Datasheet NSI50350AD (ON Semiconductor) - 5

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NSI50350ADT4G APPLICATIONS INFORMATION
The CCR is a self biased transistor designed to regulate the current through itself and any devices in series with it. The device has a slight negative temperature coefficient, as shown in Figure 2 – Tri Temp. (i.e. if the temperature increases the current will decrease). This negative temperature coefficient will protect the LEDS by reducing the current as temperature rises. The CCR turns on immediately and is typically at 20% of regulation with only 0.5 V across it. The device is capable of handling voltage for short durations of up to 50 V so long as the die temperature does not exceed 175°C. The determination will depend on the thermal pad it is mounted on, the ambient temperature, the pulse duration, pulse shape and repetition.
Single LED String
The CCR can be placed in series with LEDs as a High Side or a Low Side Driver. The number of the LEDs can vary from one to an unlimited number. The designer needs to calculate the maximum voltage across the CCR by taking the
Figure 8.
maximum input voltage less the voltage across the LED string (Figures 7 and 8).
Higher Current LED Strings
Two or more fixed current CCRs can be connected in parallel. The current through them is additive (Figure 9).
Figure 7. Figure 9. http://onsemi.com 5