SLVSH04 November 2023 DRV8214
PRODUCTION DATA
Denoted by WSET_VSET, this parameter helps set the target ripple speed or motor voltage, based on the REG_CTRL register setting.
When REG_CTRL is set to 10b, the speed regulation mode is enabled. WSET_VSET is an 8-bit register and can be set to a value between 00h (corresponds to 0 rad/s) and FFh (corresponds to the maximum speed allowable by W_SCALE). The speed control loop matches the value of the SPEED register to the target speed set by WSET_VSET. Please note that the maximum value of the SPEED register is 255. Also note that:
When REG_CTRL is set to 11b, the motor voltage regulation mode is enabled. VM_GAIN_SEL is used to select the voltage range for a smaller or larger range of voltages.
VM_GAIN_SEL | Voltage range | Corresponding WSET_VSET range | Approximate WSET_VSET Resolution | Formula for WSET_VSET setting |
---|---|---|---|---|
0b | 0 V - 15.7 V |
0 V: 0 15.7 V: 255 |
61.56 mV/bit | WSET_VSET = Target Output Voltage x (255/15.7) |
1b | 0 V - 3.92 V |
0 V: 0 3.92 V: 255 |
15.38 mV/bit | WSET_VSET = Target Output Voltage x (255/3.92) |
As mentioned in Table 8-23 setting VM_GAIN_SEL to 1b allows the user to increase the resolution for voltage regulation at lower voltages.
When set to 0b, the motor voltage can be set to a value between 0 for 0 V and 255 for approximately 15.7 V drive output voltage. Please note that the maximum value of WSET_VSET is 255. Each bit corresponds to approximately a 61.56 mV resolution of the output voltage setting. Setting WSET_VSET to 255 sets the target voltage to 15.7 V. The formula to calculate the decimal value is represented by the equation:
For example, if desired target voltage is 5 V, Register Setting Value = 5*(255/15.7) = 81. Hence, setting a value of 81 (or 51h) outputs approximately 5 V.