MIC184YM Micrel Inc, MIC184YM Datasheet - Page 10

• Manufacturer Part Number: MIC184YM
• Description: IC SUPERVISOR LOCAL/REMOTE 8SOIC
• Manufacturer: Micrel Inc

Specifications of MIC184YM

• Output Type: I²C™/SMBus™
• Lead Free Status: Lead free
• Function: Temp Monitoring System (Sensor)
• Topology: ADC (Sigma Delta), Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -55°C ~ 125°C, External Sensor
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Temperature Sensor Function: Temp Sensor
• Package Type: SOIC
• Operating Temperature (min): -55
• Operating Temperature (max): 125C
• Operating Temperature Classification: Military
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / RoHS Status: Compliant
• Other names: 576-1676-5; MIC184YM

MIC184
the MIC184 may then be clocked out. There is one excep-
tion to this rule: If the location latched in the pointer register
from the last write operation is known to be correct (i.e.,
points to the desired register), then the “RECEIVE_DATA”
procedure may be used. To perform a RECEIVE_DATA, the
host sends an address byte to select the slave MIC184, and
then retrieves the appropriate number (one or two) of data
bytes. Figures 1 through 5 show the formats for these data
read and data write procedures.
The command byte is 8 bits (1 byte) wide. This byte carries
the address of the MIC184 register to be operated upon, and
is stored in the MIC184’s pointer register. The pointer register
is a write-only register, which is implemented for backward
compatibility to the National Semiconductor LM75 and similar
devices. The command byte (pointer register) values corre-
sponding to the various MIC184 register addresses are shown
in Table 2. Command byte values other than 0000 00XX
00
The CONFIG register is 8 bits (1 byte) wide. Therefore, com-
munications with the CONFIG register will at a minimum require
a READ_BYTE, WRITE_BYTE, or a RECEIVE_BYTE.
The TEMP, T_HYST, and T_SET registers are logically
nine bits wide. Note, though, that these registers are physi-
cally two bytes (one SMBus word) wide within the MIC184.
Properly communicating with the MIC184 involves a 16-bit
READ_WORD or RECEIVE_WORD from, or WRITE_WORD
to, these registers. This is a requirement of the I
serial data protocols, which only allow data transfers to occur
in multiples of eight bits.
Temperature Data Format
The LSB of each 9-bit logical register represents 0.5°C. The
values are in a two’s complement format, wherein the most
significant bit (D8) represents the sign: “0” for positive tem-
peratures and “1” for negative temperatures. The seven least
significant bits of each 16-bit physical register are undefined.
Therefore, physical bits D6 through D0 of the data read
from these registers must be masked off, and the resulting
binary value right justified before using the data received.
It is also possible to read only the first byte of any of these
three registers, sacrificing 0.5°C of resolution in exchange
for somewhat simpler data handling. However, all writes
to the T_SET and T_HYST registers must be in the 16-bit
WRITE_WORD format. Table 3 shows examples of the data
format used by the MIC184 for temperatures.
MIC184
h
through 03
h
are reserved, and should not be used.
T
e
m
+
+
–
+
–
–
–
1
. 0
. 0
p
2
° 0
2
4
5
2
° 5
° 5
° 0
° 5
e
° 5
° 5
° 5
a r
C
C
C
C
C
C
C
u t
C
e r
0
0
0
0
1
1
1
1
1
0
0
0
1
1
1
1
Table 3. Digital Temperature Format
1
0
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
1
0
0
1
0
1
1
R
1
0
0
0
1
1
0
0
a
0
0
0
0
1
1
0
0
w
1
1
0
0
1
1
0
1
2
B
C/SMBus
0
0
1
0
1
0
0
0
n i
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
a
X
X
X
X
X
X
X
X
y r
X
X
X
X
X
X
X
X
b
X
X
X
X
X
X
X
X
=
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
10
A/D Converter Timing
Whenever the MIC184 is not in its low power shutdown mode,
the internal A/D converter (ADC) attempts to make continuous
conversions unless interrupted by a bus transaction accessing
the MIC184. When the MIC184 is accessed, the conversion
in progress will be halted, and the partial result discarded.
When the access of the MIC184 is complete the ADC will
begin a new conversion cycle, with results valid t
that. Figure 6 shows this behavior. t
external conversions as it is for internal conversions. This al-
lows the use of a filter capacitor on the A2/T1 input without a
loss of accuracy due to the resulting longer settling times.
Power-On
When power is initially applied, the MIC184’s internal registers
are set to default states which make the MIC184 completely
backward compatible with the LM75. Also at this time, the
levels on the address inputs A2, A1, and A0 are read to es-
tablish the device’s slave address. The MIC184’s power-up
default state can be summarized as follows:
In order to accommodate the use of A2/T1 as a dual-purpose
input, there is a weak pulldown on A2/T1 that will attempt to
sink ≈25µA from the pin to ground for t
up of the MIC184. This allows the MIC184 to pull A2/T1 to a
low state when a diode junction is connected from that pin
to ground, and latch a zero as the A2 address value. If A2 is
not to be used as a diode connection, it should be connected
to V
ture sensor (if used) may not be reported until one or more
conversion cycles have been completed following power-on.
See DIODE FAULTS.
Shutdown Mode
Setting the SHDN bit in the configuration register halts the
otherwise continuous conversions by the A/D converter. The
M
• Normal-mode operation
• ZONE is set to internal
• INT function is set to comparator mode
• INT output is set to active-low operation
• Fault_Queue depth = 1
• Interrupts are enabled (IM = 0)
• T_SET = +80°C; T_HYST = +75°C
DD
0
0
0
0
1
1
1
1
a
k s
1
0
0
0
1
1
1
1
or ground. Note that a fault in the external tempera-
1
0
0
0
1
1
0
0
e
1
1
0
0
1
0
1
0
d
1
1
0
0
1
0
1
1
(MIC184 not in shutdown)
(on-chip temperature sensing)
B
1
0
0
0
1
1
0
0
0
0
0
0
1
1
0
0
n i
1
1
0
0
1
1
0
1
a
0
0
1
0
1
0
0
0
y r
b
b
b
b
b
b
b
b
M
a
k s
1
F 0
0
0
0
F 1
1
1
C
B
e
3
0
0
9
A
d
2
1
0
F
E
0
2
h
h
h
h
h
h
h
h
H
x e
CONV
POR
is twice as long for
following power-
CONV
May 2006
Micrel
after