ncv7425a ON Semiconductor, ncv7425a Datasheet - Page 5

• Manufacturer Part Number: ncv7425a
• Description: Ncv7425 Lin Transceiver With Voltage Regulator And Reset Pin
• Manufacturer: ON Semiconductor

3. The normal slope mode is entered when pin EN goes HIGH while TxD is in HIGH state during EN transition.
4. The low slope mode is entered when pin EN goes HIGH while TxD is in LOW state during EN transition. LIN transmitter gets on only after
5. The stand−by mode is entered automatically after power−up.
6. In Stand−by and Sleep mode, the High state is achieved by internal pull−up resistor to V
Normal Slope Mode
receive data via LIN bus with speed up to 20 kBaud. The
transmit data stream of the LIN protocol is present on the
TxD pin and converted by the transmitter into a LIN bus
signal with controlled slew rate to minimize EMC emission.
The receiver consists of the comparator that has a threshold
with hysteresis in respect to the supply voltage and an input
filter to remove bus noise. The LIN output is pulled HIGH
via an internal 30 kW pull−up resistor. For master
applications it is needed to put an external 1 kW resistor with
a serial diode between LIN and V
Table 4. MODE SELECTION
Slope (Note 3)
Slope (Note 4)
Normal − Low
In normal slope mode the transceiver can transmit and
TxD returns to high after the state transition.
Stand−by
Normal −
(Note 5)
Mode
Sleep
V
BB
OFF
V
ON
ON
ON
CC
power−up
Low = Dominant State
High = Recessive State
Low = Dominant State
High = Recessive State
Low after LIN
wake−up, high
otherwise (Note 6)
Clamped to V
(Note 6)
−
−LIN TRX: off
−INH: floating
−LIN term.: current source
−RxD pin: High/Low
−RSTN pin:
−
−LIN TRX: on
−INH: High/floating
−LIN term.: 30kW
−RxD pin: LIN data
−RSTN pin: High
V
V
CC
CC
Standby mode
Normal mode
BB
RxD
: on
: on
(low slope )
(or INH) − see Figure 2.
CC
V
CC_UV
High if STB = High
during state transition;
Floating otherwise
High if STB = High
during state transition;
Floating otherwise
Floating
Floating
Figure 4. State Diagram
http://onsemi.com
EN changes 1− >0 while STB=1
EN changes 1− >0 while STB=0
EN changes 0− >1 while TxD=1
INH
5
V
CC
under−voltage
The mode selection is done by EN=HIGH when TxD pin is
HIGH. If STB pin is high during the standby−to−normal
slope mode transition, INH pin is pulled high. Otherwise, it
stays floating.
Low Slope Mode
bus is reduced (rising and falling edges of the LIN bus signal
are longer). This further reduces the EMC emission. As a
consequence the maximum speed on the LIN bus is reduced
up to 10 kBaud. This mode is suited for applications where
the communication speed is not critical. The mode selection
In low slope mode the slew rate of the signal on the LIN
Normal Slope
Transceiver
Low Slope
OFF
OFF
LIN
CC
.
−
−LIN TRX: on
−INH: High/floating
−LIN term.: 30kW
−RxD pin: LIN data
−RSTN pin: High
−
−LIN TRX: off
−INH: floating
−LIN term.: current source
−RxD pin:
−RSTN pin: Low
V
V
CC
CC
(normal slope )
30 kW on LIN
Normal mode
: on
Sleep mode
: off
PD20090610 .01
OFF
OFF
ON
ON
at V
CC
Controlled by V
under−voltage
monitor
RSTN
High
High
Low
CC