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PDF AAT1274 Data sheet ( Hoja de datos )
| Número de pieza | AAT1274 | |
| Descripción | 1.5A Single Flash LED Driver IC | |
| Fabricantes | Skyworks Solutions | |
| Logotipo |  |
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DATA SHEET
AAT1274
1.5A Single Flash LED Driver IC
General Description
The AAT1274 is a high-efficiency, 1.5A high-current
boost converter for LED photo flash applications. It
maintains output current regulation by switching the
internal high-side and low-side switch transistors, pulse-
width modulated at a fixed frequency of 2MHz. The high
switching frequency allows the use of a small external
inductor and output capacitor, making the AAT1274 ide-
ally suited in all single cell, Li-ion-powered applications.
Skyworks' proprietary AS2Cwire™ (Advanced Simple
Serial Control™) serial digital interface is used to enable,
disable, configure, and program the operation of the
AAT1274. Using the AS2Cwire interface, the movie-mode
current level for each LED, and the flash-to-movie-mode
current ratio can be programmed to one of 16 levels. The
AAT1274 includes a separate Flash Enable input to initi-
ate the flash operation and a Flash Inhibit pin which
reduces the flash current to movie-mode levels during
high battery demand.
The maximum flash and movie-mode current is set by
one external resistor where the ratio of flash to movie-
mode current is set at approximately 7.3:1. The AAT1274
can drive one high current LED.
The AAT1274 contains a thermal management system to
protect the device in the event of an output short-circuit
condition. Built-in circuitry prevents excessive inrush
current during start-up. The shutdown feature reduces
quiescent current to less than 1.0μA.
The AAT1274 is available in a Pb-free, thermally-enhanced
TDFN33-14 package and operates over the -40°C to 85°C
temperature range.
Features
• Input Voltage Range: 2.7V to 5.5V
• Single Channel Flash Output
• Up to 1.5A Regulated Output Current
• Up to 88% Efficiency
• 2 MHz Switching Frequency
• Separate Flash Enable
• Single Resistor Sets Flash and Movie Mode Current
▪ AS2Cwire Single Wire Programming:
• Movie Mode Current
• Flash/Movie Mode Current Ratio
• True Load Disconnect
• Soft-Start and Input Current Limit
• Over-Voltage (Open LED, Open Circuit), Short Circuit,
and Over-Temperature Protection
• -40°C to +85°C Temperature Range
• TDFN33-14 Package
Applications
• LED Photo Flash / Torch
• Camera Enabled Mobile Devices
• Cellphones/Smartphones
• Digital Still Cameras (DSCs)
• Multimedia Mobile Phones
Typical Application
L1 1μH
VBAT = 2.7V to 5.5V
Enable/Set Input
Flash Enable
Flash Inhibit
CIN
2.2μF
IN
SW
OUT
AAT1274
EN/SET
FL
COUT
2.2μF
Flash LED
FLEN
FLINH
RSET
RSET
PGND AGND FLGND
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201981A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 21, 2012
1
1 page  
Typical Characteristics
Flash Mode Efficiency vs. Input Voltage
100
320mA, VF = 2.91V
90
540mA, VF = 3.00V
700mA, VF = 3.04V
900mA, VF = 3.04V
80 1500mA, VF = 3.15V
1200mA, VF = 3.27V
70
60
50
40
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
Boost Switching Frequency vs. Input Voltage
(Movie Mode; L = 1µH)
3
2.5
2
1.5
1
85°C
0.5 25°C
-40°C
0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
1000
900
800
700
600
500
400
300
200
100
0
2.7
Supply Current vs. Input Voltage
(VEN = VFLEN = 3.6V)
85°C
25°C
-40°C
3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
DATA SHEET
AAT1274
1.5A Single Flash LED Driver IC
Movie Mode Efficiency vs. Input Voltage
90
204mA
85 104mA
80 52mA
75
70
65
60
55
50
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
Shutdown Current vs. Input Voltage
(VEN/SET = VFLEN = 0V)
0.03
0.025
0.02
0.015
0.01
0.005
0
25°C
-40°C
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
Movie Mode LED Current vs. Temperature
(IFL = 206mA/Ch; VIN = 3.6V; L = 1µH)
225
220
215
210
205
200
195
190
185
-40 -15
10
35
60
85
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201981A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 21, 2012
5
5 Page 
Address
0
1
2
3
EN/SET
Rising
Edges
17
20
Default
Function (No Programming)
Movie Mode
Current
Not Used
Not Used
Flash/Movie
Mode Cur-
rent Ratio
100%
1/7.3
Table 1: AS2Cwire Serial Interface Addressing.
AS2Cwire Serial Interface
AS2Cwire latches data or address after the EN/SET pin
has been held high for longer than tLAT (500μs). Address
or data are differentiated by the number of EN/SET rising
edges. Since the data registers are 4 bits each, the dif-
ferentiating number of pulses is 24 or 16, so that Address
0 is signified by 17 rising edges, and Address 3 by 20
rising edges. Data is inclusively applied to any number of
rising edges between 1 and 16. A typical write protocol is
a burst of EN/SET rising edges which signify a particular
address that is followed by a pause with EN/SET held
high for the prescribed tLAT timeout period, then a burst
of rising edges signifying data, and a tLAT timeout for the
data registers. Once an address is set, then multiple
writes to the corresponding data register are allowed.
Address 0 is the default address on the first rising edge
DATA SHEET
AAT1274
1.5A Single Flash LED Driver IC
after the AAT1274 has been disabled. When EN/SET is
transitioned from high to low and held low longer than
tOFF (500μs), the device enters a shutdown mode and
draws less than 1uA from the input supply. All data and
address are cleared (reset to 0) during shutdown.
AS2Cwire addressing allows for control of the movie mode
output current, and the ratio of movie-mode current to
flash current. If there are no programmed write instruc-
tions applied to the EN/SET pin prior to the assertion of
the FLEN pin and the device is enabled, then all registers
will be loaded with their default values shown in Table 1.
In the event that the number of rising edges applied at
the EN/SET pin is less than 17, the internal state machine
will interpret instruction to program the output currents
to the desired current level for movie-mode operation.
Movie Mode Current – Address 0
The AAT1274 movie mode current settings are controlled
using the AS2Cwire interface. The default ratio between
the flash current level and maximum movie mode cur-
rent level is 1:7.3.
For example, if an RSET value of 107kΩ is chosen, then
the flash current is set to 1500mA. For movie mode
operation, the maximum current available is then:
IMOVIE
MODE
=
IFL(MAX)
7.3
=
1500mA
7.3
= 206mA
EN/SET
Address
Address
T HI
T LO
TLAT
12
16 17
0
Data
TLAT
1 2 . . . n ≤ 16
1
Data Reg 1
0
Figure 1: AS2Cwire Serial Interface Timing Diagram.
n
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201981A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 21, 2012
11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet AAT1274.PDF ] | |
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