IM483H/IM805H Rev. R032206
22
23
IM483H/IM805H Rev. R032206
Stepping motor drivers are designed with the intent that a user’s power supply
output will ramp up to greater than or equal to the minimum operating voltage.
The initial current surge is substantial and could damage the driver if the supply
is undersized. The output of the power supply could fall below the operating
range of the driver upon a current surge, if it is undersized. This could cause the
power supply to start oscillating in and out of the voltage range of the driver
and result in damage to either the supply, the driver, or both. There are two
types of supplies commonly used, regulated and unregulated, both of which can
be switching or linear. Each have advantages and disadvantages.
R e g u l a t e d v s . U n r e g u l a t e d
An unregulated linear supply is less expensive and more resilient to current
surges, however, the voltage decreases with increasing current draw. This can
cause problems if the voltage drops below the working range of the drive. Also
of concern are the fluctuations in line voltage. This can cause the unregulated
linear supply to be above or below the anticipated or acceptable voltage.
A regulated supply maintains a stable output voltage, which is good for high
speed performance. These supplies are also not effected by line fluctuations,
however, they are more expensive. Depending on the current regulation, a regu-
lated supply may crowbar or current clamp and lead to an oscillation that, as
previously stated, can cause damage to the driver and/or supply. Back EMF can
cause problems for regulated supplies as well. The current regeneration may be
too large for the regulated supply to absorb. This could lead to an over voltage
condition which could damage the output circuitry of the IM483H/IM805H.
Non IMS switching power supplies and regulated linear supplies with overcur-
rent protection are not recommended because of their inability to handle the
surge currents inherit in stepping motor systems.
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Table 5.1: Motor Power Supply Specifications
