St Mb467 User manual

STMicroelectronics

MB467

Airbag EVA Board

UM0178

User manual

Rev 1

February 2006

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Rev 1

February 2006 1/37

UM0178

USER MANUAL

MB467

Airbag Eva Board

Introduction

The MB467 Airbag Eva Board is a complete demonstrator of an airbag system based on

STMicroelectronics devices. The board implements a flexible and open design demonstrating

the capability of the STMicroelectronics 16/32bit microcontrollers and safing devices for airbag

applications.

The MB467 Airbag Eva Board mounts two safing devices with SQUIB drivers and satellite

sensor interfaces L9654 and L9658 plus a safety power regulator L4998.

The board has opened connectivity to ST CPU boards, SQUIBs and to external power supply.

A prototyping area allows users to do needed specific circuit.

Main components

●L9658, octal squib driver and quad sensor interface ASIC for safety application

●L9654, quad squib driver and dual sensor interface ASIC for safety application

●L4998, Safety Power Regulator

●Standardized CPU board connector providing access to off board I/O, PWM, SPI and

power supply

●Connector for Squibs

●Connector for Satellites

●Connector for Hall Sensors

Features

●Support the ST30F7xx and ST10F3xx EVA boards

●Support for up to 6 satellites or 4 satellites and 2 Hall sensors, real or simulated

●Support for up to 12 Squibs, real or simulated

●Diagnostic testing and validation of safing functionality

– SPI arming and deployment

– Squibs and deployment drivers

– Loss of ground and short circuit

– Micro/satellites communication

●On board standard 100 mils prototyping area

●Main power supply 12V

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Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.2 Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.3 Board connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2 Before you start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.1 Jumper settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3 Using the board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1 How to exercise diagnostic functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1.1 Arming interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1.2 Squibs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1.3 Deployment drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1.4 Satellites communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.2 L9658 octal squib driver and quad sensor interface ASIC . . . . . . . . . . . . . . .11

4.3 L9654 quad squib driver and dual sensor interface ASIC . . . . . . . . . . . . . . . 12

4.4 L4998 Safety Power Regulator ASIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.5 Satellite/Sensor interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.5.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.5.2 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.5.3 Satellite SPI interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.5.4 Board satellite functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.6 Arming interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.6.1 Arming SPI interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.6.2 ASIC diagnostic functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.7 Squib and deployment drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.7.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.7.2 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.7.3 Board functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.8 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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4.9 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.10 CPU Board connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.11 Prototyping area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.12 Jumpers summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.13 Connectors summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Appendix A Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Appendix B Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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List of tables

Table 1. Satellite connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 2. Satellite jumpers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 3. Arming interface jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 4. Deployment Enable jumpers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 5. Squib connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 6. Squib dummy loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Table 7. Power supply jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 8. Power supply jumpers (testing only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 9. Reset jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Table 10. CPU Board connector pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Table 11. Jumpers summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 12. Connectors summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 13. Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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List of figures

Figure 1. The MB467 Airbag Eva Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 2. MB467 Airbag Eva Board layout block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 3. MB467 Airbag Eva Board system block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 4. Satellite jumpers location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 5. SPI configuration on Arming for eva board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 6. Arming SPI daisy-chain configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 7. Arming jumpers location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 8. Squib jumpers location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 9. Power supply jumpers location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 10. Reset jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 11. L4998 Safety Power Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 12. L9658 Octal Squib Driver and Quad Sensor Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 13. L9654 Quad Squib Driver and Dual Sensor Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 14. Connector to CPU board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

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1 Introduction UM0178

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1 Introduction

The MB467 Airbag Eva Board is intended as a low cost development platform to demonstrate

the capability of the L9658/L9654 safing and L4998 voltage regulator ASIC’s. The board

includes also a CPU board connector to interface with ST10/ST30 EVA board.

Main functionality includes deployment of airbags, switched-power sources to satellite sensors,

diagnostic of sensing/deployment module and arming inputs.

1.1 Features

General features of this board are:

●Complete airbag evaluation system

●Full compatibility with other microcontroller boards designed for the CPU board connector

●Full access to diagnostic functionality of the safing ASIC:

– SPI arming and deployment

–Squibs

– Deployment drivers

– Satellites communication

Figure 1. The MB467 Airbag Eva Board

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1.2 Devices

The MB467 Airbag Eva Board mounts the following devices:

●L9658 octal squib driver and quad sensor interface ASIC for safety application

– 64-pin TQFP version

– 8 deployment drivers

– interface with 4 satellite sensors

– support Manchester protocol for satellite sensors

– supports for variable bit rate detection

– SPI interface

– Hall effect sensor support on satellite channels 3 and 4

●L9654 quad squib driver and dual sensor interface ASIC for safety application

– 48-pin TQFP version

– 4 deployment drivers

– interface with 2 satellite sensor

– support Manchester protocol for satellite sensor

– supports for variable bit rate detection

– SPI interface.

●L4998 Safety Power Regulator

– boost regulator able of sourcing up to 90 mA

– buck regulator operating in Continuous Conduction Mode able of sourcing up to

250mA output current

– one 5.0 V linear regulator (Vcc) able of sourcing up to 200 mA output current

– current limit and thermal shutdown protection

1.3 Board connections

The board provides the connections listed below:

●CPU board Connector to microcontroller I/O, PWM, SPI and power supply

●Connectors for 6 satellites or 4 satellites and 2 Hall sensors, real or simulated

●Connectors for 12 squibs, real or simulated

●On board standard 100 mils prototyping area

●Main power supply 12V

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2 Before you start UM0178

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2 Before you start

This section describes operations needed before powering up the board.

Please, refer to Chapter 4 on page 10 for detailed information on board configuration and

jumper settings.

2.1 Jumper settings

For the location and (default) settings of the various jumpers, please refer as follows:

1. Close the jumper J51 to supply the board.

2. Close jumpers J48-J50 to supply VCC.

3. Close jumpers J23-J25 to supply 35V Vboost to the board.

4. Close jumpers J31-J33, J40-J41 and J43-J44 to supply 8V Vbuck to the board

5. Close the jumper J46 to supply a soft start function to SPR internal regulator (Cslew).

6. Close jumpers J22, J26-J30, J34-J35, J37-J39, J42 and J45. These jumpers are only for

testing purpose and must always be closed.

7. Close the jumper J36 to pull up the RST signal at power on.

8. Close the jumper J14 to provide the clock signal to the Satellite/Deployment interface.

9. Connect satellites for L9658 to pin 1 of jumpers J5-J8. If you want to simulate them, close

jumpers J5-J8 and provide the appropriate signals to the DICH1-DICH4 pins on the CPU

board connector.

10. Connect satellites for L9654 to pin 1 of jumpers J54-J55. If you want to simulate them,

close jumpers J54-J55 and provide the appropriate signals to the DICH5-DICH6 pins on

the CPU board connector.

11. Close the jumper J15 to enable deployment on L9654.

12. Close the jumper J21 to enable deployment on L9658.

13. Close the jumper J20 to provide the clock signal to the Arming interface.

14. Close the jumpers J13, J16, J17, J18, J19 to enable the squibs.

15. Connect squibs to connectors TP1, TP2 and TP7. If you want to simulate squib loads

instead of connecting them, close jumpers J1-J4, J9-J12, J52-J53 and J56-J57.

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3 Using the board

3.1 How to exercise diagnostic functionality

3.1.1 Arming interface

Arming communication between micro and ASIC can be exercised by interrupting clock signal

of the specific SPI. This can be done opening the jumper J20.

3.1.2 Squibs

This board support both real squibs or simulated loads. Real squib can be connected to

TP1,TP2, TP7 plus the relative grounds J13, J16-J19. Loads can be simulated by closing

jumpers J1-J4, J9-J12, J52-J53 and J56-J57.

3.1.3 Deployment drivers

The whole logic of the two ASIC can be exercised without firing the squib by keeping low the

DEPEN signal of the relative ASIC. This can be done by opening the jumper J21 for L9658 or

jumper J15 for L9654.

3.1.4 Satellites communications

Satellite and deployment communication between micro and ASIC can be exercised by

interrupting clock signal of the specific SPI. This can be done opening the jumper J14.

4 Hardware UM0178

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4 Hardware

This chapter describes all the hardware modules of the board.

4.1 Overview

The MB467 Airbag Eva Board is a specific platform for airbag with SPI interface.

Figure 2. MB467 Airbag Eva Board layout block diagram

SQUIB

L9654 POWER

L9654

CPU BOARD SQUIB

L9658 PROTOTYPE AREA

L4998

CONNECTOR L9658

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4.2 L9658 octal squib driver and quad sensor interface ASIC
L9658 is intended to deploy up to 8 squibs and to interface up to 4 satellites. Two satellite 
interfaces can be used to interface Hall sensors. Squib drivers are sized to deploy 1.2A 
minimum for 2ms minimum during load dump and 1.75A minimum for 1ms minimum during 
load dump. Diagnostic of squib driver and squib resistance measurement is controlled by micro 
controller. Satellite interfaces support Manchester decoder with variable bit rate.
The main features set are described below:
●8 deployment drivers sized to deliver 1.2A (min.) for 2ms (min.) and 1.75A(min) for 
1ms(min).
●Independently controlled high-side and low-side MOS for diagnosis
●Analog output available for resistance
●Squib short to ground, short to battery and MOS diagnostic available on SPI register
●Capability to deploy the squib with 1.2A (min.) or 1.75A under 40V load-dump condition 
and the low side MOS is shorted to ground
●Capability to deploy the squib with 1.2A (min.) at 6.9V VRES and 1.75A at 12V VRES.
●Interface with 4 satellite sensors
Figure 3. MB467 Airbag Eva Board system block diagram
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4 Hardware UM0178
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●Programmable independent current trip points for each satellite channel
●Support Manchester protocol for satellite sensors
●Supports for variable bit rate detection
●Independent current limit and fault timer shutdown protection for each satellite output
●Short to ground and short to battery detection and reporting for each satellite channel
●5.5MHz SPI interface
●Satellite message error detection
●Hall effect sensor support on satellite channels 3 and 4.
●Low voltage internal reset
●2kV ESD capability on all pins
●Package: 64LD TQFP
●Technology: ST Proprietary BCD5 (0.65µm)
4.3 L9654 quad squib driver and dual sensor interface ASIC
L9654 is intended to deploy up to 4 squibs and to interface up to 2 satellites. Squib drivers are 
sized to deploy 1.2A minimum for 2ms minimum during load dump and 1.75A minimum for 1ms 
minimum during load dump. Diagnostic of squib driver and squib resistance measurement is 
controlled by micro controller. Satellite interfaces support Manchester decoder with variable bit 
rate.
The main features set are described below:
●4 deployment drivers sized to deliver 1.2A (min.) for 2ms (min.) and 1.75A(min) for 
1ms(min).
●Independently controlled high-side and low-side MOS for diagnosis
●Analog output available for resistance
●Squib short to ground, short to battery and MOS diagnostic available on SPI register
●Capability to deploy the squib with 1.2A (min.) or 1.75A under 40V load-dump condition 
and the low side MOS is shorted to ground
●Capability to deploy the squib with 1.2A (min.) at 6.9V VRES and 1.75A at 12V VRES.
●Interface with 2 satellite sensors
●Programmable independent current trip points for each satellite channel
●Support Manchester protocol for satellite sensors
●Supports for variable bit rate detection
●Independent current limit and fault timer shutdown protection for each satellite output
●Short to ground and short to battery detection and reporting for each satellite channel
●5.5MHz SPI interface
●Satellite message error detection
●Low voltage internal reset
●2kV ESD capability on all pins
●Package: 48LD TQFP
●Technology: ST Proprietary BCD5 (0.65µm)
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4.4 L4998 Safety Power Regulator ASIC
The L4998 integrated circuit is intended for automotive applications.The main feature set is 
described below:
●Boost regulator able of sourcing up to 90mA output current
●Buck regulator operating in Continuous Conduction Mode able of sourcing up to 250 mA 
output current
●One 5.0V linear regulator (VCC) able of sourcing up to 200mA output current
●Regulator soft-start control (CSLEW)
●Buck voltage out-of-regulation detection (BCKFLT)
●VCC out-of-regulation detection with reset delay (RST)
●Current-limit and thermal shutdown protection
●Package: PowerSSO14
4.5 Satellite/Sensor interface
The devices provide output current limited a 60 mA to drive up to six satellites or four satellites 
and two Hall sensors.
The L9658/L9654 will monitor the current flow from its output pin and “demodulate” the current 
to be decoded using Manchester protocol. Decoded satellite message is communicated to an 
external microprocessor via SPI. 
4.5.1 Features
●Interface with 6 satellite sensors
●Programmable independent current trip points for each satellite channel
●Support Manchester protocol for satellite sensors
●Supports for variable bit rate detection
●Independent current limit and fault timer shutdown protection for each satellite output
●Short to ground and short to battery detection and reporting for each satellite channel
●5.5MHz SPI interface
●Satellite message error detection
●Hall effect sensor support on satellite channels 3 and 4.
4.5.2 Functional description
Each output channel senses the current drawn by the remote satellite sensor; the circuit 
modulates the load current into logic voltage levels for post processing by a manchester 
decoder.
The L9658/L9654 decode satellite messages based on Manchester decoding, each of the six 
satellite channels have a Manchester decoder that can be enabled or disabled through a 
register.
Each output has a short circuit protection by independent current limit. When a short circuit 
occurs the output becomes current limited, a fault timer latch the output off and a fault condition 
bit is reported via SPI.That output returns to normal operation when it is re-enabled via SPI and 
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4 Hardware UM0178
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the current limit condition was removed, this fault condition does not interfere with the operation 
of any of the other output channels.
Channels 3 and 4 of the L9658 can by used to provide an analog feed back current as a 1/
100th ratio of the sense current in this mode internal FIFO and decoder are bypassed. This will 
allow the IF3/V3 and IF4/V4 pins to be connected to a resistor to ground and provide an analog 
voltage equivalent to the sense current to be read by an A/D port. Otherwise the IF3/V3 and 
IF4/V4 pins can be configured as discrete output pins that provide logic level output voltage of 
the sensed current based on the internal current threshold set by the user through the CCR 
Register, which when used in conjunction with satellite sensors connected to channels 3 and 4 
it can provide raw data out of the satellite message bypassing the internal decoder.
4.5.3 Satellite SPI interface
The board support up to 6 satellites (4 handled from L9658 and 2 from L9654). 
The L9658/L9654 support two different communication protocols that are widely used by 
different automotive manufactures. One is based on the protocol used by Delphi satellite 
sensors and the other is a generic protocol that supports variable length messages based on 
BOSH, PAS3 and PAS4 protocols.
All decoded satellite messages are communicated to the external microcontroller via SPI. The 
MOSI input takes data from the master microprocessor while either CS_S1 (chip select of the 
L9658) or CS_S2 (chip select of the L9654) is asserted.The MISO reported the status of L9658/
L9654 output channels. It is possible drive the two satellite interfaces (L9658/L9654) separately 
because there are two chip select, CS_S1 and CS_S2.
4.5.4 Board satellite functionality
Satellites can be connected directly to the ASIC’s through pin 1 of jumpers J5-J8 and J54-J55. 
Table 1. Satellite connector
Diagnostic functionality of satellite communication can be tested using jumper J14. Opening 
this jumper interrupts the SCLK signal of the SPI used for satellite and deployment thus 
blocking any communication between the micro and the ASIC.
It is possible to simulate satellite signals by closing jumpers J5-J8 and J54-J55 and providing 
the appropriate signal to pins DICH1-DICH6 on the CPU board connector. You must drive the 
base of the BJT with a particular signal in order to generate the correct word to decode with 
manchester decoding and then to transmit via SPI. This dynamic digital signal shall be 
generated by using 2 PWM outputs provide on ST30F7xx board (or an ST10F27x board). This 
signal will be sent into the base of the BJT’s to simulate the local acceleration values. 
Name Figure Description
J5 pin 1 Figure 4 L9658 satellite channel 1 (ICH1)
J6 pin 1 Figure 4 L9658 satellite channel 2 (ICH2)
J7 pin 1 Figure 4 L9658 satellite/sensor channel 3 (ICH3)
J8 pin 1 Figure 4 L9658 satellite/sensor channel 4 (ICH4)
J54 pin 1 Figure 4 L9654 satellite channel 1 (ICH1)
J55 pin 1 Figure 4 L9654 satellite channel 2 (ICH2)
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Table 2. Satellite jumpers
4.6 Arming interface 
The arming interface is used as a fail-safe to prevent inadvertent airbag deployment. Along with 
deployment command, these signals provide redundancy. Pulse stretch timer is provided for 
each channel/loop. Either ARM signal or deployment command shall start the pulse stretch 
timer.
Arming interface has a dedicated 8-bit SPI interface. The devices can deploy a channel, only 
when the deployment enable is asserted and any of the following conditions are satisfied:
●the respective deployment command is sent during a valid pulse stretch timer, which 
initiated by ARM signal
●the respective SPI ARM command is sent during a valid pulse stretch timer, which initiate 
by deployment command.
Name Figure Description
J14 Figure 4 Interrupt SPI communication for Satellite and Deployment
J5 Figure 4 Enable load simulation for L9658 satellite channel 1 through DICH1 
J6 Figure 4 Enable load simulation for L9658 satellite channel 2 through DICH2
J7 Figure 4 Enable load simulation for L9658 satellite/sensor channel 3 through 
DICH3
J8 Figure 4 Enable load simulation for L9658 satellite/sensor channel 4 through 
DICH4
J54 Figure 4 Enable load simulation for L9654 satellite channel 1 through DICH5
J55 Figure 4 Enable load simulation for L9654 satellite channel 2 through DICH6
Figure 4. Satellite jumpers location
J5
J6
J8
J7
J55
J54
J14
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There are on board two different deployment enables for L9658 and L9654. When these pins 
are asserted, L9658/L9654 are able to turn on its high (SQH) and low side (SQL) drivers upon 
receiving a valid deployment command or a MOS diagnostic request. When a deployment is 
initiated, it cant be terminated, except during a reset event.
4.6.1 Arming SPI interface
L9654 and L9658 arming commands are based on 8bit SPI messages.
In a real airbag system, all the devices should be daisy-chained. Here, as this board has been 
designed for training purposes for each ASIC, ASIC’s are connected on the same SPI and 
selected with different chip selects CS_A1 and CS_A2. You find the chips select on the CPU 
board connector at the position D30 and C27.
The above figure is representing the SPI configuration for the system evaluation board where 
ASIC’s are sharing a common SPI. 
Diagnostic functionality of the arming interface can be tested using jumper J20. Opening this 
jumper interrupts the SCLK_A signal of the SPI used for arming thus blocking any 
communication between the micro and the ASIC. 
Table 3. Arming interface jumpers
Figure 5. SPI configuration on Arming for eva board 
Name Figure Description
J20 Figure 7 Interrupt SPI communication for Arming
CS_A2 CS_A1
MOSI
MISO
SCLK
CS_A1
IC_1
MOSI_A
MISO_A
SCLK_A
CS_A2
IC_2
MOSI_A
MISO_A
SCLK_A
µP
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Daisy chain configuration
Arming SPI interface shall support a daisy-chain configuration. In this configuration, the 
processor can send arming commands to multiple L9658 devices without having to use 
additional pins. The functioning is underline in the following figure:
In order to obtained daisy-chain configuration it’s enough to connect the MOSI from 
microprocessor to MOSI_A of the ASIC, MISO_A to MOSI_A in fall and MOSI_A to the MISO of 
the microprocessor.
4.6.2 ASIC diagnostic functionality
Diagnostic on the L9658 can be performed by disabling deployment through the signal DEPEN. 
This signal is mapped to pin DEPEN1 of CPU board connector. DEPEN1 can also be manually 
forced low by opening the jumper J21.
Diagnostic on the L9654 can be performed by disabling deployment through the signal DEPEN. 
This signal is mapped to pin DEPEN2 of CPU Board connector. DEPEN2 can also be manually 
forced low by opening the jumper J15.
L9658/L9654 are able to perform a short to battery, a short to ground, a resistance 
measurement and a MOS diagnostics on their deployment drivers. A short to ground and an 
open circuit conditions are distinguished using a resistance measurement. The diagnostic is 
performed when a valid SPI command is received.
Table 4. Deployment Enable jumpers
Figure 6. Arming SPI daisy-chain configuration
Name Figure Description
J21 Figure 7 Deployment enable for L9658
J15 Figure 7 Deployment enable for L9654
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4.7 Squib and deployment drivers
The on-chip deployment drivers are designed to deliver 1.2A (min.) at 6.9V VRES. Deployment 
current is be 1.2A (min.) for 2ms (min.). The high side driver can survives deployment with 
1.47A, 40V at VRES and SQL is shorted to ground for 2.5ms. Minimum load resistance is 1.7 
Ohm. At the end of a deployment, a deploy success flag is asserted via SPI. Each VRES and 
GND connection are used to accommodate 8 loops that can be deployed simultaneously.
Upon receiving a valid deployment condition, the respective SQH and SQL drivers are turned 
on. SQH and SQL drivers are also turned on momentarily during a MOS diagnostic. Otherwise, 
SQH and SQL are inactive under any normal, fault, or transient conditions. Upon a successful 
deployment of the respective SQH and SQL drivers, a deploy command success flag is 
asserted via SPI.
4.7.1 Features
●8 deployment drivers sized to deliver 1.2A (min.) for 2ms (min.) and 1.75A (min.) for 1ms 
(min.).
●Independently controlled high-side and low-side MOS for diagnosis.
●Analog output available for resistance.
●Squib short to ground, short to battery and MOS diagnostic available on SPI register.
●Capability to deploy the squib with 1.2A (min.) or 1.75A under 40V load-dump condition 
and the low side MOS is shorted to ground.
●Capability to deploy the squib with 1.2A (min.) at 6.9V VRES and 1.75A at 12V VRES.
Figure 7. Arming jumpers location
J21
J15
J20
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