STK672-080 Sanyo Semicon Device, STK672-080 Datasheet - Page 14

• Manufacturer Part Number: STK672-080
• Description: Stepping Motor Driver (Sine Wave Drive) Output Current : 2.8 A (No Heat Sink)
• Manufacturer: Sanyo Semicon Device

Thermal Design
<Hybrid IC Average Internal Power Loss Pd>
The main elements internal to this hybrid IC with large average power losses are the current control devices, the
regenerative current diodes, and the current detection resistor. Since sine wave drive is used, the average power loss
during microstepping drive can be approximated by applying a waveform factor of 0.64 to the square wave loss during 2
phase excitation.
The losses in the various excitation modes are as follows.
2 phase excitation
1-2 phase excitation
W1-2 phase excitation
2W1-2 phase excitation
4W1-2 phase excitation
Here, t1 and t3 can be determined from the same formulas for all excitation methods.
t1 = ———— ·
However, the formula for t2 differs with the excitation method.
2 phase excitation
W1-2 phase excitation t2 = ——— – t1
fclock: CLK input frequency (Hz)
Vsat: The voltage drop of the power MOSFET and the current detection resistor (V)
Vdf: The voltage drop of the body diode and the current detection resistor (V)
I
t1: Phase current rise time (s)
t2: Constant-current operating time (s)
t3: Phase switching current regeneration time (s)
OH
: Phase current peak value (A)
R + 0.35
–L
n (1 – ————— · I
t2 = ——— – (t1 +t3)
fclock
t3
Pd
Pd
Pd
Pd
Pd
R + 0.35
2
V
fclock
2EX
1-2EX
W1-2EX
2W1-2EX
4W1-2EX
CC
Motor Phase Current Model Figure (2 Phase Excitation)
7
t1
1
= (Vsat + Vdf) · ——— · I
= 0.64 · {(Vsat + Vdf) · ——— · I
= 0.64 · {(Vsat + Vdf) · ——— · I
= 0.64 · {(Vsat + Vdf) · ——— · I
= 0.64 · {(Vsat + Vdf) · ——— · I
V
L: Motor inductance (H)
R: Motor winding resistance (W)
OH
CC
1: Supply voltage applied to the motor (V)
)
fclock
STK672-080
t2
2
t3 = —— ·
fclock
OH
1-2 phase excitation
2W1-2 phase excitation
4W1-2 phase excitation
fclock
4
fclock
fclock
8
· t2 + ————— · (Vsat · t1 + Vdf · t3)
16
16
–L
R
OH
I
OH
OH
OH
OH
· t2 + ————— · (Vsat · t1 + Vdf · t3)}
n (——————————)
· t2 + ————— · (Vsat · t1 + Vdf · t3)}
· fclock
· t2 + ————— · (Vsat · t1 + Vdf · t3)}
· t2 + ————— · (Vsat · t1 + Vdf · t3)}
2
I
OH
I
OH
I
I
I
OH
· R + V
OH
OH
V
· fclock
t2 = ——— – t1
4
CC
· fclock
· fclock
· fclock
I OH
8
16
16
t2 = ——— – t1
1 + 0.35
CC
fclock
A13270
1 + 0.35
3
fclock
15
No. 6507-14/17