OSRAM OPTOTRONIC Constant current LED power supplies with 3DIM - Manual (Page 27)

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3.3.1.3. Application solution 3 – NPC SM6611 solution
SM6611 (NCP) is a temperature switch IC able to change
the state of an output pin (invert) when the chip temperature
exceeds a preset temperature (Tset
TH
). The Tset
TH
tempera-
ture detection is managed by hysteresis (10 °C) to prevent
unstable output switching (sensed temperature close to the
preset temperature). SM6611 series propose 6 preset Tset
TH
temperatures, 2 output confi gurations (push-pull, open drain).
In fi gure 19a, a reference schematic is shown. The maximum
operating voltage of the IC is +15 V and the open drain
output can withstand 10 V maximum. The control could be
directly used as in fi gure 19a. A safer implementation is
shown in fi gure 19b where the output pin is connected to
the Vset via transistor (in case of a voltage higher than 10 V).
A maximum leakage current of 1 µA on the open drain
output allows the use of the IC without affecting the control
accuracy (over the Iset).
LEDset APPLICATIONS
Figure 19a: Thermal protection – SM6611 solution. Figure 19b: Thermal protection – SM6611 solution.
Example:
Considering a Tset
TH
of 75 °C, the following devices can
be used:
• SM6611DAH in case of direct connection to LEDset
(case a – not recommended)
• SM6611DBH in case of direct connection to LEDset via
transistor (case b)
For more information, please see the general notes on page 33.