SMH4044 Datasheet, PDF (13/20 Pages) Summit Microelectronics, Inc. – Compact PCI Hot-Swap Controller With IPMI Support

SMH4044
Preliminary
V_CC or
HST_3V_MON
DRVREN# &
SGNL_VLD#
V_TRIP
t_VTPD
VGATE3 &
VGATE5
CARD_3V_MON or
CARD_5V_MON
V_TRIP
LOCAL_PCI_RST#
t_VTR
2057 Fig03
Figure 3. Loss-of-Voltage Timing Sequence
3) CARD_3V_MON and CARD_5V_MON are at or above
their respective trip levels (MONITOR1 and/or MONI-
TOR2 are above 1.25 V if configured as CARD Side
monitors);
4) PWR_EN is high; and
5) PCI_RST# is high.
The PCI-RST# input must be high for the reset outputs to
be released. Assuming all of the conditions listed above
have been met and tPURST has expired, a low input of
greater than 40ns duration on the PCI_RST# input will
initiate a reset cycle. The duration of the reset cycle will
be determined by the PCI_RST# input. If PCI_RST# low
is shorter than tPURST, the reset outputs will be driven
active for tPURST. If PCI_RST# is longer than tPURST the
reset outputs will remain active until PCI_RST# is re-
leased.
Also see Figure 5.
CBI_3 or
CBI_5
t_CBTC
FAULT#
VGATE3 &
VGATE5
PWR_EN
2057 Fig04
Figure 4. Circuit Breaker Timing Sequence
Reset Control
While in the power sequencing mode, the reset outputs
are the last to be released. When they are released all
conditions of a successful power-up sequence must have
been met:
1) VCC and HST_3V_MON are at or above their respec-
tive VTRIP levels (MONITOR1 and/or MONITOR2 are
above 1.25 V if configured as Host Side monitors);
2) BD_SEL# inputs are low;
SOFTWARE CONTROL AND STATUS REPORTING
The SMH4044 features advanced software control and
status reporting over the serial interface. This is accom-
plished through writes and reads to a status register
located at word address 02HEX, device address 1001BIN.
The status register can be read any time the SMH4044 is
not in a nonvolatile write cycle. All of the bits in the register
are read-only except for bit 5. When read this bit indicates
the state of the VGATE5 and VGATE3 outputs. It can also
be written to a “1” to turn on the VGATE5 and VGATE3
outputs if the PWR_EN pin is low. A write to the other bits
in the status register is ignored.
The status register bit assignments are as follows:
Bit 7: Indicates the state of the HEALTHY# output. If
HEALTHY# is low then this bit will be low. This bit is read-
only.
Bit 6: Indicates the state of the SGNL_VLD# output. If
SGNL_VLD # is low then this bit will be low. This bit is read-
only.
Bit 5: Indicates whether VGATE5 and VGATE3 are on. If
they are high then this bit will read high. If they are low and
the PWR_EN pin is low then this bit can be written high
to turn them on. The bit can also be written low to turn them
off but only if the PWR_EN pin is low.
Bit 4: Indicates whether the SMH4044 is in reset. If the
part is in reset then the bit will read high. This bit is read-
only.
SUMMIT MICROELECTRONICS, Inc.
2057 1.x 8/16/01
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