33902 datasheet(11/31 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33902

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).

33902 数据表(PDF) 11 Page - Freescale Semiconductor, Inc

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