IPMC Power Control Bypass ---------------------------- Initial Rev. 13-Feb-2020 Current Rev. 17-Feb-2020 During normal operation of the Hub Module the IPMC controls the powered-up vs powered-down state of the Hub. This control is accomplished via the normal ATCA Shelf Manager power control sequence and uses the "12V_Enable" signal (aka the Payload Enable signal) from the IPMC to either turn On or turn Off the Isolated 48 Volt to 12 Volt DCDC Converter on the Hub Module. Before going further it is useful to review the operation of the 5 basic blocks in the Hub Module's power system: 1. The Power Entry module receives 48 Volt power from the backplane and an Enable signal from the backplane. This Enable signal is only asserted when the Hub Module is fully plugged into the backplane, i.e. this Enable signal has the shortest pin length of all of the multi length backplane pins. The backplane Enable signal to the Power Entry module has nothing to do with the Front Panel Handle Switch or with the 12V_Enable signal (aka Payload Enable signal) from the IPMC to the Isolated 48 V to 12 V DCDC Converter. At anytime when the Power Entry module receives 48 Volt backplane power AND the backplane Enable signal then it sends out: Always_On 3.3 Volts to the IPMC, Always_On 5.0 Volts to the Hub's Power Supervisor circuits, and 48 Volts to the input of the Isolated 48 V to 12 V DCDC Converter. All connections to the Power Entry module are shown in drawing number 6. 2. The Isolated 48 V to 12 V DCDC Converter is shown in drawing number 7. It is this converter that is either enabled or disabled to turn the Hub module On or Off. The On Off control of the Isolate 48V to 12V Converter is implemented via the OPT1 optical isolator and the Off/On Control pin #2 on this isolated converter. 3. The next step in the Hub's power system is the 9 "point of load" converters that use the Isolated 12V power from the Isolated 48V to 12V Converter as their input to make the 9 power rails that supply the various circuits on the Hub Module. These 9 "point of load" converters are shown in drawing number 24. Note that there are actually 11 power rails but I'm not counting the 2 reference supplies in this description. 4. The power system Supervisor circuits on the Hub Module are shown in drawing numbers: 30, 30_Blk, 31, and 31_Blk. The Power Supervisor controls the power-up and power-down sequence and the ramp rates of the 9 "point of load" converters. Once all 9 converters have ramped up and are operating within their output voltage limits then the Power Supervisor de-asserts the Board_Startup_Reset_B signal. The power-up and power-down sequences are shown in drawings number: 28 and 29. The Hub's power system Supervisor is operational anytime that the Hub is plugged into the backplane, i.e. anytime that the Always_On 5.0 Volt power is available from the Power Entry module. Specifically the power Supervisor is operational before the Isolated 12V power is turned On. Note that the proper operation of the Hub's power Supervisor is depended on the correct programming of the 7 GE Power Trends "point of load" DCDC converts. 5. The final component of the Hub's power system is the Enable_12V signal, aka Payload Enable signal, that comes from the IPMC and via the optical isolator OPT1 is used to turn the Isolated 48V to 12V Converter On or Off. This signal from the IPMC is shown in drawing number 14. For a complete description of the operation of the Power Entry module and the Isolated 48V to 12V DCDC Converter please see their data-sheets in the Hub's web site: https://web.pa.msu.edu/hep/atlas/l1calo/hub/hardware/components/power/ A complete description of the Hub's power system, the power supervisor circuits, and the power-up and power-down sequences is given in: https://web.pa.msu.edu/hep/atlas/l1calo/hub/hardware/details/hub_0_ab_power_system.txt Bypass of the IPMCs Hub On/Off Power Control: --------------------------------------------- During normal operation the IPMC is in control of the Power On/Off state of the Hub Module, but there are a number of special cases when we need to bypass the IPMC's control of the Hub On/Off state. These special cases include: - During initial bench testing of a Hub Module at the end of its MSU Final Assembly when the Hub is running on the bench (outside of a Shelf) from the stand alone 48 Volt power supply. - Any time that a Hub needs to be operated without an IPMC card installed or with an IPMC card that does not have the appropriate software installed on it. - Any time that a Hub is being repaired or tested on the bench and it is operating from the stand alone 48 Volt power supply. - During the time when we did not have software to provide correct operation of the IPMC's power control function, i.e. when the IPMC would power cycle the Hub once per minute. Simplest way to Bypass the IPMC's Power Control: ------------------------------------------------ The simplest way to bypass the IPMC's power control of the Hub module is to: - Either remove the IPMC or remove Jumper JMP5 or remove both of them AND - Solder the wires from a miniature toggle switch across the pads for JMP6 This is the simplest way to operate the Hub Module on the bench during MSU Final Assembly from the stand alone 48 Volt power supply. To operate this way one would: - Set the miniature toggle switch across jumper JMP6 in its Open position. - Turn On the 48 Volt bench supply and turn On this supply's ATCA backplane Enable signal. - Wait a second or two (for the Power Entry Module to start up) and then close the miniature toggle switch that is across JMP6 and the Hub will begin its power-up sequence. Note that if you have the miniature toggle switch across JMP6 in its closed position when you turn On the bench supply and its ATCA Enable signal then the Hub will NOT start up. This is because the 48 Volt Output of the Power Entry Module must not be loaded while the Power Entry Module is doing its own start up routine. If the Hub's Front Panel LEMO connector is not yet installed then this miniature toggle switch can be temporarily mounted in the Front Panel hole for the LEMO connector. Different IPMC Power Control Bypass used on Hubs Shipped to CERN with an IPMC installed and without an Extra Toggle Switch Dangling from the Front Panel: ----------------------------------------------------- A slightly different IPMC Power Control Bypass setup was used when we needed to deliver Hub cards with installed IPMCs to CERN but we did not have IPMC software that did not power cycle the Hub once per minute and we needed to have the Front Panel Handle Switch connected to the IPMC in the normal ATCA required way and we did not want an extra toggle switch dangling from the front of the Hub on some long wires because the LEMO connector was installed so we could not mount an extra toggle switch in the LEMO connector hole. For this special case of operation we used the Front Panel Handle switch for two different and independent purposes. These two purposes were: - When the Hub was fully inserted and latched into position then the Front Panel Handle Switch sent an On signal to the On/Off control of the Isolated 48V to 12V DCDC Converter. It did this by the long Yellow wire that ran up the front of the Hub Module from the Handle Switch to the common terminal of jumpers JMP5 and JMP6. Note that for this special case of operation both JMP5 and JMP6 were removed. - When the Hub's Handle Switch was un-latched or in the position to extracted the card from the Shelf then the Handle Switch sent both an Off signal to the Isolated 48V to 12V Converter and it sent the "Operator Wants to Extract this Card" signal to the IPMC. Note that for normal ATCA operation where the IPMC controls the Hub's powered-up / powered-down state then the Front Panel Handle Switch is only used to send the "Operator Wants to Extract this Card" signal to the IPMC. The On / Off control signal to the Isolated 48V to 12V Converter comes from the IPMC itself. Recall that when using this special dual purpose Front Panel Handel Switch setup that you must have the card fully inserted in the Shelf and then rest in that position for a few seconds before allowing the Handle Switch to snap into its Latched position. Again this is because the Power Entry module must Not have a load on it when it is doing its own power up routine. Recall that for the normal standard ATCA setup and operation of the Hub Module that the Front Panel Handle Switch connects only to an input of the IPMC that is used to tell the IPMC that a human wants to extract the card from the Shelf. In a normal standard setup the Front Panel Handle Switch does NOT directly turn the Isolated 48V to 12V Converter On/Off (or directly turn the card On/Off). Please see Hub Circuit Diagram numbers 59 and 60 for schematics of the normal ATCA standard way of wiring the IPMC Power Control and of the two ways to Bypass the IPMC Power Control that were described above. Cleanest Way to Bypass the IPMC: -------------------------------- What should have been available from the very start was an IPMC that did not need to communicate with the Shelf Manager before asserting its 12V_Enable signal. At the IPMC's power up it could have just waited 5 seconds and then asserted its 12V_Enable signal. From then on it could have just used the signal from the Front Panel Handle Switch to assert or de-assert its 12V_Enable signal, i.e. to turn the Isolated 48V to 12V Converter On or Off. All of the ATCA card developers could have made good use of such a simple piece of IPMC software. It is still a worthwhile thing to have.