33902 Datasheet, PDF (11/31 Pages) Freescale Semiconductor, Inc – High Speed CAN Interface with Embedded 5.0 V Supply

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
TRANSMIT DATA (TXD)
This input is the CAN transmit data pin. It is the interface
from the MCU to the output on the CAN bus. If TxD is low
(dominant), then the signal on the CAN bus will be dominant
(CANH is ~5.0 V and CANL is ~0 V). If TxD is high
(recessive), then the signal on the CAN bus will be recessive
(CANH and CANL will be ~2.5 V). The TxD thresholds are
3.3 V and 5.0 V compatible (depending on VIO voltage) to
accommodate the implementation of various MCUs. There
are three slew rates available, which are selected via the
Pseudo SPI.
GROUND (GND)
Ground termination pin.
VOLTAGE DIGITAL DRAIN (VDD)
This is the dedicated embedded supply voltage for the
CAN interface. A capacitor must be connected to this pin.
CAN interface current is sourced from this pin if device is in
transmit and receive mode. In low power modes, current for
the CAN interface is sourced directly from the VSUP pin.
RECEIVE DATA (RXD)
This output pin is the CAN receive data. It is the interface
to the MCU, which reports the state of the CAN bus. If the
CAN bus is recessive (CANH and CANL ~2.5 V), then the
signal on RxD will be high (recessive). If the CAN bus is
dominant (CANH is ~5.0 V and CANL is ~0 V), then the
signal on RxD will be low (dominant). This pin is also an
active-low wake-up flag in low power, which reports a wake-
up event to the MCU. RxD thresholds are 3.3 V and 5.0 V
compatible (depending on the VIO voltage) to accommodate
the implementation of various MCUs.
VOLTAGE SUPPLY FOR I/O (VIO)
This is the dedicated input supply pin to determine voltage
thresholds for the digital input/output pins. The VIO
thresholds range from 2.75 V to 5.5 V to accommodate the
implementation of 3.3 V or 5.0 V MCUs.
ENABLE (EN)
This is the enable input pin for device static mode control.
This pin is connected to the MCU to place transceiver in the
desired mode. Functional voltage thresholds are determined
by VIO voltage to accommodate the implementation of 3.3 V
or 5.0 V MCUs. MOSI (Master Out, Slave In) during Pseudo
SPI communication.
INHIBIT (INH)
The inhibit output pin controls an external power supply
regulator. When the INH output is low, the external regulator
is expected to shut down, which would then turn off the MCU
and any other device that is powered up by the external
regulator. This should considerably decrease the module’s
current consumption.
ACTIVE LOW ERROR (ERR)
The dedicated active low flag reporting pin reports any
static errors, flags and wake-ups to the MCU depending on
devices operating state. MISO (Master In, Slave Out) during
Pseudo SPI communication.
WAKE (WAKE)
The Wake input pin is used to wake-up the device from
sleep mode after a Battery to Gnd, or Gnd to Battery
transition. This pin is usually connected to an external switch
in the application module, and SHOULD NOT be left open. If
Wake pin functionality is not being used, it should be
connected to GND to avoid false wake-ups. This pin exhibits
a high-impedance for low input current when implemented
below 18 V. If voltage exceeds 18V at the pin, a series
resistor should be used to limit the amount of current that the
device will start sinking.
VOLTAGE SUPPLY (VSUP)
This is the power supply input pin. The DC operating
voltage for the device is 5.5 V to 27 V. A reverse battery
protection diode should be implemented. This pin is able to
sustain automotive transient conditions, such as 40 V load
dumps and 27 V jump start conditions. The device’s
quiescent sleep current is typically around 10 μA.
SPLIT (SPLIT)
This is the output pin for middle point connection of CANH
and CANL when implementing split termination. Pin voltage
is typically around half of VDD (2.5 V) with or without loads.
This pin must be left open if split CAN termination is not
implemented.
CAN HIGH (CANH)
This is the CAN High input/output pin. CANH circuitry is
design to work as a high side switch connected to VDD. In the
recessive state, this switch is turned off and CANH is then
biased to SPLIT voltage or GND, depending on device’s
operating state. In the dominant state, the switch is turned on
and CANH is biased to VDD voltage. The CANH pin is
protected and diagnostics reporting is available against short
to Battery, Gnd, and 5.0 V (VDD).
Analog Integrated Circuit Device Data
Freescale Semiconductor
33902
11