adt6402 Analog Devices, Inc., adt6402 Datasheet - Page 10

• Manufacturer Part Number: adt6402
• Description: Low Cost, 2.7 V To 5.5 V, Pin-selectable Temperature Switches In Sot-23
• Manufacturer: Analog Devices, Inc.

ADT6401/ADT6402
Hysteresis
A hysteresis value of 2°C or 10°C can be selected. The digital
comparator ensures excellent accuracy for the hysteresis value.
Hysteresis prevents oscillation on the output pin when the
temperature is approaching the trip point and after the output
pin is activated. For example, if the temperature trip is 45°C and
the hysteresis selected is 10°C, the temperature must go as low
as 35°C before the output deactivates.
TEMPERATURE CONVERSION
The conversion clock for the part is generated internally. No
external clock is required. The internal clock oscillator runs an
automatic conversion sequence. During this automatic conversion
sequence, a conversion is initiated every 600 ms. At this time, the
part powers up its analog circuitry and performs a temperature
conversion.
TOVER
TOVER
V
Figure 18. ADT6401 TOVER Transfer Function
Figure 19. ADT6402 TOVER Transfer Function
V
HYSTERESIS
HYSTERESIS
COLD
COLD
10°C
10°C
HYSTERESIS
HYSTERESIS
2°C
2°C
TTH
TTH
HOT
HOT
TEMP
TEMP
Rev. 0 | Page 10 of 12
This temperature conversion typically takes 30 ms, after which
the analog circuitry of the part automatically shuts down. The
analog circuitry powers up again 570 ms later, when the 600 ms
timer times out and the next conversion begins. The result of
the most recent temperature conversion is compared with the
factory-set trip point value. If the temperature measured is
greater than the trip point value, the output is activated. The
output is deactivated once the temperature crosses back over
the trip point threshold, plus whatever temperature hysteresis is
selected. Figure 18 to Figure 21 show the transfer function for
the output trip pin of each generic model.
TUNDER
TUNDER
Figure 20. ADT6401 TUNDER Transfer Function
Figure 21. ADT6402 TUNDER Transfer Function
V
V
COLD
COLD
TTH
TTH
HYSTERESIS
HYSTERESIS
2°C
2°C
HYSTERESIS
HYSTERESIS
10°C
10°C
HOT
HOT
TEMP
TEMP