– Ability to read and write any internal register via the SMBus
Eleven General Purpose Input/Output pins
– Each pin may be individually configured as an input or output
– Each pin may be individually configured as an interrupt input
– Some pins have selectable alternate functions
Packaged in 19mm x 19mm 324-ball BGA with 1mm ball spacing
Product Description
Utilizing standard PCI Express interconnect, the PES8T5 provides the most efficient I/O connectivity solution for applications requiring high
throughput, low latency, and simple board layout with a minimum number of board layers. It provides connectivity for up to 5 ports across 8 integrated
serial lanes. Each lane provides 2.5 Gbps of bandwidth in both directions and is fully compliant with PCI Express Base specification revision 1.1.
The PES8T5 is based on a flexible and efficient layered architecture. The PCI Express layer consists of SerDes, Physical, Data Link and Transac-
tion layers. The PES8T5 can operate either as a store and forward switch or a cut-through switch and is designed to switch memory and I/O transac-
tions. It supports eight Traffic Classes (TCs) and one Virtual Channel (VC) with sophisticated resource management to allow efficient switching for
applications requiring additional narrow port connectivity.
Processor
Processor
North
Bridge
Memory
Memory
Memory
Memory
South
Bridge
x4
PES8T5
x1
GE
LOM
x1
GE
LOM
x1
GE
x1
1394
Figure 2 I/O Expansion Application
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IDT 89HPES8T5 Data Sheet
x4
PES8T5
x1
x1
x1
x1
Figure 3 Configuration Option
SMBus Interface
The PES8T5 contains two SMBus interfaces. The slave interface provides full access to the configuration registers in the PES8T5, allowing every
configuration register in the device to be read or written by an external agent. The master interface allows the default configuration register values of
the PES8T5 to be overridden following a reset with values programmed in an external serial EEPROM. The master interface is also used by an
external Hot-Plug I/O expander.
Six pins make up each of the two SMBus interfaces. These pins consist of an SMBus clock pin, an SMBus data pin, and 4 SMBus address pins. In
the slave interface, these address pins allow the SMBus address to which the device responds to be configured. In the master interface, these
address pins allow the SMBus address of the serial configuration EEPROM from which data is loaded to be configured. The SMBus address is set up
on negation of PERSTN by sampling the corresponding address pins. When the pins are sampled, the resulting address is assigned as shown in
Table 1.
Bit
1
2
3
4
5
6
7
Slave
SMBus
Address
SSMBADDR[1]
SSMBADDR[2]
SSMBADDR[3]
0
SSMBADDR[5]
1
1
Master
SMBus
Address
MSMBADDR[1]
MSMBADDR[2]
MSMBADDR[3]
MSMBADDR[4]
1
0
1
Table 1 Master and Slave SMBus Address Assignment
As shown in Figure 4, the master and slave SMBuses may be used in a unified or split configuration. In the unified configuration, shown in Figure
4(a), the master and slave SMBuses are tied together and the PES8T5 acts both as a SMBus master as well as a SMBus slave on this bus. This
requires that the SMBus master or processor that has access to PES8T5 registers supports SMBus arbitration. In some systems, this SMBus master
interface may be implemented using general purpose I/O pins on a processor or micro controller, and may not support SMBus arbitration. To support
these systems, the PES8T5 may be configured to operate in a split configuration as shown in Figure 4(b).
In the split configuration, the master and slave SMBuses operate as two independent buses and thus multi-master arbitration is never required.
The PES8T5 supports reading and writing of the serial EEPROM on the master SMBus via the slave SMBus, allowing in system programming of the
serial EEPROM.
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IDT 89HPES8T5 Data Sheet
PES8T5
Processor
SMBus
Master
Serial
EEPROM
...
Other
SMBus
Devices
PES8T5
Processor
SMBus
Master
...
Other
SMBus
Devices
SSMBCLK
SSMBDAT
MSMBCLK
MSMBDAT
SSMBCLK
SSMBDAT
MSMBCLK
MSMBDAT
Serial
EEPROM
(a) Unified Configuration and Management Bus
(b) Split Configuration and Management Buses
Figure 4 SMBus Interface Configuration Examples
Hot-Plug Interface
The PES8T5 supports PCI Express Hot-Plug on each downstream port. To reduce the number of pins required on the device, the PES8T5 utilizes
an external I/O expander, such as that used on PC motherboards, connected to the SMBus master interface. Following reset and configuration, when-
ever the state of a Hot-Plug output needs to be modified, the PES8T5 generates an SMBus transaction to the I/O expander with the new value of all of
the outputs. Whenever a Hot-Plug input changes, the I/O expander generates an interrupt which is received on the IOEXPINTN input pin (alternate
function of GPIO) of the PES8T5. In response to an I/O expander interrupt, the PES8T5 generates an SMBus transaction to read the state of all of the
Hot-Plug inputs from the I/O expander.
General Purpose Input/Output
The PES8T5 provides 11 General Purpose Input/Output (GPIO) pins that may be used by the system designer as bit I/O ports. Each GPIO pin may
be configured independently as an input or output through software control. Some GPIO pins are shared with other on-chip functions. These alternate
functions may be enabled via software, SMBus slave interface, or serial configuration EEPROM.
Pin Description
The following tables lists the functions of the pins provided on the PES8T5. Some of the functions listed may be multiplexed onto the same pin. The
active polarity of a signal is defined using a suffix. Signals ending with an “N” are defined as being active, or asserted, when at a logic zero (low) level.
All other signals (including clocks, buses, and select lines) will be interpreted as being active, or asserted, when at a logic one (high) level.
Note:
In the PES8T5, the 4 downstream ports are labeled ports 2 through 5. There is no port 1.
Signal
PE0RP[3:0]
PE0RN[3:0]
PE0TP[3:0]
PE0TN[3:0]
PE2RP[0]
PE2RN[0]
PE2TP[0]
PE2TN[0]
PE3RP[0]
PE3RN[0]
PE3TP[0]
PE3TN[0]
Type
I
O
I
O
I
O
Name/Description
PCI Express Port 0 Serial Data Receive.
Differential PCI Express receive
pairs for port 0.
PCI Express Port 0 Serial Data Transmit.
Differential PCI Express trans-
mit pairs for port 0.
PCI Express Port 2 Serial Data Receive.
Differential PCI Express receive
pairs for port 2.
PCI Express Port 2 Serial Data Transmit.
Differential PCI Express trans-
mit pairs for port 2.
PCI Express Port 3 Serial Data Receive.
Differential PCI Express receive
pair for port 3.
PCI Express Port 3 Serial Data Transmit.
Differential PCI Express trans-
mit pair for port 3.
Table 2 PCI Express Interface Pins (Part 1 of 2)
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IDT 89HPES8T5 Data Sheet
Signal
PE4RP[0]
PE4RN[0]
PE4TP[0]
PE4TN[0]
PE5RP[0]
PE5RN[0]
PE5TP[0]
PE5TN[0]
PEREFCLKP[2:1]
PEREFCLKN[2:1]
Type
I
O
I
O
I
Name/Description
PCI Express Port 4 Serial Data Receive.
Differential PCI Express receive
pair for port 4.
PCI Express Port 4 Serial Data Transmit.
Differential PCI Express trans-
mit pair for port 4.
PCI Express Port 5 Serial Data Receive.
Differential PCI Express receive
pair for port 5.
PCI Express Port 5 Serial Data Transmit.
Differential PCI Express trans-
mit pair for port 5.
PCI Express Reference Clock.
Differential reference clock pair input. This
clock is used as the reference clock by on-chip PLLs to generate the clocks
required for the system logic and on-chip SerDes. The frequency of the dif-
ferential reference clock is determined by the REFCLKM signal.
PCI Express Reference Clock Mode Select.
This signal selects the fre-
quency of the reference clock input.
0x0 - 100 MHz
0x1 - 125 MHz
Table 2 PCI Express Interface Pins (Part 2 of 2)
REFCLKM
I
Signal
MSMBADDR[4:1]
MSMBCLK
Type
I
I/O
Name/Description
Master SMBus Address.
These pins determine the SMBus address of the
serial EEPROM from which configuration information is loaded.
Master SMBus Clock.
This bidirectional signal is used to synchronize
transfers on the master SMBus. It is active and generating the clock only
when the EEPROM or I/O Expanders are being accessed.
Master SMBus Data.
This bidirectional signal is used for data on the mas-
ter SMBus.
Slave SMBus Address.
These pins determine the SMBus address to
which the slave SMBus interface responds.
Slave SMBus Clock.
This bidirectional signal is used to synchronize trans-
fers on the slave SMBus.
Slave SMBus Data.
This bidirectional signal is used for data on the slave
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