33797 Datasheet, PDF (26/34 Pages) Freescale Semiconductor, Inc – Four Channel Squib Driver IC

FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSIS FEATURES
Table 8. Command Programming and Diagnostic Bit Definitions (continued)
Hex
Code
Command
Description
90 ^{Reserved for}
Freescale
Read NVM Low
Command Programming Input and Diagnostic Data Out (Available on Next Command) ⁽²³⁾
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
X
X
X
X
X
91 ^{Reserved for}
X
X
X
X
X
X
X
X
Freescale
Read NVM High
92 Reserved for
Freescale
NVM Enable
X
X
X
X
X
X
X
X
93 ^{Reserved for}
X
X
X
X
X
X
X
X
Freescale
Test Mode Enable
96 ^{SPI Integrity Check}
1
0
0
1
0
1
1
0
Response DATA
0
1
1
0
1
0
0
1
OUT: $69 Echo to
Diagnose the SPI
Integrity
Notes
23 The second byte for command programming will be treated as a NOP if any FET is firing. The programming commands have to be
sequential or they will be treated as a NOP.
PROTECTION AND DIAGNOSIS FEATURES
The diagnostic circuit’s internal references are provided by
a bandgap voltage reference, and by scaled currents
determined by the resistor value of R_DIAG and the value of
the bandgap voltage. Refer to Table 7, Diagnostic Bit
Definitions, and Table 8, Command Programming and
Diagnostic Bit Definitions, as necessary throughout this
section.
R_DIAG and R_LIMIT_X RESISTOR DIAGNOSTICS
($C8 COMMAND)
This function monitors reference currents derived by the
R_LIMIT_1, R_LIMIT_2, and R_DIAG resistors. An open pin
or short to ground will cause the comparator to give an “out
of range resistor value” indication. A short to VDD will have
the same effect as an open pin and will cause an “out of range
resistor value” indication.
R_LIMIT_X and R_DIAG DATA RESULTS
If R_LIMIT_X is open, shorted to ground, or shorted to
VDD, the bit R_LIMIT_NO_FAULT will be set to “0”. Standard
operation will have this bit set to “1”.
If R_DIAG is open, shorted to ground, or shorted to VDD,
the bit R_DIAG_NO_FAULT will be set to “0”. Standard
operation will have this bit set to “1”.
The FEN 1 and FEN 2 status bits are a reflection of the
FEN_1 and FEN_2 pins.
HIGH-SIDE SAFING SENSOR DIAGNOSTICS
($C0 COMMAND)
This function monitors the VFIRE_XX pin connection to
the VDIAG_X pin. The high-side safing function is attached to
the VFIRE _1A and VFIRE_2A pins. The high-side safing
function is not available on the VFIRE _1B and VFIRE_2B
pins.
When enabled, this diagnostic circuit will typically draw
less than 500 µA from the VFIRE supply voltage source.
33797
26
Analog Integrated Circuit Device Data
Freescale Semiconductor