OSRAM OPTOTRONIC Constant current LED power supplies with 3DIM - Manual (Page 25)

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The schematic of the circuit is shown in fi gure 13. Proper
by-pass capacitors (100 nF 25V X7R SMD type) should be
added on the supply line and Rtemp to ensure a noiseless
application.
The hysteresis of the temperature threshold can be set in
two different ways:
• 5 °C if pin 4 is grounded;
• 10 °C if pin 4 is connected to pin 6 (Vcc).
A setting resistance (Rset) can be integrated into the
circuit in order to set the operating current of the system
as described in 3.1.1.
Example:
Conditions:
Iout = Inom
max
Tset
TH
= 80 °C
Form E96 series, a commercial value is 432 kΩ ± 1 %.
Based on this value, the
For Rset, a 39 kΩ ± 1 % will provide that Iout = 100 %
Inom
max
. Connecting pin 4 to the GNDset enables a hysteresis
of 5 °C. Figure 14 shows the resulting behavior of this circuit.
LEDset APPLICATIONS
Figure 14: TMP300 solution – output characteristic.
Figure 15: TMP300 solution – real circuit (1) appearance with connector
block (2).
Rtemp 433 kΩ
10 ( 50 + Tset
TH
)
3
Tset
TH
79.6 °C 50
3 Rtemp
10
2
1