MAX1455 Datasheet, PDF (15/25 Pages) Maxim Integrated Products – Low-Cost Automotive Sensor Signal Conditioner

Low-Cost Automotive Sensor Signal
Conditioner
Table 8. Control Location (CL[15:0])
FIELD
15:8
NAME
CL[15:8]
Reserved
DESCRIPTION
7:0
CL[7:0]
Control Location. Secure-Lock is activated by setting this to FFhex, which disables DIO serial
communications and connects OUT to PGA output.
Table 9. IRSA Decoding
IRSA[3:0]
DESCRIPTION
0000
Write IRSD[3:0] to DHR[3:0] (Data Hold register)
0001
Write IRSD[3:0] to DHR[7:4] (Data Hold register)
0010
Write IRSD[3:0] to DHR[11:8] (Data Hold register)
0011
Write IRSD[3:0] to DHR[15:12] (Data Hold register)
0100
Reserved
0101
Reserved
0110
Write IRSD[3:0] to ICRA[3:0] or IEEA[3:0] (Internal Calibration register address or internal EEPROM address
nibble 0)
0111
Write IRSD[3:0] to IEEA[7:4] (internal EEPROM address, nibble 1)
1000
Write IRSD[3:0] to IRSP[3:0] or IEEA[9:8] (Interface register set pointer where IRSP[1:0] is IEEA[9:8])
1001
Write IRSD[3:0] to CRIL[3:0] (Command register to internal logic)
1010
Write IRSD[3:0] to ATIM[3:0] (analog timeout value on read)
1011
Write IRSD[3:0] to ALOC[3:0] (analog location)
1100 to 1110
Reserved
1111
Write IRSD[3:0] = 1111bin to relearn the baud rate
and stored in the upper 3 bits of EEPROM location
161hex (EEPROM upper configuration byte).
The MAX1455 internal clock controls timing functions,
including the signal path gain, DAC functions, and com-
munications. It is recommended that, while in digital
mode, the Configuration register CLK bits be assigned
the values contained in EEPROM (upper configuration
byte). The 3 CLK bits represent a two’s-complement
number with a nominal clock adjustment of 9% per bit.
Table 12 shows the codes and adjustment available.
Any change to the CLK bit values contained in the
Configuration register must be followed by the
MAX1455 baud rate learning sequence (reinitialize and
initialize commands). To maximize the robustness of
the communication system during clock resetting only,
change the CLK bits by 1LSB value at a time. The rec-
ommended setting procedure for the Configuration reg-
ister CLK bits is, therefore, as follows. (Use a minimum
baud rate of 9600 during the setting procedure to pre-
vent potential overflow of the MAX1455 baud rate
counter with clock values near maximum.)
The following example is based on a required CLK
code of 010 binary:
1) Read the CLK bits (3MSBs) from EEPROM location
161hex. CLK = 010 binary.
2) Set the CLK bits in the Configuration register to 001
binary.
3) Send the reinitialize command, followed by the ini-
tialize (baud rate learning) command.
4) Set the CLK bits in the Configuration register to 010
binary.
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