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U6268B
Side-Airbag Sensor Dual Interface
Description
The U6268B is an interface IC for remote automotive sensors. It links the crash sensors in the driver- and passenger door with the main airbag unit in the dashboard. Two identical channels supply the external sensors and receive digital information from them via one active wire each. The interface supplies the external sensors with a pre-regulated smoothed voltage, the external units transmit the digital information back to the interface by current modulation. As the device is for safety critical applications, highest data transmission security is mandatory. With high immunity against cross-coupling between the two channels, the U6228B is tailored for the harsh automotive environment.
Features
D Two identical interface channels D Provides a pre-regulated smoothed voltage and a
supply current up to 50 mA for the sensors
D TTL-compatible input activate the sensor D Data output can be directly connected to a microcontroller input
D Receives data from the sensors by current modulation
with a transmission rate of 60 kBaud (transmission bandwidth 500 kHz)
D Operation supply voltage range 5.7 V
method 3015.7
v V v 40 V
S
D ESD protection according to MIL-STD-883C test D High-level EMI protection
D Current modulation provides high noise immunity for
data transfer
Benefits
D Voltage supply and data transmission with one active
wire over long distances
Ordering Information
Extended Type Number U6268B Package SO16 Remarks
Block Diagram
Data Channel 1 Enable Voltage comparator I/U converter Smoothed voltage regulator Channel 1 power supply Data trans- mission Crash sensor
C
Enable Channel 2 Data
Channel 1 Channel 2
Temperature monitor
Short circuit detection Channel 2 power supply Data trans- mission
Smoothed voltage regulator Voltage comparator I/U converter
Crash sensor
13839
Figure 1. Block diagram
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
1 (12)
Preliminary Information
U6268B
Pin Description
Pin 1 2 Symbol Function GND Ground and reference pin RETURN1 Return line of the external unit, internally connected to GND via a line-protection transistor OUT1 Voltage-stabilized supply output and current-modulation input VS Supply voltage of the IC OUT2 Voltage stabilized supply output and current modulation input SC Smooth time constant for slow voltage change at both OUT pins RETURN2 Return line of the external unit, internally connected to GND via a line-protection transistor GND Ground and reference pin ENABLE1 Controls OUT1 voltage, ENABLE1 High means OUT1 active, ENABLE1 Low or open means OUT1 switched off CLL2 Current logic level output, low at high OUT2 current, monitoring via OCM2 OCM2 Analog current output, representing 1/10 current of OUT2 OCM1 Analog current output, representing 1/10 current of OUT1 CLL1 Current logic level output, low at high OUT1 current, monitoring via OCM1 ENABLE2 Controls OUT2 voltage, ENABLE2 High means OUT2 active, ENABLE1 Low or open means OUT2 switched off GND Ground and reference pin
GND 1 RETURN1 2 OUT1 3 VS 4
16 GND 15 ENABLE1 14 CLL1 13 OCM1 12 OCM2
3 4 5 6
OUT2 5 SC 6 RETURN2 7 GND 8
13321
7 11 CLL2 10 ENABLE2 9 GND 11 8, 9 10
Figure 2. Pinning
12 13 14
15
16
Figure 3. Application circuit
Functional Description
VS
The IC and the external units are powered via the VS Pin 4. This pin is connected to the battery via a reverse battery protection diode. An electrolythic capacitor of 22 mF smoothes the voltage and absorbes positive and negative transients. voltage for the external units and monitors the output current. During normal operating conditions, the OUTx voltage is typ. 3 V below VS, and changes very slowly with a varying battery voltage in order to suppress disturbances in the data transmission. At low VS (5.7 to 8.5 V), the OUTx voltage is typ. 0.5 V below VS. This voltage difference is reduced in order to ensure sufficient supply voltage for the external unit between OUTx and RETURNx. The output current capability is 50 mA. The internal pull-down current at OUTx is typically 3 mA.
OUT1, OUT2
OUTx provides a smoothed, very slowly changing supply
2 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
U6268B
35 Vout max 30 Vout min 25 Vout ( V ) 22.4 21.4 20
15
9.4 10 8.2 7.7 5.4 5 4.9 0 0
13322
5 5.7 8.5
10 15 11.3 12.0
20 VS ( V )
25 28.6
30 32.6
35
40
Figure 4. Output voltage with tolerances vs. supply voltage
The data transmission from the external unit to the interface IC is carried out on the same line by varying the current level. The quiescent current consumption of the external unit is about 5 to 15 mA. This current level is interpreted as logic high level at CLL-pin. The external unit can switch on an additional current of 30 mA, interpreted by the interface as logic low. The current changes within approximately 1 ms, sufficient for a transmission rate of about 60 kBaud, requiring a transmission bandwidth of about 500 kHz for the currentmonitoring subcircuit and the OCM output. For a good current transmission behaviour, the dynamic resistance of OUTx may not exceed 12 W inside the bandwidth range (total of 15 W for OUTx and RETURN). The OUTx- voltage can be switched off by ENABLEx = LOW to reset the external unit and to reduce power dissipation during fault conditions. The OUT pins are overtemperature- and short-circuit protected. A reverse polarity diode at Pin VS (Pin 4) ensures that no current is fed back to the VBatt-system in the case of a short between OUTx and VBatt. A minimum capacity of 33 nF is required at the pins OUTx .
D Low or open circuit applied to ENABLEx switches
the related OUTx and RETURNx off (high impedance). A sink current at Pin OUTx discharges the capacitive load.
D High applied to ENABLEx switches the related
OUTx and RETURNx on to supply the external unit.
OCM1, OCM2
The output current of OUTx is monitored with a transmission factor of 0.1 to the OCMx. With a resistor from OCM to GND, the current is converted to a voltage. The electrical characteristics are specified by ROCM = 750 W. The CLL-current threshold, the OUT-current limitation and the OUT-current detection can be changed by varying ROCM in a range from 500 W to 1 kW. The current monitoring enables to detect overcurrent conditions at OUTx (short circuit to GND or RETURNx) and to detect low current conditions at OUTx (short circuit to VBatt or open load). The internal pull-down current at the OUTx creates no OCMx-current. During enable, the minimum voltage at OCMx is the saturation voltage of an internal NPN-transistor with typically 0.1 V. The maximum voltage at OCM is limited by an internal clamping diode to 5.3 V.
ENABLE1, ENABLE2
ENABLEx is a microcontroller-compatible input which switches the related output on or off. TELEFUNKEN Semiconductors Rev. A1, 21-May-97
CLL1, CLL2
The current at Pin OUTx is logical evaluated and ready to use for a microcontroller input. With this stage, the 3 (12)
Preliminary Information
U6268B
logic data transmission from the external unit to the interface is completed. CLLx is the output stage of a comparator with an internal threshold and with the OCMx input. A OCMx-voltage higher than 2.4 V creates a logic low at CLLx, and a OCMx-voltage lower than 1.43 V creates a logic high at CLLx. The comparator has an internal hysteresis with typically 0.4 V. With the pull-down resistor ROCMx = 750 W at OCMx, the correct OUTx-current threshold related to the logical output CLLx is ensured. The CLLx is 'low' if the OUTx-current is higher than 27.3 mA, and the CLLx is 'high', if the OUTx-current is lower than 19.1 mA. The comparator has an internal hysteresis of typically 5 mA. The tolerance of the ROCM resistor is assumed to be 0%. The CLL-pin is an open-collector output and needs a pull-up resistor of typically 2 kW to the 5-V supply. For ESD protection, a 7-V Zener diode is implemented. tion from the four GND pins to the metal parts of the modul housing is also recommended.
Power Dissipation
Worst case calculation of the supply current IS: IS = 1,278 ( IOUT1 + IOUT2 ) + 18 mA
Worst case calculation of the IC's power dissipation PV: PV = (VS IS) - [(VS - Vdiff - Vret-sat) (IOUT1 + IOUT2) +ROCM ((IOUT12 + IOUT22) / 81)] VS = supply voltage 5.7 to 25 V voltage difference VS to VOUTx Vdiff = 3.6 at 12 V 25 V S 8.5 V Vdiff = 0.8 at 5.7 V S Vret-sat = 0.5 V saturation voltage return IOUTx = output current at Pin OUTx = 0 to 60 mA ROCM = resistor at Pin OCMx
vV v vV v
RETURN 1, RETURN 2
The RETURNx pin provides a low-ohmic connection to GND via a switched open-collector NPN-transistor. If ENABLEx is high, RETURNx is switched on with a satu50 mA. If ration voltage less than 0.5 V at IRETURNx ENABLEx is low or open, RETURNx is a current sink with 2 mA. RETURNx is current-limited at typically 150 mA.
Selective Overtemperature Protection
An overtemperature protection is integrated which generates a switch-off signal at a chip temperature of typically Tj = 160C and a switch-on signal at typically Tj = 150C. In case of a detected overtemperature, only the corresponding channel is disabled. The other channel stays enabled. The RETURNx is switched off if the voltage at RETURNx is higher than 2 V (short-circuit comparator threshold) and overtemperature is detected. The OUTx is switched off if the voltage at OCMx is higher than 4.6 V (overcurrent detection level) and overtemperature is detected. The OCM voltage monitors the output current at OUTx via the current ratio of 0.1. The overcurrent-detection level of OUTx can be varied by changing the OCMx resistor. If OUTx is switched off by overtemperature and overcurrent detection, the CLLx output remains logic low (overcurrent). As the IC is only overtemperature-protected for short-circuit conditions at RETURNx or OUTx, it has to be checked in each application that the chip temperature does not exceed Tjmax = 150C in normal operation.
v
v
SC
The smooth capacitor is designed to realize the long-time constant for the slow voltage change at OUTx for both interface channels. The capacity is typ. 22 nF. At the rising edge of VBatt, the maximum slew rate is VOUTx = 5 V/ms, and at the falling edge of VBatt, the maximum slew rate is VOUTx = 10 V/ms.
GND-Pins
By means of a GND bond from the chip to Pin 1 and Pin 8, high ground breakage security is achieved and lowest voltage drop and ground shift between IC- and circuit ground is provided. The four GND pins and the die pad are directly connected to the copper leadframe, resulting in a very low thermal resistance, RthJC. In order to achieve a good thermal resistance, RthJA, a good copper connec-
Test Hint
The overtemperature signal can be activated by con-necting ENABLE1 or ENABLE2 to 9 V/ 10 mA.
4 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
U6268B
Absolute Maximum Ratings
Parameters Supply voltage Voltage at pins CLL1, CLL2, ENABLE1, ENABLE2 Voltage at SC Voltage at OCM1, OCM2 Voltage at RETURN1, RETURN2 Voltage at OUT1, OUT2 Current at supply (both channels OUTx and RETURNx shorted) Current at logical pins: CLL1, CLL2 ENABLE1, ENABLE2 Current at SC (SC related to GND or VBatt) Current at pins to external unit OUT1, OUT2, RETURN1, RETURN2 ESD classification Human body model (100 pF, 1.5 kW) Machine model (200 pF, 0.0 W) Ambient temperature range Junction temperature range Storage temperature range Symbol VS VSC VOCMx VRETURNx VOUTx IS ICCLx IENABLEx ISC Min. -0.6 -0.3 -0.3 -0.3 -1 -1 Typ. Max. 40 6 30 6.8 27 40 240 3 0.1 220 Unit V V V V V V mA mA mA
-110 internal limited
mA
All pins
"2000 "200
-40 -40 -55 95 150 125
Tamb Tj Tstg
V V C C C
Thermal Resistance
Parameters Junction to pin Junction ambient is reachable with a big pad size for GND near a screw or the metal housing Symbol RthJC RthJA Value 36 65 Unit k/W k/W
Electrical Characteristics
Tamb = -40 to 95C and Tj = -40 to 150C, operation supply voltage range 5.7 to 18 V continuously, V for max. 25 min, The current values are based on the 750 W 0% resistor at OCM1/OCM2 Parameters Supply current pp y Tj 125C
v25
v40 V for up to 500 ms.
Min. Typ. Max. 8 14 13 18 56 90 146 171 200 Unit mA mA mA mA mA mA mA mA mA
w
Test Conditions / Pins Outputs disabled, VS 18 V Outputs disabled, VS 40 V One output enabled, VS 18 V Both outputs enabled, VS 18 V Output load 2 15 mA, VS V Output load 2 28 mA, VS V Output load 2 50 mA, VS V Output load 2 60 mA, VS 18 V (Tj > 125C) Both channels OUTx and RETURNx shorted, VS 18 V
v v
v
v v v18 v18 v18
Symbol IS IS IS IS IS IS IS IS IS
v
Function SC TELEFUNKEN Semiconductors Rev. A1, 21-May-97 5 (12)
Preliminary Information
U6268B
Parameters Voltage at SC Voltage at SC Maximal voltage at SC SC-discharge current Test Conditions / Pins VS = 5.7 V VS = 12.5 V VS = 40 V Voltage SC = VSC - 3 V 5.7 V VS 40 V SC-charge current Voltage SC = VSC - 3 V 5.7 V VS 40 V Function OUT1 and OUT2 (see figure 4) Voltage difference, IOUTx = 5 to 50 mA VS to VOUTx 5.7 V VS 8.5 V 12 V VS 25 V Output voltage OUTx 8.5 V VS 11.3 V Maximal voltage at VS = 40 V OUTx Current mirror ratio, VS 40 V, IOUTx = 5 to 15 mA IOCMx/IOUTx VS 25 V, IOUTx =15 to 50mA VS 40 V, IOUTx =15 to 50mA Linearity of mirror ratio IOCMx/IOUTx Dynamic resistance VS 40 V IOUT = 15 to 50 mA OUTx Dynamic resistance VS 40 V IOUT = 15 to 50 mA OUTx + RETURNx OUTx current limitation VS 18 V (OUTx short to GND) VS 40 V Overcurrent detection Tj < 125C level general Overcurrent detection Tj 125C level Always valid: current limitation is higher than overcurrent detection Maximum OUTx current VS = 14 V, OCMx shorted to GND (OUTx short to GND) Leakage current at OUT short to GND VS 25 V disabled OUTx OUT short to GND VS 38.5 V Leakage voltage at OUT open VS 38.5 V disabled OUTx Internal pull-down VS 18 V current VS 40 V Supply rejection-ratio VSC = 7.6 V Supply rejection-ratio Variation of VS 8.4 to 40 V in 10 ms Minimum capacity at OUTx for phase margin Delay time with Switching on ENABLE = 1 to Cout = 47 nF 90% VOUT reached Switching off ENABLE = 0 to 10% VOUT reached Function OCM1, OCM2 Symbol VSC VSC VSCmax ISC_dis ISC_ch Min. 5.1 9 Typ. Max. 5.3 9.4 30 82 -20 Unit V V V
vv vv
33 -58
mA mA
vv vv vv
Vdiff_low Vdiff_high VOUT_med VOUT_max
0.3 2.6 7.7 25 0.09 0.10 0.097 -5 2 4 -80 -105 -70 -60
0.8 3.6 30 0.12 0.11 0.11 5 12 15 -60 -60 -51 -51
V V V V
v v v v v v v
IOUT_ratio Ratio_lin ROUT RDyn IOUT_lim IOUT_det IOUT_det
%
W W
mA mA mA mA
w
IOUT_max IOUT_leak VOUT_leak IOUT_sink Vrej_mV Vrej_dB COUT_min Enable_on Enable_off
-140 -0.02 -12
-85
mA mA mA V mA mA mV dB nF
v v
v
v v
4.3 1.8 2.5 51.9 33 3 30 30 100 4 4.5 80
ms ms
6 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
U6268B
Parameters Voltage threshold CLLcomparator Test Conditions / Pins CLLx low-level voltage threshold CLLx high-level voltage threshold Voltage hysteresis IOUT = 0 to 5 mA Symbol VCLL_L VCLL_H VCLL_hys VOCM_min VOCM_lim VOCM_det Min. 1.75 1.43 0.26 Typ. Max. 2.4 1.9 0.6 0.5 5.3 4.9 0.5 0.45 0.5 2 60 70 0.8 1.4 1.1 0.2 3 30 8 150 200 2 2 1.5 0.7 30 90 Unit V V V V V V V mA V
Minimal voltage at OCMx Current-limitation level VS 40 V OUTx short to GND Overcurrent-detection VS 40 V level Current limitation minus VOCM_lim - VOCM_over overcurrent detection Intern. pull-down current Function RETURN1, RETURN2 Enable high saturation IRETURN = 50 mA voltage Dynamic resistance dI 10 mA Current limitation Enable high, VRETURNx = 2 V
v v
4.3 4.2 0.15 0.1
D_lim_OCM
IOCM_sink Vret_sat Rret Iret_lim Iret_lim Iret_lim Iret_low Iret_high Iret_hys tdRet_on tdRet_off
w
W
mA mA mA V V
RETURNx is always higher than current limitation OUTx Overcurrent-detection level
Enable high, VRETURNx Enable low VRETURNx
v 18 V v 18 V
Delay time CRETURN = 47 nF
Threshold comparator, switch-off return Threshold comparator, switch-on return Hysteresis Switching on IRETURN at 50 mA Switching off IRETURN at 1 mA
ms ms
mA mA mA V
V
Function CLL1, CLL2 (CLLx with 2 kW to 5 V) IOUT threshold CLL ROCM = 750 W comparator CLL low-level threshold CLL high-level threshold Hysteresis CLL saturation voltage ICLL 2.5 mA CLL leakage current VCLL 6.5 V Response time to current IOUT to CLL rise change IOUT to CLL fall Max. difference between rise and fall time CLL output switching Rise speed Fall Current transmission rate Current transmission 3 dB bandwidth Function ENABLE1, ENABLE2 Enable low-level threshold Enable high-level threshold
v v
ICLL_L ICLL_H ICLL_hys VCLL_sat ICLL_leak tCll_rise tCll_fall tD rise-fall tCLL_rise tCLL-fall
23.3 19.1 3.5
0.1 0.1
27.3 22.3 8.2 0.4 1 2 2 1 1 1
mA ms ms ms ms ms
60 500
kHz kHz
VEnable_off VEnable_on
2 -0.3
6.5 0.8
V V
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
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Preliminary Information
U6268B
Parameters Test Conditions / Pins Enable input pull-down current (to ensure output disabled during power-off and reset of microcontroller) Power dissipation Power dissipation 1 VS = 18 V, Tj 125C IOUT1 = 28 mA, IOUT2 at overcurrent detection level or IOUT2 = 28 mA, IOUT1 at overcurrent detection level Power dissipation 2 VS = 18 V, Tj 125C IOUT1 = IOUT2 = 28 mA Selective overtemperature protection Logic AND connected Switch off with overcurrent detecSwitch on tion (RETURNx, OUTx) Hysteresis Time delay until overVS = 25 V, Tamb = 125C temperature shut-down OUT1 = OUT2 = GND Symbol IEnable Min. 10 Typ. Max. 100 Unit
mA
w w
Pdis1
1
W
Pdis2
0.75
W
Temp_off Temp_on Temp_hys tdel
155 145 5 100
165 155 20
C C C ms
Timing Diagrams
V Supply 14.0 V 12.0 V
V SC 10.7 V 8.7 V
V OUTx 10.7 V 8.7 V
0.4 ms
0.2 ms
t
13841
Figure 5. Variation of power supply
8 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
U6268B
V ENABLEx 5.0 V
IOUTx 75 mA
overcurrent overtemperature shut down
overcurrent
overcurrent
15 mA 100 ms V CLLx 5.0 V 150 ms 75 ms Pause / pulse for example
t
13842
(Pulse / pause time depends on power disipation and R thja )
Figure 6. Overcurrent protection
V ENABLEx
V OUTx 13 V
30 s 200 mV discharge of C OUT = 47 nF with internal current
IOUTx 40 mA 10 mA V OCMx 4.7 V 3.0 V 0.75 V V CLLx 5.0 V 0V
charge time C OUT = 47 nF
150 s current modulation from sensor 50 s
overcurrent
t
13840
Figure 7. Data transmission
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
9 (12)
Preliminary Information
U6268B
Application Circuit
+VBatt
100 nF
220 mF VCC = 5V 4 VS I/O I/O 14 15 13 750 CLL1 Out1 3 5V
Sensor 1
Interface1
Enable1 OCM1 2 47 nF
Return1
mC
I/O I/O
VCC = 5V
U6268B
Out2 11 10 12 CLL2 5
47 nF
Sensor 2
5V
Interface2
Enable2 OCM2 GND 1, 8, 9, 16 6 22 nF Return2 SC 7
47 nF
750
47 nF
96 11710
10 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
U6268B
Package Information
Package SO16
Dimensions in mm
10.0 9.85 5.2 4.8 3.7
1.4 0.4 1.27 8.89 16 9 0.25 0.10 0.2 3.8 6.15 5.85
technical drawings according to DIN specifications
13036
1
8
TELEFUNKEN Semiconductors Rev. A1, 21-May-97
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Preliminary Information
U6268B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances ( ODSs). The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency ( EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively. TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances.
We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423
12 (12)
Preliminary Information
TELEFUNKEN Semiconductors Rev. A1, 21-May-97

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