Connections; Output Overload - Stanford Research Systems SIM918 Operating And Service Manual

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1.2.4.2 Bias shield

1.2.5 Output overload

output overload limits

1.3 Connections

Panel BNC
Front Input
Bias
Output
Rear Shield Program Voltage
Ref Clock Sync
Successive presses of the [BIAS Shield] button float the outer
shell of the Bias BNC and connect it to ground. The state of the
bias shield connection is indicated by one of two LEDs: the yel-
low BIAS Shield Float or the green BIAS Shield GND.
Note that it is the electric potential at the Bias terminal, not the po-
tential di erence across the Bias connector, that the autozero circuit
uses as the reference for the input voltage.
An overload condition is recognized and the OUTPUT OVLD
is activated if the absolute value i
limits are typically 10 0 V and are between
10 4 V V
min
The overloaded state is also recognized, and OUTPUT OVLD acti-
vated, if the raw output of the transimpedance stage, V
exceeds these limits. To distinguish between the two output over-
load possibilities, use the OVLD? query. The overload LED stays on
for a minimum of 50 ms; after this time it turns o if the overload
condition has ceased.
There are five BNC connectors in the SIM918, three on the front panel
and two at the rear.
Terminal
Center
Shield
Center
Shield
Center
Shield
Center
Shield
Center
Shield
Table 1.1: BNC connections in the SIM918.
For a further discussion of grounding, see Section 2.2.1. The SIM
interface connector is discussed in Section 1.6.1.
R exceeds certain limits. These
in F
9 9 V 9 9 V V
max
Signal
Input current
Shield program voltage,
bias voltage, signal ground
Bias voltage
Float, power ground
Output voltage
Signal ground
Shield program voltage
Chassis ground
Reference clock
Chassis ground
SIM918 Precision Current Preamplifier
Getting Started
LED
10 4 V
i R
bias in F
Direction
Input
Output
Input
Output
Output
Input
Input, output
Input, output