DS18S20 Maxim Integrated Products, DS18S20 Datasheet - Page 4

• Manufacturer Part Number: DS18S20
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of DS18S20

• Full Temp Accuracy: +/- 2 C
• Package / Case: TO-92
• Digital Output - Bus Interface: Serial (1-Wire)
• Digital Output - Number Of Bits: 9 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Figure 2. Temperature Register Format
S = SIGN
Table 1. Temperature/Data Relationship
*The power-on reset value of the temperature register is +85°C.
OPERATION—ALARM SIGNALING
After the DS18B20 performs a temperature conversion, the temperature value is compared to the user-
defined two’s complement alarm trigger values stored in the 1-byte T
The sign bit (S) indicates if the value is positive or negative: for positive numbers S = 0 and for negative
numbers S = 1. The T
device is powered down. T
in the Memory section.
Figure 3. T
Only bits 11 through 4 of the temperature register are used in the T
are 8-bit registers. If the measured temperature is lower than or equal to T
an alarm condition exists and an alarm flag is set inside the DS18B20. This flag is updated after every
temperature measurement; therefore, if the alarm condition goes away, the flag will be turned off after the
next temperature conversion.
LS BYTE
MS BYTE
TEMPERATURE (°C)
BIT 7
+25.0625
-25.0625
+10.125
-10.125
S
+125
+85*
+0.5
-0.5
-55
H
0
BIT 15
and T
BIT 7
2
S
3
BIT 6
L
2
6
H
Register Format
and T
BIT 14
H
BIT 6
2
and T
S
DIGITAL OUTPUT
0000 0111 1101 0000
0000 0101 0101 0000
0000 0001 1001 0001
0000 0000 1010 0010
0000 0000 0000 1000
0000 0000 0000 0000
1111 1111 1111 1000
1111 1111 0101 1110
1111 1110 0110 1111
1111 1100 1001 0000
2
L
BIT 5
registers are nonvolatile (EEPROM) so they will retain data when the
2
(BINARY)
L
5
can be accessed through bytes 2 and 3 of the scratchpad as explained
BIT 13
BIT 5
2
S
1
BIT 4
2
4
4 of 22
BIT 12
BIT 4
2
S
0
BIT 3
DIGITAL OUTPUT
2
3
BIT 11
BIT 3
(HEX)
07D0h
00A2h
FF5Eh
FE6Fh
FC90h
FFF8h
0550h
0191h
0008h
0000h
2
S
-1
H
BIT 2
and T
2
2
H
and T
L
BIT 10
BIT 2
L
or higher than or equal to T
2
2
comparison since T
-2
6
L
BIT 1
registers (see Figure 3).
2
1
BIT 1
BIT 9
2
2
-3
5
BIT 0
2
0
H
DS18B20
and T
BIT 0
BIT 8
2
2
-4
4
H
L
,