SKT672-040-E Datasheet, PDF (7/19 Pages) ON Semiconductor – Stepping Motor Driver

STK672-040-E
Printed Circuit Board Design Recommendations
This hybrid IC has two grounds, the PG pins (pins 3 and 4) and the SG pin (pin 22). These are connected internally in
the hybrid IC.
Two power supplies are required: a motor drive supply and a 5V supply for the hybrid IC itself. If the ground
connections for these supplies are not good, the motor current waveforms may become unstable, motor noise may
increase, and vibration levels may increase. Use appropriate wiring for these grounds. Here we present two methods for
implementing these ground connections.
If the grounds for the motor drive supply and the hybrid IC 5V supply are connected in the immediate vicinity of the
power supplies:
• If PG and SG are shorted at the power supply, connect only the PG line to pins 3 and 4 on the hybrid IC. Also, be sure
that no problems occur due to voltage drops due to common impedances. In the specifications, this must be VCC2
±5%.
• The current waveforms will be more stable if the Vref ground is connected to pin 22.
• For initial values, use 100μF or over for C1 and 10μF or over for C2.
Locate C1 as close to the hybrid IC as possible, and the capacitor ground line must be as short as possible.
+
Motor
drive
power ^--
supply _PG
Stepping motor
C1 ⁺
STK672-040-E
+
5V
power _--
supply
SG
100μF or over
Oscillator
circuit
(CLK)
3
PG
4
7 VCC2
+
8 Vref
14
CLK
22
SG
ITF02372
If the grounds for the motor drive supply and the hybrid IC 5V supply are separated:
• Insert a capacitor (C1) of 100μF or over as close as possible to the hybrid IC. The capacitor ground line must be as
short as possible.
The capacitor C2 may be included if necessary. Its ground line should also be as short as possible.
+
Motor
drive
power ^--
supply _PG
Separation
+
5V
power _--
supply
SG
Stepping motor
C1 ⁺
100μF or over
+
Oscillator
circuit
(CLK)
STK672-040-E
3
PG
4
7 VCC2
8 Vref
14 ^CLK
22
SG
ITF02373
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