TC72 Ver la hoja de datos (PDF) - Microchip Technology
Número de pieza
componentes Descripción
Fabricante
TC72 Datasheet PDF : 24 Pages
| |||
3.1 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 the TC72 is specified from -55°C to +125°C.
Example:
Temperature
= 41.5°C
MSB Temperature Register= 00101001b
= 25 + 23 + 20
= 32 + 8 + 1 = 41
LSB Temperature Register = 10000000b = 2-1 = 0.5
TABLE 3-1: TC72 TEMPERATURE
OUTPUT DATA
Temperature
Binary
MSB / LSB
Hex
+125°C
+25°C
0111 1101/0000 0000 7D00
0001 1001/0000 0000 1900
+0.5°C
+0.25°C
0000 0000/1000 0000 0080
0000 0000/0100 0000 0040
0°C
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 3-2: 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
3.2 Power-Up And Power-Down
The TC72 is in the low power consumption shutdown
mode at power-up. The Continuous Temperature Con-
version mode is selected by performing a Write opera-
tion to the Control register, as described in Section 4.0,
“Internal Register Structure”.
A supply voltage lower than 1.6V (typical) is considered
a power-down state for the TC72. If the supply voltage
drops below the 1.6V threshold, the internal registers
are reset to the power-up default state.
TC72
3.3 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. The TC72 operates as a
slave and is compatible with the SPI bus specifications.
The serial interface is designed to be compatible with
the Microchip PICmicro® family of microcontrollers.
The CE input is used to select the 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 oper-
ation, while the falling edge of CE completes a read or
write operation.
The SCK input is provided by the external microcontrol-
ler and is used to synchronize the data on the SDI and
SDO lines. The SDI input writes data into the TC72’s
Control register, while the SDO outputs the tempera-
ture data from the Temperature register and the status
of Shutdown bit of the Control register.
The 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 3-2.
Table 3-3 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 3-3.
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 3-3. In the 3-byte
packet, the data sequence consists of the MSb temper-
ature data, LSb temperature data, followed by the Con-
trol register data. The multi-byte read feature is initiated
by writing the highest address of the desired packet to
registers. The TC72 will automatically send the register
addressed and all of the lower address registers, as
long as the Chip Enable pin is held active.
2002 Microchip Technology Inc.
DS21743A-page 9
Share Link: 