A8513 ALLEGRO [Allegro MicroSystems], A8513 Datasheet - Page 15

• Manufacturer Part Number: A8513
• Description: Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver
• Manufacturer: ALLEGRO [Allegro MicroSystems]

A8513
Fault protection during operation
The A8513 constantly monitors the state of the system to deter-
mine if any fault conditions occur. The response to a triggered
fault condition is summarized in the table below.
Note: Some of the protection features might not be active during
startup, to prevent false triggering of fault conditions.
Fault Mode Table
Output Overvoltage
Current Protection
Secondary Switch
LED String Open
Overtemperature
Secondary OVP
Primary Switch
(cycle-by-cycle
LED Pin Short
Fault Name
Undervoltage
Current Limit
current limit)
ISET Short
VIN UVLO
Protection
Protection
Protection
Protection
Protection
Protection
Output
Auto-restart
Auto-restart
Auto-restart
Auto-restart
Auto-restart
Auto-restart
Latched
Latched
Latched
Type
NA
Active
Always
Always
Always
Startup
Always
Always
Always
Always
Always
Always
shuts down
Flag Set
regulator
Yes until
internal
Fault
Wide Input Voltage Range, High Efficiency
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
This fault condition is triggered by the cycle-by-cycle
current limit I
exceeding I
When the current through the boost switch exceeds
the secondary current SW limit, I
immediately shuts down.
Secondary overvoltage protection is used for open
diode detection. When diode D1 opens, the switch pin
voltage will increase until V
This fault prevents the A8513 from starting-up if
the LED pin is shorted to ground. After the short is
removed, soft-start is allowed to begin.
This fault occurs when the I
150% of the maximum Allowable ISET Current,
I
disable the LED sinks until the fault is removed. When
the fault is removed, the IC tries to regulate to the
preset LED current.
This fault occurs when the OVP pin exceeds the
V
switching. If at the same time, the LED voltage is below
regulation, the IC will shut down.
This fault occurs when the OVP pin exceeds V
threshold (for example, during a load dump). The
A8513 immediately stops switching, but continues to
sink current through the LED pin.
This fault occurs when the OVP pin senses less than
110 mV on the pin.
This fault occurs when the die temperature exceeds
T
This fault occurs when V
fault resets all latched faults.
SET
TSD
OVPHI(th)
(max). The boost will stop switching and the IC will
.
threshold. The A8513 immediately stops
The latching faults can be cleared in two ways:
• Keep the EN/PWM pin low for more than 16 ms.
• Cycle the power to create a UVLO condition.
Fault behavior diagrams are shown in figures 18, 19 and 20.
SW(LIM)
SW(LIM)
.
. Prevents current in inductor from
Description
IN
Fault Tolerant LED Driver
drops below V
OVP(sec)
SET
current goes above
SW(LIM2)
is reached.
, the A8513
UVLOfall
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
OVPHI(th)
. This
Off for a single
Boost
cycle
Off
Off
Off
Off
Off
Off
Off
Off
Off
driver
Sink
On
Off
Off
Off
Off
Off
On
Off
Off
Off
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