Linear Technology LTC2983 - Page 63

LTC2983
63
2983fc
For more information www.linear.com/LTC2983
Custom RTD table data is formatted in Ω (sensor output
resistance) vs Kelvin (see Table 73). Each table entry pair
spans six bytes. The first set of data can begin at any
memory location greater than or equal to 0x250 and end
at or below 0x3CF.
In order to program the LTC2983 with the custom RTD
table, both the resistance data and the Kelvin data are
converted to 24-bit binary values. The sensor output
CUSTOM RTDS
resistance (units=Ω) follows the convention shown in
Table 74, where the first 13 bits are the integer part and
the remaining 11 bits are the fractional part.
In order to simplify the temperature field, temperature
values are input in Kelvin as an unsigned value, but the
final temperatures reported by the LTC2983 are reported
in °C or °F. The sensor temperature (Kelvin) follows the
Table 73. RTD Example Resistance vs Kelvin Data Memory Map
POINT SENSOR OUTPUT
RESISTANCE (Ω)
TEMPERATURE
(K)
START
ADDRESS
STOP
ADDRESS
BYTE 1 BYTE 2 BYTE 3 BYTE 1 BYTE 2 BYTE 3
P0 0 112.3 0x28C 0x291
P1 80 200.56 0x292 0x297
P2 150 273.16 0x298 0x29D
P3 257.36 377.25 0x29E 0x2A3
P4 339.22 489.66 0x2A4 0x2A9 Resistance Data Temperature Data
P5 388.26 595.22 0x2AA 0x2AF
P6 512.99 697.87 0x2B0 0x2B5
P7 662.3 765.14 0x2B6 0x2BB
P8 743.5 801.22 0x2BC 0x2C1
P9 2001.89 900.5 0x2C2 0x2C7
Table 74. Example RTD Resistance Values
BYTE 1 BYTE 2 BYTE 3
B23 B22 B21 B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
Resistance 2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
2
–1
2
–2
2
–3
2
–4
2
–5
2
–6
2
–7
2
–8
2
–9
2
–10
2
–11
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
80 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0
150 0 0 0 0 0 1 0 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0
257.36 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 1 1 1 0 0 0 0 1
339.22 0 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 0 1 0
388.26 0 0 0 0 1 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 0 1 0 0
512.99 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 0 1 0 1 1
662.3 0 0 0 1
0 1 0 0 1 0 1 1 0 0 1 0 0 1 1 0 0 1 1 0
743.5 0 0 0 1 0 1 1 1 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0
2001.89 0 0 1 1 1 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 1 1 1 0