Linear Technology LTC2983 - Page 66

LTC2983
66
2983fc
For more information www.linear.com/LTC2983
Custom thermistor table data is formatted in Ω (sensor
output resistance) vs Kelvin (see Table 77). 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 below 0x3CF.
In order to program the LTC2983 with the custom therm-
istor table, both the resistance data and the Kelvin data
are converted to 24-bit binary values. The sensor output
resistance (units=Ω) follows the convention shown in
CUSTOM THERMISTORS
Table 77. NTC Thermistor 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 0 457.5 0x2C8 0x2CD
P1 80 400.2 0x2CE 0x2D3
P2 184 372.3 0x2D4 0x2D9
P3 423.2 320.1 0x2DA 0x2DF
P4 973.36 290.55 0x2E0 0x2E5 Resistance Data Temperature Data
P5 2238.728 249.32 0x2E6 0x2EB
P6 5149.0744 240.3 0x2EC 0x2F1
P7 26775.18688 230 0x2F2 0x2F7
P8 139230.9718 215.3 0x2F8 0x2FD
P9 724001.0532 200 0x2FE 0x303
Table 78, where the first 20 bits are the integer part and
the remaining four 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
convention shown in Table 79, where the first 14 bits
are the integer part and the remaining 10 bits are the
fractional part.
Table 78. Example Thermistor 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
19
2
18
2
17
2
16
2
15
2
14
2
13
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
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 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0
184 0 0
0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 0 0 0 0 0 0 0
423.2 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 1 1 1 0 0 1 1
973.36 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 0 1
2238.728 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 1 1 1 1 0 1 0 1 1
5149.074 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 1 1 1 0 1 0 0 0 1
26775.19 0 0 0 0 0 1 1 0 1 0 0
0 1 0 0 1 0 1 1 1 0 0 1 1
139231 0 0 1 0 0 0 0 1 1 1 1 1 1 1 0 1 1 1 1 1 0 0 0 0
724001.1 1 0 1 1 0 0 0 0 1 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1