AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
1
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
General Description
The AAT1410 is a step-up single channel LED driver with
an input voltage range of 2.7V to 5.5V. The wide input
voltage range, small solution size, advanced dimming
features and high efficiency is suitable for LED backlight
solutions for single cell Li-ion based equipment. A preci-
sion, high voltage current sink maintains the maximum
LED current set by an external resistor from 10 to 31mA.
The high switching frequency supports ultra small, low
cost filtering components.
Two dimming controls are available; 32 dimming steps
using the S2Cwire™ interface, and direct PWM control.
The frequency range of the PWM dimming extends up to
100 kHz eliminating audible noise and suitable for CABC
(Content Adaptive Brightness Control) applications.
The device includes over-temperature protection and
programmable over-voltage protection and recovers
automatically when the fault is removed. The AAT1410 is
available in a 10-pin wafer-level chip scale package
(WLCSP) and is rated over the -40°C to +85°C tempera-
ture range.
Features
•Input Voltage Range: 2.7 to 5.5V
•Drives up to 20V with 4 Series LEDs at 31mA
•1MHz Switching Frequency Allows Small External
Components
•Up to 86% Efficiency
•Dimming Control Options:
▪ 32 Steps - S2Cwire Single Wire Interface
▪ Direct PWM
•Low Operating Current at 2.3mA
•Shutdown Current < 1µA
•Over-Voltage Protection for Open-LED Faults
•Over Temperature Protection
•Ultra Small, Low Profile 10-pin 1.55 x 1.15mm WLCSP
Package
Applications
•Digital Still Cameras (DSC)
•Mobile Handsets
•Netbooks and Notebooks
•Portable Media Players
•White LED Drivers
Typical Application
LX
OVP
D1
VIN:
2.7V–5.5V
AAT1410
CS
L1 10μH
VOUT:
Up to 20V
at 31mA
COUT
1µF
25V
CIN
4.7µF
IN
GND
EN/SET
S2C
R1
R2
RSET
10k PGND
RSET
CCOMP
56nF
COMP
PWM
Up to 4
WLEDs
PWM
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
2Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Pin Descriptions
Pin # Symbol Function
A1 LX Switching node of boost converter. Connect an inductor between LX and input supply (VIN); Schottky
rectier anode is connected between LX pin while cathode is connected to output capacitor.
A2 IN Supply input for the IC. Connect a 4.7µF 6.3V/10V ceramic capacitor from this pin to GND.
A3 EN/SET Enable on/off control and S2Cwire interface input.
B1 PGND Power ground pin.
B3 PWM Input PWM pin. Pull high to disable the PWM dimming feature.
C1 GND Ground pin.
C3 COMP
Compensation pin. Connect a capacitor from this pin to GND. Compensation components are mainly
related to the output capacitor valued. See the Capacitor Selection section in the Application Infor-
mation section of this datasheet.
D1 CS Connect to the cathode of the last diode of the LED string.
D2 RSET Connect a resistor to GND to set maximum LED current up to 31mA.
D3 OVP Feedback pin for over-voltage protection.
Pin Configuration
WLCSP10 1.1 x1.5
(Top View)
A1 A2 A3
B1
C1
D1 D2
B3
C3
D3
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
3
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
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. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
3. Check Electrical Characteristics.
Absolute Maximum Ratings1
Symbol Description Value Units
VIN IN to GND, PGND -0.3 to 6.0 V
VLX LX to GND, PGND -0.3 to 24 V
VCS SINK to GND, PGND -0.3 to 20 V
VEN/SET
,VPWM, VRSET
,
VCOMP, VOVP
EN/SET, PWM, RSET, COMP, OVP to GND/PGND -0.3 to IN +0.3 V
Thermal Information2
Symbol Description Value Units
ΘJA Thermal Resistance 122 OC/W
PDMaximum Power Dissipation 820 mW
TJMaximum Junction Operating Temperature -40 to +155 OC
TLEAD Maximum Soldering Temperature (at leads, 10 sec.) 300
Recommended Operating Conditions
Symbol Description Min Typ Max Units
VIN Input Supply Voltage 2.7 5.5 V
VOUT Boosted Output Voltage VIN + 3V VOUT3V
L1 Inductor Value 4.7 10 22 μH
FPWM-D Input Direct PWM Frequency 100 100,000 Hz
TAAmbient Temperature Range - 40 85 °C
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
4Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
1. The AAT1410 is guaranteed to meet performance specification over the –40°C to +85°C operating temperature range, and is assured by design, characterization and correla-
tion with statistical process controls.
Electrical Characteristics1
VIN = 3.6V, CIN = 4.7µF, COUT = 1µF, L = 10µH, RSET = 10KΩ, TA = -40°C to 85°C unless otherwise noted. Typical values
are at TA= 25°C.
Symbol Description Conditions Min Typ Max Units
VIN Input Voltage Range 2.7 5.5 V
VOUT Maximum Output Voltage 20 V
IQQuiescent Supply Current VENSET = VIN 430 700 µA
ISHDN Input Shutdown Current VENSET = 0V 1 µA
IQSW Input Switching Current VENSET = VIN 2.3 mA
RDS(ON)N NMOS On-Resistance TA = 25°C 650 mΩ
η Maximum Efciency IOUT = 31mA 86 %
Fosc Switching Frequency TA = 25°C 1.0 MHz
TSS Soft-Start Time VENSET = VIN to 95% of output regulation,
CCOMP = 56nF 6 ms
DMAX Maximum Duty Cycle 94.0 %
VOVP-T OUT Over-Voltage Protection Threshold VOVP rising 1.1 1.2 1.3 V
VOVPH Over-Voltage Protection Hysteresis 75 mV
TSD Over-Temperature Shutdown Threshold 155 °C
THYS Over-Temperature Shutdown Hysteresis 15 °C
VCS Current Sink Voltage IOUT = 31mA 500 mV
ICS(ACC) Current Sink Accuracy RSET = 10KΩ 27.9 31.0 34.1 mA
VRSET RSET Voltage RSET = 10KΩ 1.206 V
EN/SET
VEN/SET (L) EN/SET VIN = 2.7V to 5.5V 0.4 V
VEN/SET (H) EN/SET VIN = 2.7V to 5.5V 1.4 V
tEN/SET(LOW) EN/SET Input Low Time 0.3 75 µs
tEN/SET(HI_MIN) EN/SET Minimum High Time 100 ns
tEN/SET(HIMAX) EN/SET Maximum High Time 75 µs
tEN/SET(OFF) EN/SET Input Off Timeout 500 µs
tEN/SET(LAT) EN/SET Latch Timeout 500 µs
IEN/SET (LK) EN/SET Input Leakage VENSET = 5V, VIN = 5V -1 1 µA
PWM
VPWM(L) Logic Threshold Low 0.4 V
VPWM(H) Logic Threshold High 1.4 V
IPWM(LK) PWM Input Leakage VPWM = 5V, VIN = 5V -1 1 µA
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
5
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Typical Characteristics
Quiescent Current vs. Input Voltage
Input Voltage (V)
Quiescent Current (µA)
2.73.1 3.53.9 4.34.7 5.
15
.5
85°C
25°C
-40°C
380
400
420
440
460
480
500
Shutdown Current vs. Input Voltage
Input Voltage (V)
Shutdown Current (µA)
2.73.1 3.53.9 4.34.7 5.
15
.5
0.00
0.02
0.04
0.06
0.08
0.10
85°C
25°C
-40°C
Efficiency vs. Output Current
(RSET = 10KΩ, L = 10µH, 4 LEDs)
Output Current (mA)
Efficiency (%)
0816 24 324122028
30
35
40
45
50
55
60
65
70
75
80
85
90
VIN = 2.7V
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
VIN = 5.0V
VIN = 5.5V
LED Current Accuracy vs. S2C
(VIN = 3.6V, L = 10µH)
S2C Data
Current (mA)
1917 25 335132129
0
4
8
12
16
20
24
28
32
RSET = 10KΩ
RSET = 15KΩ
RSET = 20KΩ
RSET = 25KΩ
RSET = 30KΩ
Sink Current Accuracy vs. Temperature
(VIN = 3.6V, RSET = 15kΩ)
Temperature (°C)
Current (mA)
-40-15 10 35 60 85
18.0
18.8
19.6
20.4
21.2
22.0
Sink Current Accuracy vs. Temperature
(VIN = 3.6V, RSET = 10kΩ)
Temperature (°C)
Current (mA)
-40-15 10 35 60 85
30.0
30.4
30.8
31.2
31.6
32.0
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
6Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Typical Characteristics
LED Current Accuracy vs. Input Voltage
(VIN = 3.6V, RSET = 15KΩ)
Input Voltage (V)
Current (mA)
2.73.1 3.53.9 4.34.7 5.15.5
18.8
19.2
19.6
20.0
20.4
20.8
21.2
Startup Time vs. C
COMP
(4 WLEDs)
CCOMP (nF)
t
SU
(ms)
10 20 30 40 50 60 70 80 90 100
0
3
6
9
12
15
EN Input High Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
EN(H)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
0.5
0.6
0.7
0.8
0.9
1.0
1.1
85°C
25°C
-40°C
EN Input Low Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
EN(L)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
0.4
0.5
0.6
0.7
0.8
0.9
1.0
85°C
25°C
-40°C
NMOS R
DS(ON)N
vs. Input Voltage
Input Voltage (V)
R
DS(ON)
(mΩ)
2.73.1 3.53.9 4.34.7 5.15.5
400
500
600
700
800
900
1000
85°C
25°C
-40°C
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
7
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Typical Characteristics
PWM Input High Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
PWM(H)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
0.5
0.6
0.7
0.8
0.9
1.0
1.1
85°C
25°C
-40°C
PWM Input Low Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
PWM(L)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
0.4
0.5
0.6
0.7
0.8
0.9
1.0
85°C
25°C
-40°C
OVP High Threshold Voltage vs. Input Voltage
Input Voltage (V)
V
OVP(H)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
1.15
1.17
1.19
1.21
1.23
1.25
85°C
25°C
-40°C
OVP Low Threshold Voltage vs. Input Voltage
Input Voltage (V)
V
OVP(L)
(V)
2.73.1 3.53.9 4.34.7 5.15.5
1.00
1.04
1.08
1.12
1.16
1.20
85°C
25°C
-40°C
LED Current vs. PWM Duty Cycle
(VIN = 3.6V, RSET = 10KΩ)
Duty Cycle (%)
Current (mA)
1020 030405060708090100
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
LED Current vs. PWM Duty Cycle
(VIN = 3.6V, RSET = 15KΩ)
Duty Cycle (%)
Current (mA)
1020 030405060708090100
0
2
4
6
8
10
12
14
16
18
20
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
8Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Typical Characteristics
Startup Waveform
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF,
CCOMP = 56nF, RSET = 10KΩ, 4 LEDs)
Time (2ms/div)
EN
(5V/div)
VOUT
(10V/div)
IIN
(200mA/div)
ILED
(20mA/div)
0
0
0
0
Turn Off
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF,
CCOMP = 56nF, RSET = 10KΩ, 4 LEDs)
Time (100µs/div)
EN
(5V/div)
VOUT
(20V/div)
IIN
(200mA/div)
ILED
(20mA/div)
0
0
0
0
Operation Waveform
(VIN = PWM = 3.6V; CIN = 4.7μF, COUT = 1μF,
CCOMP = 56nF, RSET = 10KΩ, 4 WLEDs)
Time (1µs/div)
VLX
(10V/div)
VOUT (AC)
(200mV/div)
IINDUCTOR
(200mA/div)
ILED
(20mA/div)
0
0
0
0
PWM Dimming Operation Waveform
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF,CCOMP = 56nF,
RSET = 10KΩ, PWM = 1kHz, 50% Duty Cycle, 4 WLEDs)
Time (400µs/div)
PWM
(5V/div)
VOUT (AC)
(200mV/div)
VIN (AC)
(200mV/div)
ILED
(20mA/div)
0
0
0
0
LED Current Transition by S2C
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF, CCOMP = 56nF,
RSET = 10KΩ, 31mA to 15mA, 4 LEDs)
Time (400µs/div)
EN/SET
(5V/div)
VOUT
(10V/div)
IIN
(100mA/div)
ILED
(20mA/div)
0
0
0
0
LED Current Transition by S2C
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF, CCOMP = 56nF,
RSET = 10KΩ, 15mA to 31mA, 4 LEDs)
Time (1ms/div)
EN/SET
(5V/div)
VOUT
(10V/div)
IIN
(100mA/div)
ILED
(20mA/div)
0
0
0
0
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
9
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Typical Characteristics
LED Current Transition by PWM
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF, CCOMP = 56nF, RSET = 10KΩ,
PWM = 10KHz, Duty Cycle = 50% to 100%, 4 LEDs)
Time (200µs/div)
PWM
(5V/div)
VOUT
(10V/div)
IIN
(100mA/div)
ILED
(20mA/div)
0
0
0
0
LED Current Transition by PWM
(VIN = 3.6V; CIN = 4.7μF, COUT = 1μF, CCOMP = 56nF, RSET = 10KΩ,
PWM = 10KHz, Duty Cycle = 50% to 100%, 4 LEDs)
Time (200µs/div)
PWM
(5V/div)
VOUT
(10V/div)
IIN
(100mA/div)
ILED
(20mA/div)
0
0
0
0
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Functional Description
The AAT1410 is a small size, high efficiency, current mode
controlled step-up converter LED driver for up to 4 white
LEDs. It is available with up to 20V output voltage to
allow up to 4 series connected LEDs to be driven with
currents up to 31mA. The device uses a single current
sink to regulate the LED current by controlling the output
voltage. The maximum LED current is programmed by an
external resistor with range from 10mA to 31mA. The
LED current dimming is controlled via one of two options,
using either the S2Cwire 32-step single-wire interface or
PWM control.
The over-voltage protection function is designed to pro-
tect the boost converter during the fault of the open
circuit of the LED string. The over-temperature function
is targeted to protect the converter if an over-tempera-
ture fault occurs. The AAT1410 will recover to normal
operation automatically when the OVP or OTP fault is
removed.
Soft Start / Enable
The AAT1410 is enabled by EN/SET pulled to high after
power on with a certain delay time. Internal soft start
circuitry limits the input inrush current and eliminates
output voltage overshoot. When ENSET is pulled low the
AAT1410 enters a low-power, non-switching state. The
total input current during shutdown is less than 1μA. An
external diode limits VOUT to the level of VIN during shut-
down. The diode consumes a small amount of additional
input current depending on the OVP resistor divider
value.
Over-Temperature Protection
Thermal protection disables the AAT1410 when internal
dissipation becomes excessive. Thermal protection dis-
ables the power MOSFET. The junction over-temperature
threshold is 155°C with 15°C of temperature hysteresis.
The output voltage automatically recovers when the
over-temperature fault condition is removed.
Functional Block Diagram
GND
PWM
EN/SET
COMP
IN
LX PGND
OVP
OSC
REF
Interface
Control
CS
RSET
OVP
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
11
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Over-Voltage Protection
Over-voltage protection prevents damage to the AAT1410's
LX pin during open-circuit or high output voltage condi-
tions. An over-voltage event is defined as a condition
where the voltage on the OVP pin exceeds the over-volt-
age protection threshold (VOVP-T). When VOVP has reached
the threshold limit, the converter stops switching and the
output voltage decays. Switching resumes when the lower
hysteresis limit of VOVP is reached, thereby maintaining an
average output voltage between the upper and lower OVP
thresholds.
LED Current Setting
The maximum LED current is determined by the RSET
resistor value. With a fixed 1.2V voltage on RSET
, the LED
maximum current is a linear ratio to the current flowing
through RSET
.
V
SET
R
SET
I
LED
= · 258
The LED dimming is controlled via one of two options,
either using the 32-step S2Cwire single-wire interface via
the EN/SET pin or PWM control with varied duty cycle up
to 100kHz frequency. 32 S2Cwire rising-edge steps set the
LED current from 100% to 2% percentage of the maxi-
mum LED current value when PWM control is disabled by
pulling the PWM pin high. S2Cwire can also be used to set
maximum LED current along with a PWM signal to dim the
LED lighting from 100% to 1% of duty cycle.
S2Cwire™ Serial Interface
The LED current magnitude can be controlled by the EN/
SET pin using the S2Cwire interface. The interface records
rising edges of the EN/SET pin and decodes them into 32
individual current level settings. Code 1 is full scale
(maximum LED current), and Code 32 is 2% of the full
scale. The modulo 32 interface wraps states back to state
1 after the 32nd clock. The counter can be clocked at
speeds up to 1MHz, so intermediate states are not visi-
ble. The first rising edge of EN/SET enables the IC and
initially sets the output LED current to full scale after
500µs tLAT. Once the final clock cycle is input for the
desired brightness level, the EN/SET pin should be held
high to maintain the device output current at the pro-
grammed level. The device is disabled 500μs after the
EN/SET pin enters a logic low state. The EN/SET timing
is designed to accommodate a wide range of data rates
from 20kHz to 1MHz.
After the first rising edge of EN/SET, the boost converter
is enabled and reaches full capacity after the soft-start
time. Exact counts of clock pulses for the desired current
level should be entered on the EN/SET pin with a single
burst of clocks. The counter refreshes each time a new
clock input to the EN/SET pin is detected. A constant cur-
rent is maintained as long as EN/SET remains in a logic
high state. To save power, the boost converter is switched
off after EN/SET has remained in the low state for at least
the tOFF timeout period as shown in Figure 1.
S2Cwire Serial Interface Timing
1
EN/SET
2n-1 n ≤32
Data Reg
0n
0
THI
TLO TLAT TOFF
Figure 1: S2Cwire Timing Diagram.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Application Information
LED Current Setting
The maximum LED current is determined by value of the
external resistor RSET from 10mA to 31mA. The value of
RSET is determined by the voltage of RSET and the LED
current, and can be calculated by:
V
SET
· 258
I
LED
R
SET
=
Where VSET = 1.2V. Table 1 lists examples of standard 1%
metal film RSET values for different maximum LED current
requirements.
Maximum LED Current (mA) RSET (kΩ)
31 10
20 15
15 20
12 25
10 30
Table 1: Examples of Standard 1% RSET Values for
Setting Maximum LED Current Levels.
LED current dimming is controlled either via the S2Cwire
single-wire interface through the EN/SET pin in 32 steps
or via PWM control with varied duty cycle up to 100kHz
frequency. The S2Cwire interface programs the LED cur-
rent from the maximum LED current set by RSET to 2%
of the maximum LED current as shown in Table 2.
S2Cwire
Data
LED Current
(% IMAX)
S2Cwire
Data
LED Current
(% IMAX)
1 100 17 48
2 97 18 45
3 94 19 42
4 90 20 39
5 87 21 35
6 84 22 32
7 81 23 29
8 77 24 26
9 74 25 23
10 71 26 19
11 68 27 16
12 65 28 13
13 61 29 10
14 58 30 6
15 55 31 3
16 52 32 2
Table 2: S2Cwire Dimming Control
Current Settings.
Figure 2 illustrates the LED current value at different
S2Cwire code settings when RSET is 15kΩ with a maxi-
mum LED current of 20mA.
I
LED
(mA)
ILED (mA)
135791113151719212325272931246810 12 14 16 18 20 22 24 26 28 30 32
0
2
4
6
8
10
12
14
16
18
20
22
Figure 2: S2Cwire Dimming Control
at Maximum LED Current (20mA max).
Direct PWM Dimming
The AAT1410 provides a PWM input as an additional
means of providing dimming control for CABC applica-
tions. The LED current reduces percentage linearly as
the duty cycle decreasing. Frequencies of up to 100kHz
can be applied. The PWM signal turns the LED string cur-
rent on and off directly with the same duty cycle PWM
fed in. The average DC LED current is dimmed linearly
as the duty cycle decreases.
I
LED
(mA)
Duty Cycle (%)
100 90 80 70 60 50 40 30 20 10 095 85 75 65 55 45 35 25 15 5
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
Figure 3: Direct PWM Dimming Duty Cycle vs.
Maximum LED Current (31mA max).
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
13
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Capacitor Selection
A compensation capacitor CCOM is used for step-up con-
verter loop compensation and soft startup time control.
Loop compensation requires matching values for CCOM,
COUT
, ILED, and VOUT:
LED
30 · 10
-6
· V
OUT
OUT
C
COM
<
The AAT1410 can drive up to 4 white LEDs with forward
voltages up to 4V each. In a worst case with VF of 4V, a
COUT value of 1µF, and LED maximum current of 20mA,
the value of CCOM should be higher than 3.6nF.
C
OUT
· 30 · V
OUT
I
LED
1 · 30 · 16
20
C
COM
> (nF) = (nF) = 24nF
A higher value for CCOM lengthens the soft startup time.
The relationship between CCOM and startup time is almost
linear, with startup time x 105 magnification of CCOM; thus
56nF CCOM leads to a soft startup time of 5.6ms. Table 3
gives several examples of minimum CCOM values at differ-
ent COUT and ILED and the step-up converter's operation
stable. Values of 56nF for CCOM and 1µF for COUT are suit-
able in most cases.
ILED (mA) COUT (µF) VOUT (V) CCOM_MIN (nF)
31 0.1 16 1.6
31 1 16 16
20 0.1 16 2.4
20 1 16 24
10 0.1 16 4.8
10 1 16 48
Table 3: Minimum CCOM Values vs. ILED and COUT
(Step-Up Converter Operation Stable).
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 as input, output and compen-
sation capacitors in the AAT1410 step-up converter LED
driver application. MLC capacitors of type X7R or X5R are
recommended to ensure good capacitance stability over
the full operating temperature range. A 4.7µF/6.3V input
capacitor is recommended and a 1µF/25V output capaci-
tor is suitable as noted above. Table 4 lists some recom-
mended capacitors for use with the AAT1410.
Inductor Selection
Inductor value, saturation current and DCR is most impor-
tant parameter in selecting an inductor for AAT1410.
The suitable inductance range for the AAT1410 is 4.7µH
to 22µH. Higher inductance lowers the step-up convert-
er's RMS current value. Together with lower DCR value
of the inductor, it makes the total inductor power loss
become much lower. Considering inductor size and cost,
10µH inductance is most suitable. Figure 4 illustrates
AAT1410 efficiency at different inductance with similar
DCR value.
Efficiency (%)
ILED (mA)
24068101214161820222426283
03
2
30
34
38
42
46
50
54
58
62
66
70
74
78
82
86
90
4.7µH
10µH
22µH
Figure 4: AAT1410 Efficiency at Different
Inductance with Similar DCR (VIN = 3.6V).
Manufacturer Part Number Value (µF) Voltage (V) Temperature Range Case Size
Murata
GRM188R60J475K 4.7 6.3 X5R 0603
GRM188R71H104KA93 0.1 50 X7R 0603
GRM188R61E105K 1.0 25 X5R 0603
Table 4: Examples of AAT1410 Input and Output Capacitor Selection.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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Manufacturer Part Number
Inductance
(µH)
Maximum DC ISAT
Current (mA)
DCR
(mΩ, typ)
Size (mm)
LxWxH Type
Sumida CDRH3D18-100 10 900 164 4.0x4.0x2.0 Shielded
CDRH3D23-220 22 550 219 3.9x3.9x2.5 Shielded
Murata LQH44PN100MP0L 10 1150 160 4.0x4.0x1.65 Non-shielded
LQH44PN220MP0L 22 800 370 4.0x4.0x1.65 Non-shielded
Coilcraft EPL2014-103MLC 10 600 440 2.1x2.2x1.0 Shielded
LPS4012-223MLC 22 790 600 4.1x4.1x1.2 Shielded
Coiltronics SD18-100-R 10 982 158 5.8x5.8x1.8 Shielded
Table 5: Example of AAT1410 Inductor Selection.
Considering the inductor copper loss, the inductor DCR
value together with the RMS current value flowing
through the inductor leads to inductor conduction loss
and also affects total efficiency. Larger DCR leads to
larger conduction loss and decreases total efficiency. The
inductor conduction loss can be estimated as shown in
the equation:
1
3
P
L_LOSS
= I
2
L_RMS
· DCR
=· (I
2
L_MAX
+ I
2
L_MIN
+ I
L_MAX
· I
L_MIN
) · DCR
IL_MAX and IL_MIN are the inductor peak current and mini-
mum current. Figure 5 shows DCR effects on efficiency
with a 10µH inductor.
Efficiency (%)
ILED (mA)
24068101214161820222426283
03
2
30
34
38
42
46
50
54
58
62
66
70
74
78
82
86
90
10µH DCR 235mΩ 3.2x3.2x1.55mm
10µH DCR164mΩ 4.0x4.0x2.0mm
10µH DCR 36mΩ 8.3x8.3x3.0mm
Figure 5: Inductor DCR Effects on
Total Efficiency with 10µH at 3.6V VIN.
Inductor saturation current is also a key parameter in
selecting an inductor. For the step-up converter, the peak
inductor current is the DC input current plus half the
inductor peak-to-peak current ripple.
DC input current:
V
OUT
· I
LED
V
IN
· η
I
IN
=
Inductor peak-to-peak current ripple:
V
IN
· (V
OUT
- V
IN
)
V
OUT
· L · f
I
L_PP
=
Inductor peak current:
V
IN
· (V
OUT
- V
IN
)
2 · V
OUT
· L · f
V
OUT
· I
LED
V
IN
· η
I
L_PP
2
I
L_PEAK
= I
IN
+ = +
For example, for a white LED with 3.2V VF and 20mA
current at 82% efficiency, the inductor peak current is
3.6 · (3.2 · 4 - 3.6)
2 · 3.2 · 4 · 10µ · 1M
3.2 · 4 · 0.02
3.6 · 0.82
I
L_PEAK
= + = 218mA
Table 5 gives some examples of recommended inductors
for use with the AAT1410.
OVP Setting
Over-voltage protection is designed to protect the step-up
converter from a LED string open fault. The OVP threshold
is 1.2V. For 4 white LEDs with VF up to 4V, the resistor
divider values for R1 and R2 can be calculated by:
V
OUT
V
OVP_TH
R
1
= - 1· R
2
Higher resistor divider values decrease the power loss on
the resistors. The total resistor value for 16V VOUT should
be less than 1.6MΩ for better noise immunity. Values of
634kΩ for resistor R1 and 51kΩ for resistor R2 are rec-
ommended.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
15
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Manufacturer
Part
Number
Maximum
DC Blocking
Voltage VR
(V)
Maximum
DC Forward
Current IF
(mA)
Non-repetitive
Peak Forward
Surge Current
IFSM (A)
Forward
Voltage
VF (V) Case
Size WxLxH
(mm)
Diodes SDM20U40 40 250 1.0 0.37@20mA SOD523 0.9x1.7x0.65
SD103BW 30 350 1.5 0.37@20mA SOD123 1.7x3.85x1.35
Central CMDSH2-3 30 200 1.0 0.32@15mA SDD323 1.35x2.6x1.0
Fairchild MBR0520 20 500 5.5 0.3@0.1A SOD123 1.7x3.85x1.35
MBR0530 30 500 5.5 0.375@0.1A SOD123 1.7x3.85x1.35
TSC SS13L 30 1100 30 0.51@0.5A Sub SMA 1.9x3.8x1.43
SS14L 40 1100 30 0.51@0.5A Sub SMA 1.9x3.8x1.43
Table 6: Example of Typical Rectifier Diode.
Rectifier Diode Selection
An external rectifier diode is required for the non-syn-
chronous step-up converter. A low VF Schottky diode is
recommended. The diode voltage rating should be higher
than the OVP voltage. For an AAT1410 driving 4 white
LEDs with up to 4V forward voltage, the diode voltage
rating should be higher than 16V. Select a diode with DC
rated current equal to the input current to allow an ade-
quate margin for safe use.
Printed Circuit Board
Layout Recommendations
For best performance of the AAT1410, the following
guidelines should be followed when designing the PCB
layout:
1. Make the power trace as short and wide as possible,
including the input/output power lines and switching
node, etc.
2. Make sure the ground bump connected to the print-
ed circuit board with large copper area for better
thermal dissipation.
3. Put the input and output capacitor close to the IC as
close as possible to get the best filter result.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Schematic and Layout
S2Cwire/PWM
Microcontroller
AAT1410
White LED
Driver
CIN
4.7µF
L1 10µH
634k
R1
51k
R2
COUT
1μF
25V
DS1
SDM20U40
DC+
DC-
J2
PWM
CCOM
56nF
RSET
15k
VIN
R3
51k
R4
51k
C1
0.1µF
R7
1k
R8
1k
R9
1k
R5
1k
R6 51k
V_MCU EN/SET
S2C
UP
DOWN
CYCLE
PIC12F675
VDD
1
GP5
2
GP4
3
GP3
4GP2 5
GP1 6
GP0 7
VSS 8
U2
LED1
Red
J1
VIN
PGND
B1
LX A1
GND
C1
CS D1
RSET
D2
PWM
B3
COMP
C3
IN
A2
EN/SET
A3
OVP D3
AAT1410IUQ
U1
1
2
3
J3
VMCU
PWM
D1
D2
D3
D4
Figure 6: AAT1410 Evaluation Board Schematic.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
17
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Figure 7: AAT1410 Evaluation Board Figure 8: AAT1410 Evaluation Board
Top Side Layout. Top Side Layout (detail).
Figure 9: AAT1410 Evaluation Board Bottom Side Layout.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Component Part Number Description Manufacturer
U1 AAT1410IUQ High Efciency Serial LED Driver for 4 White LEDs Skyworks
U2 PIC12F675 8-Pin Flash-Based 8-Bit CMOS Microcontroller Microchip
R1 RC0603FR-07634KL Res 634kΩ 1/10W 1% 0603 SMD
Yageo
R2, R3, R4, R6 RC0603FR-0751KL Res 51KΩ 1/10W 1% 0603 SMD
RSET RC0603FR-0715KL Res 15KΩ 1/10W 1% 0603 SMD
R5, R7, R8, R9 RC0603FR-071KL Res 1KΩ 1/10W 1% 0603 SMD
CIN GRM188R60J475K Cap Ceramic 4.7μF 0603 X5R 6.3V 10%
Murata
COUT GRM188R61E105K Cap Ceramic 1μF 0603 X5R 25V 10%
C1 GRM188R71C104K Cap Ceramic 0.1μF 0603 X7R 16V 10%
CCOM GRM188R71C563K Cap Ceramic 0.056μF 0603 X7R 16V 10%
D1, D2, D3, D4 RS-0805UW 20mA White LED 0805 Realstar
DS1 SDM20U40 Surface Mount Schottky Barrier Diode Diodes
L1 CDRH3D18-100NC Power Inductor 10μH 0.9A SMD Sumida
LED1 0805KRCT Red LED 0805 HB
CYCLE, UP, DOWN 6*6*5 12V 50mA Pushbutton E-LT
Table 7: AAT1410 Evaluation Board Bill of Materials (BOM).
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
19
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
1. YY = date code.
2. Sample stock is generally held on part numbers listed in BOLD.
Ordering Information
Package Maximum # of LEDs Interface Marking1Part Number (Tape and Reel)2
WLCSP-10 4 S2C, Direct PWM G5YY AAT1410IUQ-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
WLCSP-10
1.145 ± 0.035
0.800 BSC
0.265 ± 0.015
1.545 ± 0.035
0.200 BSC
1.200 BSC
0.400 BSC
ø 0.2 (Ref.)
Pin A1 indication
Line_1 Line_2
0.100
0.100
0.300
0.300
0.380 ± 0.025
0.200 ± 0.025 0.070 ± 0.035
Bottom View Top View
End View
0.650 ± 0.085
Side View
All dimensions in millimeters.
AAT1410
DATA SHEET
Serial LED Driver with Direct PWM and 32-Step S2C Dimming Control
20 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202119A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 29, 2012
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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