STK6712BMK4 Sanyo Semicon Device, STK6712BMK4 Datasheet - Page 4

• Manufacturer Part Number: STK6712BMK4
• Description: (STK6711AMK4 - STK6714BMK4) 4-Phase Stepping Motor Driver Unipolar Self-Excitation Type(Io = 1.5A)
• Manufacturer: Sanyo Semicon Device

The operation for a 4-phase dual-excitation example is described below.
The STK6712BMK4 equivalent circuit is given in Fig. 1. The circuit consists of the phase drivers, the comparator, the
PWM excitation select and the current detect resistance. In Fig. 1 øA is input with low, and øA with high. When Q1
goes on, the +pin of IC1 (comparator) goes low, making IC1 output
increases as:
For this reason, pin voltage V
output A goes high, and Q1 turns off. The inverse voltage V
In general stepping motor coils use BIFALAR windings, so the energy stored in L1 is generated by L2, at which time the
current in L2 is i
V
This motor current on/off (constant current chopping) is repeated. This waveform is illustrated on the next page.
RO2
. When they are equal, output
i
V
ON
TP
=
= Vref =
L: motor winding inductance
R: Sum of winding resistance and current detect resistance
V
OFF
CC
1 – V
. i
R
R
OFF
O
SAT
1 + R
R
conduction continues until the charges of capacitors C1 and C2 on R3 and R4 pins (E
O
2
R7
O
(1 – e
2
at source resistor R7 increases, and when the V
–
V
S
R
L
CC
inverts and becomes low. Motor winding current i
t
) ........................................................................................................... (1)
2.......................................................................................................... (2)
STK6712BMK4 Basic Circuit
STK6712BMK4
TP
is as:
S
low also. A winding current i
RO
2 voltages of pin 8 and R
ON
again rises to V
ON
O
through Q1
No. 4867-4/10
2 are equal
RO2
C
) equal
level.