Rainbow Electronics MAX6612 - Manual (Page 4)

MAX6612
The thermal path between the plastic package and the
die is not as good as the path through the leads, so the
MAX6612, like all temperature sensors in plastic pack-
ages, is less sensitive to the temperature of the sur-
rounding air than it is to the temperature of its leads. It
can be successfully used to sense ambient tempera-
ture if the circuit board is designed to track the ambient
temperature.
As with any IC, the wiring and circuits must be kept
insulated and dry to avoid leakage and corrosion,
especially if the part is operated at cold temperatures
where condensation can occur.
The MAX6612 is a very low-power temperature sensor
and is intended to drive very light loads. As a result, the
temperature rise due to power dissipation on the die is
insignificant under normal conditions. For example, with
the MAX6612 operating from a 3V supply at +25°C
(V
OUT = 0.888V), driving a 100k
Ω load (I
OUT = 10µA),
and in the 5-pin SC70 package, the die temperature
increases above the ambient by 0.036°C. Therefore,
the error caused by power dissipation is negligible.
Driving ADC Inputs
The MAX6612’s temperature-to-voltage transfer func-
tion provides convenient LSB weights when driving
ADCs with 2.5V or 5V references. With a 5V reference,
an 8-bit ADC has an LSB value equal to 19.53mV,
which corresponds exactly to the voltage produced by
a 1°C change in the MAX6612’s temperature. An 8-bit
ADC with a 2.5V reference has an LSB value of
9.765mV, or 0.5°C.
Capacitive Loads
The MAX6612 is optimized for stability with large
capacitive loads such as noise-filtering capacitors at
the input of an ADC. For stable operation, ensure that
the MAX6612 has a load capacitance of at least
1000pF located near its output pin.
Chip Information
TRANSISTOR COUNT: 257
PROCESS: BiCMOS
High-Slope, Low-Power, Analog Temperature
Sensor in an SC70 Package
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