52 SBC347A 3U VPX Single Board Computer
Publication No. 500-9300527837-000 Rev. A.0
5.17 Power Sequencing
5.17.1 Onboard Sequencing
The Lattice ispPOWR Power Manager device sequences the power supplies in the
required order for onboard devices per
. It also monitors the backplane supply voltages and shuts
down the onboard supplies if these fall below their specified levels. It is connected
to the BMM, allowing software read-out of the voltages of all on and off-board
supplies.
When the BMM asserts the BMM_PWR_DISABLE signal, the Power Manager will
shut down all onboard supplies (except P3V3_AUX).
5.17.2 Inter-board Sequencing
The SBC347A supports a proprietary inter-board power sequencing mechanism.
This allows for the sequencing of power between several boards in a system to be
controlled (limiting overall inrush current), and is achieved via the SEQ_OUT and
SEQ_IN signals on the
, which can be daisy-chained between
boards.
The SBC347A drives the SEQ_OUT signal low when the backplane supplies are
out of specification and holds it low until all onboard supplies are within
specification. The SEQ_OUT signal is not driven low when the power is removed
as a result of the BMM_PWR_DISABLE signal being asserted.
The SBC347A holds off all onboard supplies (except P3V3_AUX) while the
SEQ_IN signal is held low.