DS18S20Z Maxim Integrated Products, DS18S20Z Datasheet - Page 4

• Manufacturer Part Number: DS18S20Z
• Description: IC THERM MICROLAN HI-PREC 8-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of DS18S20Z

• Sensing Temperature: -55°C ~ 125°C
• Output Type: Digital
• Voltage - Supply: 3 V ~ 5.5 V
• Accuracy: ±0.5°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Full Temp Accuracy: +/- 2 C
• Digital Output - Bus Interface: Serial (1-Wire)
• Digital Output - Number Of Bits: 9 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-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 DS18S20 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 8 through 1 of the temperature register are used in the T
are 8-bit registers. If the measured temperature is lower than or equal to T
condition exists and an alarm flag is set inside the DS18S20. 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.
The master device can check the alarm flag status of all DS18S20s on the bus by issuing an Alarm Search
[ECh] command. Any DS18S20s with a set alarm flag will respond to the command, so the master can
determine exactly which DS18S20s have experienced an alarm condition. If an alarm condition exists and
the T
condition.
MS BYTE
TEMPERATURE
LS BYTE
H
or T
+85.0*
BIT 7
+25.0
-25.0
-55.0
(°C)
+0.5
-0.5
S
0
L
H
settings have changed, another temperature conversion should be done to validate the alarm
BIT 15
and T
BIT 7
2
S
6
BIT 6
L
2
6
H
Register Format
and T
DIGITAL OUTPUT
0000 0000 1010 1010
0000 0000 0011 0010
0000 0000 0000 0001
0000 0000 0000 0000
1111 1111 1111 1111
1111 1111 1100 1110
1111 1111 1001 0010
BIT 14
H
BIT 6
2
and T
S
5
L
(BINARY)
BIT 5
registers are nonvolatile (EEPROM) so they will retain data when the
2
L
5
can be accessed through bytes 2 and 3 of the scratchpad as explained
BIT 13
BIT 5
2
S
4
BIT 4
2
5
4 of 23
BIT 12
BIT 4
DIGITAL OUTPUT
2
S
3
BIT 3
2
5
00AAh
(HEX)
FFCEh
FFFFh
FF92h
0032h
0001h
0000h
BIT 11
BIT 3
2
S
2
H
BIT 2
and T
2
2
H
and T
BIT 10
L
BIT 2
L
2
comparison since T
S
or higher than T
1
L
BIT 1
registers (see Figure 3).
2
1
BIT 1
BIT 9
2
S
0
BIT 0
2
H
0
, an alarm
H
DS18S20
and T
BIT 0
BIT 8
2
S
-1
L