NSI45025ZT1G Datasheet, PDF (4/6 Pages) ON Semiconductor – Constant Current Regulator & LED Driver 45 V, 25 mA  15%, 1.4 W Package

APPLICATIONS
NSI45025ZT1G
D1
Anode
Cathode
+
− ^Vin
Q1
Q2
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
Qx
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
D1
Anode
Q1
Q2
Qx
Cathode
+
− ^Vin
LED
HF3−R5570
LED
HF3−R5570
LED
HF3−R5570
Figure 7. Typical Application Circuit
(25 mA each LED String)
Number of LED’s that can be connected is determined by:
D1 is a reverse battery protection diode
LED’s = ((V_in − Q_X V_F + D1 V_F)/LED V_F)
Example: V_in = 12 Vdc, Q_X V_F = 3.5 Vdc, D1VF = 0.7 V
LED V_F = 2.2 Vdc @ 25 mA
(12 Vdc − 4.2 Vdc)/2.2 Vdc = 3 LEDs in series.
Figure 8. Typical Application Circuit
(75 mA each LED String)
Number of LED’s that can be connected is determined by:
D1 is a reverse battery protection diode
Example: V_in = 12 Vdc, Q_X V_F = 3.5 Vdc, D1VF = 0.7 V
LED V_F = 2.6 Vdc @ 75 mA
(12 Vdc − (3.5 + 0.7 Vdc))/2.6 Vdc = 3 LEDs in series.
Number of Drivers = LED current/25 mA
75 mA/25 mA = 3 Drivers (Q1, Q2, Q3)
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