MC33789FS Datasheet, PDF (1/2 Pages) Freescale Semiconductor, Inc – Airbag system basis chip (SBC) with power supply and PSI5 sensor interface

Analog, Mixed-Signal and Power Management
MC33789
Airbag system basis chip (SBC) with power supply and PSI5 sensor interface
Applications
• Automotive Airbag Safety Systems
Basic Airbag Systems
Advanced Airbag Systems
• Motorcycle – ATV Safety Systems
Frame Mounted Single Loop Airbag System
The MC33789 is a mixed signal IC for airbag
safety applications. The MC33789 provides a cost
effective and flexible system IC solution across
the range of airbag partitions used in cars and
other vehicles.
The MC33789 connects to the 12 V vehicle
battery and supplies the multiple voltages of a
typical airbag system. The MC33789 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 MC33789 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 MC33789 is well suited for use in low to high
end airbag safety systems by allowing the
designer to scale a design for the number of firing
loops needed while providing enhanced safety
and system reliability.
MC33789 Simplified Application Drawing
V_BAT
9 Input
Monitors
MC33789
IN1
WAKE
IN2
VPWR
Wake Up
IN8
BSTSW
IN9
33 V
LIN
VBST
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