TCAN330_16 Datasheet, PDF (23/40 Pages) Texas Instruments – 3.3-V CAN Transceivers with CAN FD (Flexible Data Rate)

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TCAN330, TCAN332, TCAN334, TCAN337
TCAN330G, TCAN332G, TCAN334G, TCAN337G
SLLSEQ7D – DECEMBER 2015 – REVISED APRIL 2016
Table 4. CAN Transceivers with Standby Mode with Wake
STB
HIGH
LOW/NC
Device MODE
Ultra Low Current Standby
Mode
Normal Mode
DRIVER
Disabled (OFF)⁽¹⁾
Enabled (ON)
RECEIVER
RXD Terminal
Low Power Receiver and
Bus Monitor Enabled (ON)
Enabled (ON)
High (Recessive) until
WUP, then filtered mirrors
of Bus State ⁽²⁾
Mirrors Bus State ⁽³⁾
(1) See Figure 31 for bus state.
(2) Standby Mode RXD behavior: See Figure 33.
(3) Mirrors bus state: low if CAN bus is dominant, high if CAN bus is recessive.
Table 5. CAN Transceivers with Shutdown Mode
SHDN
HIGH
LOW/NC
Device MODE
Lowest Current
Normal Mode
DRIVER
Disabled (OFF)⁽¹⁾
Enabled (ON)
RECEIVER
Disabled (OFF)
Enabled (ON)
(1) See Figure 31 for bus state.
(2) Mirrors bus state: low if CAN bus is dominant, high if CAN bus is recessive.
RXD Terminal
High (Recessive)
Mirrors Bus State ⁽²⁾
10.4.2 Normal Mode
This is the normal operating mode of the device. The CAN driver and receiver are fully operational and CAN
communication is bi-directional. The driver is translating a digital input on TXD to a differential output on CANH
and CANL. The receiver is translating the differential signal from CANH and CANL to a digital output on RXD.
10.4.3 Silent Mode
This is the silent or receive only mode of the device. The CAN driver is disabled but the receiver is fully
operational. CAN communication is unidirectional and only flows from the CAN bus through the receive path of
the transceiver to the CAN protocol controller via the RXD output pin. The receiver is translating the differential
signal from CANH and CANL to a digital output on RXD.
10.4.4 Standby Mode with Wake
This is the low power mode of the device. The CAN driver and main receiver are turned off and bi-directional
CAN communication is not possible. The low power receiver and bus monitor are enabled to allow for RXD Wake
Requests via the CAN bus. A wake up request will be output to RXD (driven low) as shown in Figure 33. The
local CAN protocol microprocessor should monitor RXD for transitions (high to low) and reactivate the device to
normal mode based on the RXD Wake Request. The CAN bus pins are weakly pulled to GND during this mode,
see Figure 32.
10.4.5 Bus Wake via RXD Request (BWRR) in Standby Mode
The TCAN334 with low power standby mode, offers a wake up from the CAN bus mechanism called bus wake
via RXD Request (BWRR) to indicate to a host microprocessor that the bus is active and it should wake up and
return to normal CAN communication.
This device uses the multiple filtered dominant wake-up pattern (WUP) from ISO11898-5 to qualify bus traffic into
a request to wake the host microprocessor. The bus wake request is signaled to the microprocessor by a falling
edge and low corresponding to a “filtered” bus dominant on the RXD terminal (BWRR).
The wake up pattern (WUP) consists of a filtered dominant bus, then a filtered recessive bus time followed by a
second filtered bus time. Once the WUP is detected the device will start issuing wake up requests (BWRR) on
the RXD terminal every time a filtered dominant time is received from the bus. The first filtered dominant initiates
the WUP and the bus monitor waits on a filtered recessive; other bus traffic does not reset the bus monitor. Once
a filtered recessive is received, the bus monitor waits on a filtered dominant and again; other bus traffic does not
reset the bus monitor. Immediately upon receiving of the second filtered dominant, the bus monitor recognizes
the WUP and transitions to BWRR mode. In this mode, RXD is driven low for all dominant bits lasting for longer
than t_{WK_FILTER}. The RXD output during BWRR matches the classical 8-pin CAN devices, such as the
TCANA1040A-Q1 device, that used the single filtered dominant on the bus as the wake up request mechanism
from ISO11898-5.
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