A8510 데이터 시트보기 (PDF) - Allegro MicroSystems
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A8510 Datasheet PDF : 33 Pages
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A8510
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
All unused pins should be connected with a 4.75 kΩ resistor to
GND, as shown in figure 5. The unused pin, with the pull-down
resistor, will be taken out of regulation at this point and will not
contribute to the boost regulation loop.
If an LEDx pin is shorted to ground the A8510 will not proceed
with soft start until the short is removed from the LEDx pin. This
prevents the A8510 from powering-up and putting an uncon-
trolled amount of current through the LEDs. The various detect
scenarios are presented in figures 4A and 4B.
A8510
LED1
LED2
LED3
LED4
LED5
LED6
LED7
GND
LED8
4.75 kΩ
A8510
LED1
LED2
LED3
LED4
LED5
LED6
LED7
GND
LED8
Figure 5. Channel select setup: (left) channel LED8 not used,
(right) using all channels.
LED1-7
C1
LED detection period
C2
LED8
C3
ISET
C4
EN/PWM
t
4A. Example with LED8 pin not being used; fSW is 2 MHz, the detect voltage
is about 150 mV; shows LED1-7 (ch1, 500 mV/div.), LED8 (ch2, 500 mV/div.),
ISET (ch3, 1 V/div.), and EN/PWM (ch4, 5 V/div.) pins, t = 500 μs/div.
Pin shorted
C1
Short removed
LED1
LED2
C2
ISET
C3
C4
EN/PWM
t
4B. Example with one LED shorted to GND. The IC will not proceed with power-
up until the shorted LED pin is released, at which point the LED is checked to
see if it is being used; shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.),
ISET (ch3, 1 V/div.), and EN/PWM (ch4, 5 V/div.) pins, t = 1 ms/div.
.
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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