
IDT SMBus Interfaces
PES34H16 User Manual
6 - 10
October 30, 2008
Notes
System design recommendations
–
I/O expander addresses and default output values may be configured during serial EEPROM
initialization. If I/O expander addresses are configured via the serial EEPROM, then the
PES34H16 will initialize the I/O expanders when normal device operation begins following the
completion of the fundamental reset sequence.
–
If the I/O expanders are initialized via serial EEPROM, then the data value for output signals
during the SMBus initialization sequence will correspond to those at the time the SMBus transac-
tions are initiated. It is not possible to toggle SMBus I/O expander outputs by modifying data
values during serial EEPROM initialization.
–
During a fundamental reset and before the I/O expander outputs are initialized, all I/O expander
output signals default to inputs. Therefore, pull-up or pull-down resistors should be placed on
outputs to ensure that they are held in the desired state during this period.
–
All hot-plug data value modifications that correspond to hot-plug outputs result in SMBus transac-
tions. This includes modifications due to upstream secondary bus resets and hot-resets.
–
The standard PCA9555 I/O expander is not able to support the number of unique addresses
required by all of the PES34H16 hot-plug I/O expanders. Therefore, it is recommended that a
MAX7313 be used instead. The MAX7313 is software and pin compatible with the PCA9555
–
I/O expander outputs are not modified when the device transitions from normal operation to a
fundamental reset. In systems where I/O expander output values must be reset during a funda-
mental reset, an I/O expander reset circuit may be used to reset the I/O expanders. Contact IDT
for more information.
I/O Expander 0
SMBus I/O
Expander
Bit
Type
Signal
Description
0 (I/O-0.0)
1
1.
I/O-x.y corresponds to the notation used for PCA9555 port x I/O pin y.
I
P1APN
Port 1 attention push button input
1 (I/O-0.1)
I
P1PDN
Port 1 presence detect input
2 (I/O-0.2)
I
P1PFN
Port 1 power fault input
3 (I/O-0.3)
I
P1MRLN
Port 1 manually-operated retention latch (MRL)
input
4 (I/O-0.4)
O
P1AIN
Port 1 attention indicator output
5 (I/O-0.5)
O
P1PIN
Port 1 power indicator output
6 (I/O-0.6)
O
P1PEP
Port 1 power enable output
7 (I/O-0.7)
O
P1ILOCKP
Port 1 electromechanical interlock
8 (I/O-1.0)
I
P3APN
Port 3 attention push button input
9 (I/O-1.1)
I
P3PDN
Port 3 presence detect input
10 (I/O-1.2)
I
P3PFN
Port 3 power fault input
11 (I/O-1.3)
I
P3MRLN
Port 3 manually-operated retention latch (MRL)
input
12 (I/O-1.4)
O
P3AIN
Port 3 attention indicator output
13 (I/O-1.5)
O
P3PIN
Port 3 power indicator output
14 (I/O-1.6)
O
P3PEP
Port 3 power enable output
15 (I/O-1.7)
O
P3ILOCKP
Port 3 electromechanical interlock
Table 6.3 I/O Expander 0 Signals
Summary of Contents for 89HPES34H16
Page 10: ...IDT Table of Contents PES34H16 User Manual iv October 30 2008 Notes...
Page 12: ...IDT List of Tables PES34H16 User Manual vi October 30 2008 Notes...
Page 18: ...IDT Register List PES34H16 User Manual xii October 30 2008 Notes...
Page 40: ...IDT Upstream Port Failover PES34H16 User Manual 2 6 October 30 2008 Notes...
Page 86: ...IDT Power Management PES34H16 User Manual 7 4 October 30 2008 Notes...
Page 172: ...IDT Configuration Registers PES34H16 User Manual 9 80 October 30 2008 Notes...