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NXP Semiconductors
TJA1101B
100BASE-T1 PHY for automotive Ethernet
If link control is enabled (LINK_CONTROL = 1; see Table 20), a PHY configured as
Master initiates the training sequence by transmitting an idle pattern. The receiver of
a PHY configured as Slave will attempt to synchronize with the idle pattern. Once the
descrambler is synchronized (SCR_LOCKED = 1), the slave PHY itself starts sending an
idle pattern using the recovered clock signal.
The link is established (LINK_STATUS = 1) when the TJA1101B PHY and the remote
PHY indicate that their local receiver status is OK.
6.3.1.4 Disable mode
When the Ethernet interface is not in use or must be disabled for fail-safe reasons, the
PHY can be switched off by pulling pin EN LOW. The PHY is switched off completely in
Disable mode, minimizing power consumption. The configuration register settings are
maintained. EN must be forced HIGH to exit Disable mode and activate the PHY.
6.3.1.5 Sleep mode
If the network manager decides to withdraw a node from the network because it is no
longer needed, the PHY can be switched to Sleep mode (powering down the entire
ECU).
In Sleep mode, the transmit and receive functions are switched off and no signal is driven
onto the twisted-pair lines. Transmit requests from the MII interface are ignored and the
MII output pins are in a high-ohmic state. The only valid SMI operations in Sleep mode
are reading the POWER_MODE status bits in the Extended control register and issuing a
Standby mode command (POWER_MODE = 1100; see Table 20).
Releasing the INH output (INH LOW) allows the ECU to switch off its main power supply
unit. Typically, the entire ECU is powered-down. The TJA1101B is kept partly alive by the
permanent battery supply and can still react to activity on the Ethernet lines. Once valid
Ethernet idle pulses longer than t
det(PHY)
are detected on the lines (with REMWUPHY =
1), the TJA1101B wakes up in Standby mode and switches on the main power unit
via the INH control signal. The TJA1101B PHY enters Normal mode via autonomous
operation once the supply voltages are stable within their operating ranges, or can be
switched to Normal mode via an SMI command if host-controlled. The communication
link to the partner can then be re-established.
Sleep mode can be entered from Normal mode via the intermediate Sleep Request mode
as well as from Standby mode, as shown in Figure 7. Note that the configuration register
settings are maintained in Sleep mode.
If CLK_IN_OUT is used to provide the clock for other devices (e.g. other PHYs), the
clock signal can be configured to remain active (CLK_HOLD = 1) along with INH even
when the PHY is in Sleep mode or disabled. When CLK_HOLD = 1, the device enters
Sleep mode automatically but remains active until a FORCE_SLEEP SMI command is
received. Note that this command forces the PHY to Sleep mode immediately (if it was
not already in Sleep mode).
6.3.1.6 Sleep Request mode
Sleep Request mode is an intermediate state used to initiate a transition to Sleep mode.
In Sleep Request mode, the PHY transmits scrambler code with an encoded LPS
command to inform the link partner about the request to enter Sleep mode.
The PHY sleep request timer (t
to(req)sleep
; see Table 37) starts when the TJA1101B
enters Sleep Request mode. This timer determines the maximum length of time the PHY
TJA1101B All information provided in this document is subject to legal disclaimers. © NXP B.V. 2021. All rights reserved.
Product data sheet Rev. 1 — 1 March 2021
12 / 58
Provided under NDA only
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