L9637
ISO 9141 INTERFACE
OPERATING POWER SUPPLY VOLTAGE
RANGE 4.5V
V
S
36V (40V FOR TRAN-
SIENTS)
REVERSE
SUPPLY
(BATTERY)
PRO-
TECTED DOWN TO V
S
-24V
STANDBY MODE WITH VERY LOW CUR-
RENT CONSUMPTION IS
SB
1
A @ V
CC
0.5V
LOW QUIESCENT CURRENT IN OFF CON-
DITION IS
OFF
= 120
A
TTL COMPATIBLE TX INPUT
BIDIRECTIONAL K-I/O PIN WITH SUPPLY
VOLTAGE DEPENDENT INPUT THRESHOLD
OVERTEMPERATURE SHUT DOWN FUNC-
TION SELECTIVE TO K-I/O PIN
WIDE
INPUT
AND
OUTPUT
VOLTAGE
RANGE -24V
V
K
V
S
K OUTPUT CURRENT LIMITATION, TYP I
K
=
60mA
DEFINED OFF OUTPUT STATUS IN UNDER-
VOLTAGE CONDITION AND VS OR GND IN-
TERRUPTION
CONTROLLED OUTPUT SLOPE FOR LOW
EMI
HIGH INPUT IMPEDANCE FOR OPEN V
S
OR
GND CONNECTION
DEFINED OUTPUT ON STATUS OF LO OR
RX FOR OPEN LI OR K INPUTS
DEFINED K OUTPUT OFF FOR TX INPUT
OPEN
INTEGRATED PULL UP RESISTORS FOR
TX, RX AND LO
EMI ROBUSTNESS OPTIMIZED
DESCRIPTION
The L9637 is a monolithic integrated circuit con-
taining standard ISO 9141 compatible interface
functions.
December 1998
TX
RX
LO
GND
LI
-
+
VS
VCC
K
1 , 7 5 V
-
+
R T X
R L O
R R X
IL I
IK
O F F
-
+
BLOCK DIAGRAM
ORDERING NUMBERS:
L9637D
L9637
SO8
Minidip
1/11
ABSOLUTE MAXIMUM RATINGS (No damage or latch)
Symbol
Parameter
Value
Unit
V
S
Supply Voltage
ISO transients t = 400ms
-24 to +36
-24 to +40
V
V
V
CC
Stabilized Voltage
-0.3 to +7
V
V
S
/dt
Supply Voltage transient
-10 to +10
V/
s
V
LI, K
Pin Voltage
-24 to V
S
V
V
LO, RX, TX
Pin Voltage
-24 to V
CC
V
Note: Max. ESD voltages are
2kV with human body model C = 100pF, R = 1.5k corresponds to maximum energy dissipation 0.2mJ according
to MIL883C.
THERMAL DATA
Symbol
Parameter
Min.
Typ.
Max.
Unit
T
JSDon
T
JSDoff
Temperature K shutdown switch on threshold
Temperature K shutdown switch off threshold
160
150
200
200
C
C
R
th j-amb
Thermal steady state junction to ambient resistance for SO8
Thermal steady state junction to ambient resistance for Minidip
130
80
155
100
180
120
C/W
C/W
PIN DESCRIPTION
N.
Name
Fun ction
1
RX
Output for K as input
2
LO
Output L comparator
3
VCC
Stabilized voltage supply
4
TX
Input for K as output
5
GND
Common GND
6
K
Bidirectional I/O
7
VS
Supply voltage
8
LI
Input L comparator
TX
K
LO
GND
LI
VS
VCC
RX
1
2
3
4
5
6
7
8
U537
PIN CONNECTION (Top view)
L9637
2/11
ELECTRICAL CHARACTERISTICS (The electrical characteristics are valid within the below defined op-
erating conditions, unless otherwise specified. The function is guaranteed by design until T
JSDon
tem-
perature shutdown switch-on-threshold.)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
S
Supply Voltage
4.5
36
V
V
CC
Stabilized Voltage
3
7
V
T
j
Junction temperature
-40
150
C
I
CC
Supply V
CC
Current
V
CC
5.5V; VLI,VTX = 0V
1.4
2.3
mA
VK
VK
high
; VLI
VLI
high
VTX = V
CC
@ V
CC
5.5V
-5
<1
5
A
IS
ON
Supply VS Current
V
S
16V; VLI, VTX = 0V
1.2
3
mA
IS
OFF
VK
VK
high
; VLI
VLI
high
VTX
VTX
high
@ V
S
12V
120
220
A
IS
SB
V
CC
0.5V @ V
S
12V
<1
A
VK
low
Input Voltage Low state
RX output status LOW
4.5V
V
S
18V
-24
0.45V
S
V
RX output status LOW
18V < V
S
-24
8
V
VK
high
Input Voltage High state
RX output status HIGH
4.5V
V
S
18V
0.55V
S
V
S
V
RX output status HIGH
18V < V
S
12
V
S
V
VK
hys
Input Threshold Hysteresis
VK
high
- VK
low
0.025
V
S
0.8
V
IK
off
Input Current
@ VTX
VTX
high
VK
V
S
V
S
, V
CC
0
or
V
S
, V
CC
= open
-5
4
25
A
RK
ON
Output ON Impedance
@ V
S
6.5V
VTX
VTX
low
I
K
7mA
1)
10
30
IK
SC
Short Circuit Current
30
60
100
mA
VTX
low
Input voltage LOW state
-24
1
V
VTX
high
Input voltage HIGH state
2.5
V
CC
V
RRX
ON
RLO
ON
Output ON Impedance
VK
VK
low
; VLI
VLI
low
V
S
6.5V I
RX, LO
1mA
1)
40
90
IRX
SC
ILO
SC
Output Short Circuit Current
9
20
35
mA
VRX
H
VLO
H
Output Voltage HIGH state
10M
R
LRX
10M
R
LLO
V
CC
-
0.25
V
CC
-
0.1
V
CC
V
RLO
RRX
Output pull-up resistance
Output status = (HIGH)
-0.15V
VLO
V
CC
+ 0.15V
-0.15V
VRX
V
CC
+ 0.15V
5
10
20
K
RTX
Input pull up resistance
-0.15V
VTX
V
CC
+ 0.15V
10
20
40
K
VLI
low
Input voltage LOW state
LO output status LOW
4.5V
V
S
18V
-24
0.45V
S
V
LO output status LOW 18V < V
S
-24
8
V
VL
high
Input voltage HIGH state
LO output status HIGH
4.5V
V
S
18V
0.55V
S
VS
V
LO output status HIGH 18V < V
S
12
VS
V
VLI
hys
Input threshold hysteresis
VLI
high
- VLI
low
0.025V
S
0.8
V
ILI
Input current
VLI
V
S
V
S
, V
CC
0
or
V
S
, V
CC
= open
-5
4
25
A
L9637
3/11
ELECTRICAL CHARACTERISTIC (continued)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
C
Ki, LO, RX
Internal output capacities
20
pF
f
LI-LO
f
K-RX
f
TX-k
Transmission Frequency
9V < V
S
< 16V
(external loads)
R
KO
= 510
, C
K
1.3nF
in active mode see Fig. 3
50
100
kHz
t
rLI-LO
t
rK-RX
t
rTX-K
Rise Time
for the definition of tr, t
f
see
Fig.1.
9V < V
S
< 16V (external loads)
R
KO
= 510
, C
K
1.3nF
2
6
s
t
fLI-LO
t
fK-RX
t
fTX-K
Fall Time
2
6
s
t
OFF,LI-LO
t
OFF,K-RX
t
OFF,TX-K
Switch OFF time
for the definition of ton, t
OFF
see
Fig.1.
9V < V
S
< 16V (external loads)
R
KO
= 510
, C
K
1.3nF
(inactive mode see Fig. 3)
4
17
s
t
ON,LI-LO
t
ON,K-RX
t
ON,TX-K
Switch ON time
4
17
s
1) For output currents lower than this value a series protection diode can become active. See also Fig. 4 and 5.
t
V
t f
t
I
V
20%
t r
80%
80%
20%
OUT
t
OFF
t ON
Figure 1: Input to Output Timings and Output Pulse Shape.
L9637
4/11
FUNCTIONAL DESCRIPTION
The L9637 is a monolithic bus driver designed to
provide bidirectional serial communication in auto-
motive diagnostic applications according to the
specification "Diagnostic Systems ISO9141".
The device provides a bidirectional link, called K,
to the V
Bat
related diagnosis bus. It also includes
a separate comparator L which is also able to be
linked to the V
Bat
bus. The input TX and output
RX of K are related to V
CC
with her integrated pull
up resistances. Also the L comparator output LO
has a pull up resistance connected to V
CC
.
The maximum external pull up resistance at K re-
lated to V
S
should not be higher than R
KO
5K
to achieve clear output ON conditions.
All V
Bat
bus defined inputs LI and K have supply
voltage dependent thresholds together with suf-
ficent hysteresis to suppress line spikes. These
pins are protected against overvoltages, shorts to
GND and V
S
and can also be driven beyond V
S
and GND. These features are also given for TX,
RX and LI only taking into account the behaviour
of the internal pull up resistances. The thermal
shut down function switches OFF the K output if
the chip temperature increases above the thermal
shut down threshold. To reactivate K again the
chip temperature must decrease below the K
switch ON temp. To achieve no fault for V
S
under-
voltage conditions the outputs will be switched
OFF and stay at high impedance. The device is
also protected against reverse battery condition.
During lack of V
S
or GND all pins shows high im-
pedance characteristic. To realize a lack of the V
S
related bus line LI and K the outputs LO and RX
shows defined ON status.
40V
u P
I/O
I/O
I/O
5V
VCC
VDD
ECU1
K
Line
L
Line
ECU2
K
L
LI
K
VS
TX
RX
LO
GND
LI
VS
VCC
K
1,75V
RTX
RLO
RRX
510 Ohm
Diagnostic
Tester
ILI
C
K
0.4 Ohm
-
+
-
+
IK OFF
R KO
C K
-
+
Figure 2: ISO Application Circuit
L9637
5/11
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