8
hivolt.de
GmbH & Co. KG
Oehleckerring
40
∙
D-22419
Hamburg
∙
Germany
∙
+49 40 537122-0
∙
+49 40 537122-99
∙
∙
www.hivolt.de
3.4
INHIBIT
Each high voltage amplifier channel can be remotely switched off through the
INHIB
input. The input is
TTL-compatible. A LOW-signal turns on the amplifier. In case of open input or HIGH-signal, the
amplifier is turned off. For manual operation, a 50
Ω
BNC-termination resistor can be used to statically
turn the amplifier channel on.
The Inhibit signal drives a semiconductor switch, short-circuiting the output (approx. 100
Ω
) within
microseconds. The switch conducts independently of the internal supply voltage, even after the device
is switched-off.
The
INHIB
input is not suitable to achieve a safe state at the amplifier output. It must not be used for
safety relevant purposes.
3.5
Loading Conditions
The amplifiers are designed to drive any combination of resistive and capacitive loads.
Full output voltage is available for resistive loads
≥
250k
Ω
. When driving capacitive loads the reactive
current must be taken into consideration. This current into the load capacitance depends on the
capacitance value and the slew-rate:
i
CL
= C
L
* dv / dt
.
The effective load capacitance consists of the connected load capacitance, the capacitance of the
output cable, and the capacitance internal to the amplifier. If the output current exceeds the peak
current capability of the amplifier module (refer to the specifications), the output voltage will become
distorted.
In case of larger load capacitances overshoot of the output may occur.
The achievable large-signal bandwidth strongly depends on the capacitance of the connected load.
Particularly with regard to the high speed versions of the amplifier modules, the cable capacitance
may become the dominant part of load capacitance. One meter of typical coaxial cable has a
capacitance of about 100pF.
Large capacitive loads driven by high frequency signals may result in a DC-offset superimposed on the
output voltage. This occurs if the final value of the desired output voltage can not be reached
periodically.
No damage to the amplifier modules will result from the different conditions mentioned.
