Keysight E4980A - Page 471

Keysight E4980A/AL User’s Guide -471
Handler Interface
Electrical Characteristics
2. /KEY_LOCK signal
The /KEY_LOCK signal (pin 25) is input to the photocoupler LED (on the
cathode side). As long as this signal is Low, the instrument’s front panel
keys are all locked. The photocoupler LED (on the anode side) is driven by
either internal supply voltage (+5 V,+12 V) or external supply voltage
(EXT.DCV2). This voltage is applied to pin 15 or 16 of the instrument’s
connector.
The pull-up voltage, selected using jumper J4, determines the voltage of
/KEY_LOCK (pin 25) in its OFF state as well as the /EXT_TRIG (pins 12 and
13) signal.
Table E-13 shows the electrical characteristics of the DC isolation input
signals.
Figure E-8 shows the circuit configuration for the input signals.
Table E-8 Electrical characteristics of the DC isolation input signals (typical)
Signal
name
Input voltage Input current (at Low) Circuit common
Pull-up voltage
LOW HIGH 5 V 12 V 15 V 24 V
/EXT_TRIG  1 V 5 V to 24 V 11.1 mA 10.5 mA 13.5 mA 10.6 mA When internal pull-up
voltage is used: 
Circuit common of 
E4980A/AL
When external
voltage is used:
COM2
/KEY_LOCK  1 V 5 V to 24 V 2.4 mA 6.6 mA 9.1 mA 14.6 mA When internal pull-up
voltage is used: 
Circuit common of 
E4980A/AL
When external
voltage is used:
COM2