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NCV7425DW0G

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
NCV7425
www.onsemi.com
4
Figure 3. Pin Assignment
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
BB
V
CC
LIN
GND
GND
WAKE
INH
OTP_SUP
n.c.
RxD
TxD
RSTN
STB
EN
TEST
n.c.
NCV7425
Table 3. PIN FUNCTION DESCRIPTION
Pin Number Pin Name Description
1 V
BB
Battery supply input
2 LIN LIN bus output/input
3 GND Ground
4 GND Ground
5 WAKE High voltage digital input pin to switch the part from sleep− to standby mode
6 INH Inhibit output
7 OTP_SUP Supply for programming of trimming bits at factory testing, needs to be grounded in the application
8 n.c. not connected
9 n.c. not connected
10 TEST Digital input for factory testing, needs to be grounded in the application
11 EN Enable input for mode control
12 STB Standby mode control input
13 RSTN Reset output; open−drain output with an on−chip pull−up resistor
14 TxD Transmit data input, Low in dominant state
15 RxD Receive data output; Low in dominant state; push−pull output
16 V
CC
Voltage regulator output
FUNCTIONAL DESCRIPTION
Overall Functional Description
LIN is a serial communication protocol that efficiently
supports the control of mechatronic nodes in distributed
automotive applications. The domain is class−A multiplex
buses with a single master node and a set of slave nodes.
NCV7425 is designed as a master or slave node for the
LIN communication interface with an integrated 3.3 V or
5 V voltage regulator having a current capability up to
150 mA for supplying any external components
(microcontroller, CAN node, etc.).
NCV7425 contains the LIN transmitter, LIN receiver,
voltage regulator, power−on−reset (POR) circuits and
thermal shutdown (TSD). The LIN transmitter is optimized
for the maximum specified transmission speed of 20 kBaud
with EMC performance due to reduced slew rate of the LIN
output.
The junction temperature is monitored via a thermal
shutdown circuit that switches the LIN transmitter and
voltage regulator off when temperature exceeds the TSD
trigger level.
NCV7425 has four operating states (normal mode, low
slope mode, standby mode, and sleep mode) that are
determined by the input signals EN, WAKE, STB, and TxD.
Operating States
NCV7425 provides four operating states, two modes for
normal operation with communication, one standby without
communication and one low power mode with very low
current consumption − see Figure 4 and Table 4.
NCV7425
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5
Table 4. MODE SELECTION
Mode V
CC
RxD INH
LIN
Transceiver
30 kW on LIN
RSTN
Normal −
Slope (Note 3)
ON Low = Dominant State
High = Recessive State
High if STB = High
during state transition;
Floating otherwise
Normal Slope ON High
Normal − Low
Slope (Note 4)
ON Low = Dominant State
High = Recessive State
High if STB = High
during state transition;
Floating otherwise
Low Slope ON High
Standby
(Note 5)
ON Low after LIN
wake−up, High
otherwise (Note 6)
Floating OFF OFF Controlled by V
CC
undervoltage
monitor
Sleep OFF Clamped to V
CC
(Note 6)
Floating OFF OFF Low
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 TxD
returns to High after the state transition.
5. The standby mode is entered automatically after power−up.
6. In standby and Sleep mode, the High state is achieved by internal pull−up resistor to V
CC
.
Standby mode
−
−LIN TRX: off
−INH: floating
−LIN term.: current source
−RxD pin: High/Low
−RSTN pin:
Normal mode
(normal slope )
−
−LIN TRX: on
−INH: High/floating
−LIN term.: 30kW
−RxD pin: LIN data
−RSTN pin: High
Normal mode
(low slope )
−
−LIN TRX: on
−INH: High/floating
−LIN term.: 30kW
−RxD pin: LIN data
−RSTN pin: High
Sleep mode
−
−LIN TRX: off
−INH: floating
−LIN term.: current source
−RxD pin:
−RSTN pin: Low
EN changes 0−>1 while TxD=1
EN changes 1−>0 while STB=1
EN changes 0−>1 while TxD=0
EN changes 1−>0 while STB=1
EN changes 1−>0 while STB=0
EN changes 1−>0 while STB=0
PD20090610.01
Figure 4. State Diagram
V
CC
undervoltage
V
CC_UV
V
CC
: on
V
CC
: on
V
CC
: on
V
CC
: off
at V
CC
V
CC
undervoltage
V
BB
power−up
Normal Slope Mode
In normal slope mode the transceiver can transmit and
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
BB
(or INH) − see Figure 2. 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
In low slope mode the slew rate of the signal on the LIN
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
NCV7425
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6
is done by EN=High when TxD pin is Low. In order not to
transmit immediately a dominant state on the bus (because
TxD = Low), the LIN transmitter is enabled only after TxD
returns to High. If STB pin is High during the
standby−to−low slope mode transition, INH pin is pulled
High. Otherwise, it stays floating.
Standby Mode
The standby mode is always entered after power−up of the
NCV7425. It can also be entered from normal mode when
the EN pin is Low and the standby pin is High. From sleep
mode it can be entered after a local wake−up or LIN
wake−up. In standby mode the V
CC
voltage regulator for
supplying external components (e.g. a microcontroller)
stays active. Also the LIN receiver stays active to be able to
detect a remote wake−up via bus. The LIN transmitter is
disabled and the slave internal termination resistor of 30 kW
between LIN and V
BB
is disconnected in order to minimize
current consumption. Only a pull−up current source
between V
BB
and LIN is active.
Sleep Mode
The Sleep Mode provides extremely low current
consumption. This mode is entered when both EN and STB
pins are Low coming from normal mode. The internal
termination resistor of 30 kW between LIN and V
BB
is
disconnected and also the V
CC
regulator is switched off to
minimize current consumption.
Wake−up
NCV7425 has two possibilities to wake−up from sleep or
standby mode (see Figure 4):
Local wake−up: enables the transition from sleep mode to
standby mode
Remote wake−up via LIN: enables the transition from
sleep to standby mode and can be also detected when already
in standby mode.
A local wake−up is only detected in sleep mode if a
transition from Low to High or from High to Low is seen on
the WAKE pin.
Wake
t
V
BB
Detection of Local Wake−Up
Sleep Mode Standby Mode
50% V
BB
typ.
Wake
t
V
BB
Detection of Local Wake−Up
Sleep Mode Standby Mode
PC20060427.3
50% V
BB
typ.
Figure 5. Local Wake−Up Signal
A remote wake−up is only detected if a combination of (1)
a falling edge at the LIN pin (transition from recessive to
dominant) is followed by (2) a dominant level maintained
for a time period > t
WAKE
and (3) again a rising edge at pin
LIN (transition from dominant to recessive) happens.
LIN recessive level
LIN
t
t
WAKE
Detection of Remote Wake−Up
Sleep Mode
Standby Mode
LIN dominant level
PC20060427.2
Figure 6. Remote Wake−Up Behavior
V
BB
40% V
BB
60% V
BB
The wake−up source is distinguished by pin RxD in the
standby mode:
RxD remains High after power−up or local wake−up.
RxD is kept Low until normal mode is entered after a
remote wake−up (LIN)
V
CC
Undervoltage Detection and RSTN Pin
In standby, normal and low slope modes, the V
CC
regulator is monitored. Whenever the regulator output falls
below V
CC_UV_THR
level (typically 90% of the nominal
voltage) for longer than V
CC_UV_deb
(typically 5 ms), an
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

NCV7425DW0G

Mfr. #:
Buy NCV7425DW0G
Manufacturer:
ON Semiconductor
Description:
LIN Transceivers LIN WITH 3.3V 150MA LDO
Lifecycle:
New from this manufacturer.
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