A8501KLPTR-B データシートの表示（PDF） - Allegro MicroSystems
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A8501KLPTR-B Datasheet PDF : 24 Pages
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A8501
2 MHz, 4 Channel×100 mA WLED/RGB Driver
with Output Disconnect
Performance Characteristics
0.5
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
0
LED Current Error at 100 Hz PWM
Error (%)
Corrected Error (%)
with 2.5 μs turn-on delay
10 20 30 40 50 60 70 80 90 100
PWM Duty Cycle (%)
LED Current Error at 200 Hz PWM
0
-1
-2
-3
Error (%)
-4
-5
Corrected Error (%)
with 2.5 μs turn-on delay
-6
0 10 20 30 40 50 60 70 80 90 100
PWM Duty Cycle (%)
The LED Current Error graph shows the effect of PWM duty cycles on LED current error, according to the relationship:
Error (%) = (IISET × 960 x PWM Duty cycle – ILED(av)) / (IISET × 960 x PWM Duty cycle) .
At lower PWM duty cycles, turn-on delay adversely affects LED current accuracy. This accuracy can be improved by extending the applied PWM signal
by 2.5 μs. For example, at 100 Hz PWM and 1% PWM duty cycle, the on-time would be 100 μs. The effects of that turn-on delay could be offset by
applying a 102.5 μs PWM pulse.
100
90
80
70
60
50
40
30
20
10
0
0
LED Current versus PWM Duty Cycle
PWM
100 Hz
200 Hz
20
40
60
80
100
PWM Duty Cycle (%)
Efficiency versus PWM Duty Cycle
90
89
88
87
86
85
84
83
PWM
82
100 Hz
81
200 Hz
80
0 10 20 30 40 50 60 70 80 90 100
PWM Duty Cycle (%)
Allegro MicroSystems, Inc.
10
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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