DS1621 Maxim Integrated Products, DS1621 Datasheet - Page 4

• Manufacturer Part Number: DS1621
• Description: IC THERMOMETER/STAT DIG 8-DIP
• Manufacturer: Maxim Integrated Products

Specifications of DS1621

• Function: Thermometer, Thermostat
• Topology: ADC (Sigma Delta), Comparator, Register Bank
• Sensor Type: Internal
• Sensing Temperature: -55°C ~ 125°C
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Full Temp Accuracy: +/- 2 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 12 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Table 2. TEMPERATURE/DATA RELATIONSHIPS
Since data is transmitted over the 2-wire bus MSB first, temperature data may be written to/read from the
DS1621 as either a single byte (with temperature resolution of 1°C) or as two bytes. The second byte
would contain the value of the least significant (0.5°C) bit of the temperature reading as shown in Table
1. Note that the remaining 7 bits of this byte are set to all "0"s.
Temperature is represented in the DS1621 in terms of a ½°C LSB, yielding the following 9-bit format:
Figure 2. TEMPERATURE, TH, and TL FORMAT
Higher resolutions may be obtained by reading the temperature and truncating the 0.5°C bit (the LSB)
from the read value. This value is TEMP_READ. A Read Counter command should be issued to yield the
COUNT_REMAIN value.
COUNT_PER_C value. The higher resolution temperature may be then be calculated by the user using
the following:
TEMPERATURE=TEMP_READ-0.25 +
The DS1621 always powers up in a low power idle state, and the Start Convert T command must be used
to initiate conversions.
The DS1621 can be programmed to perform continuous consecutive conversions (continuous-conversion
mode) or to perform single conversions on command (one-shot mode).
programmed through the 1SHOT bit in the configuration register as explained in the Operation and
Control section of this datasheet. In continuous conversion mode, the DS1621 begins continuous
conversions after a Start Convert T command is issued.
performed until a Stop Convert T command is issued, at which time the device goes into a low-power idle
state. Continuous conversions can be restarted at any time using the Start Convert T command.
MSB
1
TEMPERATURE
1
+125°C
1
+25°C
-25°C
-55°C
+½°C
+0°C
-½°C
0
0
1
The Read Slope command should then be issued to obtain the
1
1
(
DIGITAL OUTPUT
COUNT
01111101 00000000
00011001 00000000
00000000 10000000
00000000 00000000
11111111 10000000
11100111 00000000
11001001 00000000
T = -25°C
LSB
(Binary)
0
_
4 of 16
PER
COUNT
0
_
C
0
-
_
Consecutive conversions continue to be
COUNT
PER
0
_
C
0
_
REMAIN
0
DIGITAL OUTPUT
The conversion mode is
0
)
7D00h
C900h
FF80h
E700h
1900h
0080h
0000h
(Hex)
0