MC33797
Rev 2.0, 07/2005
Freescale Semiconductor
Technical Data
Four Channel Squib Driver IC
33797
The Four Channel Squib Driver IC is a complete squib diagnostic
and deployment interface for use in automotive air bag modules.
Extensive diagnostics and system control features are incorporated
to provide fail-safe operation. The device contains a serial peripheral
interface (SPI) compatible 8-bit interface to allow microprocessor
control.
SQUIB DRIVER
The device has the capability to be used in a standard four-channel
squib driver IC or in a cross-coupled state with the high- and low-side
squib drivers located on separate squib driver ICs. Both the high- and
low-side output drivers are protected against temporary shorts to
battery or ground. The current limit threshold is set by an external
resistor.
Features
• Four-Channel High-Side and Low-Side 2.0 A FET Switches
• Externally Adjustable FET Current Limiting
• Adjustable Current Limit Range: 0.8 A to 2.0 A
• Individual Channel Current Limit Detection with Timing Duration
Measurement, Communicated via SPI
EK SUFFIX (Pb-Free)
98ARH99137A
32-TERMINAL SOICW
• 8-Bit SPI for Diagnostics and FET Switch Activation
• Diagnostics for High-Side Safing Sensor Status
• Resistance and Voltage Diagnostics for Squibs
• Squib Driver IC Capability to Be Used for Cross-Coupled Driver
Firing Application (Allows High- and Low-Side FET Switches to Be
Located on Separate Squib Driver ICs)
ORDERING INFORMATION
Temperature
Device
Package
Range (T )
A
• Pb-Free Packaging designated by Suffix Code EK
MC33797EK/R2
-40°C to 85°C
32 SOICW
33797
/4
VIN
VBOOST1
SQB_HI
VDIAG_1
VPWR
SQUIB
(1A, 1B, 2A, 2B)
TYPICAL
AIR BAG
VFIRE_1A
VFIRE_1B
VDIAG_2
FIRING
CAP
/4
/4
SENSE
POWER SUPPLY
VBOOST2
SQB_LO
/2
VFIRE_RTN
VFIRE_2A
VFIRE_2B
FIRING
CAP
5.0 V
R_LIMIT_1
R_LIMIT_2
VDD
CS
CLK
R_DIAG
MISO
MOSI
RST
ENABLE
ENABLE
FEN_1
FEN_2
MICROPROCESSOR
GND
Figure 1. 33797 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., 2005. All rights reserved.