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Functional Description
Overall Functional Description
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
(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.
Table 1. MODE SELECTION
Mode
Vcc
Normal – Slope
ON
(Note 1)
Normal – Low Slope
ON
(Note 2)
Stand-by (Note 3)
ON
Sleep
OFF
1. The normal slope mode is entered when pin EN goes HIGH while TxD is in HIGH state during EN transition.
2. 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.
3. The stand-by mode is entered automatically after power-up.
4. In Stand-by and Sleep mode, the High state is achieved by internal pull-up resistor to VCC.
Vbb Power-up
Additional details of the NCV7425 operation and parameters can be found in the corresponding datasheet [1].
NCV7425EVB
any
external
components
RxD
Low = Dominant State
High = Recessive State
Low = Dominant State
High = Recessive State
Low after LIN Wakeup,
High Otherwise (Note 4)
Clamped to Vcc (Note 4)
Standby Mode
EN Changes 0 −> 1 while TxD = 1
− V
: On
CC
− LIN TRX: Off
EN Changes 1 −> 0 while STB = 1
− INH: Floating
− LIN Term.: Current Source
− RxD Pin: High/Low
− RSTN Pin: VCC_UV
Normal Mode
(Low Slope)
− V
: On
CC
EN Changes 1 −> 0 while STB = 0
− LIN TRX: On
− INH: High/Floating
− LIN Term.: 30 kW
− RxD Pin: LIN Data
− RSTN Pin: High
Figure 6. NCV7425 State Diagram
http://onsemi.com
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, stand-by 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 stand-by
without communication and one low power mode with very
low current consumption - see Figure 6 and Table 1.
Transceiver
INH
High if STB = High
Normal Slope
during State Transition;
Floating Otherwise
High if STB = High
Low Slope
during State Transition;
Floating Otherwise
Floating
Floating
VCC Under-voltage
LIN or Local Wake-up
− V
− LIN TRX: Off
− INH: Floating
− LIN Term.: Current Source
− RxD Pin: at VCC
− RSTN Pin: Low
3
LIN
30 kW
on LIN
ON
ON
OFF
OFF
Controlled by VCC
Under-voltage
OFF
OFF
Normal Mode
(Normal Slope)
− V
: On
CC
− LIN TRX: On
− INH: High/Floating
− LIN Term.: 30 kW
− RxD Pin: LIN Data
− RSTN Pin: High
Sleep Mode
: Off
CC
PD20090610.01
RSTN
High
High
Monitor
Low
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