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Installation and Configuration
User Options and Settings
Release 1.2 29
TTL
Shutdown
You can use the Shutdown function to disable or enable the supply's output.
Disabling the supply using TTL shutdown allows you to make adjustments to the
load or to the power supply without shutting down the power supply. With the
RS-232 interface installed, TTL shutdown is activated by a TTL signal to Pin 1 of
the J21 connector on the interface subplate. The shutdown user line uses a 0-5Vdc
TTL input with a high signal range of 2.2-5.0Vdc. The current range of the
shutdown line is 1-10mA. See Figure 2.6, “J21 User Signal Connector Circuit
Block Diagram” on page 31 for a schematic of the J21 connector containing the
shutdown user line.
You can select the logic level of the TTL input by changing the J3 connector on the
RS-232 PCB. Table 2.13 shows the TTL signal levels for the J3 jumper settings.
See Figure 2.2-3 for the location of the J3 jumper on the printed circuit board.
Table 2.13 Switch Settings for TTL Shutdown Circuit Logic
PCB Jumper J3 Position TTL Signal Level Supply Output Condition
Pin 2 to Pin 3 (default) HIGH
LOW
OFF
ON
Pin 1 to Pin 2 HIGH
LOW
ON
OFF