Data Sheets - Skyworks Solutions, Inc.

DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
General Description
Features
The AAT1290 is a high-efficiency, high-current boost
converter capable of 1.5A typical output current. It is an
ideal power solution for LED photo flash applications in
all single cell Li-ion powered products.
•VIN Range: 2.7V to 5.5V
• Single Channel Flash Output
• Up to 1.5A Regulated Output Current
• Up to 85% Efficiency with Small Inductor (1µH)
• 2 MHz Switching Frequency
• Separate Flash Enable
• User-Programmable Safety Timer
• Single Resistor Sets Flash and Movie Mode Current
•AS2Cwire Single Wire Programming:
▪ Movie Mode Current
▪ Movie Mode Enable
▪ Flash/Movie Mode Current Ratio
▪ Flash Safety Timer
• True Load Disconnect
• Soft-Start and Input Current Limit
• Over-Voltage (Open LED, Open Circuit), Short Circuit,
and Over-Temperature Protection
• Shutdown Current < 1.0µA
• 14-pin TDFN 3x3 mm Package
• -40°C to +85°C Temperature Range
The AAT1290 maintains output current regulation by
switching the internal high-side and low-side switch
transistors. The transistor switches are pulse-width
modulated at a fixed frequency of 2MHz. The high
switching frequency allows the use of a small inductor
and output capacitor, making the AAT1290 ideally suited
for small battery-powered applications.
Skyworks' proprietary AS2Cwire™ (Advanced Simple
Serial Control™) serial digital interface is used to enable,
disable, configure, and program the operation of the
AAT1290. Using the AS2Cwire interface, the movie-mode
current level for the LED, the safety timer delay, and the
flash-to-movie-mode current ratio can be programmed to
one of 16 levels. In addition, the single-wire serial protocol sets output channel control. The AAT1290 also
includes a separate Flash Enable input to initiate both the
flash operation and the default timer which can be used
either to terminate a flash event at the end of a userprogrammed delay or as a safety feature. Also included
is 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 Moviemode current is set at approximately 7.3:1. The AAT1290
can drive one high current LED.
Applications
• Camera Enabled Mobile devices
•Cellphones/Smartphones
• Digital Still Cameras (DSCs)
• LED Photo Flash/Torch
• Multimedia Mobile Phone
The AAT1290 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 AAT1290 is available in a Pb-free, thermallyenhanced 14-pin 3x3mm TDFN package.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
1
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Typical Application
L1
1µH
VBATT = 2.7V to 5.5V
CIN
2.2µF
SW
IN
OUT
COUT
2.2µF
AAT 1290
Enable /Set Input
Flash Enable
EN/SET
FLEN
Flash LED
FL
RSET
RSET
Flash Inhibit
FLINH
CT
CT
PGND AGND FLGND
Pin Descriptions
Pin #
Symbol
1
CT
2
EN/SET
3
FLEN
4, 9
AGND
5
IN
6
7
SW
PGND
8
OUT
10
FLINH
11
12
13
NC
FLGND
FL
14
RSET
EP
2
Function
Flash timer control input. Connect a capacitor between CT and AGND to set maximum duration of the flash
pulse. To disable the flash timer, connect CT to AGND.
Enable and Serial Control input. EN/SET is the AS2Cwire addressing and programming input to: a) adjust
the movie-mode current level; b) program the flash timer based on CT; c) select the Flash-to-Movie-mode
ratio; and d) enable/disable movie mode operation.
Flash enable pin. A low-to-high transition on the FLEN pin initiates a flash pulse and a high-to-low transition
on the FLEN pin terminates a flash pulse.
Analog ground pin. Connect AGND to PGND and FLGND at a single point as close to the AAT1290 as possible.
Flash output boost converter power input. Connect IN to the input power source. Connect a 2.2μF or larger
ceramic capacitor from IN to PGND and locate as close as possible to the IC package for optimum performance.
Boost converter switching node. Connect a 1µH inductor between SW and IN.
Power ground. Connect PGND to the same single point as AGND located as close to the IC as possible.
Power output of the boost converter. Connect a 2.2µF or larger ceramic capacitor from OUT to PGND as
close as possible to the AAT1290. Connect OUT to the anode of the Flash LED.
Flash inhibit pin. FLINH is an active HIGH control input with an internal 200kΩ resistor to AGND. A low-tohigh transition on the FLINH pin reduces FL sink current to the maximum (default) movie-mode current
level for the duration of FLINH. Strobing the FLINH pin low to high does not reset the flash timer.
No connect.
Flash ground pin. Connect FLGND to PGND and AGND at a single point as close to the AAT1290 as possible.
LED Flash current sink pin. Connect the cathode of Flash LED to FL.
Flash current setting input. Connect a resistor from RSET to AGND to program the desired flash current for
the current sink FL.
Exposed paddle (bottom); Connect EP to PGND as close as possible to the AAT1290.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Pin Configuration
TDFN33-14
(Top View)
TDFN 3x3mm
(Top View)
CT
1
14
RSET
EN/SET
2
13
FL
FLEN
3
12
FLGND
AGND
4
11
NC
IN
5
10
FLINH
SW
6
9
AGND
PGND
7
8
OUT
Absolute Maximum Ratings1
Symbol
Description
Value
IN, SW, OUT
Maximum Rating
-0.3 to 6.0
RSET, EN/SET, FLEN, FLINH, CT, FL
Maximum Rating
VIN + 0.3
TJ
Ts
TLEAD
Operating Temperature Range
Storage Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Units
-40 to 150
-65 to 150
300
°C
Value
Units
50
2
°C/W
W
Recommended Operating Conditions
Symbol
θJA
PD
Description
Thermal Resistance
Maximum Power Dissipation
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. The AAT1290 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
3
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Electrical Characteristics1
VIN = 3.6V; CIN = 2.2µF; COUT = 2.2µF; L = 1µH; RSET = 107kΩ; TA = -40°C to 85°C, unless otherwise noted. Typical
values are TA = 25°C.
Symbol
Description
Conditions
Power Supply
VIN
Input Voltage Range
VOUT(MAX)
Maximum Output Voltage
IIN(Q)
Supply Current
ISHDN(MAX)
IFL
VIN Shutdown Current
Output Current, Flash Mode
IMM(LOAD)
Output Current, Movie Mode
IFL(ACC)
Flash Current Accuracy
fOSC
Switching Frequency
tDEFAULT
Default Flash Timer ON Time
TSD
Thermal Shutdown Threshold
TSD(HYS)
Thermal Shutdown Hysteresis
EN/SET/ FLEN/ FLINH Logic Control
VEN/SET(L),
EN/SET, FLEN Input Low Threshold
VFLEN(L)
VEN/SET(H),
EN/SET, FLEN Input High Threshold
VFLEN(H)
IEN/SET, IFLEN
EN/SET or FLEN Input Leakage Current
VT(FLINH)
FLINH Input Threshold Voltage
RIN(FLINH)
FLINH Input Resistance to AGND
tEN/SET(LOW)
EN/SET Serial Interface Low Time
tEN/SET(HI_ MIN)
Minimum EN/SET High Time
tEN/SET(HI_ MAX)
Maximum EN/SET High Time
tEN/SET(OFF)
EN/SET Off Timeout
tEN/SET(LAT)
EN/SET Latch Timeout
tFLEN_ON
FLEN ON Delay Time
tFLEN_OFF
FLEN OFF Delay Time
tFLINH_ON
FLINH ON Delay Time
Min
Typ
2.7
EN/SET = FLEN = IN, IFL = 1.5A
EN/SET = IN, FLEN = AGND
EN/SET = FLEN = FLINH = AGND
RSET = 107kΩ
RSET = 107kΩ , Movie Mode Current Set
= 100%
IFL = 1.2A
TA = 25˚C
CT = 68nF
Max
Units
5.5
5.5
V
1.4
0.23
mA
1
1.2
-10
1.5
1.5
µA
A
206
mA
2.0
600
140
15
10
2.5
0.4
1.4
VEN/SET,VFLEN = VIN
-1
1
½VIN
200
0.3
75
50
75
500
500
EN/SET = AGND
EN/SET = AGND
25
10
15
%
MHz
ms
°C
°C
V
µA
V
kΩ
µs
ns
µs
1. The AAT1290 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Typical Characteristics
Movie Mode Efficiency vs Input Voltage
Flash Mode Efficiency vs Input Current
90
90
206mA
80
104mA
52mA
80
Efficiency (%)
Efficiency (%)
85
75
70
65
60
60
50
320mA, Vf = 2.91V
40
540mA, Vf = 3.00V
30
900mA, Vf = 3.08V
1.2A, Vf = 3.15V
20
50
10
2.7
2.7
3.1
3.5
3.9
4.3
4.7
5.5
5.1
3
Current Accuracy (%)
3
2
1
0
-1
-2
-3
35
60
5.1
-1
-2
-3
-40
-15
10
35
60
85
Temperature (°C)
Flash On Time Delay vs Input Voltage
(IFL = 206mA; L = 1µH)
(IFL = 1.5A; COUT = 2.2µF; L = 1µH)
40
3
35
2
30
TFLEN_OND (µs)
4
1
0
-1
-2
-3
25
20
15
10
85°C
25°C
-40°C
5
2.7
3.1
3.5
3.9
4.3
Input Voltage (V)
4.7
5.1
5.5
0
Movie Mode Current Accuracy vs. Input Voltage
-4
4.7
1
85
Temperature (°C)
4.3
2
-4
10
3.9
(IFL = 206mA; VIN = 3.6V; L = 1µH)
4
-15
3.5
Movie Mode Current Accuracy vs Temperature
4
-40
3.1
Input Voltage (V)
(IFL= 1.5A; VIN= 3.6V; L = 1µH)
-4
1.5A, Vf = 3.3V
Flash Mode Current Accuracy vs Temperature
Current Accuracy (%)
700mA, Vf = 3.04V
55
Input Voltage (V)
Current Accuracy (%)
70
0
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
5
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Typical Characteristics
Flash Timeout Delay vs CT Capacitor
Flash Timeout vs Temperature
(IFL = 1.5A; VIN = 3.6V; CT = 68nF)
(IFL = 1.5A; VIN = 3.6V)
1200
700
1000
660
Flash Timeout (ms)
Flash Timeout (ms)
680
640
620
600
580
560
540
520
500
-40
-15
10
35
60
800
600
400
200
0
85
60
80
100
120
140
EN/SET Latch Timeout vs Input Voltage
400
400
350
350
300
300
TEN/SET(LAT) (µs)
TEN/SET(OFF) (µs)
40
CT Capacitor (nF)
EN/SET Off Timeout vs Input Voltage
250
200
150
250
200
150
100
85°C
100
85°C
50
25°C
50
25°C
0
-40°C
2.7
3.1
3.5
3.9
4.3
4.7
5.1
0
5.5
1.3
1.2
1.2
1.1
1.1
VEN/SET, VFLEN (V)
1.3
1
0.9
0.8
85°C
25°C
0.6
0.5
2.7
3.5
3.9
4.3
Input Voltage (V)
4.7
3.5
5.1
3.9
4.3
4.7
5.1
1
0.9
0.8
85°C
0.7
0.5
5.5
5.5
EN/SET, FLEN Low Threshold Voltage vs
Input Voltage
25°C
0.6
-40°C
3.1
3.1
Input Voltage (V)
EN/SET, FLEN High Threshold Voltage vs
Input Voltage
0.7
-40°C
2.7
Input Voltage (V)
VEN/SET, VFLEN (V)
20
Temperature (°C)
6
0
-40°C
2.7
3.1
3.5
3.9
4.3
4.7
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
5.1
5.5
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Typical Characteristics
Boost Switching Frequency vs Input Voltage
Supply Current vs Input Voltage
(VEN/SET = VFLEN = VIN; IFL = 0mA; Non-Switching)
4
400
3.5
350
Supply Current (µA)
Switching Frequency (MHz)
(TA = 25°C; L = 1µH)
3
2.5
2
1.5
1
0.5
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
Input Voltage (V)
300
250
200
150
100
50
0
5.5
2.7
4.7
5.1
5.5
Flash Mode Ripple
V OUT
150mV/div
AC Coupling
V SW
2V/div
V SW
2V/div
0V
0V
ISW
50mA/div
ISW
100mA/div
100mA
1.65A
500ns/div
Flash Turn On Characteristic
200ns/div
Movie Mode to Flash Turn On Characteristic
(IFL= 206mA to 1.5A; COUT = 2.2µF, VIN = 3.6V, L = 1µH)
(IFL = 1.5A; COUT = 2.2µF; VIN = 3.6V; L = 1µH)
IFL
1A/div
4.3
(IFL = 1.5A; COUT = 2.2µF; VIN = 3.6V; L = 1µH)
V OUT
50mV/div
AC Coupling
V SINK
2V/div
3.9
Input Voltage (V)
Movie Mode Ripple
V OUT
2V/div
3.5
(IFL = 206mA; COUT = 2.2µF; VIN=3.3V; L =1µH)
V FLEN
5V/div
3.1
V FLEN
5V/div
0V
V OUT
2V/div
0V
V SINK
2V/div
0V
IFL
1A/div
0V
50ns/div
0V
2V
0V
0A
50ns/div
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
7
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Typical Characteristics
Movie Mode Turn On Characteristic
Movie Mode Transistion Characteristic
(IFL= 206mA to 376mA/ch; COUT = 2.2µF, VIN = 3.6V, L = 1µH)
(IFL= 206mA; COUT = 2.2µF, VIN = 3.6V, L = 1µH)
V EN/SET
5V/div
V EN/SET
2V/div
0V
V OUT
2V/div
V OUT
2V/div
V SINK
2V/div
V SINK
500mV/div
0V
0V
0V
0V
0V
IFL
100mA/div
IFL
100mA/div
0A
0A
100µs/div
100µs/div
8
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Functional Block Diagram
FL
EN/SET
FLEN
System Control
Enable and AS2C Interface
FLINH
FLGND
RSET
CT
AGND PGND
Functional Description
The AAT1290 is a boost converter with a current regulated output designed to drive high current white LEDs
used in camera flash applications. The AAT1290 has a
constant current sink channel to accurately regulate the
current flow through a high current, high intensity white
Flash LED. There are two basic modes of operation in the
AAT1290; a Flash mode controlled by the FLEN pin and
the movie mode controlled through the AS2Cwire interface.
Flash Mode
A flash pulse is initiated by strobing the FLEN input pin
low-to-high. This also starts an internal flash timer. The
maximum flash current in the AAT1290 is set by an
external resistor, RSET, which programs the maximum
flash current and the maximum movie-mode current.
The AAT1290’s flash timer will terminate the flash current regardless of the status of the FLEN pin. This can be
used either for a simple flash pulse timing or a safety
timer in the event of a control logic malfunction to prevent the LED from over-heating. The maximum flash
time is determined by an external timing capacitor connected to the CT pin. The flash duration can be set from
50ms up to a maximum of 1s. The AS2Cwire interface
allows flexible adjustment of the flash timer duration.
This allows the flash timer duration to be reduced in 16
linear steps from the maximum time set by the timing
capacitor. If the safety timer is not needed in the application, it can be disabled by connecting the CT pin directly
to AGND.
In mobile GSM systems where the phone remains in
constant contact with the base station by regular communication, a FLINH pin is provided to prevent both the
camera flash and PA transmission pulses from occurring
simultaneously. This avoids potential dips to the Li-ion
battery voltage below the system’s undervoltage lockout
threshold (UVLO). During a flash event, strobing the
FLINH pin low-to-high reduces the LED current to the
default movie-mode current level for the duration of
FLINH. Strobing FLINH high-to-low instructs the AAT1290
to revert to the maximum flash LED current level,
assuming that the FLEN pin is still active (HIGH) and the
flash timer has not expired.
Movie Mode
The movie / torch mode current level, and the flash to
maximum movie mode current ratio are programmed by
the AAT1290 AS2Cwire interface. The movie-mode current level can be adjusted to one of 16 steps using a
logarithmic scale where each code level is 1dB below the
previous code. The maximum movie to flash mode current ratio can be set from 1:2 to OFF with respect to the
maximum programmed flash current as set by the RSET
resistor. The manual FLEN signal has priority over moviemode operation.
Movie mode operation is controlled entirely by the
AS2Cwire interface via the EN/SET pin. The FLEN signal
will override movie-mode AAT1290 operation when toggled 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
AS2Cwire interface to the desired movie mode operation.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
9
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Over-Temperature Protection
The AAT1290 has internal thermal protection circuitry to
disable the device if the power dissipation exceeds a
preset thermal limit. The junction over-temperature
threshold is 140°C with 15°C of temperature hysteresis.
During Flash or movie-mode operation, should an environmental condition, flash current sink or the boost converter cause the internal die temperature to rise above
140°C, the boost converter will be shut down. The boost
converter output operation will automatically recover
when the over-temperature fault condition is removed.
Over-Voltage Protection
(Open LED, Open Circuit)
The AAT1290’s output voltage is limited by internal overvoltage protection circuitry, which prevents damage to
the AAT1290 from open LED or open circuit conditions.
During an open circuit event, the boost converter output
will rise to the over-voltage protection (OVP) threshold
at 5.5V (typical). Upon sensing the OVP event, the boost
converter will be disabled to prevent damage to the
device. Once the open circuit fault condition is removed,
boost converter switching will resume.
Short Circuit Protection
The AAT1290 is equipped with an auto-disable feature
for the flash LED current sink. After the IC is enabled and
system start up commences, a test current of 2-3mA
(typical) is forced through the current sink. The current
sink 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 of the flash LED short-circuit failure. This small
test current is added to the set output current in both
Flash and movie mode conditions.
Timing Diagram
FLASH
FLASH
FLASH
FLASH
FLASH
FLASH TIMES OUT
tDLY(CT)
MOVIE MODE
NO FLASH
LED CURRENT
t DLY(CT)
NO FLASH
FLASH TIMES OUT
SET BY CT
FLASH LOWERED
TO DEFAULT
MOVIE-MODE
DURING FLINH
DATA TO
MOVIE-MODE
LEVEL
EN/SET
FLASH ENABLE
FLASH INHIBIT
No AS2C address programming shown.
10
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Applications Information
Flash Mode LED Current
The flash sink current can be programmed up to a maximum flash current level of 1.5A.
The maximum flash current is set by the RSET resistor.
For the desired flash current in output, the resistor value
can be calculated using the following equation:
RSET =
1A
∙ 162kΩ
IFL(MAX)
age of the maximum movie mode current level. Address
1 controls the safety timer duration as a percentage of
the maximum value set by an external timing capacitor.
Address 2 enables the LED channel during movie mode.
Finally, 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 a default value of 1/7.3. The last column in Table 1 shows the default values for each of the
address registers.
AS2Cwire Serial Interface
A flash event is initiated by asserting the FLEN pin. A
flash event is automatically terminated when FLEN is deasserted or if the safety timer terminates before the
FLEN pin is de-asserted. Any time that the FLINH pin is
asserted, the default movie-mode current level will
appear at FL. The default movie-mode current level will
be maintained on FL as long as the FLINH and FLEN pins
are asserted, and the safety timer continues to run.
AS2Cwire Control of Movie Mode
Operation and Flash Safety Timer
In the AAT1290, control of the movie mode operation
and flash timer is managed by the Advanced Simple
Serial Control (AS2Cwire) interface. AS2Cwire relies on
the number of rising edges of the EN/SET pin to address
and load the AAT1290’s registers. As shown in Table 1,
Address 0 controls the Movie Current level as a percent-
AS2Cwire latches data or address after the EN/SET pin
has been held high for longer than tLAT (500µs). Address
or data is differentiated by the number of EN/SET rising
edges. Since the data registers are 4 bits each, the differentiating number of pulses is 24 or 16, so that Address
0 is signified by 17 rising edges, Address 1 by 18 rising
edges and Address 2 by 19 rising edges and Address 3
by 20 rising edges. Data is applied to any number of rising edges between 1 and 16, inclusive. A typical write
protocol is a burst of EN/SET rising edges, signifying a
particular address, followed by a pause with EN/SET
held high for the prescribed tLAT timeout period, 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
after the AAT1290 has been disabled.
Address
EN/SET
Rising Edges
Function
Default
(No programming)
0
1
2
3
17
18
19
20
Movie Mode Current
Flash Safety Timer
Movie Mode Output Configuration
Flash/Movie Mode Current Ratio
100%
16/16
OFF
1/7.3
Table 1: AS2Cwire Serial Interface Addressing.
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11
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
When EN/SET is strobed low and held low longer than
tOFF (500µs), the AAT1290 enters shutdown mode and
draws less than 1µA from VIN. All data and address are
cleared (reset to 0) during shutdown.
IMOVIE MODE =
Address 0 controls precise movie mode current levels.
The FL movie-mode current can be adjusted in logarithmic fashion to one of 16 steps represented as a fraction
of the maximum movie mode current in Table 2. To
adjust the movie-mode current the user must first
access Address 0 before writing the data to set the MM
Current value.
The AS2Cwire addressing allows the control of the moviemode output current, the safety timer delay, the FL current sink, and the ratio of movie-mode current to flash
current.
If there are no programmed write instructions 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 AAT1290’s state machine will
interpret instruction to program the output currents to
the desired current level for movie-mode operation.
Data
Percentage of Maximum MM Current
1*
100%
2
89%
3
79%
4
71%
5
63%
6
56%
7
50%
8
45%
9
40%
10
36%
11
32%
12
28%
13
25%
14
22%
15
20%
16
0%
Movie Mode Current – Address 0
The AAT1290 movie mode current settings are controlled
using the AS2Cwire interface. Movie Mode current has a
maximum value of 50% of the flash current with 240
possible current levels. The maximum movie mode current is set by Address register 3 (discussed below). The
default ratio between the maximum movie mode current
level and the flash current level is 1:7.3. The corresponding FL maximum movie mode current can be calculated:
IMOVIE MODE =
IFLMAX
1500mA
=
= 206mA
7.3
7.3
IFLMAX
7.3
Table 2: Address 0, Movie Mode
Current Programming.
For example, if an RSET value of 107kΩ is chosen, then
the FL flash current is set to 1500mA. For movie mode
operation, the maximum current available at FL is then:
Address
Data
T HI
T LO
TLAT
TLAT
EN/SET
1
Address
Data Reg 1
2
16
17
1
0
2...
n ≤ 16
1
0
n
Figure 1: AS2CwireTM Serial Interface Timing.
* Denotes the default value.
12
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DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Flash/Safety Timer – Address 1
A timer function that enables the flash current sinks for
a programmed amount of time is incorporated in the
AAT1290. The on-time is programmed by loading the
Timing Register at Address 1 with a value from 1 to 16
and by choosing a value for the external timing capacitor, CT (see Table 3). When data is latched into Address
1, the data will be used at the next occurrence of an
asserted FLEN, it will then revert to the default value of
Data 1, or 16/16. This feature eliminates the need for an
external, housekeeping baseband controller to contain a
safety delay routine. The flash safety timer also serves
as a protection feature to minimize thermal issues with
the flash LEDs in the event the external controller’s flash
routine experiences a software failure. If no write
instruction is applied to Address 1, then the safety timer
will default to the maximum delay programmed externally by CT.
The Flash Time T can be calculated by the following
equation:
T=
8.82s
× CT(µF)
µF
Ratio of MM Timeout
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
16/16
15/16
14/16
13/16
12/16
11/16
10/16
9/16
8/16
7/16
6/16
5/16
4/16
3/16
2/16
1/16
Table 3: Address 1, Flash Safety Timer
Programming; Maximum Value
Programmed by CT.
Movie Mode Enable – Address 2
Where T is in seconds and CT is in µF.
For example, using a 47nF capacitor at CT sets the flash
timeout to:
Flash Timeout =
Data
8.82s
× 68nF = 600ms
µF
The relationship between the flash safety timeout and
the capacitance of the timer capacitor is illustrated in
Figure 2.
Flash Timeout Delay vs CT Capacitor
To enable or disable the flash, a write instruction to
Address 2 is applied to the AAT1290’s EN/SET pin. If no
write instruction is applied, the default value for Address
2 is OFF. During a flash event, the LED will be enabled
regardless of the movie-mode setting.
Data
Movie Mode Enable
1*
2
3
4
OFF1
OFF1
ON
ON
Table 4: Address 2, Movie Mode
Output Configuration.
(IFL = 1.5A; VIN = 3.6V)
1200
Flash Timeout (ms)
1000
800
600
400
200
0
0
20
40
60
80
100
120
140
CT Capacitor (nF)
Figure 2: Flash Safety Timeout
vs. Timer Capacitor.
1 A small current will flow due to the start-up test current.
* Default value.
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13
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Maximum Movie to Flash Mode
Current Ratio – Address 3
The maximum movie-mode current is a fixed ratio of the
flash current controlled by Address 3. The ratio may be
varied from 1:2 to OFF in 16 linear steps as shown in
Table 5. The default value for Address 3 is Data=4 and
represents a flash to maximum movie mode current
level of 7.3 to 1.
Data
MM to FL Ratio
1
2
3
4*
5
6
7
8
9
10
11
12
13
14
15
16
1/1.92
1/3.7
1/5.5
1/7.3
1/9
1/10.7
1/12.4
1/14
1/15.9
1/17.5
1/19.1
1/20.8
1/22.4
1/24
1/25.6
OFF1
IMOVIE MODE =
IFLMAX 1500mA
=
= 206mA
7.3
7.3
The maximum movie mode current level can be calculated using the following equation:
IMOVIE MODE =
162kΩ × A
1
=
= Max Movie Mode Current
RSET
FL to MM Ratio
Shutdown
Since the sink switches are the only power returns for all
loads, there is no leakage current to the load when the
sink switches are disabled. When EN/SET pin is held low
for an amount of time greater than tOFF (500µs), the
AAT1290 enters shutdown mode and draws less than
1µA from VIN. All data and address registers are cleared
(reset to 0) during shutdown.
Selecting the Boost Inductor
Table 5: Address 3, Movie/Flash
Mode Current Ratio.
* Denotes the default value.
The default maximum movie mode current can be calculated:
IMOVIE MODE =
For example, if an RSET value of 107kΩ is chosen, then
the FL flash current is set to 1500mA. For movie mode
operation, the maximum current available at FL is then:
IFLMAX
7.3
The AAT1290 DC/DC boost controller utilizes PWM control
with a fixed switching frequency. To maintain a 2MHz
maximum switching frequency and stable operation, a
1μH inductor is recommended. Manufacturer’s specifications list both the inductor DC current rating, which is a
thermal limitation, and peak inductor current rating,
which is determined by the saturation characteristics.
Measurements at full load and high ambient temperature
should be performed to ensure that the inductor does not
saturate or exhibit excessive temperature rise.
Manufacturer
Part Number
Inductance
(µH)
Saturated Rated
Current (A)
DCR
(mΩ)
Size (mm)
LxWxH
Cooper Bussmann
Cooper Bussmann
Cooper Bussmann
Sumida
Coilcraft
SD3812-1R0-R
SDH3812-1R0-R
SD10-1R0-R
CDH38D11/S
LPS4012-102NLC
1
1
1
1
1
2.69
3
2.25
2.8
2.5
48
45
44.8
48.8
60
4.0x4.0x1.2
3.8x3.8x1.2
5.2x5.2x1.0
4.0x4.0x1.2
4.1x4.1x1.2
Type
Shielded
Shielded
Shielded
Shielded
Shielded
Table 6: Typical Suggested Surface Mount Inductors.
1. A small current will flow due to the short circuit test current.
14
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Drum
Drum
Drum
Drum
Drum
Core
Core
Core
Core
Core
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
The inductor (L) is selected to avoid saturation at minimum input voltage and maximum output load conditions.
Worst-case peak current occurs at minimum input voltage (maximum duty cycle) and maximum load. Bench
measurements are recommended to confirm actual IPEAK
and to ensure that the inductor does not saturate at
maximum LED current and minimum input supply voltage. The RMS current flowing through the boost inductor
is equal to the DC plus AC ripple components. Under
worst case RMS conditions, the current waveform is
critically continuous. The resulting RMS calculation yields
worst case inductor loss. The RMS current value should
be compared against the inductor manufacturer’s temperature rise, or thermal derating guidelines:
IRMS =
IPEAK
3
For a given inductor type, smaller inductor size leads to
an increase in DCR winding resistance and, in most
cases, increased thermal impedance. Winding resistance
degrades boost converter efficiency and increases the
inductor’s operating temperature:
PLOSS(INDUCTOR) = I2RMS · DCR
Manufacturer
Murata
Selecting the Boost Capacitors
It is good design practice to place a decoupling capacitor
(input capacitor) between the IN and GND pins. An input
capacitor in the range of 2.2μF to 10μF is recommended.
A larger input capacitor in this application may be
required for stability, transient response, and/or ripple
performance. The high output ripple inherent in the
boost converter necessitates the use of low impedance
output filtering. Multi-layer ceramic (MLC) capacitors
provide small size and adequate capacitance, low parasitic equivalent series resistance (ESR) and equivalent
series inductance (ESL), and are well suited for use with
the AAT1290 boost regulator. MLC capacitors of type X7R
or X5R are recommended to ensure good capacitance
stability over the full operating temperature range. The
output capacitor is selected to maintain the output load
without significant voltage droop (∆VOUT) during the
power switch ON interval. A 2.2μF ceramic output capacitor is recommended (see Table 7). Typically, 6.3V or 10V
rated capacitors are required for this flash LED boost
output. Ceramic capacitors selected as small as 0603 are
available which meet these requirements. MLC capacitors
exhibit significant capacitance reduction with applied
voltage. Output ripple measurements should confirm
that output voltage droop and operating stability are
within acceptable limits. Voltage derating can minimize
this factor, but results may vary with package size and
among specific manufacturers. To maintain stable operation at full load, the output capacitor should be selected
to maintain ∆VOUT between 100mV and 200mV. The boost
converter input current flows during both ON and OFF
switching intervals. The input ripple current is less than
the output ripple and, as a result, less input capacitance
is required.
Part Number
Capacitance (μF)
Voltage Rating (V)
Temp Co.
Case Size
GRM185R60J225KE26
GRM188R71A225KE15
GRM21BR70J225KA01
GRM21BR71A225KA01
GRM219R61A475KE19
2.2
2.2
2.2
2.2
4.7
6.3
10
6.3
10
10
X5R
X7R
X7R
X7R
X5R
0603
0603
0805
0805
0805
GRM21BR71A106KE51
10
10
X7R
0805
Table 7: Typical Suggested Surface Mount Capacitors.
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15
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
PCB Layout Guidelines
Boost converter performance can be adversely affected
by poor layout. Possible impact includes high input and
output voltage ripple, poor EMI performance, and
reduced operating efficiency. Every attempt should be
made to optimize the layout in order to minimize parasitic PCB effects (stray resistance, capacitance, and
inductance) and EMI coupling from the high frequency
SW node. A suggested PCB layout for the AAT1290 1.5A
step-up regulator is shown in Figures 4 and 5. The following PCB layout guidelines should be considered:
1. Minimize the distance from capacitor CIN and COUT’s
negative terminals to the PGND pins. This is especially true with output capacitor COUT, which conducts
high ripple current from the output to the PGND pins.
2. Minimize the distance under the inductor between IN
and switching pin SW; minimize the size of the PCB
area connected to the SW pin.
3. Maintain a ground plane and connect to the IC PGND
pin(s) as well as the PGND connections of CIN and
COUT.
4. Consider additional PCB exposed area for the flash
LEDs to maximize heatsinking capability. This may
be necessary when using high current application
and long flash duration application.
5. Connect the exposed paddle (bottom of the die) to
PGND. Connect AGND, FLGND to PGND as close as
possible to the package.
DC
DC +
JP 6
JP7
R10
0
10k
MCU
Safety Timer
(S.T.)
Movie Mode Enable Control
(A/B)
R6
R7
10K
10K
10K
U2
1
SW1
0
2
4
Movie Mode Current Control
(M.M.C.)
R5
2
3
1
3
5
4
SW2
0
2
4
1
3
5
2
4
1
3
5
VSS
GP 5
GP 0
GP 4
GP 1
GP 3
GP 2
PIC12F675
8
C4
1 µF
FLEN
7
6
0
R8
5
R9
330
LED2
330
2
4
1
3
5
0
SW4
FLINH
2
4
JP3
LED1
RED
GRN
SW
0
VDD
1
3
5
R3
R4
100k
100k
( opt )
SW 5
JP4
JP1
0
D1
U1
1
2
3
JP 5
EN / SET
R2
100K
4
5
6
L1
C1
2 .2 µF
1µH
7
C3
CT
RSET
FL
ENSET
FLEN
FLGND
NC
AGND
IN
FLINH
SW
AGND
PGND
OUT
14
13
12
11
10
9
8
AAT1290TDFN33-14
74 nF
C2
R1
107k
Figure 3: AAT1290 Evaluation Board Schematic.
16
VOUT
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2 .2 µF
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Figure 4: AAT1290 Evaluation Board
Top Side Layout.
Component
Part Number
U1
AAT1290IWO
U2
SW1 – SW5
R1
R2, R3, R4
R5, R6, R7, R10
R8, R9
JP1, JP2(Not Mounted), JP7
C1, C2
C3
C4
L1
D1, D2(Not Mounted)
LED1
LED2
JP3, JP4, JP5, JP6
Figure 5: AAT1290 Evaluation Board
Bottom Side Layout.
Description
Manufacturer
PIC12F675
PTS645TL50
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
1.5A Step-Up Current Regulator for Flash LEDs;
TDFN33-14 package
8-bit CMOS, FLASH-based μC; 8-pin PDIP package
Switch, SPST, 5mm
107kΩ, 1%, 1/4W; 0402
100kΩ, 1%, 1/4W; 0603
10kΩ, 1%, 1/4W; 0603
330Ω, 1%, 1/4W; 0603
Microchip
ITT Industries
Vishay
Vishay
Vishay
Vishay
Chip Resistor
0Ω, 1%
Vishay
2.2µF, 10V, X7R, 0603
Murata
74nF, 10V, X7R, 0402
Murata
1µF, 10V, X5R, 0805
Murata
Drum Core, 1µH, 2.69A, 48mΩ
White Flash LED
Red LED; 1206
Green LED; 1206
Conn. Header, 2mm zip
Cooper Bussmann
Lumileds, Philips
Chicago Miniature Lamp
Chicago Miniature Lamp
Sullins Electronics
GRM188R71A225KE15
GRM155R71A743KA01
GRM216R61A105KA01
SD3812-1R0-R
LXCL-PWF4
CMD15-21SRC/TR8
CMD15-21VGC/TR8
PRPN401PAEN
Skyworks
Table 8: AAT1290 Evaluation Board Bill of Materials.
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17
DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-14
U6XYY
AAT1290IWO-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information
TDFN33-143
Detail "A"
3.000 ± 0.050
2.500 ± 0.050
Index Area
3.000 ± 0.050
1.650 ± 0.050
Top View
Bottom View
+ 0.100
- 0.000
Pin 1 Indicator
(Optional)
0.180 ± 0.050
Side View
0.400 BSC
0.000
0.203 REF
0.750 ± 0.050
0.425 ± 0.050
Detail "A"
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3.The leadless package family, which includes QFN, TQFN, DFN, TDFN, and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
18
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DATA SHEET
AAT1290
1.5A Step-Up Current Regulator for Flash LEDs
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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19