STK672-110 Sanyo Semicon Device, STK672-110 Datasheet - Page 6

• Manufacturer Part Number: STK672-110
• Description: Two-Phase Stepping Motor Driver (Square Wave Drive) Output Current: 1.8 A
• Manufacturer: Sanyo Semicon Device

• Thermal design
T1: Motor rotation operation time
T2: Motor hold operation time
T3: Motor current off time
T2 may be reduced, depending on the application.
T0: Single repeated motor operating cycle
IO1 and IO2: Motor current peak values
Due to the structure of motor windings, the phase current is a positive and negative current with a pulse form.
Note that figure 3 presents the concepts here, and that the on/off duty of the actual signals will differ.
[Operating range in which a heat sink is not used]
The STK672-110 package has a structure that uses no screws, and is recommended for use without a heat sink. This
section discusses the safe operating range when no heat sink is used.
In the maximum ratings specifications, Tcmax is specified to be 105°C, and when mounted in an actual end product
system, the Tcmax value must never be exceeded during operation. Tc can be expressed by formula (A) below, and
thus the range for ∆Tc must be stipulated so that Tc is always under 105°C.
As shown in figure 6, the value of ∆Tc increases as the hybrid IC internal average power dissipation P
As shown in figure 5, P
example shown in the motor current timing chart in figure 3.
Since there are periods when current flows and periods when the current is off during actual motor operation, P
cannot be determined from the data presented in figure 5. Therefore, we calculate P
operation consists of repetitions of the operation shown in figure 3.
The hybrid IC internal average power dissipation P
P
(Here, P1 is the P
If the value calculated in formula (I) above is under 1.4 W, then from figure 6 we see that operation is allowed up to an
ambient temperature Ta of 60°C.
While the operating range when a heat sink is not used can be determined from formula (I) above, figure 5 is merely a
single example of one operating mode for a single motor.
For example, while figure 5 shows a 2-phase excitation motor, if 1-2 phase excitation is used with a 500-Hz clock
frequency, the drive will be turned off for 25% of the time and the dissipation P
figure 5.
It is extremely difficult for Sanyo to calculate the internal average power dissipation P
conditions. After performing the above rough calculations, always install the hybrid IC in an actual end product and
verify that the substrate temperature Tc does not rise above 105°C.
D
= (T1 P1 + T2 P2 + T3) T0
Tc = Ta + ∆Tc (A)
Ta: Hybrid IC ambient temperature, ∆Tc: Temperature increase across the aluminum substrate
D
for IO1 and P2 is the P
Motor phase current
(sink side)
D
increases with the motor current. Here we describe the actual P
(I)
Figure 3 Motor Current Timing
D
for IO2)
D
STK672-110
can be calculated from the following formula.
D
will be reduced to 75% of that in
D
D
assuming that actual motor
for all possible end product
D
calculation using the
D
increases.
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D