100 | 0x0C | 11.04 | 011 1100 | 0x3C | 88.32 | 110 1100 | 0x6C | 706.56 | ||
000 1101 | 0x0D | 11.96 | 011 1101 | 0x3D | 95.68 | 110 1101 | 0x6D | 765.44 | ||
000 1110 | 0x0E | 12.88 | 011 1110 | 0x3E | 103.04 | 110 1110 | 0x6E | 824.32 | ||
000 1111 | 0x0F | 13.8 | 011 1111 | 0x3F | 110.4 | 110 1111 | 0x6F | 883.2 | ||
001 1000 | 0x18 | 14.72 | 100 1000 | 0x48 | 117.76 | 111 1000 | 0x78 | 942.08 | ||
001 1001 | 0x19 | 16.56 | 100 1001 | 0x49 | 132.48 | 111 1001 | 0x79 | 1059.84 | ||
001 1010 | 0x1A | 18.4 | 100 1010 | 0x4A | 147.2 | 111 1010 | 0x7A | 1177.6 | ||
001 1011 | 0x1B | 20.24 | 100 1011 | 0x4B | 161.92 | 111 1011 | 0x7B | 1295.36 | ||
001 1100 | 0x1C | 22.08 | 100 1100 | 0x4C | 176.64 | 111 1100 | 0x7C | 1413.12 | ||
001 1101 | 0x1D | 23.92 | 100 1101 | 0x4D | 191.36 | 111 1101 | 0x7D | 1530.88 | ||
001 1110 | 0x1E | 25.76 | 100 1110 | 0x4E | 206.08 | 111 1110 | 0x7E | 1648.64 | ||
001 1111 | 0x1F | 27.6 | 100 1111 | 0x4F | 220.8 | 111 1111 | 0x7F | 1766.4 |