A8514KLPTR-T Allegro Microsystems Inc, A8514KLPTR-T Datasheet - Page 21

• 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
Boost switch overcurrent protection
The boost switch is protected with cycle-by-cycle current limiting
set at a minimum of 3.0 A. There is also a secondary current limit
that is sensed on the boost switch. When detected this current
limit immediately shuts down the A8514. The level of this cur-
Figure 26. Normal operation of the switch node (SW); inductor current
(I
configuration; shows SW node (ch1, 20 V/div.), inductor current I
1 A/div.), V
time = 2 μs/div.
C1
C2
C3
C4
L
) and output voltage (V
OUT
(ch3, 10 V/div.), and PWM/EN (ch4, 5 V/div.),
OUT
) for 9 series LEDs in each of four strings
PWM/EN
SW node
t
V
OUT
I
L
Figure 28. Secondary boost switch current limit; when this limit is hit, the
A8514 immediately shuts down; shows PWM (ch1, 5 V/div.), V
5 V/div.), SW node (ch3, 50 V/div.), and inductor current I
time = 100 ns/div.
C1
C2
C3
C4
Wide Input Voltage Range, High Efficiency
L
(ch2,
t
rent limit is set above the cycle-by-cycle current limit to protect
the switch from destructive currents when the boost inductor is
shorted. Various boost switch overcurrent conditions are shown in
figures 26 through 28.
Figure 27. Cycle-by-cycle current limiting; inductor current (yellow trace, I
note reduction in output voltage as compared to normal operation with the
same configuration (figure 26); shows SW node (ch1, 20 V/div.), inductor
current I
time = 2 μs/div.
C1
C2
C3
C4
L
(ch2, 1 A/div.), V
Fault Tolerant LED Driver
PWM/EN
SW node
L
FAULT
(ch4, 2 A/div.),
I
L
OUT
OUT
(ch2,
(ch3, 10 V/div.), and PWM/EN (ch4, 5 V/div.),
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
PWM/EN
SW node
t
V
OUT
I
L
21
L
),