FAN5640S7X Datasheet, PDF (6/11 Pages) Fairchild Semiconductor – FAN5640 Dual High-Side Constant Current Source for High-Voltage Keypad LED Illumination

Typical Characteristics (Continued)
Unless otherwise noted, C_IN = 4.7µF, V_EN=1.8V, T_A = 25°C, white LED with V_F=3.3V at I_OUT=10mA.
1
4 LEDs
0
I_OUT=2.5mA
-1
V_OUT=13V
V_OUT=11V
-2
I_OUT=25mA
-3
Approaching
-4
Dropout Region
-5
12 13 14 15 16 17 18 19 20
Input Voltage (V)
0.18
0.15
V_IN=18V
I_OUT=10mA
0.12
0.09
0.06
0.03
0
5
7
9
11
Output Voltage (V)
I_OUT=25mA
13
15
Figure 10. Line Regulation
Figure 11. Variation of I_OUT Current vs. Output Voltage
100
10
1
0.1
1
10
100
R_EXT (k )
1000
Figure 12. I_OUT Current vs. R_EXT Voltage
284
283
V_IN=18V, V_EN=1.8V
282
281
280
279 ^{2 LEDs}
2 LEDs
278
277
4 LEDs
276
275
0
5
10
15
20
25
30
I_OUT Current (mA)
Figure 13. Current Mirror Ratio vs. LED Current
30
V_IN=18V, V_EN=1.8V
25
Fpwm=300Hz
3.0
I_OUT=2.5mA
2.5
20
2.0
15
I_OUT=25mA _1.5
10
1.0
5
0.5
0
0.0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Duty Cycle
Figure 14. PWM Dimming on EN Pin
30
3.0
V_IN=18V, V_EN=1.8V
25
Fpwm=300Hz
2.5
20
I_OUT=2.5mA
2.0
15
1.5
10
I_OUT=25mA
1.0
5
0.5
0
0.0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Duty Cycle
Figure 15. PWM Dimming on VIN Pin
© 2006 Fairchild Semiconductor Corporation
FAN5640 • Rev. 1.0.2
6
www.fairchildsemi.com