MAX6647MUA+ Maxim Integrated Products, MAX6647MUA+ Datasheet - Page 14

• Manufacturer Part Number: MAX6647MUA+
• Description: IC SMBUS REMOTE SENSOR 8-UMAX
• Manufacturer: Maxim Integrated Products

Specifications of MAX6647MUA+

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -55°C ~ 125°C, External Sensor
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Temperature Threshold: Programmable
• Full Temp Accuracy: +/- 0.8 C
• Digital Output - Bus Interface: 2-Wire, SMBus
• Digital Output - Number Of Bits: 11 bit
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Supply Current: 12 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When measuring the temperature of a CPU or other IC
with an on-chip sense junction, thermal mass has virtu-
ally no effect; the measured temperature of the junction
tracks the actual temperature within a conversion cycle.
When measuring temperature with discrete remote sen-
sors, smaller packages, such as SC70s or SOT23s,
yield the best thermal response times. Take care to
account for thermal gradients between the heat source
and the sensor, and ensure that stray air currents
across the sensor package do not interfere with mea-
surement accuracy.
+145°C Precision SMBus-Compatible Remote/
Local Sensors with Overtemperature Alarms
14
______________________________________________________________________________________
OVERT
ALERT
DXN
GND
DXP
V
CC
Q
Q
S
R
S
R
DIODE
FAULT
REMOTE
LOCAL
MUX
ALERT RESPONSE ADDRESS
REMOTE TEMPERATURE
LOCAL TEMPERATURE
ALERT THRESHOLD
OVERT THRESHOLD
REGISTER BANK
COMMAND BYTE
Self-heating does not significantly affect measurement
accuracy. Remote-sensor self-heating due to the diode
current source is negligible. For the local diode, the
worst-case error occurs when autoconverting at the
fastest rate and simultaneously sinking maximum cur-
rent at the ALERT output. For example, with V
5.0V, at a 4Hz conversion rate and with ALERT sinking
1mA, the typical power dissipation is:
ø
assuming no copper PC board heat sinking, the result-
ing temperature rise is:
Even under nearly worst-case conditions, it is difficult to
introduce a significant self-heating error.
J-A
ADC
for the 8-pin µMAX package is +221°C/W, so
5.0V x 500µA + 0.4V x 1mA = 2.9mW
MAX6646/MAX6647/MAX6649
T = 2.9mW x +221°C/W = +0.6409°C
8
8
READ
WRITE
7
ADDRESS
DECODER
CONTROL
SMBus
LOGIC
2
Functional Diagram
SDA
SCLK
CC
=