MAX1455 Datasheet, PDF (14/25 Pages) Maxim Integrated Products – Low-Cost Automotive Sensor Signal Conditioner

Low-Cost Automotive Sensor Signal
Conditioner
DIO
IRS COMMAND (8 BITS)
IRSA [3:0] IRSD [3:0]
0000
DHR [3:0]
0001
DHR [7:4]
0010 DHR [11:8]
0011 DHR [15:12]
0100 RESERVED
0101 RESERVED
0110
ICRA [3:0]
IEEA [3:0]
0111
IEEA [7:4]
1000
IRSP [3:0]
IEEA [9:8]
1001
CRIL [3.0]
(EXECUTE)
1010 ATIM [3:0]
1011 ALOC [3:0]
1100 TO
1110
RESERVED
1111
RELEARN
BAUD RATE
TABLE 9. INTERFACE REGISTER
SET COMMANDS
BIDIRECTIONAL
16-BIT
DATA
LATCH
DHR [7:0]
DHR [15:8]
ICRA [3:0] CALIBRATION REGISTER
0000
CONFIG
0001
ODAC
0010
OTCDAC
0011
FSODAC
0100
FSOTCDAC
0101 TO
1111
RESERVED
TABLE 16. INTERNAL CALIBRATION
REGISTERS
EEPROM
MEMORY
768 X 8 BITS
ADDR DATA
CRIL [3:0]
FUNCTION
0000
LOAD ICR
0001
WRITE EEPROM
0010
ERASE EEPROM
0011
READ ICR
0100
READ EEPROM
0101
READ IRS
0110
ANALOG OUT
0111
ERASE PAGE
1000 TO
1111
RESERVED
TABLE 10. CRIL ACTIONS
LOOKUP
ADDRESS
TEMP INDEX [7:0]
ENABLE ANALOG OUTPUT
OUTPUT
TIMER
IRSP [3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010 TO
1111
RETURNS
DHR [7:0]
DHR [F:8]
IEEA [7:4], ICRA [3:0]
CRIL [3:0], IRSP [3:0]
ALOC [3:0], ATIM [3.0]
IEEA [7:0]
IEED [7:0]
TEMP-INDEX [7:0]
BITCLK [7:0]
RESERVED
11001010 - (USE TO
CHECK COMMUNICATION)
TABLE 11. IRS POINTER FUNCTIONS (READS)
PGA
OUTPUT
OUT
MUX
Figure 5. MAX1455 Serial Command Structure and Hardware Schematic
Figure 4 shows an example transmit/receive sequence
with the RDIRS command (59hex) being sent and the
MAX1455 responding with a byte value of 10hex.
Internal Clock Settings
Following initial power-up, or after a power reset, all of
the calibration registers within the MAX1455 contain
0000hex and must be programmed. Note that in analog
mode, the internal registers are automatically refreshed
from the EEPROM.
When starting the MAX1455 in digital mode, pay spe-
cial attention to the 3 CLK bits: 3MSBs of the
Configuration register. The frequency of the MAX1455
internal oscillator is measured during production testing
and a 3-bit adjustment (calibration) code is calculated
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