• Calculate the temperature using the formula:
• Verify that the temperature measured is within ±2°C
of the ambient board temperature. Measure the
ambient board temperature using an accurate cali-
brated temperature sensor.
• Connect OUT to ground (OUT to V
CC
for cold
threshold versions) and observe the state change of
the logic output.
• Disconnect OUT from ground and observe that the
logic output reverts to its initial state.
Hysteresis Testing
The MAX6516–MAX6519 can be programmed with 2°C
or 10°C of hysteresis by pin strapping HYST to V
CC
or
GND, respectively. Below is a test feature that can be
used to measure the accuracy of the device’s hystere-
sis using a device with a +65°C threshold:
• Power up the device and observe the state of the
digital output.
• Drive the OUT voltage down gradually.
• When the digital output changes state, note V
OUT
.
•V
OUT
trip = V
OUT
at logic output change of state
(high to low or low to high).
• Calculate trip temperature (T1) using:
• Gradually raise V
OUT
until the digital output reverts to
its initial state and note V
OUT
.
• Calculate trip temperature (T2).
•T
HYST
= T2 - T1.
Thermal Considerations
The MAX6516–MAX6519 supply current is typically 22µA.
When used to drive high-impedance loads, the devices
dissipate negligible power. Therefore, the die tempera-
ture is essentially the same as the package temperature.
Accurate temperature monitoring depends on the thermal
resistance between the device being monitored and the
MAX6516–MAX6519 die. Heat flows in and out of plastic
packages, primarily through the leads. Pin 2 of the 5-pin
SOT23 package provides the lowest thermal resistance to
the die. Short, wide copper traces between the
MAX6516–MAX6519 and the object whose temperature
is being monitored ensures heat transfers occur quickly
and reliably. The rise in die temperature due to self-heat-
ing is given by the following formula:
ΔT
J
= P
DISSIPATION
✕ θ
JA
where P
DISSIPATION
is the power dissipated by the
MAX6516–MAX6519, and θ
JA
is the thermal resistance
of the package.
The typical thermal resistance is 140°C/W for the
5-pin SOT23 package. To limit the effects of self-
heating, minimize the output current. For example, if the
MAX6516–MAX6519 sink 1mA, the open-drain output
voltage is guaranteed to be less than 0.3V. Therefore,
an additional 0.3mW of power is dissipated within the
IC. This corresponds to a 0.042°C shift in the die tem-
perature in the 5-pin SOT23 package.
Chip Information
PROCESS: BiCMOS
.
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