A8514KLPTR-T Allegro Microsystems Inc, A8514KLPTR-T Datasheet - Page 17

• Manufacturer Part Number: A8514KLPTR-T
• Description: IC LED DVR WHT 4X80MA 16-ETSSOP
• Manufacturer: Allegro Microsystems Inc

Specifications of A8514KLPTR-T

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

A8514
As an example, a system that delivers a full LED current of
80 mA per LED would deliver 60 mA of current per LED when
an APWM signal is applied with a duty cycle of 25% (figures
16 and 17).
Although the order in which APWM and the PWM signal are
enabled does not matter, when enabling the A8514 into low cur-
rent output while PWM and APWM dimming, the APWM signal
Figure 16. Diagram showing the transition of LED current from 60 mA
to 80 mA, when a 25% duty cycle signal is removed from the APWM pin.
PWM = 1; shows I
PWM/EN (ch3, 5 V/div.), time = 500 μs/div.
Figure 18. Diagram showing power-up sequencing LED current of 5 mA
per channel with a 10% duty cycle PWM signal and a 95% duty cycle
APWM signal; shows APWM (ch1, 5 V/div.), I
PWM/EN (ch3, 5 V/div.), and V
C1
C1
C2
C3
C2
C4
C3
LED
(ch1, 50 mA/div.), APWM (ch2, 10 V/div.), and
OUT
PWM/EN
PWM/EN
t
t
(ch4, 10 V/div.), time = 500 μs/div.
APWM
APWM
V
I
I
LED
LED
OUT
LED
(ch2, 50 mA/div.),
Wide Input Voltage Range, High Efficiency
Figure 19. Transition of output current level when a 50% duty cycle signal
is applied to the APWM pin, in conjunction with a 50% duty cycle PWM
dimming being applied to the PWM pin; shows I
APWM (ch2, 10 V/div.), and PWM/EN (ch3, 5 V/div.), time = 500 μs/div.
should be enable before or at the same time as the PWM signal.
This sequence will prevent the light output intensity from chang-
ing during power up of the IC.
Figure 18 shows the sequencing of the APWM and PWM signal
during power-up to prevent inadvertent light intensity changes.
The full intensity light output with no APWM or PWM dimming
is 80 mA per channel.
Figure 17. Diagram showing the transition of LED current from 80 mA
to 60 mA, when a 25% duty cycle signal is applied to the APWM pin;
PWM = 1; shows I
PWM/EN (ch3, 5 V/div.), time = 500 μs/div.
C1
C2
C3
C1
C2
C3
Fault Tolerant LED Driver
PWM/EN
LED
APWM
I
OUT
(ch1, 50 mA/div.), APWM (ch2, 10 V/div.), and
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
PWM/EN
t
t
APWM
I
LED
OUT
(ch1, 50 mA/div.),
17