NSI45030AZT1G_11 Datasheet, PDF (4/7 Pages) ON Semiconductor – Constant Current Regulator & LED Driver

NSI45030AZT1G
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 45 V so long as the die temperature does
not exceed 150°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
maximum input voltage less the voltage across the LED
string (Figures 7 and 8).
Figure 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
4