MAX31722MUA+ Maxim Integrated Products, MAX31722MUA+ Datasheet - Page 11

• 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

Table 3. Configuration/Status Register Bit Descriptions (continued)
Table 5. Function Table
Table 4. Thermometer Resolution
Configuration
as depicted in the AC Electrical Characteristics. The user
has read/write access to the R1 and R0 bits, which are
nonvolatile. See Table 4.
The devices offer the flexibility to choose between two
serial interface modes. They can communicate with the
SPI interface or with a 3-wire interface. The interface
method used is determined by the SERMODE pin. When
SERMODE is connected to V
is selected. When SERMODE is connected to ground,
3-wire communication is selected.
Note: CPHA bit polarity must be set to 1.
*CPOL is the clock polarity bit that is set in the control register of the microcontroller.
**SDO remains at high impedance until 8 bits of data are ready to be shifted out during a read.
R1
0
0
1
1
Disable reset
BIT 2
BIT 1
BIT 0
MODE
R0
Read
Write
0
1
0
1
RESOLUTION (BITS)
THERMOMETER
R1: Thermostat resolution bit 1. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the con-
version resolution (see Table 4).
R0: Thermostat resolution bit 0. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the con-
version resolution (see Table 4).
SD: Factory power-up state = 1. The user has read/write access to the SD bit, which is stored in nonvolatile
memory.
0 = The devices continuously perform temperature conversions and store the last completed result in the tem-
perature register.
1 = The conversion in progress is completed and stored, and then the devices revert to a low-power shutdown
mode. The communication port remains active.
Digital Thermometers and Thermostats
10
11
12
9
High
High
Low
CE
Serial Interface
DD
, SPI communication
MAX CONVERSION
TIME (ms)
100
200
25
50
CPOL = 1*, SCLK rising
CPOL = 0, SCLK falling
CPOL = 1, SCLK falling
CPOL = 0, SCLK rising
Input disabled
SCLK
with SPI/3-Wire Interface
The SPI is a synchronous bus for address and data
transfer. The SPI mode of serial communication is select-
ed by connecting SERMODE to V
for the SPI: SDO (serial-data out), SDI (serial-data in), CE
(chip enable), and SCLK (serial clock). The devices are
the slave device in an SPI application, with the microcon-
troller being the master. SDI and SDO are the serial-data
input and output pins for the devices, respectively. The
CE input is used to initiate and terminate a data transfer.
SCLK is used to synchronize data movement between
the master (microcontroller) and the slave (IC) devices.
The serial clock (SCLK), which is generated by the
microcontroller, is active only when CE is high and dur-
ing address and data transfer to any device on the SPI
bus. The inactive clock polarity is programmable in some
microcontrollers. The devices offer an important feature
in that the level of the inactive clock is determined by
sampling SCLK when CE becomes active. Therefore,
either SCLK polarity can be accommodated. Input data
(SDI) is latched on the internal strobe edge and output
data (SDO) is shifted out on the shift edge (see Table 5
and Figure 7). There is one clock for each bit transferred.
Address and data bits are transferred in groups of eight,
MSB first.
Input disabled
Data bit latch
Serial Peripheral Interface (SPI)
SDI
X
DD
Next data bit shift**
. Four pins are used
High impedance
High impedance
SDO
11