Diodes AP3064 - Manual (Page 14)

Preliminary Datasheet
Boost Type LED Driver with 4-Channel Current Source AP3064
Jul. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited
14
Application Information (Continued)
9. LED Open-circuit Protection
The AP3064 integrates an LED Open-circuit
Protection circuit. When any LED string is open,
V
OUT
will boost up until the voltage at OVP pin
reaches an approximate 2.0V threshold. The IC will
automatically ignore the open string whose
corresponding pin voltage is less than 100mV and the
remaining string will continue operation. If all the
strings are open and the voltage at OVP reaches a
threshold of 2.0V, the MOSFET drive GATE will turn
off and IC will shut down and latch.
10. V
OUT
Short / Open Schottky Diode
Protection
The AP3064 monitors the OVP pin, if the OVP pin
voltage is less than 0.1V, MOSFET drive output will
turn off. This protects the converter if the output
Schottky diode is open or V
OUT
is shorted to ground.
11. Under Voltage Lockout
The AP3064 provides an under voltage lockout
circuit to prevent it from undefined status when
startup. The UVLO circuit shuts down the device
when V
CC
drops below 3.6V. The UVLO circuit has
200mV hysteresis, which means the device starts up
again when V
CC
rise to 3.8V.
12. Over Temperature Protection
The AP3064 features Over Temperature Protection, if
the junction temperature exceeds approximately
160ºC, the IC will shut down until the junction
temperature is less than approximately 140ºC. When
the IC is released from over temperature shutdown, it
will start a soft-start process.
13. Schottky Diode/Inductor Short Cir-
cuit Protection
The AP3064 features Schottky diode/inductor
short-circuit protection circuit. When CS pin voltage
exceeds 0.8V for greater than 16 switching clocks,
the IC will latch. The voltage of CS is monitored
after a short delay of LEB.
14. Shut Down under Abnormal Cond-
ition
The AP3064 features shutdown under abnormal
condition protection circuit. When OVP pin voltage
exceeds 3.2V, the IC will latch. Toggle EN to restart
the IC. This feature can be used for any other
protection to shut down the IC.