DRV10983_15 Datasheet, PDF (33/57 Pages) Texas Instruments – DRV10983 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

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DRV10983
SLVSCP6B – JULY 2014 – REVISED FEBRUARY 2015
AVSMMd = 1 – AVS mode becomes active when VCC reaches 24 V. The motor acts as a generator and returns
energy into the power supply until VCC reaches 24 V. This mode can be used to enable faster deceleration of
the motor in applications where returning energy to the power supply is allowed.
9.4.8.2 Inductive AVS Function
When DRV10983 transitions from driving the motor into a high-impedance state, the inductive current in the
motor’s windings continues to flow and the energy returns to the power supply through the intrinsic body diodes
in the FET output stage (see Figure 34).
S1
S3
S5
U1
M
S2
S4
S6
S1
S3
S5
U1
M
S2
S4
S6
Driving State
High Impedance State
Figure 34. Inductive Mode Voltage Surge
To prevent the inductive energy from being returned to the power supply, the DRV10983 system transitions from
driving to a high-impedance state by first turning off the active high-side drivers, and then after a fixed period of
time, turning off the low-side drivers (see Figure 35).
S1
S3
S5
U1
M
S2
S4
S6
S1
S3
S5
U1
M
S2
S4
S6
Driving
AVS State
Figure 35. Inductive AVS
In this example, current is applied to the motor through the high-side driver on phase U (S1) and returned
through the low-side driver on phase W (S6). The high-side driver on phase U is turned off and after a period of
time (to allow the inductive energy in the resulting LR circuit to decay) the low-side driver on phase W is turned
off.
9.4.9 PWM Output
The DRV10983 has 16 options for PWM deadtime which can be used to configure the time between one of the
bridge FETs turning off and the complementary FET turning on. Deadtime[3:0] can be used to configure
deadtimes between 40 to 640 ns. Take care that the deadtime is long enough to prevent the bridge FETs from
shooting through.
The DRV10983 offers two options for PWM switching frequency. When the configuration bit DoubleFreq is set to
0, the output PWM frequency will be 25 kHz and when DoubleFreq is set to 1, the output PWM frequency will be
50 kHz.
9.4.10 FG Customized Configuration
The DRV10983 provides information about the motor’s speed through the frequency generate (FG) pin. FG also
provides information about the driving state of the DRV10983.
9.4.10.1 FG Output Frequency
The FG output frequency can be configured by FGcycle[1:0]. The default FG toggles once every electrical cycle
(FGcycle = 00). Many applications configure the FG output so that it provides two pulses for every mechanical
rotation of the motor. The configuration bits provided in DRV10983 can accomplish this for 4-pole, 6-pole, 8-pole,
and 12-pole motors, as shown in Figure 36.
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