POW3 Power Supply
The POW3 power supply board (part number P041) is a sophisticated small form-factor power supply board. It accepts inputs in the range of 9 to 18 VDC (others ranges on request) and outputs a variety of supply lines to energize all instrumentation and boards used with small form-factor instruments. Outputs include:
- ±5VDC and 300 mA, isolated and with extra filtering, for analog and related boards.
- 3.3VDC and 500 mA (or 5 and 400 mA) VDC, isolated for digital boards.
- 12VDC and 250 mA, isolated, for external sensors such as the Sea-Bird SBE3/4 thermometer and conductivity sensor.
- ±12VDC and 150 mA (or ±15VDC and 125 mA), isolated for optional analog and related boards
- 8.4 to 17.4VDC (diode feed through from input) non-isolated to operate other devices such as the SBE5 pump.
The POW3 can be configured for normal operation where the outputs are available as long as the input is within its specified range. However, it can also be configured to sequence its outputs up and down in response to an external switch or logic signal and in response to control signals provided by the Persistor CF2 interface board. In the sequence mode, the POW3 will gracefully turn power on and off so that data files are saved without corruption.
For example, when instructed by an external (user supplied) signal to turn itself on, the POW logic will test that the input is within specification. It will then turn on the 3.3VDC and test the input voltage again. It will continue by turning on other supplies and testing the input voltage until all supplies are on and the input remains within specification. Upon a successful final test, the POW3 will signal the CF2 interface that power is good so that the CF2 micro-controller can start its boot process. If the input voltage fails its test at any stage in the power-up sequence, the CF2 will not be notified that power is good and the CF2 processor will not boot up.
When the user signals that the power is to be turned off, the POW3 will notify the CF2 micro-controller which will stop data acquisition, flush all buffers, close all open files and save the file allocation table to its solid-state disk drive. The CF2 interface will then notify the POW3 that it is safe to turn off the power and the POW will respond by turning off all of its outputs.
The logic on the POW3 is non-volatile and a small, user replaceable, lithium cell allows it to monitor control signals for up to 3 years.
The control logic makes it easy for an external instrument (such as the supervisor in an ARGOS float) to control the starting and ending of microstructure data acquisition. The input power line of 12VDC (nominal, 9 to 18VDC) does not need to be turned off when data acquisition has stopped because the POW3 consumes less than 30 micro-amps when its outputs are turned off.
