tb6585fg TOSHIBA Semiconductor CORPORATION, tb6585fg Datasheet - Page 14

• Manufacturer Part Number: tb6585fg
• Description: 3-phase Sine-wave Pwm Driver For Bldc Motors
• Manufacturer: TOSHIBA Semiconductor CORPORATION

<Sine-Wave PWM Signal Generation>
The modulated waveform is generated using the Hall signals. The sine-wave PWM signal is then generated
by comparing the modulated waveform with the triangular wave.
The time between the rising edges (falling edges) and the immediately-following falling edges (rising edges)
of any of the three Hall signals (interval of 60 electrical degrees) are calculated by the counter. This period is
used for data generation of the next 60-electrical-degree interval.
The modulated waveform of 60-electrical-degree interval consists of 32 data items. The time period for a
single data item is 1/32 of the previous 60-electrical-degree interval. The modulated waveform advances by
this period. (Operating waveforms when CW/CCW = Low)
As illustrated above, the modulated waveform ) (1)’advances by 1/32 of the period between the rising edge
(
period between the falling edge (
If the next edge does not occur even after completing the generation of 32 data, data for the next
60-electrical-degree interval are generated based on the same time period until the next edge occurs.
Also, the phase alignment with the modulated waveform is performed at every zero-cross point. The
modulated waveform is reset by being synchronized with the rising and falling edges of the position
detection signal at every 60 electrical degrees. Therefore, the modulated waveform becomes discontinuous
) of HU and the falling edge (
S
V
HUP
HVP
HWP
S
S
Sw
U
V
* t = t (1) × 1/32
*t
*t
1
(5)
2
3
4
(6)
5
) of HW and the rising edge (
) of HW. Likewise, the modulated waveform (2)’ advances by 1/32 of the
6
32 data
(1)
(6)
(1)’
(2)
(1)
14
(3)
(2)
30
31
32
(3)
) of HV.
*: Though the HUP, HVP and
HWP pins are Hall effect
inputs, they are indicated as
square waveforms for the
sake of simplicity.
TB6585FG
2008-03-04