Farnell TSV 70 - Stability Factors; Load Change Effects; Mains Supply Influence; Temperature Variation Impact

be restored by adding a capacitor of approx imately 2000uF at
l00 volts directly across the load.
It may also be necessary to de couple the output and
sensing terminal pairs with low voltage electrolytic
capacitors. For the + oUTPUT and + SENSE terminal pair the
capacitor positive should be connected to the + OUTPUT
terminal and for the - OUTPUT and - SENSE terminal pair, the
NOTE: CARE MUST BE TAKEN NOT TO DRAW LOAD CURRENT FROM THE
SENSE TERMINALS.
TYPICAL PERFORMANCE.
STABILITY.
causes.
(a)
(b)
Output voltage changes are due mainly to the following
(c)
Load Change.
(1)
(11)
(111)
a) Load change.
b) Mains supply change.
c) Conponent temperature change.
Steady load - for a change in steady load
from zero to full load, the specification on
page
holds.
Transient response Typical response to a
pulsed load is shown in figure 3. P.l4.
Output impedance for alternating load
superimposed on a steady load, the output
impedance of the supply increases with
frequency ue to fall off in gain of the
control amplifier, until eventually it is
determined by the output capacitor and lead
inductance. A typical output impedance/
frequency curve is shown in figure 4. P.15.
Mains Supply Change.
Surges on the mains in the form of short rise time
pulses may be fed on to the output terminals by stray
capacitances. When monitoring the output waveform,
both oscilloscope leads should be connected to the same
output terminal before mak ing a measurement to ensure
that pulses which may not appear across the output
terminals are not present.
Where mains borne pulses exist it may be necessary
to fit some form of mains input filter to the mains lead.
Component Temperature Change.
Output variation is caused by component value
change due to temperature change. The temperature
- 11
capacitor positive should be connected to the SENSE terminal