Linear Technology LTC2983 - Page 68

LTC2983
68
2983fc
For more information www.linear.com/LTC2983
In addition to custom table driven thermistors, it is also
possible to directly input Steinhart-Hart coefficients into
the LTC2983 (thermistor type 11010, see Table 51).
Steinhart-Hart coefficients are commonly specified
parameters provided by thermistor manufacturers. The
Steinhart-Hart equation is:
1
T
= A+B•ln(R)+C•ln(R)
2
+D•ln(R)
3
+E •ln(R)
4
+F •ln(R)
5
CUSTOM THERMISTORS
Steinhart-Hart data is stored sequentially in any memory
location greater than or equal to 0x250 and below 0x3CF.
Each coefficient is represented by a standard, single-
precision, IEEE754 32-bit value (see Table 81).
Example Custom Steinhart-Hart Thermistor
In this example a Steinhart-Hart equation is entered into
memory starting at location 0x300 (see Table 82).
Table 81. Steinhart-Hart Custom Thermistor Data Format
ADDRESS COEFFICIENT VALUE
0x250 + 4 *Start Address A 32-Bit Single-Precision Floating Point Format
0x250 + 4 *Start Address + 4 B 32-Bit Single-Precision Floating Point Format
0x250 + 4 *Start Address + 8 C 32-Bit Single-Precision Floating Point Format
0x250 + 4 *Start Address + 12 D 32-Bit Single-Precision Floating Point Format
0x250 + 4 *Start Address + 16 E 32-Bit Single-Precision Floating Point Format
0x250 + 4 *Start Address + 20 F 32-Bit Single-Precision Floating Point Format
Table 82. Custom Steinhart-Hart Data Example
COEFFICIENT VALUE START
ADDRESS
SIGN EXPONENT MANTISSA
MSB LSB MSB LSB
A 1.45E-03 0x300 0 0 1 1 1 0 1 0 1 0 1 1 1 1 1 0 0 0 0 0 1 1 0 1 1 1 1 0 1 1 0 1
B 2.68E-04 0x304 0 0 1 1 1 0 0 1 1 0 0 0 1 1 0 0 1 0 0 0 0 0 1 0 0 1 0 1 1 0 1 0
C 0 0x308 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 0 0 0 0 0 0 0
D 1.64E-07 0x30C 0 0 1 1 0 1 0 0 0
0 1 1 0 0 0 0 0 0 0 1 0 1 1 1 1 1 1 1 1 0 1 0
E 0 0x310 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 0 0 0 0 0 0 0
F 0 0x314 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 0 0 0 0 0 0 0