Programming BOP 100W, 200W or 400W to output a ramp using a BIT 4886 card, SN programmer or TLD programmer produces an undesired transient. Can this be suppressed?

Answer For BIT 4886 Card: A BOP 100W, 200W or 400W power supply operating with a BIT 4886 card has two control ranges. When the unit is turned on, or the *RST or FUNC:MODE command is sent to the power supply, the unit operates in automatic Range mode (the default). In automatic range mode when the programmed voltage or current is over 1/4 the nominal output, the unit is in high range (x1). (The nominal outputs for a BOP 50-2M, for example, are 50V and 2A.) When programmed voltage or current is less than 1/4 the nominal output, the unit automatically switches to low range (x4). A ramp produced by a series of commands that sequentially increase or decrease the output by regular increments may cause the range to shift automatically, resulting in a brief transient as the unit changes range.

Programming the unit to a specific range prevents the unit from switching ranges. Sending CURR:RANG 1 for a current ramp or VOLT:RANG 1 for a voltage ramp causes the unit to stay in high range. Sending CURR:RANG 4 for a current ramp or VOLT:RANG 4 for a voltage ramp causes the unit to stay in low range. Send the command to the unit once at the start of the ramp. This prevents the unit from switching ranges and the transient will disappear.

It is important to remember that issuing *RST, or FUNC:MODE CURR commands will set the unit back to automatic range mode. Automatic range mode can also be restored by sending CURR:RANG AUTO or VOLT:RANG AUTO.