STK672-532
(2) I
V
Operating Waveforms in Non-avalanche Mode
D and DSS
Although the waveforms during avalanche mode are given in Figure 1, sometimes an avalanche does not result during
actual operations.
Factors causing avalanche are listed below.
• Poor coupling of the motor’s phase coils (electromagnetic coupling of A phase and AB phase, B phase and
BB phase).
• Increase in the lead inductance of the harness caused by the circuit pattern of the P.C. board and motor.
• Increases in V
, tAVL, and IAVL in Figure 1 due to an increase in the supply voltage from 24V to 36V.
DSS
If the factors above are negligible, the waveforms shown in Figure 1 become waveforms without avalanche as
shown in Figure 2.
Under operations shown in Figure 2, avalanche does not occur and there is no need to consider the allowable loss
range of PAVL shown in Figure 3.
V
DS
I
: Motor current peak value
OH
I
D
ITF02558
Figure 2 Output Current, I , and Voltage, V , Waveforms 2 of the STK672-5** Series when Driving a
DS
D
2-Phase Stepping Motor with Constant Current Chopping
Figure 3 Allowable Loss Range, PAVL-I
During STK672-532 Avalanche Operations
OH
PAVL - I
OH
6
5
4
3
2
1
0
0
0.5
1.0
1.5
2.0
2.5
Motor phase current, I
- A
OH
Note:
The operating conditions given above represent a loss when driving a 2-phase stepping motor with constant current
chopping.
Because it is possible to apply 3.7W or more at I =0A, be sure to avoid using the MOSFET body diode that is used
OH
to drive the motor as a zener diode.
No. A2111-17/23
SANYO [ SANYO SEMICON DEVICE ]
