System Current Monitor
The system current monitor on the power share backplane sends a power usage report to the server via the I2C communications bus. The backplane microcontroller contains
If either the +5 V or +12 V load from the system board or the peripherals goes beyond the CSA Level 3 requirement of 240 VA, the power is shut off immediately by disserting PON. It is impossible to draw 240 VA from the
3.3Volt power supply output even when three supplies are installed in the server. The following table shows the maximum current allowed by each voltage output for a server with three 360 watt power supplies.
Voltage | Maximum Current in Amperes | 240 VA Limit |
+3.3 V | 33 A | N/A |
+5 V | 96 A | 48 A |
+12 V | 36 A (or 48 A for 12 ns maximum) | 20 A |
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A voltage level within the range of 0 to 5 V is supplied by the current sense circuits on the power share backplane. The current limit threshold is set to 44 A ±4 A for each +5 V channel and 16 A +4 A for each +12 V channel.
Power Supply FAULT
Each power supply provides a power good (PGOOD) signal that is asserted high. If a power supply fails, its PGOOD signal goes low. The power supply outputs are enabled through assertion of the PON signal. If the PGOOD signal goes low, indicating a power bad condition while PON is asserted, a FAULT is generated and applied to one of the FAULT inputs of the backplane microcontroller.
Power Supply Presence DETECT
The DETECT signal senses the number of power supplies (operational or not) in the server. Each power supply presents a grounding connection to one of the backplane microcontroller input pins to show that a power supply is present. If a power supply is not present, the backplane microcontroller input pin will be pulled high through a
M440LX Server System Product Guide | 167 |
