A8514KLPTR-T Allegro Microsystems Inc, A8514KLPTR-T Datasheet - Page 24

• 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
internal fault registers. As an example, at a 2 MHz clock fre-
quency, it will take approximately 16.3 ms to shut down the IC
into the low power mode (figure 33). When the A8514 is shut
down, the IC will disable all current sources and wait until the
PWM/EN signal goes high to re-enable the IC. If faster shut
down is required, the FSET/SYNC pin can be used.
Fault protection during operation
The A8514 constantly monitors the state of the system to deter-
mine if any fault conditions occur during normal operation. The
response to a triggered fault condition is summarized in the Fault
Mode table.
Continued on the next page…
Fault Mode Table
overcurrent protection
Secondary switch
Input disconnect
Secondary OVP
(cycle-by-cycle
Primary switch
Fault Name
current limit)
current limit
current limit
Auto-restart
Latched
Latched
Latched
Type
Active
Always
Always
Always
Always
Fault
Flag
Set
Yes
Yes
Yes
No
Wide Input Voltage Range, High Efficiency
This fault condition is triggered by the cycle-by-
cycle current limit, I
When the current through the boost switch exceeds
secondary current SW limit (I
immediately shuts down the disconnect switch,
LED drivers, and boost. The Fault flag is set. To re-
enable the device, the PWM/EN pin must be pulled
low for 32,750 clock cycles.
The device is immediately shut off if the voltage
across the input sense resistor is 2X the preset
current value. The Fault flag is set. If the input
current limit is between 1X and 2X, the Fault flag
is set but the IC will continue to operate normally
for t
the device the PWM/EN pin must be pulled low for
32,750 clock cycles.
Secondary overvoltage protection is used for open
diode detection. When diode D1 opens, the SW pin
voltage will increase until V
fault latches the IC. The input disconnect switch is
disabled as well as the LED drivers, and the Fault
flag is set. To re-enable the part the PWM pin must
be pulled low for 32,750 clock cycles.
GFAULT1
or until it is shut down. To re-enable
The possible fault conditions that the device can detect are: Open
LED pin, LED pin shorted to ground, shorted inductor, V
short to ground, SW pin shorted to ground, ISET pin shorted to
ground, and input disconnect switch source shorted to ground.
Note the following:
• Some of the protection features might not be active during
• Some of these faults will not be protected if the input disconnect
startup, to prevent false triggering of fault conditions.
switch is not being used. An example of this is V
ground.
Description
SW(LIM)
.
OVP(SEC)
SW(LIM2)
Fault Tolerant LED Driver
is reached. This
) the device
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
a single
Boost
Off for
cycle
Off
Off
Off
Disconnect
switch
On
Off
Off
Off
OUT
short to
OUT
driver
Sink
On
Off
Off
Off
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