MAX31722MUA+ Maxim Integrated Products, MAX31722MUA+ Datasheet - Page 8

• Manufacturer Part Number: MAX31722MUA+
• Description: Board Mount Temperature Sensors SPI/3-Wire Digital Temp Sensor
• Manufacturer: Maxim Integrated Products

Specifications of MAX31722MUA+

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Digital Thermometers and Thermostats
with SPI/3-Wire Interface
The core of the devices’ functionality is its direct-to-digital
temperature sensor. The devices measure temperature
through the use of an on-chip temperature measure-
ment technique with a -55NC to +125NC operating range.
The devices power up in a power-conserving shutdown
mode. After power-up, the devices can be placed in a
continuous conversion mode or in a one-shot conver-
sion mode. In the continuous conversion mode, the
devices continuously compute the temperature and
store the most recent result in the temperature register at
addresses 01h (LSB) and 02h (MSB). As conversions are
performed in the background, reading the temperature
register does not affect the conversion in progress. The
temperature value is not updated until the SPI or 3-wire
interface is inactive. In other words, CE must be inactive
for the temperature register to be updated with the most
recent temperature conversion value. In the one-shot
conversion mode, the devices perform one temperature
conversion and then return to the shutdown mode, storing
temperature in the temperature register. This conversion
Table 1. 12-Bit Resolution Temperature/Data Relationship
Figure 5. Temperature, T
8
MSB
TEMPERATURE
2
+25.0625
S
-25.0625
-1
+10.125
-10.125
Measuring Temperature
+125
+0.5
(NC)
-0.5
-55
0
HIGH
2
2
-2
, and T
6
LOW
2
2
-3
5
Register Format
2
2
-4
4
0111 1101 0000 0000
0001 1001 0001 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
DIGITAL OUTPUT
(UNITS = NC)
(BINARY)
2
0
3
mode is ideal for power-sensitive applications. Details on
how to change the setting after power-up are contained
in the Programming section.
The resolution of the temperature conversion is con-
figurable (9, 10, 11, or 12 bits) with 9 bits reading the
default state. This equates to a temperature resolution
of 0.5NC, 0.25NC, 0.125NC, or 0.0625NC. Following each
conversion, thermal data is stored in the temperature
register in two’s complement format. The information
can be retrieved over the SPI or 3-wire interface with the
address set to the temperature register, 01h (LSB) and
then 02h (MSB). Table 1 describes the exact relation-
ship of output data to measured temperature. Table 1
assumes the devices are configured for 12-bit resolution.
If the devices are configured in a lower resolution mode,
those bits contain zeros. The data is transmitted serially
over the digital interface, MSB first for SPI communica-
tion and LSB first for 3-wire communication. The MSB of
the temperature register contains the sign (S) bit, denot-
ing whether the temperature is positive or negative.
2
0
2
2
0
1
LSB
DIGITAL OUTPUT
2
0
0
(HEX)
7D00
0A20
C900
1910
0080
0000
FF80
F5E0
E6F0
02h
01h