MAX6691MUB+ Maxim Integrated Products, MAX6691MUB+ Datasheet - Page 6

• Manufacturer Part Number: MAX6691MUB+
• Description: IC TEMP-TO-PULSE WIDTH 10-UMAX
• Manufacturer: Maxim Integrated Products
• Type: Temperature Sensorr

Specifications of MAX6691MUB+

• Input Type: Logic
• Output Type: Voltage
• Interface: 1-Wire
• Current - Supply: 600µA
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Full Temp Accuracy: +/- 1 C
• Digital Output - Bus Interface: Serial (1-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

bypass V
ceramic bypass capacitor close to the supply pin of the
devices.
Self-heating degrades the temperature measurement
accuracy of thermistors. The amount of self-heating
depends on the power dissipated and the dissipation
constant of the thermistor. Dissipation constants
depend on the thermistor’s package and can vary con-
siderably.
A typical thermistor might have a dissipation constant
equal to 1mW/°C. For every milliwatt the thermistor dis-
sipates, its temperature rises by 1°C. For example, con-
sider a 10k
5110
bias. If it is one of the standard thermistors previously
mentioned, its resistance is 5325
The power dissipated in the thermistor is:
Four-Channel Thermistor Temperature-to-Pulse-
Width Converter
Table 1. Standard Thermistors
6
Betatherm
Dale
Thermometrics
MANUFACTURER
_______________________________________________________________________________________
(5V)
resistor operating +40°C with a constant 5V
2
CC
(5325 ) / (5325 + 5110 )
(at +25°C) NTC thermistor in series with a
to GND by placing a 0.1µF to 1.0µF
Thermal Considerations
C100Y103J
1M1002
10K3A1
PART
at this temperature.
2
= 1.22mW
www.betatherm.com/indexna.htm
www.vishay.com/brands/dale/main.html
www.thermometrics.com
This thermistor therefore has a self-heating error at
+40°C of 1.22°C. Because the MAX6691 uses a small
reference voltage and energizes each thermistor for
only about 25ms per conversion cycle, the self-heating
of the thermistor under the same conditions when used
with the MAX6691 is far less. Assuming one conversion
cycle every 5s, each thermistor is energized only 0.5%
of the time:
TRANSISTOR COUNT: 7621
PROCESS: BiCMOS
(1.22)
only about 0.00036°C self-heating error.
R+
R-
T1
T2
T3
T4
2
(5325)(0.005) / (5325 + 5110)
WEBSITE
REFERENCE
Functional Diagram
Chip Information
MAX6691
VOLTAGE-TO-PWM
CONVERTER
2
= 0.364µW, or
I/O