L9669 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L9669' PDF : 13 Pages View PDF
L9669
1. FUNCTIONAL DESCRIPTION
The L9669 is a monolithic integrated circuit which provides all main functions for an automotive body CAN sys-
tem. The device guarantees a clearly defined behavior in case of failure to avoid permanent CAN bus errors. It
is primarily intended for low speed applications in passenger cars.
1.1 Transceiver
– Supports double wire unshielded busses
– Baud rates up to 125 kBaud
– Single wire operation possible (automatic switching to single wire upon bus failures)
– Bus not loaded in case of unpowered transceiver
The CAN transceiver stage is able to transfer serial data on two independent communication wires either differ-
entially (normal operation) or in case of a single wire fault on the remaining line. The physical bitcoding is done
using dominant (transmitter active) and overwritable recessive states. Too long dominant phases are detected
internally and further transmission is automatically disabled (malfunction of protocol unit does not affect com-
munication on the bus (“fail safe mechanism”)).
1.2 Modes of Operation
Five different functional modes exist to enable or establish the usage of low power or receive only operation.
NSTB
EN
Mode
INH
NERR
RXD
RTL
0
0
standby
VS
0
0
sleep
floating
active LOW wake-up interrupt signal
(if VCC is present)
switched to VS
(typ. 13kΩ)
0
1
“go to sleep”
1
1
normal
RXonly
active LOW
error flag
HIGH=recessive
LOW=dominant
received data
switched to VCC
1
0
Power on
VS
active LOW
active LOW
VS power-on
flag if VCC is
wake-up interrupt
signal if VCC is
switched to VS
present
present
Note: Wake-up interrupts are released when entering RXonly or normal mode.
The following state diagram shows these modes and the possible state interactions depending on the input sig-
nals NSTB and EN.
7/13
Share Link: 
