AAT1274

1.5A Single Flash LED Driver IC

DATA SHEET

10

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201981A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 21, 2012

Movie mode operation is controlled entirely by the

will override movie-mode AAT1274 operation when tog-

gled to a logic high level. The part will not reenter movie

mode when FLEN is brought low. To reenter movie mode

after a flash event the part must be cycled off and back

on to reset the movie mode and reprogrammed via the

Over-Voltage Protection

(Open Flash LED, Open Circuit)

The AAT1274 boost converter output is voltage limited by

internal overvoltage protection circuitry to prevent dam-

age to the device in the event an open LED or open circuit

condition occurs. During an open circuit condition, the

output voltage will rise to 5.5V (typical). The OVP circuit

disables the boost converter to prevent the output voltage

from rising above 5.5V. Once the open circuit condition is

removed, normal boost operation will resume.

Short Circuit Protection

The AAT1274 is equipped with an auto-disable feature

for the flash LED channel. After the IC is enabled and

system start up commences, a test current of 2-3mA

(typical) is forced through the sink channel. The channel

will be disabled if the voltage of the SINK pin does not

drop to a predetermined threshold. This feature is very

convenient for disabling the current sink in the event the

flash LED fails to a short circuit. This small test current

is added to the set output current in both Flash and

movie mode conditions.

Over-Temperature Protection

The AAT1274 has internal thermal

protection circuitry to

a preset thermal limit. The junction over-temperature

threshold is 140°C with 15°C of temperature hysteresis.

During flash or movie-mode operation, if an environmen-

tal condition, flash current sink, or the boost converter

causes the internal die temperature to rise above 140°C,

the boost converter will be shut down. The boost con-

verter output operation will automatically recover when

the over-temperature fault condition is removed.

Application Information

Flash Mode LED Current

Flash sink current can be programmed up to a maximum

resistor. For the desired flash current, the resistor value

can be calculated using the following equation:

162k

Ω × A

R

SET

162k

Ω

107k

Ω

I

=

= 1.5A

A flash event is initiated by asserting the FLEN pin. A

flash event is automatically terminated when FLEN is

deasserted. Any time that the FLINH pin is asserted, the

default movie-mode current level will appear at FL chan-

nel. The default movie mode current level will be main-

tained on FL as long as the FLINH and FLEN pins are

the flash current can be changed after FLEN is asserted

by programming the movie mode current register with

16 different steps.

of Movie Mode Operation

In the AAT1274 control of the movie mode operation is

of the EN/SET pin to address and load internal data reg-

isters. Referring to Table 1:

 Address 0 controls the movie mode (MM) current level

as a percentage of the maximum movie mode current

level.

 Address 3 sets the maximum possible current for movie

mode operation. The maximum movie mode current is

set as a fraction of the flash current with a peak value

of 1/2 and default value of 1/7.3.

 The last column in Table 1 shows the default values for

each of the address registers.