
Monolithic bus driver with ISO 9141 interface
Features
■ Operating power supply voltage range
4.5 V ≤ V
■ Reverse supply (battery) protected down to
V
≥ -24 V
S
■ Standby mode with very low current
consumption IS
■ Low quiescent current in off condition
IS
OFF
■ TTL compatible TX input
■ Bidirectional K-I/O pin with supply voltage
dependent input threshold
■ Overtemperature shut down function Selective
to K-I/O pin
■ Wide input and output voltage range
-24 V ≤ V
■
K output current limitation, typ. IK = 60 mA
■ Defined OFF output status in undervoltage
condition and V
■ Controlled output slope for low EMI
Table 1. Device summary
≤ 36 V (40 V for transients)
S
≤ 1 mA @ VCC ≤ 0.5 V
SB
= 120 µA
≤ V
K
S
or GND interruption
S
L9637
SO8
■ High input impedance for open V
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
containing standard ISO 9141 compatible
interface functions.
or GND
S
Order code Package Packing
L9637D SO8 Tube
L9637D013TR SO8 Tape and reel
E-L9637D
E-L9637D013TR
1. Device in ECOPACK® package (see Section 4: Package information on page 13).
June 2009 Doc ID 1765 Rev 7 1/15
(1)
(1)
SO8 Tube
SO8 Tape and reel
www.st.com
15

Contents L9637
Contents
1 Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Electrical specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2/15 Doc ID 1765 Rev 7

L9637 Block diagram and pin description
1 Block diagram and pin description
1.1 Block diagram
Figure 1. Block diagram
VS
K
LI
1.2 Pin description
Figure 2. Pin connection (top view)
RTX RLO RRX
-
IK
OFF
+
+
-
ILI
RX
LO
VCC
TX GND
+
8
2
3
4
7
6
5
VCC
TX
1,75V
RX
LO
GND
LI1
VS
K
Table 2. Pin description
N. Name Function
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
Doc ID 1765 Rev 7 3/15

Electrical specification L9637
2 Electrical specification
2.1 Absolute maximum ratings
Table 3. Absolute maximum ratings (No damage or latch)
Symbol Parameter Value Unit
V
S
V
CC
ΔV
S/dt
V
LI, K
V
LO, RX, TX
Supply voltage ISO transients
t = 400 ms
Stabilized voltage -0.3 to +7 V
Supply voltage transient -10 to +10 V/µs
Pin voltage
-24 to +36
-24 to +40
V
-24 to VS V
-24 to VCC 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.
2.2 Thermal data
Table 4. Thermal data
Symbol Parameter Min. Typ. Max. Unit
T
JSDon
T
JSDoff
R
th j-amb
Temperature K shutdown switch on threshold 160 - 200 °C
Temperature K shutdown switch off threshold 150 - 200 °C
Thermal steady state junction to ambient resistance 130 155 180 °C/W
2.3 Electrical characteristics
The electrical characteristics are valid within the below defined operating conditions, unless
otherwise specified. The function is guaranteed by design until T
temperature
JSDon
shutdown switch-on-threshold.
Table 5. Electrical characteristics
Symbol Parameter Test condition Min. Typ. Max. Unit
V
V
CC
T
I
CC
4/15 Doc ID 1765 Rev 7
Supply voltage - 4.5 - 36 V
S
Stabilized voltage see note
Junction temperature - -40 - 150 °C
j
V
CC
Supply VCC current
VK ≥ VK
VTX = V
(1)
357V
≤ 5.5 V; VLI,VTX = 0 V - 1.4 2.3 mA
; VLI ≥ VLI
high
@ VCC ≤ 5.5 V
CC
high
-5 <1 5 µA

L9637 Electrical specification
Table 5. Electrical characteristics (continued)
Symbol Parameter Test condition Min. Typ. Max. Unit
IS
IS
IS
VK
VK
V
RK
OFF
Khys
I
Koff
ON
SB
low
high
ON
V
Supply VS current
VK ≥ VK
VTX ≥ VTX
VCC ≤ 0.5 V @ VS ≤ 12 V - <1 - µA
RX output status LOW
4.5 V ≤ VS ≤ 18 V
Input voltage low state
RX output status LOW
18 V < VS
RX output status HIGH
4.5 V ≤ VS ≤ 18 V
Input voltage high state
RX output status HIGH
18 V < VS
Input threshold hysteresis VK
@ VTX ≥ VTX
Input current
VK ≤ V
@ V
Output ON impedance
VTX ≤ VTX
IK ≥ 7 mA
≤ 16 V; VLI, VTX = 0 V - 1.2 3 mA
S
; VLI ≥ VLI
high
high
@ VS ≤ 12 V
high
- 120 220 µA
-24 - 0.45V
S
-24 - 8 V
- VK
high
low
; VS, VCC ≥ 0 or
S
V
S
≥ 6.5 V
S
low
(2)
0.55V
12 - V
-
high
-5 4 25 µA
, VCC = open
-1030Ω
-VSV
S
0.025
V
S
S
0.8 V
V
V
IK
VTX
VTX
RRX
RLO
IRX
ILO
VRX
VLO
RLO
RRX
SC
Short circuit current 30 60 100 mA
Input voltage LOW state -24 - 1 V
low
Input voltage HIGH state 2.5 - V
high
ON
Output ON impedance
ON
SC
Output short circuit current 9 20 35 mA
SC
H
Output voltage HIGH state
H
VK ≤ VK
≥ 6.5 V I
V
S
10MΩ ≤ R
10MΩ ≤ R
; VLI ≤ VLI
low
RX, LO
LRX
LLO
Output status = (HIGH)
Output pull-up resistance
-0.15 V ≤ VLO ≤ V
-0.15 V ≤ VRX ≤ V
RTX Input pull up resistance -0.15 V ≤ VTX ≤ V
LO output status LOW
VLI
Input voltage LOW state
low
4.5 V ≤ VS ≤ 18 V
LO output status LOW 18 V < V
low
≥ 1 mA
+ 0.15 V
CC
+ 0.15 V
CC
+ 0.15 V 10 20 40 kΩ
CC
-
V
CC
0.25
-
40 90
VCC-
0.1
51020kΩ
-24
-24
S
- 0.45V
CC
V
Ω
VCC-V
V
S
8
Doc ID 1765 Rev 7 5/15