TC72(2011) 查看數據表（PDF） - Microchip Technology
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TC72 Datasheet PDF : 28 Pages
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TC72
4.1 Temperature Data Format
Temperature data is represented by a 10-bit two’s com-
plement word with a resolution of 0.25°C per bit. The
temperature data is stored in the Temperature registers
in a two’s complement format. The ADC converter is
scaled from -128°C to +127°C, but the operating range
of TC72 is specified from -55°C to +125°C.
EXAMPLE 4-1:
Temperature
MSB Temperature Register
LSB Temperature Register
= +41.5°C
= 00101001b
= 25 + 23 + 20
= 32 + 8 + 1 = 41
= 10000000b = 2-1 = 0.5
TABLE 4-1: TC72 TEMPERATURE
OUTPUT DATA
Temperature
Binary
MSB / LSB
Hex
+125°C
+25°C
+0.5°C
0111 1101/0000 0000
0001 1001/0000 0000
0000 0000/1000 0000
7D00
1900
0080
+0.25°C
0°C
0000 0000/0100 0000 0040
0000 0000/0000 0000 0000
-0.25°C
-25°C
-55°C
1111 1111/1100 0000
1110 0111/0000 0000
1100 1001/0000 0000
FFC0
E700
C900
TABLE 4-2: TEMPERATURE REGISTER
D7 D6 D5 D4 D3 D2 D1 D0
Address/
Register
Sign 26
25
24
23
23
21
20
02H
Temp. MSB
2-1 2-2 0
0
0
0
0
0
01H
Temp. LSB
4.2 Power-Up And Power-Down
TC72 is in low-power consumption Shutdown mode at
power-up. The Continuous Temperature Conversion
mode is selected by performing a Write operation to the
Control register, as described in Section 5.0 “Internal
Register Structure”.
A supply voltage lower than 1.6V (typical) is considered
a power-down state for TC72. If the supply voltage
drops below the 1.6V threshold, the internal registers
are reset to the power-up default state.
4.3 Serial Bus Interface
The serial interface consists of the Chip Enable (CE),
Serial Clock (SCK), Serial Data Input (SDI) and Serial
Data Output (SDO) signals. TC72 operates as a slave
and is compatible with the SPI bus specifications. The
serial interface is designed to be compatible with the
Microchip PIC® family of microcontrollers.
The CE input is used to select TC72 when multiple
devices are connected to the serial clock and data
lines. The CE is active-high, and data is written to or
read from the device, when CE is equal to a logic high
voltage. The SCK input is disabled when CE is low. The
rising edge of the CE line initiates a read or write
operation, while the falling edge of CE completes a
read or write operation.
The SCK input is provided by the external
microcontroller and is used to synchronize the data on
the SDI and SDO lines. The SDI input writes data into
TC72’s Control register, while the SDO outputs the
temperature data from the Temperature register and
the status of Shutdown bit of the Control register.
TC72 has the capability to function with either an
active-high or low SCK input. The SCK inactive state is
detected when the CE signal goes high, while the
polarity of the clock input (CP) determines whether the
data is clocked and shifted on either the rising or falling
edge of the system clock, as shown in Figure 4-2.
Table 4-3 gives the appropriate clock edge used to
transfer data into and out of the registers. Each data bit
is transferred at each clock pulse, and the data bits are
clocked in groups of eight bits, as shown in Figure 4-3.
The address byte is transferred first, followed by the
data. A7, the MSb of the address, determines whether
a read or write operation will occur. If A7 = ‘0’, one or
more read cycles will occur; otherwise, if A7 = ‘1’, one
or more write cycles will occur.
Data can be transferred either in a single byte or a
multi-byte packet, as shown in Figure 4-3. In the 3-byte
packet, the data sequence consists of the MSb
temperature data, LSb temperature data, followed by
the Control register data. The multi-byte read feature is
initiated by writing the highest address of the desired
packet to registers. TC72 will automatically send the
register addressed and all of the lower address
registers, as long as the Chip Enable pin is held active.
DS21743B-page 12
© 2011 Microchip Technology Inc.
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