AAT3369-1 - Skyworks Solutions, Inc.

DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
General Description
Features
The AAT3369-1 is a low-noise, constant-frequency charge
pump DC/DC converter that uses a dual-mode load switch
(1x) and fractional (1.5x) conversion to maximize efficiency for white LED CABC (Content Adaptive Brightness
Control) applications. The AAT3369-1 is capable of driving
6 white LEDs at a total 126mA in a wide input range. The
current sinks may be operated individually or in parallel
for driving higher-current LEDs. A low external parts
count (two 1µF flying capacitors and two small 1µF capacitors at IN and OUTCP) makes the AAT3369-1 ideally
suited for small battery-powered applications.
2.7V to 5.5V Supply Voltage Range
Drives up to 6 LEDs with up to 21mA each
126mA of Total Drive Current
Charge Pump with Automatic Switching Between 1x
and 1.5x Modes
Linear LED Output Control
• S2C Interface: 32 Steps from 21mA to 0.3mA
• PWM Interface: Up to 100kHz from 1% to 100%
Duty Cycle
< 1.0µA Input Current in Shutdown
Small Application Circuit
Short Circuit Protection
0.9MHz Constant Frequency
Automatic Soft-Start Limits Inrush Current
-40°C to 85°C Temperature Range
RoHS Compliant and Halogen Free TQFN3x2.2-18L
Package
Skyworks' S2Cwire serial digital input is used to enable
and set maximum current to one of 32 levels for the
LEDs. The maximum LED current ranges from 21mA to
0.3mA. A PWM input can also be adopted to dim the LED
current from the maximum LED current to 1% of maximum LED current by PWM frequencies up to 100kHz.
Low level at both S2Cwire and PWM inputs shutdown the
IC with less than 1µA input current.
Each output of the AAT3369-1 is equipped with built-in
short-circuit protection and auto-recover when the fault
condition is removed. The soft-start circuitry prevents
excessive inrush current at start-up and mode transitions. The AAT3369-1 is available in the Pb-free, spacesaving TQFN3x2.2-18L package, and operates over the
-40°C to +85°C ambient temperature range.
Applications
•
•
•
•
•
Camera Phone
LED Photo Flash/Torch
MP3/MP4 Players
PDAs and Notebook PCs
Smart Phone
Typical Application
VIN
2.7V ~ 5.5V
C1
1µF
CIN
1µF
PWM
S2C
CFLT
56nF
C1+
C2+
C1C2IN OUTCP
AAT3369-1
PWM
EN/SET
FCAP
GND
C2
1µF
COUT
1µF
WLEDs
D1
D2
D3
D4
D5
D6
D1
D2
D3
D4
D5
D6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
1
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Pin Descriptions
Pin #
Symbol
Function
1, 18
2
3
4
5
6
7
OUTCP
C1C1+
C2N/C
IN
GND
O
I
I
I
P
PG
8
PWM
I
9
FCAP
I
10
11
12
13
14
15
D1
D2
D3
D4
D5
D6
I
I
I
I
I
I
16
EN/SET
I
17
C2+
EP
I
Description
Charge-pump output. Connect a 1µF bypass capacitor between this pin to ground.
Flying capacitor C1 negative terminal. Connect a 1.0µF capacitor between C1+ and C1-.
Flying capacitor C1 positive terminal. Connect a 1.0µF capacitor between C1+ and C1-.
Flying capacitor C2 negative terminal. Connect a 1.0µF capacitor between C2+ and C2-.
Not connected.
Input power supply pin. Connect a 1µF bypass capacitor from this pin to ground.
Ground connection.
PWM signal input. Connect a PWM signal to dim the LED current linearly from the max LED current
set by S2Cwire to 1% by PWM duty cycle. The default max LED current is 21mA when EN/SET is
low. The frequency of the PWM signal may be up to 100kHz. Tie to ground if PWM is not used.
PWM filter capacitor. For 50kHz PWM signal, a 56nF capacitor is recommended. If PWM control is
not used, leave this pin open.
LED driver current sink terminal D1. Connect LED cathode to this pin. Tie to OUTCP if not used.
LED driver current sink terminal D2. Connect LED cathode to this pin. Tie to OUTCP if not used.
LED driver current sink terminal D3. Connect LED cathode to this pin. Tie to OUTCP if not used.
LED driver current sink terminal D4. Connect LED cathode to this pin. Tie to OUTCP if not used.
LED driver current sink terminal D5. Connect LED cathode to this pin. Tie to OUTCP if not used.
LED driver current sink terminal D6. Connect LED cathode to this pin. Tie to OUTCP if not used.
Charge pump max LED current enable/set input. Connect a S2Cwire signal to set max LED current from 21mA to 0.2mA by 32 steps. Pull low together with PWM low to shut down AAT3369-1
with less than 1µA input current. Tie to ground if not used.
Flying capacitor C2 positive terminal. Connect a 1.0µF capacitor between C2+ and C2-.
Exposed pad. Connect to ground directly beneath the package.
Pin Configuration
TQFN3x2.2-18
(Top View)
OUTCP
C1C1+
C21
2
3
4
N/C
IN
GND
PWM
FCAP
5
18
6
17
7
16
8
15
9
14
OUTCP
C2+
EN/SET
D6
D5
13
12
11
10
D4
D3
D2
D1
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Absolute Maximum Ratings1
TA = 25OC unless otherwise noted.
Symbol
VIN
VEN
IOUT
TJ
TS
TLEAD
Description
Input Voltage
EN/SET, PWM to GND Voltage
Maximum DC Output Current (continuous)2
Maximum Junction Operating temperature
Storage Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6.0
-0.3 to 6.0
200
-40 to 150
-65 to 150
300
V
V
mA
°C
°C
°C
Value
Units
65.83
38.90
1.5
°C/W
°C/W
W
Thermal Information3
Symbol
θJA
θJC
PD
Description
Thermal Resistance from Junction to Ambient
Thermal Resistance from Junction to Case
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.
2. Based on long-term current density limitation.
3. Mounted on an FR4 board.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
3
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Electrical Characteristics1
VIN = 3.6V; CIN = 1µF; COUT = 1µF; CFLY = 1µF; CFLT = 56nF; TA = -40°C to 85°C, unless otherwise noted. Typical values
are TA = 25°C.
Symbol
Description
Conditions
Input Power Supply
VIN
Input Voltage Range
VOUT (max)
Maximum Output Voltage
IQ
Operating Current
ISHDN(MAX)
Shutdown Current
Charge Pump Section
IOUT(MAX)
Maximum Output Current
fosc
Oscillator Frequency
tSS
Charge Pump Set Up Time
VIN_(TH)
Charge Pump Mode Hysteresis
LED Current Sink Outputs
IDX
IDX(MATCH)
VD_(TH)
Typ
Max
Units
5.5
V
V
2.7
1x Mode, No Load Current, CP enabled
1.5x Mode, ID1 = FS, excluding ID1,
VD2 = VD3 = VD4 = VD5 = VD6= IN
EN = 0
1.5x to 1x Transition, ID1 = ID2 = ID3 =
ID4 = ID5 = ID6 = 21mA
Data 1 and PWM = 100%, TA = 25°C
Data 32 only, TA = 25°C
Current Marching Between Any Two Current
Sinks3
VF; D1:D6 = 3.6V
Charge Pump Mode Transition
1x to 1.5x Mode, ID1 = ID2 = ID3 = ID4 =
ID5 = ID6 = 21mA
5.5
0.5
1
2
4
1.0
VF = 3.6V
ISINK Current Accuracy2
S Cwire Control and EN/SET Control
VEN/SET (L)
EN/SET or PWM Input Low Threshold Voltage
VEN/SET (H)
EN/SET or PWM Input High Threshold Voltage
ILEAK
EN/SET Input Leakage
tEN/SET(LOW)
EN/SET Input Low Time
tEN/SET(HI_MIN) EN/SET Minimum High Time
tEN/SET(HIMAX) EN/SET Maximum High Time
tEN/SET(OFF)
EN/SET Input Off Timeout4
tEN/SET(LAT)
EN/SET Latch Timeout5
PWM Control
VPWM(L)
PWM Input Low Threshold Voltage
VPWM(H)
PWM High Threshold Voltage
TPWM(ON)
PWM Turn On Delay
FPWM(MIN)
PWM Minimum Input Control Frequency
FPWM(MAX)
PWM Maximum Input Control Frequency
FPWM(MIN)
PWM Minimum Duty Cycle
Thermal
TSD
TJ Thermal Shutdown Threshold
THYS
TJ Thermal Shutdown Hysteresis
Min
mA
µA
126
0.9
100
mA
MHz
µs
300
mV
-10
+10
±15
%
-5
+5
200
mV
2
0.4
1.4
-1
0.3
1
75
50
75
500
500
0.4
1.4
500
100
100
FPWM = 50kHz, Full Scale
1
140
20
V
V
mA
µs
ns
µs
µs
µs
V
V
µs
Hz
kHz
%
O
C
1.The AAT3369-1 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.
2. Determined by the average of all active channels.
3. Current matching is defined as the deviation of any sink current from the average of all active channels.
4. The EN/SET pin must remain logic low (less than VIL) for the duration of longer than 500μs to guarantee the off timeout.
5. The EN/SET pin must remain logic high (greater than VIH) for the duration of longer than 500μs to guarantee the latch timeout.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Typical Characteristics
Operating Current vs. Input Voltage
Operating Current vs. Input Voltage
(1.5x Mode)
1.2
3.0
1.0
2.5
0.8
2.0
IQ (mA)
IQ (mA)
(1x Mode)
0.6
0.4
85°C
25°C
-40°C
0.2
0.0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
85°C
25°C
-40°C
1.5
1.0
0.5
0.0
2.7
5.5
3.1
3.5
Input Voltage (V)
Input Current vs. Input Voltage
0.08
0.06
0.04
2.7
3.1
3.5
3.9
4.3
4.7
5.1
0.00
-40
5.5
-15
Input Voltage (V)
100%
Frequency (MHz)
70%
60%
50%
3.1
3.5
3.9
4.3
Input Voltage (V)
60
85
0.92
80%
2.7
35
Frequency vs. Temperature
VF = 3.3V, ILED = 21mA
VF = 3.1V, ILED = 10mA
VF = 2.9V, ILED = 5mA
90%
10
Temperature (°C)
Efficiency vs. Input Voltage
Efficiency (%)
5.5
0.02
0.04
40%
5.1
0.08
0.12
0.00
4.7
0.10
VF = 3.3V, ILED = 21mA
VF = 3.1V, ILED = 10mA
VF = 2.9V, ILED = 5mA
0.16
4.3
Shutdown Current vs. Temperature
ISHDN (µA)
Input Current (A)
0.20
3.9
Input Voltage (V)
4.7
5.1
5.5
0.91
0.90
0.89
0.88
0.87
-40
-15
10
35
60
85
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
5
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Typical Characteristics
Current Matching vs. Input Voltage
Current Matching vs. Input Voltage
(S2C Data = 1)
(S2C Data = 32)
0.50
0.44
21
D1
D2
D3
D4
D5
D6
19
17
15
Current (mA)
Current (mA)
23
2.7
3.1
3.5
3.9
4.3
4.7
5.1
0.38
D1
D2
D3
D4
D5
D6
0.32
0.26
0.20
2.7
5.5
Input Voltage (V)
3.1
21.6
0.38
Current (mA)
Current (mA)
0.40
21.0
D1
D2
D3
D4
D5
D6
-15
10
35
60
0.34
0.30
-40
85
1.0
0.8
0.8
VENL (V)
VENH (V)
1.0
0.6
85°C
25°C
-40°C
3.5
3.9
4.3
Input Voltage (V)
6
-15
10
4.7
35
60
85
EN Input Low Threshold Voltage
vs. Input Voltage
1.2
3.1
D1
D2
D3
D4
D5
D6
1.2
2.7
5.5
Temperature (°C)
EN Input High Threshold Voltage
vs. Input Voltage
0.2
5.1
0.36
0.32
Temperature (°C)
0.4
4.7
(S2C Data = 32)
22.2
19.8
4.3
Current Matching vs. Temperature
(S2C Data = 1)
20.4
3.9
Input Voltage (V)
Current Matching vs. Temperature
19.2
-40
3.5
5.1
0.6
85°C
25°C
-40°C
0.4
0.2
2.7
5.5
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
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
5.1
5.5
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Typical Characteristics
EN/SET Input OFF Time vs. Input Voltage
450
450
390
390
330
tOFF (µs)
tLAT (µs)
EN/SET Input Latch Time vs. Input Voltage
270
85°C
25°C
-40°C
210
150
2.7
3.1
3.5
3.9
4.3
4.7
330
270
85°C
25°C
-40°C
210
5.1
150
2.7
5.5
3.1
3.5
Input Voltage (V)
1.2
1.2
1.0
1.0
0.8
0.6
85°C
25°C
-40°C
0.4
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Turn On to 1x Mode
(VIN = 4.2V, CIN = COUT = 1μF, CF = 56nF, 21mA/Channel)
VOUT
(2V/div)
ILED
(20mA/div)
4.7
5.1
5.5
0.8
0.6
85°C
25°C
-40°C
0.4
0.2
2.7
3.1
Input Voltage (V)
EN
(2V/div)
IIN
(200mA/div)
4.3
PWM Input Low Threshold Voltage
vs. Input Voltage
VPWML (V)
VPWMH (V)
PWM Input High Threshold Voltage
vs. Input Voltage
0.2
3.9
Input Voltage (V)
0
Time (20ms/div)
4.7
5.1
5.5
Turn On to 1.5x Mode
ILED
(20mA/div)
0
4.3
(VIN = 3.6V, CIN = COUT = 1μF, CF = 56nF, 21mA/Channel)
VOUT
(2V/div)
0
3.9
Input Voltage (V)
EN
(2V/div)
IIN
(200mA/div)
0
3.5
0
0
0
0
Time (20ms/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
7
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Typical Characteristics
Turn Off
CP Mode Transient
(VIN = 3.6V, CIN = COUT = 1μF, CF = 56nF, 21mA/Channel)
EN
(2V/div)
IIN
(200mA/div)
VOUT
(2V/div)
(VIN = 3.6V to 4.2V, CIN = COUT = 1μF, 21mA/Channel)
VIN
(2V/div)
VOUT
(2V/div)
0
0
ILED
(20mA/div)
IIN
(200mA/div)
0
Time (100µs/div)
0
0
0
Time (100µs/div)
LED Current Transient
LED Current Transient
(VIN = 3.6V, CF = 56nF, 0.4mA to 21mA)
VEN
(2V/div)
IIN
(200mA/div)
(VIN = 3.6V, 21mA to 0.4mA)
VEN
(2V/div)
IIN
(200mA/div)
0
0
VOUT
(2V/div)
0
ILED
(20mA/div)
VOUT
(2V/div)
ILED
(20mA/div)
0
Time (20ms/div)
0
0
Time (100µs/div)
(VIN = 3.6V, CIN = COUT = 1μF,
PWM with 100kHz, 50% Duty Cycle)
VIN (AC coupled)
(50mV/div)
VOUT (AC coupled)
(50mV/div)
0
0
IIN
(100mA/div)
IIN
(100mA/div)
0
ILED
(20mA/div)
0
0
0
0
0
Time (1µs/div)
8
0
1.5x Mode Operating Characteristics
(VIN = 3.6V, CIN = COUT = 1μF,
S2C Control Mode, 21mA/Channel)
ILED
(20mA/div)
0
1.5x Mode Operating Characteristics
VIN (AC)
(50mV/div)
VOUT (AC)
(100mV/div)
4.2V
0
0
ILED
(20mA/div)
3.6V
Time (1µs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Functional Block Diagram
IN
C1+
C1C2+
C2-
Dual-mode
Charge Pump
1X/1.5X
OUTCP
6
EN/SET
D1
32-step S2Cwire
Backlight Control
D2
Control
Logic
PWM
PWM Filter
D3
D4
D5
D6
FCAP
GND
Functional Description
The AAT3369-1 is a high efficiency charge pump white
LED driver for portable applications. It can drive 6 white
LEDs.
The AAT3369-1 is a fractional charge pump and can multiply the input voltage by 1 or 1.5 times automatically.
The charge pump switches at a fixed frequency of
0.9MHz. The internal mode-selection circuit automatically switches the mode between 1x and 1.5x based on
the input voltage, output voltage and load current. This
mode switching maximizes the efficiency throughout the
entire LED load range.
When the input voltage is high enough, the AAT3369-1
operates in 1x mode (no charge pump) to provide maximum efficiency. If the input voltage is too low to supply
the programmed LED current, typically when the battery
discharges and the voltage decays, the 1.5x charge pump
mode is automatically enabled. When the battery is connected to a charger and the input voltage become high
enough again, the device will switch back to 1x mode.
The current sink magnitude is controlled by either the
EN/SET serial data S2Cwire interface, a PWM interface or
both. The S2Cwire interface records rising edges of the
EN/SET pin and decodes them into 32 maximum individual current level settings from 21mA to 0.3mA each.
The PWM interface receives an input switching frequency
where the duty cycle is varied to dim or light the LED by
changing the LED current between 100% and 1% of the
maximum value for CABC applications to reduce or
increase display power. To avoid switching noise and
flicker in the output LED, the PWM input frequency is
filtered via an internal resistor and small external capacitor to provide a continuous LED current. The AAT3369-1
is disabled by both EN/SET and PWM pulled low.
Current Level Settings
LED current level is set via Skyworks' Simple Serial
Control (S2Cwire) interface in a linear scale where LED
current of each code is smaller than the one of the previous code, as shown in Table 1. In this manner, the LED
current decreases linearly with each increasing code.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202167A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 12, 2012
9
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
S2Cwire
Data
LED Current
(mA)
S2Cwire
Data
LED Current
(mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
21.0
20.3
19.6
19.0
18.3
17.6
16.9
16.3
15.6
14.9
14.2
13.5
12.9
12.2
11.5
10.8
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
10.2
9.5
8.8
8.1
7.5
6.8
6.1
5.4
4.7
4.1
3.4
2.7
2.0
1.4
0.7
0.3
accommodate a wide range of data rates. After the first
rising edge of EN/SET, the charge pump is enabled and
reaches full capacity after the soft-start time (TSS). 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 burst clock input
to the EN/SET pin is detected. A constant current is sunk
as long as EN/SET remains in a logic high state. The current sink pins are switched off after EN/SET and PWM
has remained low state for at least the tOFF timeout
period (see Figure 1).
PWM Control
The AAT3369-1 also includes a PWM input as an additional means of providing dimming control for CABC
application. Before the PWM signal is activated the EN/
SET pin must be held for the tLATCH period which sets the
maximum current available to the LEDs. For example, if
the maximum current of 19.8mA is required, then three
rising edges of the EN/SET followed by tLATCH will allow
19.8mA to flow through the LED. By applying a variable
duty cycle on the PWM pin this current can be adjusted.
The minimum duty cycle is dependent upon the PWM
frequency. Frequencies of up to 100kHz can be applied.
To avoid output flicker and noise, the input control PWM
frequency is filtered by an internal resistor in conjunction
with an external filter capacitor. A 56nF ceramic capacitor is recommended.
Table 1: S2C Data vs. LED Current.1
S2Cwire EN/SET Interface
The LED current magnitude is 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
(21mA), and Code 32 is 0.3mA. The modulo 32 interface
wraps states back to state 1 after the 32nd clock. The
counter can be clocked at speeds up to 0.9MHz, so intermediate states are not visible. The first rising edge of EN/
SET enables the IC and initially sets the output LED current to full scale, the lowest setting equal to 0.3mA. 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 programmed level. The
device is disabled 500μs after the EN/SET and PWM pin
enters a logic low state. The EN/SET timing is designed to
To specify 21mA maximum LED current, there are two
ways to realize the dimming. One is feeding a simple rising edge of EN/SET followed by tLATCH, then applying a
pulse width modulation signal to the PWM pin to control
the dimming; the other is keeping EN/SET low and
applying a PWM signal directly with the duty cycle
between 100% and 1%.
THI
TLO
TOFF
T LAT
EN/SET
1
2
n-1
0
Data Reg
n ≤ 32
n
0
Figure 1: S2Cwire Timing Diagram When PWM is Low.
1. The LED current accuracy is compromised at high DATA settings.
10
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DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Application Information
LED current can also be programmed by PWM duty ratio
control through the PWM pin when EN/SET is pulled low.
The maximum LED current is 21mA at this condition. Up
to 100kHz PWM signal is valid as the control signal. The
high level duty ratio from 100% to 1% of the PWM signal
controls the LED current linearly from 21mA to 1.1mA as
shown in Figure 3. To get an ideal linear LED current control and avoid flicker, a suitable capacitor is required
between FCAP and ground as CFLT. The CFLT value is related to the PWM frequency. Refer to the “Capacitor
Selection” section of this datasheet to select a suitable
capacitor to filter the PWM signal.
Setting LED Current
ILED (mA)
The AAT3369-1's six LED current channels can be programmed by S2Cwire, PWM or S2Cwire with PWM at the
same time. Table 1 and Figure 2 shows 32 steps of LED
current setting by S2Cwire through the EN/SET pin.
When only the S2C wire interface is used, connect the
PWM pin to ground.
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
S2C Code
Figure 2: LED Current Controlled by S2Cwire Only.
22
20
18
ILED (mA)
16
14
12
10
8
6
4
2
0
100
90
80
70
60
50
40
30
20
10
0
PWM Duty Cycle (%)
Figure 3: LED Current Controlled by PWM Duty Ratio Only.
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DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
S2Cwire and PWM signal can work together to control the
LED current. S2Cwire is used to set the maximum LED
current by changing the data register, and varying the
PWM duty ratio changes the LED current value between
100% of the maximum value and 1% of maximum.
Figure 4 illustrates the timing requirement.
the charge pump. Tantalum and aluminum electrolytic
capacitors are not recommended due to their high ESR.
Some recommended capacitors are listed in Table 1.
Ceramic capacitors with X5R temperature characteristic
are preferred for most AAT3369-1 applications. These
capacitors have good capacitor tolerance over a wide
temperature range (X5R: ±15% over -55°C to +85°C).
Capacitors with Y5V or Z5U temperature characteristic
are generally not recommended for AAT3369-1. They
have wide capacitance tolerance over special temperature (Y5V: +22%, -82% over -30°C to +85°C, Z5U:
+22%, -56% over +10°C to +85°C).
As an example, after three rising edges of S2Cwire and
TLAT, 19.6mA per channel maximum LED current is set.
Up to 100kHz PWM signal is employed to change the LED
constant current linearly from 19.6mA to 0.2mA by varying the PWM duty ratio from 100% to 1%.
Capacitor Selection
CFLT is adopted as the capacitor of the RC filter to filter
the PWM control signal to a constant voltage for internal
LED current control. To internal 500kΩ R, and set the RC
filter rejection frequency is 1/20 of the PWM frequency.
The CFLT minimum value can be calculated by the following formula:
The AAT3369-1 requires five capacitors for a typical application: CIN, COUT, C1, C2 and CFLT. Among them, CIN, C1, C2
and COUT are 1.5x mode charge pump necessary components. 1µF surface-mount multi-layer ceramic capacitors
with less than 100mΩ Equivalent Series Resistance (ESR)
are recommended. Though the ESR of the capacitors will
not affect the ability of the capacitor to store energy, they
have large effect on the performance such as equivalent
output resistance, efficiency and output voltage ripple of
CFLT ≥
20
2πR · fPWM
THI
T LO
TOFF
T LAT
EN/SET
1
2
n-1
n ≤ 32
>10µs
PWM
(Up to 100kHz)
0
Data Reg
n
0
Figure 4: S2Cwire and PWM Control Timing.
Manufacturer
Murata
TDK
Part Number
Value (µF)
Voltage
Temp. Co.
ESR (mΩ) at 1MHz
Case
GRM188R61C105KA93
GRM185R60J105KE21
C1608X5R1C105K
1
1
1
16
6.3
16
X5R
X5R
X5R
18
16
5.5
0603
0603
0603
Table 1: Capacitor Recommendation.
12
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DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Table 2 shows some minimum CFLT values for different
PWM frequency. For most application, 56nF is a suitable
value. If PWM control is not used, CFLT is unnecessary.
fPWM (kHz)
Minimum CFLT (nF)
0.1
1
10
30
50
80
100
59
6
0.6
0.2
0.1
0.08
0.06
Table 2. Minimum CFLT Value Examples.
-or-
VF
η (%) = V · 100
IN
1.5x Charge Pump Mode Efficiency
The AAT3369-1 contains a fractional charge pump which
will boost the input supply voltage in the event where VIN
is less than the voltage required to supply the output.
The efficiency (η) can be simply defined as a linear voltage regulator with an effective output voltage that is
equal to one and one half times the input voltage.
Efficiency (η) for an ideal 1.5x charge pump can be calculated by the following equation:
LED Selection
η=
A good LED lighting application circuit is not only determined by the LED driver but also the LED selected. A
higher luminous efficacy LED emits a higher amount of
luminous flux (lumens) for a given power. Most LED
manufacture datasheet provides the luminous efficacy
by the luminous flux curve (LED forward current vs luminous flux). From the luminous flux curve, increasing the
LED forward current may increase the LED light. While
increased LED forward current also increases LED forward voltage with higher rating.
The AAT3369-1 is designed to drive high-intensity white
LEDs. It is particularly suitable for LEDs with an operating forward voltage VF in the range of 1.5V to 4.0V. To
the white LEDs with lower forward voltage (VF), it switches the charge pump mode 1x and 1.5x mode automatically to maintain the continuous LED current accuracy at
lower input voltage and obtains higher efficiency at the
mode transfer input voltage point.
Charge Pump Efficiency
-or-
POUT VF · IOUT
=
PIN
VIN · IIN
=
VF · IOUT
VF
≈
VIN · 1.5 · IOUT 1.5 · VIN
VF
η (%) = 1.5 · V · 100
IN
Thermal and Short Circuit Protection
When the device internal junction temperature reaches
125°C, the AAT3369-1 starts thermal protection by shutting down the charge pump. When the fault condition is
removed and the junction temperature drops, the charge
pump recovers automatically.
When OUTCP is fault by being shorted to ground, the
AAT3369-1 protects itself by limiting the input current to
below 600mA, and shuts down the charge pump if the
current exceeds this value. It will recover to normal
operation automatically when the fault condition is
removed.
1x Mode Efficiency
Additional Applications
The AAT3369-1's 1x mode is operational at all times and
functions alone to enhance device power conversion efficiency when VIN is higher than the voltage across the
load. When in 1x mode, voltage conversion efficiency is
defined as output power divided by input power.
The current sinks of the AAT3369-1 can be combined to
drive higher current levels through a single LED. As an
example, Figure 5 illustrates driving a single white LED
with 186mA by connecting D1-D6 together to the LED
cathode.
An expression for the ideal efficiency (η) in 1X charge
pump mode can be expressed as:
η=
POUT VF · IOUT
V
=
≈ F
PIN
VIN · IIN
VIN
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13
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
C1
1µF
VIN
2.7V ~ 5.5V
C1+
C2+
C1-
C2-
IN
PWM
C OUT
1µF
D1
PWM
2
S C
When designing a PCB for the AAT3369-1, the key
requirements are:
D1
Up to
126mA
D2
EN/SET
C FLT
56nF
C2
1µF
OUTCP
AAT 3369-1
C IN
1µF
Printed Circuit Board
Layout Recommendations
D3
FCAP
D4
1. Place the flying capacitors C1 and C2 as close to the
chip as possible; otherwise 1.5x mode performance
will be compromised.
2. Place input and output decoupling capacitors as
close to the chip as possible to reduce switching
noise and output ripple.
3. Connect the exposed pad to GND plane to get best
power dissipation.
D5
D6
GND
Figure 5: Higher Current, Single LED Application.
14
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DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Schematic and Layout
U1
AAT 3369-1
J1
DC+
DC+
C1
1µ F
3
2
6
3
CIN
1µ F
7
DC-
EN/SET
PWM
9
R8
20k
FCAP
CF
56nF
PWM
R7
20k
17
4
18
1
C2
1µF
COUT
1µF
EP
D1
D2
D3
D4
D5
D6
10
11
12
13
14
15
VMCU
S1
DOWN
D2
D3
D4
D5
D6
R1
0
R2
0
R3
0
R4
0
R5
0
R6
0
AAT 3369-1
White LED Driver
EN/SET
R10 R11 R12
1k
1k 1k
D1
GND
16
8
V_MCU
C2+
C2OUTCP
OUTCP
C1+
C1IN
1
2
3
4
U2
PIC12F675
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
C3
0.1µF
8
7
6
5
VMCU
S2
UP
R13
20k
R9
1k
S2Cwire
and PWM
Microcontroller
LED2
Red
3 2 1
J2
S3
CYCLE
Figure 6: AAT3369-1 Evaluation Board Schematic.
Figure 7: AAT3369-1 Evaluation Board
Top Side Layout. Figure 8: AAT3369-1 Evaluation Board
Bottom Side Layout.
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15
DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Component
Part Number
U1
AAT3369IDT-1
U2
R1, R2, R3, R4, R5, R6
R7, R8, R13
R9, R10, R11, R12
C1, C2, CIN, COUT
C3
CF
D1, D2, D3, D4, D5, D6
LED2
CYCLE, UP, DOWN
PIC12F675
RC0603FR-070RL
RC0603FR-0720KL
RC0603FR-071KL
GRM188R71C105K
GRM188R71C104K
GRM188R71C563K
RS-0805UW
0805KRCT
6*6*5
Description
Manufacturer
High Efficiency, 6 Channel, 1X/1.5X Charge Pump for
White LED Driver
8-Pin Flash-Based 8-Bit CMOS Microcontrollers
Res 0Ω 1/10W 1% 0603 SMD
Res 20kΩ 1/10W 1% 0603 SMD
Res 1kΩ 1/10W 1% 0603 SMD
Cap Ceramic 1μF 0603 X7R 16V 10%
Cap Ceramic 0.1μF 0603 X7R 16V 10%
Cap Ceramic 56nF 0603 X7R 16V 10%
20mA White LED 0805
Red LED 0805
12V 50mA Pushbutton
Skyworks
Microchip
Yageo
Murata
Realstar
HB
E-LT
Table 3: AAT3369-1 Evaluation Board Bill of Materials (BOM).
16
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DATA SHEET
AAT3369-1
High Efficiency, Six-Channel, 1X/1.5X Charge Pump for White LED Applications
Ordering Information
Package
Part Marking1
Part Number (Tape and Reel)2
TQFN3x2.2-18L
9NXXY
AAT3369IDT-1-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
TQFN3x2.2-183
Index Area
Pin 1 Indicator
(optional)
0.40 BSC
0.20 ± 0.05
0.203 REF
0.75 ± 0.05
3.00 ± 0.05
1.90 ± 0.05
0.30 ± 0.05
0.05 ± 0.05
Side View
2.20 ± 0.05
Top View
1.10 ± 0.05
Bottom View
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.
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
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THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
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17