Datasheet

SN65HVDA195-Q1
www.ti.com SLLS961A –JULY 2009–REVISED OCTOBER 2009
Local Interconnect Network (LIN) Bus
This I/O pin is the single-wire LIN bus transmitter and receiver.
Transmitter Characteristics
The driver is a low-side transistor with internal current limitation and thermal shutdown. There is an internal
30-kΩ pullup resistor with a serial diode structure to V
SUP
, so no external pullup components are required for LIN
slave mode applications. An external pullup resistor of 1 kΩ, plus a series diode to V
SUP
must be added when the
device is used for master node applications.
Voltage on LIN can go from –40-V to 40-V dc without any currents other than through the pullup resistance.
There are no reverse currents from the LIN bus to supply (V
SUP
), even in the event of a ground shift or loss of
supply (V
SUP
).
The LIN thresholds and ac parameters are LIN Protocol Specification Revision 2.0 compliant.
During a thermal shut down condition, the driver is disabled.
Receiver Characteristics
The receiver’s characteristic thresholds are ratio-metric with the device supply pin. Typical thresholds are 50%,
with a hysteresis between 5% and 17.5% of supply.
The receiver is capable of receiving higher data rates (>100 kbps) than supported by LIN or SAEJ2602
specifications. This allows the SN65HVDA195 to be used for high-speed downloads at end-of-line production or
other applications. The actual data rates achievable depend on system time constants (bus capacitance and
pullup resistance) and driver characteristics used in the system.
Transmit Input (TXD)
TXD is the interface to the MCU’s LIN protocol controller or SCI/UART used to control the state of the LIN output.
When TXD is low, the LIN output is dominant (near ground). When TXD is high, the LIN output is recessive (near
battery). The TXD input structure is compatible with microcontrollers with 3.3-V and 5-V I/O. TXD has an internal
pulldown resistor. This device does not have a TXD dominant time out protection circuit so that low data rates
may be used.
Receive Output (RXD)
RXD is the interface to the MCU’s LIN protocol controller or SCI/UART, which reports the state of the LIN bus
voltage. LIN recessive (near battery) is represented by a high level on RXD and LIN dominant (near ground) is
represented by a low level on RXD. The RXD output structure is an open-drain output stage. This allows the
SN65HVDA195 to be used with 3.3-V and 5-V I/O microcontrollers. If the microcontroller’s RXD pin does not
have an integrated pullup, an external pullup resistor to the microcontroller I/O supply voltage is required.
RXD Wake-up Request
When the SN65HVDA195 has been in low-power mode and encounters a wake-up event from the LIN bus or
NWake pin, RXD goes low, while the device enters and remains in standby mode (until EN is reasserted high
and the device enters normal mode).
Supply Voltage (V
SUP
)
V
SUP
is the SN65HVDA195 device power supply pin. V
SUP
is connected to the battery through an external
reverse battery blocking diode. The characterized operating voltage range for the SN65HVDA195 is from 7 V to
27 V. V
SUP
is protected for harsh automotive conditions up to 40 V.
The device contains a reset circuit to avoid false bus messages during undervoltage conditions when V
SUP
is less
than V
SUP_UNDER
.
Ground (GND)
GND is the SN65HVDA195 device ground connection. The SN65HVDA195 can operate with a ground shift as
long as the ground shift does not reduce V
SUP
below the minimum operating voltage. If there is a loss of ground
at the ECU level, the SN65HVDA195 does not have a significant current consumption on LIN bus.
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Product Folder Link(s): SN65HVDA195-Q1