MIC280_06 Datasheet, PDF (7/23 Pages) Micrel Semiconductor – Precision IttyBitty Thermal Supervisor

MIC280
Functional Description
Serial Port Operation
The MIC280 uses standard SMBus Write_Byte, Read_Byte,
and Read_Word operations for communication with its host.
The SMBus Write_Byte operation involves sending the
device’s slave address (with the R/W bit low to signal a write
operation), followed by a command byte and the data byte.
The SMBus Read_Byte operation is a composite write and
read operation: the host first sends the device’s slave address
followed by the command byte, as in a write operation. A
new start bit must then be sent to the MIC280, followed by a
repeat of the slave address with the R/W bit (LSB) set to the
high (read) state. The data to be read from the part may then
be clocked out. A Read_Word is similar, but two successive
data bytes are clocked out rather than one. These protocols
are shown in Figure 1, Figure 2, and Figure 3.
The Command byte is eight bits (one byte) wide. This byte
carries the address of the MIC280 register to be operated
upon. The command byte values corresponding to the vari-
ous MIC280 registers are shown in Table 1. Other command
byte values are reserved, and should not be used.
Slave Address
The MIC280 will only respond to its own unique slave ad-
dress. A match between the MIC280’s address and the
address specified in the serial bit stream must be made to
Micrel
initiate communication. The MIC280’s slave address is fixed
at the time of manufacture. Eight different slave addresses
are available as determined by the part number. See Table
2 below and the Ordering Information table above.
Part Number
Slave Address
MIC280-0BM6
100 1000_b = 48_h
MIC280-1BM6
100 1001_b = 49_h
MIC280-2BM6
100 1010_b = 4A_h
MIC280-3BM6
100 1011_b = 4B_h
MIC280-4BM6
100 1100_b = 4C_h
MIC280-5BM6
100 1101_b = 4D_h
MIC280-6BM6
100 1110_b = 4E_h
MIC280-7BM6
100 1111_b = 4F_h
Table 2: MIC280 Slave Addresses
Alert Response Address
In addition to the Read_Byte, Write_Byte, and Read_Word
protocols, the MIC280 adheres to the SMBus protocol for
response to the Alert Response Address (ARA). The MIC280
expects to be interrogated using the ARA when it has as-
serted its /INT output.
Temperature Data Format
The least-significant bit of each temperature register (high
bytes) represents one degree Centigrade. The values are in
a two’s complement format, wherein the most significant bit
Target Register
Command Byte
Value
Label
Description
Read Write
TEMP0
TEMP1h
STATUS
CONFIG
IMASK
THIGH0
TLOW0
THIGH1h
TLOW1h
LOCK
TEMP1l
THIGH1l
TLOW1l
CRIT1
CRIT0
MFG_ID
DEV_ID
Local temperature result
Remote temperature result, high byte
Status
Configuration
Interrupt mask register
Local temperature high limit
Local temperature low limit
Remote temperature high limit, high byte
Remote temperature low limit, high byte
Security register
Remote temperature result, low byte
Remote temperature high limit, low byte
Remote temperature low limit, low byte
Remote over-temperature limit
Local over-temperature limit
Manufacturer Identification
Device and revision identification
00_h
n/a
01_h
n/a
02_h
n/a
03_h
03_h
04_h
04_h
05_h
05_h
06_h
06_h
07_h
07_h
08_h
08_h
09_h
09_h
10_h
n/a
13_h
13_h
14_h
14_h
19_h
19_h
20_h
20_h
FE_h
n/a
FF_h
n/a
* The lower nibble contains the die revision level, e.g., Rev 0 = 00h.
Table 1: MIC280 Register Addresses
Power-on
Default
00_h (0°C)
00_h (0°C)
00_h
80_h
07_h
3C_h (60°C)
00_h (0°C)
50_h (80°C)
00_h (0°C)
00_h
00_h
00_h
00_h
64_h (100°C)
46_h (70°C)
2A_h
0x_h*
May 2006
7
MIC280