MC74 ON Semiconductor, MC74 Datasheet - Page 7

• Manufacturer Part Number: MC74
• Manufacturer: ON Semiconductor

DATA_RDY
REGISTER SET and PROGRAMMER’S MODEL
MC74 Command Set
(SMBus READ_BYTE and WRITE_BYTE)
Command Byte Description
Configuration Register (CONFIG), 8–BITS,
READ/WRITE
Configuration Register (Config)
*DATA_RDY bit reset at power–up and SHDN enable (see below).
SHDN
D[5]—D[0]
Command
D[7]
SHDN
RWCR
D[7]
D[6]
V
RTR
Bit
Figure 3. . DATA_RDY, SHDN Operation Logic
DD
Data Rdy
D[6]
POR
0
0
0
Code
00h
01h
Function
STANDBY switch
Data Ready*
Reserved — Al-
ways returns zero
when read.
Reserved
D[5]
Function
Read Temperature (TEMP)
Read/Write Configuration (CONFIG)
Diagram
t conv
D[4]
D[3]
Read/
Type
Write
Read
Only
N/A
D[2]
t conv
Operation
1 = standby,
0 = normal
1 = ready,
0 = not ready
N/A
D[1]
http://onsemi.com
D[0]
MC74
7
Temperature Register (TEMP), 8–Bits,
READ–ONLY
represents temperature of the integrated sensor following a
conversion cycle. The registers are automatically updated in
an alternating manner.
Temperature Register (TEMP)
represents one degree (Celsius).
2’s–complement binary format such that a reading of 0000
0000b corresponds to 0 C. Examples of this temperature to
binary value relationship are shown in the following table.
Temperature–to–Digital Value Conversion (TEMP)
Register Set Summary
registers are 8–bits wide.
*NOTE: The TEMP register immediately will be updated by the
Name
TEMP
CONFIG
MSB
D[7]
TEMPERATURE
The binary value (2’s complement format) in this register
In the temperature data registers, each unit value
The MC74’s register set is summarized below. All
+130.00 C
+127.00 C
+126.50 C
+25.25 C
ACTUAL
-25.00 C
-25.25 C
-54.75 C
-55.00 C
-65.00 C
+0.50 C
+0.25 C
-0.25 C
-0.50 C
-0.75 C
-1.00 C
0.00 C
A/D converter after the DATA_RDY bit goes high.
D[6]
x
Description
Internal sensor
temperature (2’s
complement)
CONFIG register
D[5]
x
TEMPERATURE
REGISTERED
D[4]
x
+127 C
+127 C
+127 C
+25 C
-25 C
-25 C
-55 C
-55 C
-65 C
+1 C
-1 C
-1 C
0 C
0 C
0 C
0 C
0000 0000b*
0000 0000b
D[3]
POR State
x
D[2]
x
The value is in
BINARY HEX
0001 1001
0000 0001
0000 0000
0000 0000
0000 0000
0000 0000
1100 1001
1100 1001
0111 1111
0111 1111
0111 1111
1110 0111
1110 0110
1011 1111
1111 1111
1111 1111
Read
D[1]
x
Write
D[0]
LSB