Specifications
REMOTE SENSE CHARACTERISTICS (PD-A & PD-E MODELS > 600W)
OUTPUT NOISE: Any noise picked up on the sense leads will appear at the supply's
output and may adversely affect CV load regulation. Twist the sense leads to minimize
External noise pickup and run them parallel and close to the load leads. In noisy
environments, it may be necessary to shield the sense leads. Ground the shield at the power
supply end only. Do not use the shield as one of the sensing conductors
STABILITY: When the supply is connected for remote sensing, it is possible for the
impedance of the load wires and the capacitance of the l
oad to form a filter, which will
become part of the supply's CV feedback loop. The extra phase shift created by this filter
can degrade the supply's stability and can result in poor transient response performance. In
extreme cases, it can cause oscillation.
It is difficult to state simple rules defining the conditions under which this can occur, and
which corrective action to take. A certain amount of trial and error may be called for. Three
guidelines that are almost always valid are:
a. Keepthe leads as short as possible
b. Twistthe load leads together to minimize
Inductance.
c. Shield he sense lead and ground shield at
Supply.
In most circumstances, once these two guidelines are followed, problems associated with
the load lead inductance are eliminated. This leaves the load lead resistance and load
capacitance as the major cause of the reduced stability. In this case, you may obtain further
improvement to the stability by:
a. Keeping the load capacitance as small as
possible.
b.Increasing the diameter of the load lea to
reduce resistance.
If heavier gauge load leads (# 10 or greater) are used, circumstances may arise when the
load lead inductance and the load capacitance can form an under damped filter. This filter
occasionally has the effect of destabilizing phase response. In this case, the above steps can
worsen stability since they will reduce damping in the system.
1 2 3 4 5 6
+OUT +S X X -S -OUT
DUT
Remote Sense
FIGURE 5.8: REMOTE SENSE CONFIGURATION FOR OUTPUT CURRENT > 30ADC
Note: Pin 1 & 2 and 5 & 6 are shorted when not using remote sense operation
5-28