MC33789 Datasheet, PDF (1/80 Pages) Freescale Semiconductor, Inc – Airbag System Basis Chip (SBC) with Power Supply and PSI5 Sensor Interface

Freescale Semiconductor
Advance Information
Document Number: MC33789
Rev. 1.0, 2/2011
Airbag System Basis Chip (SBC)
with Power Supply and PSI5
Sensor Interface
33789
The 33789 is a mixed signal IC for airbag safety applications. The
33789 provides a cost effective and flexible system IC solution across
the range of airbag partitions used in cars and other vehicles.
The 33789 connects to the 12 V vehicle battery and supplies the
multiple voltages of a typical airbag system. The 33789 can detect
switched input states, communicate with both local and remote crash
sensors. It offers an industry standard interface (SPI) and four PSI5
master interfaces. The 33789 has a dedicated safing state machine that
complements the airbag’s MCU hardware/software safing approach.
Also included are a diagnostic - self protection capability and a
programmable analog interface accessible by the system MCU.
The 33789 is well suited for use in low to high end airbag systems by
allowing the designer to scale a design for the number of firing loops
needed while providing enhanced safety and system reliability.
Features
• Designed to operate 5.2 V ≤ V_PWR ≤ 20 V, up to a 40 V transient
• Safing state machine with programmable sensing thresholds
• Two configurable high side/low side drivers with PWM capability
• Four PSI5 satellite sensor master interfaces
• Self-protected and diagnostic capability
• Watchdog and system Power ON Reset (POR)
• Supports complete airbag system power supply architecture,
including system power mode control, supplies for squib firing
(33 V), satellite sensors (6.3 V), and local ECU sensors and ECU
logic circuits (5.0 V)
• Nine configurable switch input monitors for simple switch and Hall-
effect sensor interfaces with internal power supply
• 16-bit SPI interface
• LIN 2.1 physical layer interface
V_BAT
33789
Wake Up
IN1
WAKE
9 Input
Monitors
IN2
VPWR
IN8
BSTSW
IN9
LIN
VBST
AUTO RESTRAINT
AE SUFFIX (PB-FREE)
EXPOSED PAD
98ASA10763D
64-PIN LQFP
ORDERING INFORMATION
Device
MCZ33789AE/R2
Temperature
Range (T_A)
-40 to 125 °C
Package
64 LQFP EP
33 V
V_BAT
4 Satellite
Sensor
Interfaces
PSI5_1
PSI5_2
PSI5_3
VER
ERSW
Energy
Storage
5.0 V
5.0 V
V_PWR
PSI5_4
OUT1_D
OUT1_S
BUCKSW
VBUCK
9.0 V
VFIRE_x
SQB_H1
SQB_H1
5.0 V
X/Y Axis
Accel.
Sensor
5.0 V
SPI_A
VDD AIN
Sensor SPI
SPI
AOUT
RESET
VCCDRI
VCC
ARM
5.0 V _Squib
Output _{Driver 1}
Squib
Driver 2
SQB_L1
FEN_1
FEN_2
SQB_L1
Cross-coupled
Squib
Connections
RESET
SPI_B
MCU
Squib Driver SPI
2 ARM_X and ARM_Y for Squib Driver 2 FENs
RESET
SPI
Figure 1. 33789 Simplified Application Diagram
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2010-2011. All rights reserved.