STMICROELECTRONICS L9903

L9903
MOTOR BRIDGE CONTROLLER
PRODUCT PREVIEW
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OPERATING SUPPLY VOLTAGE 8V TO 20V,
OVERVOLTAGE MAX. 40V
OPERATING SUPPLY VOLTAGE 6V WITH
IMPLEMENTED STEPUP CONVERTER
QUIESCENT CURRENT IN STANDBY MODE
LESS THAN 50µA
ISO 9141 COMPATIBLE INTERFACE
CHARGE PUMP FOR DRIVING A POWER
MOS AS REVERSE BATTERY PROTECTION
PWM OPERATION FREQUENCY UP TO
30KHZ
PROGRAMMABLE CROSS CONDUCTION
PROTECTION TIME
OVERVOLTAGE, UNDERVOLTAGE, SHORT
CIRCUIT AND THERMAL PROTECTION
REAL TIME DIAGNOSTIC
SO20
ORDERING NUMBER: L9903
DESCRIPTION
Control circuit for power MOS bridge driver in automotive applications with ISO 9141bus interface.
BLOCK DIAGRAM
VS
10
ST
1
R CP
Ref erence
BIAS
+
VCC
Charge
pump
= V
STH
f ST
VCC
RDG
EN
2
CB1
12
GH1
14
4
5
RDI R
V CC
R S1
V S1TH =
19
3
PR
6
18
R PWM
I SO-Interface
TX
8
15
GH2
16
CB2
9
7
VCC
S2
R S2
Timer
R RX
GL2
R GL2
V S2TH =
RX
GL1
R GL1
17
PWM
S1
Thermal shutdown
REN
DIR
CP
13
Ov ervoltage
Undervoltage
Control Logic
DG
11
K
= 0.5 • V
VS
R TX
IKH
20
GND
June 2000
This is preliminary information on a new product now in development. Details are subject to change without notice.
1/17
L9903
PIN FUNCTION
N°
Pin
Description
1
ST
2
DG
3
PWM
4
EN
Enable input
5
DIR
Direction select input for H-bridge control
6
PR
Programmable cross conduction protection time
7
RX
ISO 9141 interface, receiver output
8
TX
ISO 9141 interface, transmitter input
9
K
ISO 9141 Interface, bidirectional communication K-line
10
VS
Supply voltage
11
CP
Charge pump for driving a power MOS as reverse battery protection
12
GH1
Gate driver for power MOS highside switch in halfbridge 1
13
CB1
External bootstrap capacitor
14
S1
Source/drain of halfbridge 1
15
GH2
Gate driver for power MOS highside switch in halfbridge 2
16
CB2
External bootstrap capacitor
17
S2
Source/drain of halfbridge 2
18
GL2
Gate driver for power MOS lowside switch in halfbridge 2
19
GL1
Gate driver for power MOS lowside switch in halfbridge 1
20
GND
Ground
Open Drain Switch for Stepup converter
Open drain diagnostic output
PWM input for H-bridge control
PIN CONNECTION (Top view)
ST
1
20
GND
DG
2
19
GL1
PWM
3
18
GL2
EN
4
17
S2
DIR
5
16
CB2
PR
6
15
GH2
RX
7
14
S1
TX
8
13
CB1
K
9
12
GH1
10
11
CP
VS
SO20
2/17
L9903
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
VCB1 , VCB2 Bootstrap voltage
I CB1 , ICB2
Bootstrap current
Value
Unit
-0.3 to 40
V
-100
mA
VCP
Charge pump voltage
-0.3 to 40
V
ICP
Charge pump current
-1
mA
-0.3 to 7
V
±1
mA
VDIR ,VEN Logic input voltage
,VPWM ,V TX
IDIR ,IEN
,IPWM ,I TX
Logic input current
VDG ,VRX
Logic output voltage
-0.3 to 7
V
IDG ,IRX
Logic output current
-1
mA
-0.3 to VSX + 10
V
-1
mA
-0.3 to 10
V
-10
mA
VGH1, VGH2 Gate driver voltage
IGH1 , IGH2
Gate driver current
VGL1 , VGL2 Gate driver voltage
IGL1 , IGL2
Gate driver current
VK
K-line voltage
-20 to VS
V
VPR
Programming input voltage
-0.3 to 7
V
IPR
Programming input current
-1
mA
V S1 , VS2
Source/drain voltage
-2 to VVS + 2
V
I S1 , IS2
Source/drain current
-10
mA
-0.3 to 40
V
-1
mA
-0.3 to 27
V
Pulse supply voltage (T £ 500ms)
40
V
DC supply current
-10
mA
VST
Output voltage
IST
Step up output current
VVSDC
VVSP
IVS
DC supply voltage
For externally applied voltages or currents exceeding these limits damage of the device may occur!
All pins of the IC are protected against ESD. The verification is performed according to MIL883C, human body
model with R=1.5kΩ, C=100pF and discharge voltage ±2kV, corresponding to a maximum discharge energy of
0.2mJ.
3/17
L9903
THERMAL DATA
Symbol
Parameter
Operating junction temperature
TJ
TJSD
Junction temperature thermal shutdown threshold
TJSDH
Junction thermal shutdown hysteresis
Rth j-amb
Thermal resistance junction to ambient 1)
Value
Unit
-40 to 150
°C
min 150
°C
typ 15
°C
85
°C/W
1. see application note 110 for SO packages.
ELECTRICAL CHARACTERISTCS (8V < VVS < 20V, VEN = HIGH, -40°C ≤ TJ ≤ 150°C, unless otherwise specified. The voltages are refered to GND and currents are assumed positive, when current flows into the pin.
Symbol
Parameter
Test Conditio n
Min.
Typ.
Max.
Unit
20
22
24
V
Supply (VS)
VVS OVH Overvoltage disable HIGH
threshold
V VS OVh
Overvoltage threshold hysteresis 2)
VVS UVH
Undervoltage disable HIGH
threshold
VVS UVh
Undervoltage threshold
hysteresis 2)
1.6
6
V
7
0.66
V
V
IVSL
Supply current
V EN = 0 ; VVS = 13.5V; TJ< 85°C
50
µA
I VSH
Supply current
V VS= 13.5V; VEN= HIGH;
V DIR= LOW;
20
mA
1.5
V
fPWM = 20kHz; CCBX = 0.1µF;
C GLX = 4.7nF; CGHX = 4.7nF;
R PR = 10kΩ; CPR = 150pF
Enable input (EN)
VENL
Low level
VENH
High level
VENh
Hysteresis threshold 2)
REN
Input pull down resistance
3.5
V
1
V EN = 5V
16
50
V
100
kΩ
1.5
V
H-bridge control inputs (DIR, PWM)
VDIRL
VPWML
Input low level
VDIRH
VPWMH
Input high level
VDIRh
VPWMh
Input threshold hysteresis 2)
R DIR
RPWM
Internal pull up resistance
to internal VCC 3)
4/17
3.5
V
1
V DIR = 0; VPWM = 0
16
50
V
100
kΩ
L9903
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
Test Conditio n
Min.
Typ.
Max.
Unit
0.6
V
kΩ
DIAGNOSTIC output (DG)
V DG
Output drop
IDG = 1mA
R DG
Internal pull up resistance
to internal VCC 3)
V DG = 0V
10
20
40
2
2.2
Programmable cross conduction protection 4)
NPR
Threshold voltage ratio VPRH/
VPRL
R PR = 10kΩ
1.8
IPR
Current capability
VPR = 2V
-0.5
mA
ISO interface, transmission input (TX)
VTXL
Input low level
VTXH
Input high level
VTXh
Input hysteresis voltage 2)
RTX
Internal pull up resistance to
internal VCC 3)
1.5
3.5
V
1
VTX = 0
10
4.5
V
20
V
40
kΩ
5.5
V
10
20
kΩ
90
W
ISO interface, receiver output (RX)
VRXL
Output voltage high stage
TX = HIGH; IRX = 0; VK = VVS
RRX
Internal pull up resistance
to internal VCC 3)
TX = HIGH;
V RX = 0V
ON resistance to ground
TX = LOW;
IRX = 1mA
40
tRXH
Output high delay time
Fig. 1
0.5
µs
tRXL
Output low delay time
0.5
µs
R RXON
5
ISO interface, K-line (K)
VKL
Input low level
-20V
0.45 ·
VVS
VKH
Input high level
0.55 ·
VVS
VVS
VKh
Input hysteresis voltage 2)
IKH
Input current
V TX = HIGH
R KON
ON resistance to ground
V TX = LOW; IK=10mA
I KSC
Short circuit current
V TX = LOW
fK
0.025·
VVS
Transmission frequency
-5
10
40
60
100
0.8V
25
µA
30
W
130
mA
kHz
2. not tested in production: guaranteed by design and verified in characterization
3. Internal VVCC is 4.5V ... 5.5V
4. see page 18 for calculation of programmable cross conduction protection time
5/17
L9903
ELECTRICAL CHARACTERISTICS (continued)
Symbol
tKr
Parameter
Rise time
Test Conditio n
Min.
V VS = 13.5V; Fig. 1
External loads at K-line:
R K = 510Ω pull up
to VVS
Typ.
Max.
Unit
2
6
µs
C K = 2.2nF to GND
tKf
Fall time
2
6
µs
tKH
Switch high delay time
4
17
µs
tKL
Switch low delay time
4
17
µs
tSH
Short circuit detection time
10
40
µs
VVS+
7V
VVS+
10V
VVS+
10V
VVS+
14V
VVS+
14V
VVS
+14V
V VS = 13.5V;
TX = LOW
V K > 0.55 · VVS
Charge pump
VCP
Charge pump voltage
V VS = 8V
V VS = 13.5V
V VS = 20V
ICP
Charging current
VCP= VVS + 8V
V VS = 13.5V
-50
tCP
Charging time 2)
VCP= VVS + 8V
V VS = 13.5V
C CP = 10nF
fCP
Charge pump frequency
V VS = 13.5V
250
7.5
10
10
µA
-75
1.2
4
ms
500
750
kHz
14
14
14
V
V
V
10
W
V CBX = 8V; VSX = 0
IGHX = 50mA; TJ = 125°C
20
W
10
20
W
W
Drivers for external highside power MOS
VCB1
VCB2
Bootstrap voltage
V VS = 8V; ICBX = 0; V SX = 0
V VS =13.5V; ICBX = 0; VSX = 0
V VS = 20V; ICBX = 0; VSX = 0
R GH1L
R GH2L
ON-resistance of SINK stage
V CBX = 8V; VSX = 0
IGHX = 50mA; TJ = 25°C
R GH1H
R GH2H
ON-resistance of SOURCE stage
IGHX = -50mA; TJ = 25°C
IGHX = -50mA; TJ = 125°C
VGH1H
VGH2H
Gate ON voltage (SOURCE)
V VS= VSX = 8V; I GHX = 0;
C CBX = 0.1µF
VVS
+6.5V
VVS
+14V
V VS = VSX = 13.5V; I GHX = 0;
C CBX = 0.1µF
VVS+
10V
VVS
+14V
V VS = VSX = 20V; IGHX = 0;
C CBX = 0.1µF
VVS
+10V
VVS
+14V
6/17
L9903
ELECTRICAL CHARACTERISTICS (continued)
Symbol
R GH1
R GH2
R S1
R S2
Parameter
Gate discharge resistance
Test Conditio n
EN = LOW
Sink resistance
Min.
Typ.
Max.
Unit
10
100
kΩ
10
100
kΩ
Drivers for external lowside power MOS
RGL1L
RGL2L
ON-resistance of SINK stage
IGLX = 50mA; TJ = 25°C
IGLX = 50mA; TJ = 125°C
10
20
W
W
R GL1H,
R GL2H
ON-resistance of SOURCE stage
IGLX = -50mA; TJ = 25°C
IGLX = -50mA; TJ = 125°C
10
20
W
W
VGL1H,
VGL2H
Gate ON voltage (SOURCE)
V VS = 8V; IGLX = 0
V VS = 13.5V; IGLX = 0
V VS = 20V; I GLX = 0
Gate discharge resistance
EN = LOW
RGL1
RGL2
7V
10V
10V
10
VVS
VVS
14V
100
kΩ
2. not tested in production: guaranteed by design and verified in characterization
Timing of the drivers
tGH1LH
tGH2LH
Propagation delay time
Fig. 2
V VS = 13.5V
V S1 = VS2 =0
C CBX = 0.1µF
500
ns
1.3
µs
500
ns
500
ns
1.3
µs
500
ns
RPR= 10kW
tGH1LH
tGH2LH
Propagation delay time including
cross conduction protection time
tCCP
tGH1HL
tGH2HL
Propagation delay time
tGL1LH
tGL2LH
Propagation delay time
Fig. 2
V VS = 13.5V
V S1 = VS2 =0
C CBX = 0.1µF
0.7
1
C PR= 150pF;
R PR= 10kΩ;
5)
Fig. 2
V VS = 13.5V
V S1 = VS2 =0
C CBX = 0.1µF
R PR= 10kΩ
tGL1LH
tGL2LH
Propagation delay time including
cross conduction protection time
tCCP
tGL1HL
tGL2HL
Propagation delay time
Fig. 2
V VS = 13.5V
V S1 = VS2 =0
C CBX = 0.1µF
0.7
1
C PR= 150pF;
R PR= 10kΩ;
5)
7/17
L9903
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
tGH1r
tGH2r
Rise time
tGH1f
tGH2f
Fall time
tGL1r
tGL2r
Rise time
tGL1f
tGL2f
Fall time
Test Conditio n
Min.
Typ.
Fig. 2
V VS = 13.5V
V S1 = VS2 =0
C CBX = 0.1µF
C GHX = 4.7nF
C GLX = 4.7nF
R PR= 10kΩ;
Max.
Unit
1
µs
1
µs
1
µs
1
µs
Short Circuit Detection
VS1TH
VS2TH
tSCd
Threshold voltage
4
Detection time
Step up converter (ST)
5
15
µs
10
V
2
V
20
Ω
149
kHz
(5.2V ≤ V VS < 10V)
VSTH
ST disable HIGH threshold
VSTh
ST disable threshold hysteresis
voltage 2)
R DSON
10
V
Open drain ON resistance
1
V VS = 5.2V;
IST = 50mA
fST
Clock frequency
50
2. not tested in production: guaranteed by design and verified in characterization
5. tested with differed values in production but guaranteed by design and verified in characterization
8/17
100
L9903
Figure 1. Timing of the ISO-interface
V
TX
0.7 • V V C C
0.3 • V V C C
0.3 • V V C C
t
V
t KL
t KH
K
t
t
Kf
Kr
80%
IK > I KSC
0.5 5 • V V S
0 .45 • V V S
20%
t
V
t
t
RX L
R XH
RX
0.7 • V V C C
0 .3 • V V C C
t
t SH
o p e n d r ai n
tr a n sis to r a t
K -p in
ON
O FF
Figure 2. Timing of the drivers for the external MOS regarding the inputs DIR and PWM
PW M
or
D IR
t
t
G H XL H
t
t
GH X HL
t
G HX r
GH Xf
8 0%
2 0%
GHX
t
t
G L XH L
t
G L X LH
8 0%
2 0%
GL X
t
t
G L Xf
t
G LX r
9/17
L9903
Figure 3. I(V) characteristics of the K-Line for TX = HIGH and VVS=13.5V
IK [mA]
0.2
~5
0k
Ω
0.1
0.0
-0.1
~5
0k
Ω
-0.2
-0.3
-0.4
-0.5
-20
-10
0
10
20
VK [V]
Figure 4. Driving sequence
EN
D IR
PW M
GH1
G L1
GH2
Note:
Before standby mode
(EN = low) a braking phase
is mandatory to discharge
the stored energy of the
motor.
10/17
G L2
b rak in g
L9903
Figure 5. Charging time of an external capacitor of 10nF connected to CP pin at V
V S=8V and
VVS=13.5V
voltage [V]
Charging time of a 10nF load at CP
30
CP for VS=13.5V
25
CP for VS=8V
20
15
10
EN
5
0
0
1
2
3
4
time [ms]
Figure 6. Application Circuit Diagram
V
B AT
D1
VS
V olta ge
R e gu la tor
CS1
Ga te
P rote ction
10
RCP
CS 2
ST
R e f e re n ce
+
1
B IA S
C h a rg e
= V S TH
VC C
DG
2
G H1
14
S1
R
4
5
RD IR
C1
M
RS1
=
C o n tro l L o g ic
µC
CB1
12
T he rm a l s hu td o w n
RE N
DIR
13
C B1
V S1T H
EN
CP
O v e rv o lt a ge
U n de rvo lt a g e
R DG
11
pu mp
fST
VCC
R1
VC C
19
R
G L1
RGL 1
18
R
R
G L2
GL 2
VC C
17
R PW M
PW M
V S2T H
PR
CP R
S2
3
6
RS2
=
Tim e r
RP R
C B2
15
G H2
16
CB2
R
I S O- I n te rf ac e
RX
9
7
RRX
VCC
K
K-L in e
= 0 . 5 • VV S
RTX
TX
8
I
G ND
KH
20
G ND
11/17
L9903
FUNCTIONAL DESCRIPTION
General
The L9903 integrated circuit (IC) is designed to control four external N-channel MOS transistors in H-Bridge configuration for DC-motor driving in automotive applications. It includes an ISO9141 compatible interface. A typical
application is shown in fig.6.
Voltage supply
The IC is supplied via an external reverse battery protection diode to the VVS pin. The typical operating voltage
range is down to 8V.
Extended supply voltage range (ST)
The operating battery voltage range can be extended down to 6V using the additional components shown in
fig.7. A small inductor of L~150µH (Ipeak~500mA) in series to the battery supply builts up a step up converter
with the switching open drain output ST. The switching frequency is typical 100kHz with a fixed duty cycle of
50%. The step up converter starts below VVS < 8V, increases the supply voltage at the VS pin and switches off
at VVS > 10V to avoid EME at nominal battery voltage. The diode D2 in series with the ST pin is necessary only
for systems with negative battery voltage. No additional load can be driven by the step up converter.
Figure 7.
L9903
VBAT
L1
D1
VS
C1
C2
D2
ST
+
= VSTH
fST
12/17
L9903
FUNCTIONAL DESCRIPTION (continued)
Control inputs (EN, DIR, PWM)
The cmos level inputs drive the device as shown in fig.4 and described in the truth table.
The device is activated with enable input HIGH signal. For enable input floating (not connected) or VEN=0V the
device is in standby mode. When activating the device a wake-up time of 50µs is recommended to stabilize the
internal supplies.
The DIR and PWM inputs control the driver of the external H-Bridge transistors. The motor direction can be
choosen with the DIR input, the duty cycle and frequency with the PWM input. Unconnected inputs are defined
by internal pull up resistors. During wake-up and braking and before disactivating the IC via enable both inputs
should be driven HIGH.
Truth table:
Status
Control inputs
Driver stage for external
power MOS
Device status
Diagnostic
Comment
EN
DIR
PWM
TS
OV
UV
SC
GH1
GL1
GH2
GL2
DG
1
0
x
x
x
x
x
x
R
R
R
R
T
standby mode
2
1
x
x
1
0
0
0
L
L
L
L
L
thermal
shutdown
3
1
x
x
0
1
0
0
L
L
L
L
L
overvoltage
4
1
x
x
0
0
1
0
L
L
L
L
L
undervoltage
5
1
x
x
0
0
0
1
X 6)
X6)
X6)
X6
L
short circuit 6)
6
1
0
0
0
0
0
0
L
H
H
L
H
7
1
x
1
0
0
0
0
H
L
H
L
H
8
1
1
0
0
0
0
0
H
L
L
H
H
Symbols: x Don’t care
braking mode
R:Resistive output
TS:Thermal shutdown
0: Logic LOW or not active
L: Output in sink condition
OV:Overvoltage
1: Logic HIGH or active
H: Output in source condition
UV:Undervoltage
T: Tristate
SC:Short Circuit
6. Only those external MOS transistors of the H-Bridge which are in short circuit condition are switched off. All others remain driven
by DIR and PWM.
Thermal shutdown
When the junction temperature exceeds TJSD all driver are switched in sink condition (L), the K- output is off and
the diagnostic DG is LOW until the junction temperature drops below TJSD - TJHYST.
Overvoltage Shutdown
When the supply voltage VVS exceeds the overvoltage threshold VVSOVH all driver are switched in sink condition (L), the K- output is off and the diagnostic DG is LOW.
13/17
L9903
FUNCTIONAL DESCRIPTION (continued)
Undervoltage Shutdown
For supply voltages below the undervoltage disable threshold the gate driver remains in sink condition (L) and
the diagnostic DG is low.
Short Circuit Detection
The output voltage at the S1 and S2 pin of the H-Bridge is monitored by comparators to detect shorts to ground
or battery. The activated external highside MOS transistor will be switched off if the voltage drop remains below
the comparator threshold voltage VS1TH and VS2TH for longer than the short current detection time tSCd. The
transistor remains in off condition, the diagnostic output goes LOW until the DIR or PWM input status will be
changed. The status doesn’t change for the other MOS transistors. The external lowside MOS transistor will be
switched off if the voltage drop passes over the comparator threshold voltage VS1TH and VS2TH for longer than
the short current detection time tSCd. The transistor remains in off condition, the diagnostic output goes LOW
until the DIR or PWM input status will be changed. The status doesn’t change for the other MOS transistors.
Diagnostic Output (DG)
The diagnostic output provides a real time error detection, if monitors the following error stacks: Thermal shutdown, overvoltage shutdown , undervoltage shutdown and short circuit shutdown. The open drain output with
internal pull up resistor is LOW if an error is occuring.
Bootstrap capacitor (CB1,CB2)
To ensure, that the external power MOS transistors reach the required RDSON, a minimum gate source voltage
of 5V for logic level and 10V for standard power MOS transistors has to be guaranteed. The highside transistors
require a gate voltage higher than the supply voltage. This is achieved with the internal chargepump circuit in
combination with the bootstrap capacitor. The bootstrap capacitor is charged, when the highside MOS transistor
is OFF and the lowside is ON. When the lowside is switched OFF, the charged bootstrap capacitor is able to
supply the gate driver of the highside power MOS transistor. For effective charging the values of the bootstrap
capacitors should be larger than the gate-source capacitance of the power MOS and respect the required PWM
ratio.
Chargepump circuit (CP)
The reverse battery protection can be obtained with an external N-channel MOS transistor as shown in fig.6. In
this case its drain-bulk diode provides the protection. The output CP is intended to drive the gate of this transistor above the battery voltage to switch on the MOS and to bypass the drain-bulk diode with the RDSON. The
CP has a connection to VS through an internal diode and a 20kΩ resistor.
Gate drivers for the external N-channel power MOS transistors (GH1, GH2, GL1, GL2)
High level at EN activates the driver of the external MOS under control of the DIR and PWM inputs (see truth
table and driving sequence fig.4). The external power MOS gates are connected via series resistors to the device to reduce electro magnetic emission (EME) of the system. The resistors influence the switching behaviour.
They have to be choosen carefully. Too large resistors enlarge the charging and discharging time of the power
MOS gate and can generate cross current in the halfbridges. The driver assures a longer switching delay time
from source to sink stage in order to prevent the cross conduction.
The gate source voltage is limited to 14V. The charge/discharge current is limited by the RDSON of the driver.
The drivers are not protected against shorts.
14/17
L9903
FUNCTIONAL DESCRIPTION (continued)
Programmable cross conduction protection
The external power MOS transistors in H-Bridge ( two half bridges) configuration are switched on with an additional delay time tCCP to prevent cross conduction in the halfbridge. The cross conduction protection time
tCCP is determined by the external capacitor CPR and resistor RPR at the PR pin. The capacitor CPR is charged
up to the voltage limit VPRH. A level change on the control inputs DIR and PWM switches off the concerned external MOS transistor and the charging source at the PR pin. The resistor RPR discharges the capacitor CPR.
The concerned external power MOS transistor will be switched on again when the voltage at PR reaches the
value of VPRL. After that the CPR will be charged again. The capacitor CPR should be choosen between 100pF
and 1nF. The resistor RPR should be higher than 7kW. The delay time can be expressed as follows:
tCCP= RPR · CPR · ln NPR
with NPR= VPRH / VPRL = 2
tCCP= 0.69 · RPR · CPR
ISO-Interface
The ISO-Interface provides the communication between the micro controller and a serial bus with a baud rate
up to 60kbit/s via a single wire which is VBAT and GND compatible. The logic level transmission input TX drives
the open drain K-output. The K output can be connected to a serial bus with a pull up resistor to VBAT. The Kpin is protected against overvoltage, short to GND and VS and can be driven beyond VVS and GND. During lack
of VVS or GND the output shows high impedance characteristic. The open drain output RX with an internal pull
up resistor monitors the status at the K-pin to read the received data and control the transmitted data. Short
circuit condition at K-pin is recognized if the internal open drain transistor isn’t able to pull the voltage potential
at K-pin below the threshold of 0.45·VVS. Then the RX stays in high condition. A timer starts and switches the
open drain transistor after typ. 20µs off. A next low at the TX input resets the timer and the open drain transistor
switches on again.
Figure 8. Functional schematic of the ISO-interface
RX
K
R RX
=
VCC
0.5 •V VS
R TX
TX
I KH
R
Q
S
R delay
T SH
15/17
L9903
mm
DIM.
MIN.
TYP.
inch
MAX.
MIN.
TYP.
MAX.
A
2.35
2.65
0.093
0.104
A1
0.1
0.3
0.004
0.012
B
0.33
0.51
0.013
0.020
C
0.23
0.32
0.009
0.013
D
12.6
13
0.496
0.512
E
7.4
7.6
0.291
0.299
e
1.27
OUTLINE AND
MECHANICAL DATA
0.050
H
10
10.65
0.394
0.419
h
0.25
0.75
0.010
0.030
L
0.4
1.27
0.016
0.050
SO20
K
0° (min.)8° (max.)
L
h x 45°
A
B
e
A1
K
H
D
20
11
E
1
1
0
SO20MEC
16/17
C
L9903
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of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. N o license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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17/17