8
hivolt.de
GmbH & Co. KG
Oehleckerring 40
y
D-22419 Hamburg
y
+49 40 53 71 22 80
y
+49 40 53 71 22 99
y
y
http://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
:
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
250 k
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 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.
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 100 pF.
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.
