KEPCO ATE-DMG SERIES - Manual (Page 32)

2-8 ATE-DMG 042314
vide for low output noise, excellent voltage stability and good transient response. In the “fast”
mode, the output and main feedback capacitors are completely removed, thereby providing the
characteristics of a wide-band amplifier, ideal for applications requiring a current stabilizer or for
high speed voltage or current programming.
2.7.1 PRECAUTIONS.
The output capacitor, and to a lesser extent, the feedback capacitor of a power supply, control
the programming speed and the current mode recovery time. The removal of these capacitors in
the fast mode results in greatly improved power supply performance in these areas. The power
supply's dynamic stability, however, is reduced, making the output sensitive to the load phase
angle. For this reason, the load presented to the power supply in the fast mode must not contain
excessive capacitance (limit: 1000pF). Also, with the output and main feedback capacitors
removed, there will be an increase in output noise, mainly high frequency noise and pickup, so
that external shielding of programming leads and good grounding practices assume added
importance in the fast mode of operation.
2.7.2 LAG NETWORK ADJUSTMENT
The ATE power supply operating in the “fast” mode, is dynamically stabilized by means of an
internal lag network (E
O
LAG, R27, see Figure 2-3 for location). This control should be adjusted,
for each application, by monitoring the load with an oscilloscope and turning the LAG control for
best output response and maximum dynamic stability under all operating conditions.
2.7.3 CROWBAR OPERATION, FAST MODE
The crowbar circuit in the ATE power supply is not completely removed in the “fast” operating
mode, but continues to offer protection against d-c voltage surges which may harm the load.
NOTE: For fast mode operation into a load interrupted by contactors or relays (“Arcing Load”),
a small, high-frequency-type capacitor may be required across the contacts of the
interrupting device, or the power supply output terminals, or directly across the load
terminals. A ceramic disc capacitor (0.01
.F) has been found to be adequate to pre-
vent spurious triggering of the overvoltage circuit
2.7.4 MANUAL CHANGE-OVER, SLOW/FAST MODE
The ATE power supply is normally delivered for operation in the “slow” mode. By changing
jumper connections at the rear of the power supply, the user can convert from the “slow” mode
to the “fast” mode or vice versa. The following steps are illustrated in Figure 2-6.
1. Remove Links (1)-(2) and (6)-(7) on TB201. This removes the output capacitor (C
O
).
2. At the rear panel, loosen two screws and disconnect interconnection adapter A11.
3. Gain access to A11 jumpers by removing two screws securing connector A11J1 to the shell.
4. Remove jumper on adapter assembly A11 between J3 pins 1 and 2;
5. Install jumpers between J3 pins 3 and 4 and between J3 pins 5 and 6. NOTE: Spare jumpers
located on J5
6. Reassemble PC card to A11 and reconnect A11 at rear panel.