PBD3517-1 Datasheet, PDF (10/10 Pages) Ericsson – Stepper Motor Drive Circuit

PBD 3517/1
Common Fault Conditions
• V_MM supply not connected, or V_MM
supply not connected through diodes.
• The inhibit input not pulled low or
floating. Inhibit is active high.
• A bipolar motor without a center tap is
used. Exchange motor for unipolar
version. Connect according to figure
14.
• External transistors connected without
proper base-current supply resistor.
• Insufficient filtering capacitors used.
• Current restrictions exceeded.
• L_A and L_B used for continuous output at
high currents. Use the RC network to
set a proper duty cycle according to
specifications, see figures 6 through
11.
• A common ground wire is used for all
three power supplies. If possible, use
separate ground leads for each supply
to minimize power interference.
Drive Circuits
If high performance is to be achieved from
a stepper motor, the phase must be
energized rapidly when turned on and
also de-energize rapidly when turned off.
In other words, the phase current must
increase/decrease rapidly at phase shift.
Phase Turn-off
Considerations
When the winding current is turned off the
induced high voltage spike will damage
the drive circuits if not properly suppres-
sed. Different turn-off circuits
are used; e. g. :
Diode turn-off circuit (figure 21)
— Slow current decay
— Energy lost mainly in winding
resistance
— Potential cooling problems.
Resistance T O C (figure 22)
— Somewhat faster current decay
— Energy lost mainly in R-Ext
— Potential cooling problems
Zener diode T O C (figure 23)
Relatively high V gives:
Z
— Relatively fast current decay
— Energy lost mainly in V_Z
— Potential cooling problems
Power return T O C for unipolar drive
(figure 24)
Relatively high V_Z gives:
— Relatively fast current decay
— Energy returned to power supply
— Only small energy losses
— Winding leakage flux must be
considered
— Potential cooling problems
Power return to T O C for bilevel drive
(figure 25)
— Very fast current decay
— Energy returned to power supply
— Only small energy losses
— Winding leakage flux must be
considered
Ordering Information
Package
DIP Tube
SO Tube
SO Tape & Reel
Part No.
PBD 3517/1NS
PBD 3517/1SOS
PBD 3517/1SOT
Information given in this data sheet is believed to be
accurate and reliable. However no responsibility is
assumed for the consequences of its use nor for any
infringement of patents or other rights of third parties
which may result from its use. No license is granted
by implication or otherwise under any patent or patent
rights of Ericsson Components. These products are
sold only according to Ericsson Components' general
conditions of sale, unless otherwise confirmed in
writing.
Specifications subject to change without
notice.
1522-PBD 3517/1 Uen Rev. C
© Ericsson Components AB 1999
Ericsson Components AB
SE-164 81 Kista-Stockholm, Sweden
Telephone: [phone]
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