3
1 8V/20A* or 25V/7A** range selection key  Selects the 8V/20A or 25V/7A 
range and allows the full rated output to 8V/20A or 25V/7A.
2 20V/10A* or 50V/4A** range selection key  Selects the 20V/10A or 
50V/4A range and allows the full rated output to 20V/10A or 50V/4A.
3 Overvoltage protection key  Enables or disables the overvoltage protection 
function, sets trip voltage level, and clears the overvoltage condition.
4 Overcurrent protection key   Enables or disables the overcurrent protection 
function, sets trip current level, and clears the overcurrent condition.
5 Display limit key  Shows voltage and current limit values on the display and 
allows knob adjustment for setting limit values.
6 Recall operating state key  Recalls a previously stored operating state from 
location ‘‘1’’, ‘‘2’’, or ‘‘3’’.
7 Store operating state / Local key
1
  Stores an operating state in location ‘‘1’’, 
‘‘2’’, or ‘‘3’’ / or returns the power supply to local mode from remote interface 
mode.
8 Error / Calibrate key
2
  Displays error codes generated during operation, self-
test and calibration / or enables calibration mode (the power supply must be 
unsecured before performing calibration). See Service Guide for more details 
on calibration.
9 I/O Configuration / Secure key
3
 Configures the power supply for remote 
interfaces / or secure or unsecure the power supply for calibration. See 
Service Guide for more details on how to secure or unsecure the power supply.
10 Output On/Off key  Enables or disables the power supply output. This key 
toggles between on and off. 
11 Control knob  Increases or decreases the value of the blinking digit by turning 
clockwise or counter clockwise.
12 Resolution selection keys  Move the blinking digit to the right or left.
13 Voltage/current adjust selection key  Selects the knob control function for 
voltage or current adjustment.
1
The key can be used as the ‘‘Local’’ key when the power supply is in the remote 
interface mode.
2
You can enable the ‘‘calibration mode’’ by holding down this key when you 
turn on the power supply.
3
You can use it as the ‘‘Secure’’ or ‘‘Unsecure’’ key when the power supply is 
in the calibration mode.
*For Agilent E3633A Model     **For Agilent E3634A Model