DS1624
TEMPERATURE MEASURING CIRCUITRY Figure 4
SLOPE ACCUMULATOR
PRESET
COMPARE
LOW TEMPERATURE
COEFFICIENT OSCILLATOR
SET/CLEAR
LSB
COUNTER
PRESET
INC
=0
TEMPERATURE REGISTER
HIGH TEMPERATURE
COEFFICIENT OSCILLATOR
COUNTER
STOP
=0
Internally, this calculation is performed by the DS1624 to provide 0.03125°C resolution. The temperature
reading is provided in a 13–bit, two’s complement reading by issuing READ TEMPERATURE
command. Table 2 describes the exact relationship of output data to measured temperature. The data is
transmitted serially through the 2–wire serial interface, MSB first. The DS1624 can measure temperature
over the range of -55°C to +125°C in 0.03125°C increments. For Fahrenheit usage a lookup table or
conversion factor must be used.
TEMPERATURE/DATA RELATIONSHIPS Table 2
TEMP
DIGITAL OUTPUT
(Binary)
DIGITAL OUTPUT
(Hex)
+125˚C
+25.0625˚C
+½˚C
0˚C
-½˚C
-25.0625˚C
-55˚C
01111101 00000000
00011001 00010000
00000000 10000000
00000000 00000000
11111111 10000000
11100110 11110000
11001001 00000000
7D00h
1910h
0080h
0000h
FF80h
E6F0h
C900h
Since data is transmitted over the 2–wire bus MSB first, temperature data may be written to/read from the
DS1624 as either a single byte (with temperature resolution of 1°C) or as two bytes, the second byte
containing the value of the 5 least significant bits of the temperature reading as shown in Table 1. Note
that the remaining three bits of this byte are set to all 0’s.
7 of 20
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
