Artesyn AXP1440, Installation And Use Manual, Page: 142 / 156

Shelf Management Alarm Module
140 AXP1440 Installation and Use (6806800H23U )
As shown in the figure, the ShMM-1500R HRI incorporates a hot-swap buffer (IDT
QuickSwitch), which isolates the interface from the peer ShMM prior to FPGA configuration or
when the ShMM-1500R is powered down. The QuickSwitch device is guaranteed to be disabled
(open) when non-powered and does not have a low impedance path from any of the signal pins
to the power or ground rails. Hence, the device prevents an non-powered ShMM-1500R from
loading down the HRI of the peer ShMM-1500R. It also prevents a carrier from detecting the
ACTIVE# output as a zero; that is, active, during a ShMM-1500R power cycle or a ShMM-1500R
power supply failure.
The FPGA device contains a built-in CRC error checker for detecting soft errors in the
configuration data. When a CRC error is detected the signal LATCH_CRC_ERROR is set active by
the ShMM-1500R CRC error detection circuit, which immediately sets the
ShMM_STATUS[0:1]_L and ACTIVE# signals high. The peer ShMM-1500R, if it is not already
active upon detecting the loss of the status serial bit streams, becomes the active
ShMM-1500R.
The HRI also includes 13 test points for in-service monitoring of the hardware redundancy
signals and for out-of-service diagnostics, enabling the ShMM-1500R to isolate failures on the
HRI to a single cShMM-1500R pair.
Figure 7-3. SAM HRI Interconnection
ShMM-1500R A
F_ShMM_STATUS 0
F_ShMM_STATUS 1
ShMM-1500R B
PRES#
GND
GND
ShMM-1500R A buffer ShMM-1500R B buffer