SLA7020 Просмотр технического описания (PDF) - Sanken Electric co.,ltd.
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SLA7020 Datasheet PDF : 10 Pages
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SLA7024M, SLA7026M, SLA7027MU, SLA7022MU, SLA7029M,
SMA7022MU, SMA7029M, SLA7020M, SLA7021M and SDK03M
Application Note
s Determining the output current
Fig. 1 shows the waveform of the output current (motor coil
current). The method of determining the peak value (lo) of
the output current based on this waveform is shown below.
<Parameters for determining the output current lo>
Vb : Reference supply voltage
r1, r2 : Voltage-divider resistors for the reference supply
voltage
Rs : Current detection resistor
To determine rx, equation w can be modified to obtain
equation e.
rx =.. 1
r1
1
Vb
1
–1 –
Rs•lOPD
r2
.............................. e
(1) Normal rotation mode
lo is determined as follows when current flows at the
maximum level during motor rotation. See Fig. 2, 3 and
4.
lo =..
r2 • Vb
r1+r2 Rs
...................................................
q
(2) Power down mode
The circuits in Fig. 5, 6 and 7 (rx and Tr) are added in
order to decrease the coil current. lo is then determined
as follows.
IOPD =..
1+
1
r1(r2+rx)
•
Vb
Rs
r2•rx
....................................... w
Fig. 3 Circuit for fixing the coil current
Vb(5V)
r1
r2
r6
r5
C3
3,(14)
SLA7024M
SLA7026M
SLA7027MU
9,(10)
RS
Fig. 1 Waveform of coil current (Phase A excitation ON)
IO
Phase A
0
Phase A
Fig. 4 Circuit for fixing the coil current
Vb(5V)
r1
r2
r6
r5
C3
SDK03M
3
10 13 15
RS
Fig. 2 Circuit for fixing the coil current
Vb(5V)
r1
r2
SLA7022MU
r6
SLA7029M
SMA7022MU
r5
SMA7029M
3,(13) SLA7020M
C3
SLA7021M
7,(9)
RS
Fig. 5 Circuit for fixing the coil current
Vb(5V)
r1
Power down
signal
rX r2
Tr
SLA7022MU
SLA7029M
r6
SMA7022MU
SMA7029M
r5
3,(13)
SLA7020M
SLA7021M
C3
7,(9)
RS
17
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