s1r72900 Epson Electronics America, Inc., s1r72900 Datasheet - Page 32

• Manufacturer Part Number: s1r72900
• Description: Physical Layer Ic Compliant With The Ieee 1394-1995 And Ieee 1394a-2000 Standards.
• Manufacturer: Epson Electronics America, Inc.

S1R72900F00A
Cables specifically designed as per IEEE 1394 are used as media for the cable port interface. Data is transmitted through
two shielded pairs of twisted cables. As shown in Figure 7.10, each twisted pair cable is connected to the TpB pair of
the node to which the TpA pair of the own node.
Both TpA and TpB require two 56 terminating resistors appropriate to the cable impedance. Locate these terminating
resistors as close to the IC pin as possible.
On the TpA side, TpBias is connected to the terminating resistor intermediate node to set inphase DC potential of the
cable. To TpBias, connect a 1- F capacitor for decoupling.
On the TpB side, connect a 5.1k resistor and a 240-pF capacitor to the terminating resistor intermediate node for pull-
down. The 240-pF capacitor is for decoupling.
Connect the CPS pin to the cable power through a 240k resistor.
7.3.2 Port state
The SIR72900F00A complies with the IEEE 1394a-2000 standards. The IEEE P1394a-2000 standards define the
following five port states.
7.3.3 Connection detecting circuit
The SIR72900F00A is equipped with a built-in connection detecting circuit. Connection detecting circuit is a circuit
to detect the connected state of the cables and is effective while the port is not outputting TpBias.
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–Disabled:
–Disconnected:
–Suspended:
–Resuming:
–Active:
A 'disabled' port does not output signals to TpBias and TpA/TpB. And the port in this state does not detect signals
input to Bias and TpA/TpB. When the connection detection circuit detects a change in cable connection, this port
outputs an interrupt to the upper layer if the Int_enable bit is set.
A 'disconnected' port has no physical cable connection to PHY on a different node and thus does not output signals
to TpBias and TpA/TpB. And the port in this state does not detect signals input to Bias and TpA/TpB.
A 'suspended' port does have physical cable connection to PHY on a different node but does not output signals
to TpBias and TpA/TpB. And the port in this state does not detect signals input to TpA/TpB. On this port, only
the bias detection and connection detection circuits are in operation.
A 'resuming' port has physical cable connection to PHY on a different node and outputs signals to TpBias. On
detection of bias, the port stays for a specified time and becomes active. During the resuming period, it does not
detect signals input to TpA/TpB.
An 'active' port has physical cable connection to PHY on a different node and outputs signals to TpBias and TpA/
TpB. The port in this state detects signals input to Bias and TpA/TpB.
EPSON
Rev. 1.0