Rev. 1.00
1�4
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Rev. 1.00
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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Other Functions
Several other functions exist for additional motor control drive signal flexibility. These are the Dead
Time Function, Staggered Function and Polarity Control Function.
Dead Time Function
During transistor pair switching, the Dead Time function is used to prevent both upper and lower
transistor pairs from conducting at the same time thus preventing a virtual short circuit condition
from occurring. The actual dead time value can be setup to be within a value from 0.3μs to 5μs
which is selected by the application program.
The Dead Time Insertion circuit requires six independent output circuits:
When the AT0/AB0/BT0/BB0/CT0/CB0 outputs experience a rising edge, then a Dead Time is
inserted.
When the AT0/AB0/BT0/BB0/CT0/CB0 outputs experience a falling edge, then the outputs remain
unchanged.
The Dead-Time Insertion Circuit is only used during motor control. The Dead Time function is
controlled by the DTE bit in the DTS register.
AT0,AB0
BT0,BB0
CT0,CB0
Dead-Time
Insertion
Dead-Time
Insertion
Dead-Time
Insertion
Dead-Time Insertion
1. Rising Add Dead-Time Insertion
2. Falling Unchange
AT1,AB1
BT1,BB1
CT1,CB1
Dead Time Insertion Timing
A single regiter, DTS, is delicated for use by the Dead Time function.
• DTS Register
Bit
7
6
5
4
3
2
1
0
Name
DTCKS1 DTCKS0
DTE
D4
D3
D�
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
Bit 7~6
DTCKS1~DTCKS0
: Dead Time clock source selection (f
SYS
=f
H
)
0
0:
f
DT
=f
SYS
0
1:
f
DT
=f
SYS
/2
1
0:
f
DT
=f
SYS
/4
1
1:
f
DT
=f
SYS
/8
Bit 5
DTE
: Dead Time insertion control
0: Disable
1: Enable
Bit 4~0
D4~D0
: Dead Time Register bit 4 ~ bit 0
Dead Time counter. 5-bit Dead Time value for Dead Time Unit
Dead Time=(DTS[4 :0]+1)/f
DT