Page 1
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
General Description
Features
The AAT1239-1 is a high frequency, high efficiency constant current boost converter capable of driving up to
ten (10) series-connected white LEDs or 40V. It is an
ideal power solutions for backlight applications with up
to ten white LEDs in series. The input voltage is 2.7V to
5.5V for single-cell lithium-ion/polymer (Li-ion) based
portable devices.
The LED current is digitally controlled across a 6x operating range using AnalogicTech’s Simple Serial Control™
2
(S
Cwire™) interface. Programmability across 26 discrete current steps provides high resolution, low noise,
flicker-free, constant LED outputs. In programming
AAT1239 operation, LED brightness increases based on
the data applied at the EN/SET pin. The SEL logic pin
changes the feedback voltage between two programmable ranges.
The AAT1239-1 features a high current limit and fast,
stable transitions for stepped or pulsed current applications. The high switching frequency (up to 2MHz) provides fast response and allows the use of ultra-small
external components, including chip inductors and
capacitors. Fully integrated control circuitry simplifies
design and reduces total solution size. The AAT1239-1
offers a true load disconnect feature which isolates the
load from the power source while in the OFF or disabled
state. This eliminates leakage current, making the devices ideally suited for battery-powered applications.
The AAT1239-1 is available in the Pb-free, thermallyenhanced 12-pin TSOPJW package.
• Input Voltage Range: 2.7V to 5.5V
• Maximum Continuous Output 40V @ 30mA
• Drives up to 10 LEDs in Series
Constant LED Current with 3.5% Accuracy Over
Temperature and Input Voltage Range
• Digital Control with S
26 Discrete Steps
No PWM Control Required
No Additional Circuitry
2
Cwire Single Wire Interface
• Up to 85% Efficiency
• Up to 2MHz Switching Frequency Allows Small External
Chip Inductor and Capacitors
• Hysteretic Control
No External Compensation Components
Excellent Load Transient Response
High Efficiency at Light Loads
• Integrated Soft Start with No External Capacitor
• True Load Disconnect Guarantees <1.0A Shutdown
Current
• Selectable Feedback Voltage Ranges for High Resolution
Control of Load Current
• Short-Circuit, Over-Voltage, and Over-Temperature
Protection
• 12-Pin TSOPJW Package
• -40°C to +85°C Temperature Range
Applications
• Color Display Backlight
• Digital Still Cameras (DSCs)
• Digital Photo Frames
• PDAs and Notebook PCs
• White LED Drivers
Typical Application
DS1
SS16L or equivalent
R2
374k
R3
12k
R1 (R
)
BALLAST
30
.1
C2
2.2μF
M673
White LEDs
OSRAM LW M678
or equivalent
V
= 2.7V to 4. 2V
IN
Feedback Voltage
Li-Ion:
Enable/Set
Select
C1
2.2μF
PVIN
VIN
AAT1239-1
EN/SET
SEL
PGND
OVP
AGND
LIN
SW
FB
L1
2.2μH
20mA
I
LED
1239-1.2008.10.1.2 1
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Page 2
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Pin Descriptions
Pin # Symbol Function
1 PVIN Input power pin; connected to the source of the P-channel MOSFET. Connect to the input capacitor(s).
2 EN/SET IC enable pin and S
3 SEL
4 VIN Input voltage for the converter. Connect directly to the PVIN pin.
5 N/C No connection.
6, 7 SW Boost converter switching node. Connect the power inductor between this pin and LIN.
8 PGND Power ground for the boost converter.
9 AGND Ground pin.
10 FB Feedback pin. Connect a resistor to ground to set the maximum LED current.
11 OVP Feedback pin for over-voltage protection sense.
12 LIN Switched power input. Connect the power inductor between this pin and SW.
FB voltage range select. A logic LOW sets the FB voltage range from 0.4V to 0.1V; a logic HIGH sets the
FB voltage range from 0.6V to 0.3V.
2
Cwire input control to set output current.
Pin Configuration
TSOPJW-12
(Top View)
PVIN
EN/SET
SEL
VIN
N/C
SW
1
2
3
4
5
6
12
11
10
9
8
7
LIN
OVP
FB
AGND
PGND
SW
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Part Number Descriptions
SEL Polarity
Part Number
AAT1239ITP-1 0.6V ≥ VFB ≥ 0.3V 0.4V ≥ VFB ≥ 0.1V See Table 2
HIGH LOW S
2
C Feedback Voltage Programming
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Symbol Description Value Units
PVIN, VIN Input Voltage -0.3 to 6.0 V
SW Switching Node 45 V
LIN, EN/SET, SEL, FB Maximum Rating V
T
J
T
S
T
LEAD
Operating Temperature Range -40 to 150 °C
Storage Temperature Range -65 to 150 °C
Maximum Soldering Temperature (at leads, 10 sec) 300 °C
IN
Thermal Information
Symbol Description Value Units
θ
JA
P
D
Thermal Resistance 160 °C/W
Maximum Power Dissipation 625 mW
+ 0.3 V
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.
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Electrical Characteristics
1
TA = -40°C to +85°C unless otherwise noted. Typical values are at 25°C, VIN = 3.6V.
Symbol Description Conditions Min Typ Max Units
Power Supply
, V
PV
IN
IN
V
OUT(MAX)
I
Q
I
SHDN
I
OUT
ΔV
LINEREG(FB)
/ΔVINLine Regulation VIN = 2.7V to 5.5V, VFB = 0.6V 0.7 %
R
DS(ON) L
R
DS(ON) IN
T
SS
V
OVP
I
LIMIT
T
SD
T
HYS
SEL, EN/SET
V
SEL(L)
V
SEL(H)
V
EN/SET(L)
V
EN/SET(H)
T
EN/SET (LO)
T
EN/SET(HI)
T
OFF
T
LAT
I
EN/SET
AAT1239-1
V
FB
Input Voltage Range 2.7 5.5 V
Maximum Output Voltage 40 V
Operating Current SEL = GND, FB = 0.1V 70 A
Shutdown Current EN/SET = GND 1.0 A
Maximum Continuous Output
Current
2
2.7V < VIN < 5.5V, V
= 40V 30
OUT
Low Side Switch On Resistance 135 mΩ
Input Disconnect Switch
On Resistance
Soft-Start Time
Over-Voltage Protection Threshold V
Over-Voltage Hysteresis V
From Enable to Output Regulation;
VFB = 300mV
Rising 1.1 1.2 1.3 V
OUT
Falling 100 mV
OUT
180
400 s
N-Channel Current Limit 2.5 A
TJ Thermal Shutdown Threshold 140 °C
TJ Thermal Shutdown Hysteresis 15 °C
SEL Threshold Low 0.4 V
SEL Threshold High 1.4 V
Enable Threshold Low 0.4 V
Enable Threshold High 1.4 V
EN/SET Low Time V
EN/SET High Time V
EN/SET Off Timeout V
EN/SET Latch Timeout V
EN/SET Input Leakage V
FB Pin Regulation
< 0.6V 0.3 75 s
EN/SET
> 1.4V 75 s
EN/SET
< 0.6V 500 s
EN/SET
> 1.4V 500 s
EN/SET
= 5V VIN = 5V -1 1 A
EN/SET
V
= 2.7V to 5.5V, SEL = GND,
IN
EN/SET = DATA16
= 2.7V to 5.5V, SEL = HIGH,
V
IN
EN/SET = HIGH
0.085 0.1 1.115
0.54 0.6 0.66
mA
mΩ
V
1. Specification over the -40°C to +85°C operating temperature range is assured by design, characterization, and correlation with statistical process controls.
2. Maximum continuous output current increases with reduced output voltage, but may vary depending on operating efficiency and thermal limitations.
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Typical Characteristics
0
5
7
Efficiency vs. LED Current
(10 White LEDs; R
80
78
76
VIN = 5V
74
72
70
Efficiency (%)
VIN = 4.2V
68
66
2 4 6 8 10 12 14 16 18 2
VIN = 3.6V
I
LED
BALLAST
(mA)
= 30.1ΩΩ)
Shutdown Current vs. Input Voltage
(EN = GND)
1.0
0.8
0.6
0.4
0.2
Shutdown Current (µA)
0.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.
85°C
-40°C
Input Voltage (V)
25°C
Efficiency vs. LED Current
(9 White LEDs; R
78
VIN = 5V
76
74
72
70
Efficiency (%)
68
66
2 4 6 8 10 12 14 16 18 20
VIN = 4.2V
I
LED
BALLAST
VIN = 3.6V
(mA)
= 30.1ΩΩ)
Line Transient
(10 White LEDs; R
4.2V
3.6V
33.2
33
32.8
Input Voltage (top) (V)
Output Voltage (middle) (V)
Time (50µs/div)
BALLAST
= 30.1ΩΩ)
Feedback Voltage (bottom) (V)
0.62
0.6
0.58
Accuracy I
(VFB = 0.6V; R
2.0
1.5
1.0
(%)
0.5
LED
0.0
-0.5
-1.0
Accuracy I
-1.5
-2.0
2.7 3.2 3.7 4.2 4.7 5.2 5.
vs. Input Voltage
LED
BALLAST
= 30.1ΩΩ)
Input Voltage (V)
-40°C
25°C
85°C
Accuracy I
(VFB = 0.6V; R
1.5
1.0
(%)
0.5
LED
0.0
-0.5
Accuracy I
-1.0
-1.5
-40 -15 10 35 60 85
vs. Temperature
LED
BALLAST
= 30.1ΩΩ)
Temperature (°C)
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Typical Characteristics
Soft Start
(10 White LEDs; VFB = 0.6V)
0.6
0.4
0.2
0
3.3V
0V
Feedback Voltage (middle) (V)
Time (200µs/div)
Shutdown
(10 White LEDs; VFB = 0.6V)
3.3V
0V
0.6
0.4
0.2
0
EnableVoltage (top) (V)
Feedback Voltage (middle) (V)
Inductor Current (bottom) (A)
EnableVoltage (top) (V)
2
1
0
Inductor Current (bottom) (A)
0.5
0.0
Soft Start
(10 White LEDs; VFB = 0.3V)
3.3V
0V
0V
0.4
0.2
0
Feedback Voltage (middle) (V)
Time (200µs/div)
Shutdown
(10 LEDs; VFB = 0.3V)
3.3V
0V
0.4
0.2
0
EnableVoltage (top) (V)
Feedback Voltage (middle) (V)
Inductor Current (bottom) (A)
EnableVoltage (top) (V)
2
1
0
Inductor Current (bottom) (A)
0.5
0
Time (100µs/div)
Time (50µs/div)
(10 White LEDs; VIN = 3.6V; C
V
OUT
(AC Coupled)
(20mV/div)
V
SW
(20V/div)
I
L
(500mA/div)
Output Ripple
= 2.2µF; I
OUT
Time (200ns/div)
= 13mA)
LED
(10 White LEDs; VIN = 3.6V; C
V
OUT
(AC Coupled)
(20mV/div)
V
SW
(20V/div)
I
L
(500mA/div)
Output Ripple
= 2.2µF; I
OUT
Time (200ns/div)
= 20mA)
LED
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Typical Characteristics
Ω
Ω
(10 White LEDs; SEL = Low; I
34
32
30
28
Output Voltage (top) (V)
Time (50µs/div)
= 3mA to 13mA)
LED
Input Disconnect Switch Resistance
vs. Input Voltage
300
280
Transition of LED Current
260
)
240
(mΩ
220
200
DS(ON)IN
R
180
25°C
160
140
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
120°C
100°C
85°C
Input Voltage (V)
Feedback Voltage
(bottom) (V)
0.4
0.3
0.2
0.1
0.0
(10 White LEDs; SEL = Low; I
34
32
30
Output Voltage (top) (V)
Time (50µs/div)
= 13mA to 6mA)
LED
Feedback Voltage
(bottom) (V)
0.4
0.3
0.2
0.1
0.0
Transition of LED Current
Low Side Switch On Resistance
vs. Input Voltage
260
240
220
)
200
180
(mΩ
160
DS(ON)L
140
R
120
100
25°C
80
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
120°C
100°C
85°C
Input Voltage (V)
EN/SET Latch Timeout vs. Input Voltage
350
300
250
200
-40°C
85°C
EN/SET Off Timeout vs. Input Voltage
300
250
200
150
25°C
25°C
150
EN/SET Latch Timeout (µs)
100
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
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100
EN/SET Off Timeout (µs)
50
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
-40°C
85°C
Page 8
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Typical Characteristics
5
Enable High Threshold (VIH) vs. Input Voltage
1.2
) (V)
IH
1.1
1.0
-40°C
0.9
0.8
0.7
0.6
Enable High Threshold (V
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
25°C
85°C
Input Voltage (V)
Enable Low Threshold (VIL) vs. Input Voltage
1.2
) (V)
IL
1.1
1.0
-40°C
0.9
25°C
0.8
0.7
85°C
0.6
0.5
0.4
Enable Low Threshold (V
2.7 3.1 3.5 3.9 4.3 4.7 5.1
Input Voltage (V)
5.
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Functional Block Diagram
PVIN
VIN
EN/SET
FB
Reference
SEL
Output
Select
Functional Description
The AAT1239-1 consists of a DC/DC boost controller, an
integrated slew rate controlled input disconnect MOSFET
switch, and a high voltage MOSFET power switch. A high
voltage rectifier, power inductor, output capacitor, and
sense resistors are required to implement a DC/DC constant current boost converter. The input disconnect
switch is activated when a valid input voltage is present
and the EN/SET pin is pulled high. The slew rate control
on the P-channel MOSFET ensures minimal inrush current as the output voltage is charged to the input voltage, prior to the switching of the N-channel power
MOSFET. Monotonic turn-on is guaranteed by the integrated soft-start circuitry. Soft-start eliminates output
voltage overshoot across the full input voltage range and
all loading conditions.
The maximum current through the LED string is set by
the ballast resistor and the feedback voltage of the IC.
The output current may be programmed by adjusting
the level of the feedback reference voltage which is programmed through the S
selects one of two feedback voltage ranges. In the
AAT1239-1, the SEL function is inverted in that the FB
pin voltage can be programmed from 0.4V to 0.1V with
2
Cwire interface. The SEL pin
LIN
OVP
SW
Control
AGND PGND
a logic LOW applied to the SEL pin and 0.6V to 0.3V with
a logic HIGH applied to the SEL pin. The feedback voltage can be set to any one of 16 current levels within
each FB range, providing high-resolution control of the
LED current, using the single-wire S
For some applications requiring a short duration of
boosting current applying a low-to-high transition on the
AAT1239-1’s SEL pin, LED current can be programmed
up to 3x. The step size is determined by the programmed
voltage at the FB pin where the internal default setting
is 1.5x in the AAT1239-1.
2
Cwire control.
Control Loop
The AAT1239-1 provides the benefits of current mode
control with a simple hysteretic output current loop providing exceptional stability and fast response with minimal design effort. The device maintains exceptional
constant current regulation, transient response, and
cycle-by-cycle current limit without additional compensation components.
The AAT1239-1 modulates the power MOSFET switching
current to maintain the programmed FB voltage. This
allows the FB voltage loop to directly program the
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
required inductor current in order to maintain the desired
LED current.
The switching cycle initiates when the N-channel MOSFET
is turned ON and current ramps up in the inductor. The
ON interval is terminated when the inductor current
reaches the programmed peak current level. During the
OFF interval, the input current decays until the lower
threshold, or zero inductor current, is reached. The lower
current is equal to the peak current minus a preset hysteresis threshold, which determines the inductor ripple
current. The peak current is adjusted by the controller
until the LED output current requirement is met.
The magnitude of the feedback error signal determines
the average input current. Therefore, the AAT1239-1
controller implements a programmed current source
connected to the output capacitor, parallel with the LED
string and ballast resistor. There is no right-half plane
zero, and loop stability is achieved with no additional
compensation components.
An increase in the feedback voltage (V
increased error signal sensed across the ballast resistor
(R1). The controller responds by increasing the peak
inductor current, resulting in higher average current in
the inductor and LED string(s). Alternatively, when the
V
is reduced, the controller responds by decreasing the
FB
peak inductor current, resulting in lower average current
in the inductor and LED string(s).
Under light load conditions, the inductor OFF interval
current goes below zero and the boost converter enters
discontinuous mode operation. Further reduction in the
load current results in a corresponding reduction in the
switching frequency. The AAT1239-1 provides pulsed
frequency operation which reduces switching losses and
maintains high efficiency under light load conditions.
Operating frequency varies with changes in the input voltage, output voltage, and inductor size. Once the boost
converter has reached continuous mode, further increases
in the LED current will not significantly change the operating frequency. A small 2.2H (±20%) inductor is selected
to maintain high frequency switching (up to 2MHz) and
high efficiency operation for outputs up to 40V.
) results in an
FB
Soft Start / Enable
The input disconnect switch is activated when a valid
input voltage is present and the EN/SET pin is pulled
high. The slew rate control on the P-channel MOSFET
ensures minimal inrush current as the output voltage is
charged to the input voltage, prior to switching of the
N-channel power MOSFET. Monotonic turn-on is guaranteed by the built-in soft-start circuitry. Soft start eliminates output current overshoot across the full input voltage range and all loading conditions.
After the soft start sequence has terminated, the initial
LED current is determined by the internal, default FB
voltage across the external ballast resistor at the FB pin.
Additionally, the AAT1239-1 has been designed to offer
the system designer two choices for the default FB voltage based on the state of the SEL pin. Changing the LED
current from its initial default setting is easy by using the
2
S
Cwire single wire serial interface; the FB voltage can
be decreased (as in the AAT1239-1; see Table 2) relative
to the default FB voltage.
Current Limit and
Over-Temperature Protection
The switching of the N-channel MOSFET terminates when
a current limit of 2.5A (typical) is exceeded. This minimizes power dissipation and component stresses under
overload and short-circuit conditions. Switching resumes
when the current decays below the current limit.
Thermal protection disables the AAT1239-1 when internal dissipation becomes excessive. Thermal protection
disables both MOSFETs. The junction over-temperature
threshold is 140°C with 15°C of temperature hysteresis.
The output voltage automatically recovers when the
over-temperature fault condition is removed.
Over-Voltage Protection
Over-voltage protection prevents damage to the
AAT1239-1 during open-circuit or high output voltage
conditions. An over-voltage event is defined as a condition where the voltage on the OVP pin exceeds the overvoltage threshold limit (V
voltage on the OVP pin has reached the threshold limit,
the converter stops switching and the output voltage
decays. Switching resumes when the voltage on the
OVP pin drops below the lower hysteresis limit, maintaining an average output voltage between the upper
and lower OVP thresholds multiplied by the resistor
divider scaling factor.
= 1.2V typical). When the
OVP
Under-Voltage Lockout
Internal bias of all circuits is controlled via the VIN input.
Under-voltage lockout (UVLO) guarantees sufficient V
bias and proper operation of all internal circuitry prior to
soft start.
IN
10 1239-1.2008.10.1.2
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Application Information
Over-Voltage Protection
OVP Protection with Open Circuit Failure
The OVP protection circuit consists of a resistor network
tied from the output voltage to the OVP pin (see Figure
1). To protect the device from open circuit failure, the
resistor divider can be selected such that the over-voltage threshold occurs prior to the output reaching 40V
(V
to 20kΩ to minimize losses without degrading noise
immunity.
). The value of R3 should be selected from 10kΩ
OUT(MAX)
V
⎛⎞
R2 = R3 · - 1
OUT(MAX)
V
⎝⎠
OVP
VOUT
AAT1239-1
R2
OVP
GND
R3
C
OUT
Assume R3 = 12kΩ and V
= 40V. Selecting 1%
OUT(MAX)
resistor for high accuracy, this results in R2 = 374kΩ
(rounded to the nearest standard value). The minimum
OVP threshold can be calculated:
V
OUT(OVP_MIN)
= V
OVP(MIN)
· + 1
⎝⎠
R
3
⎛⎞
R
2
= 35.4V
To avoid OVP detection and subsequent reduction in the
programmed output current (see following section), the
maximum operating voltage should not exceed the
minimum OVP set point.
V
OUT(MAX)
< V
OUT(OVP_MIN)
In some cases, this may disallow configurations with
high LED forward voltage (V
series white LEDs. V
unit-to-unit tolerance can be as
FLED
) and/or greater than ten
FLED
high as +15% of nominal for white LED devices.
OVP Constant Voltage Operation
Under closed loop constant current conditions, the output voltage is determined by the operating current, LED
forward voltage characteristics (V
connected LEDs (N), and the feedback pin voltage (V
), quantity of series
FLED
).
FB
Figure 1: Over-Voltage Protection Circuit.
1.238V
40
30
Inductor Current (bottom)(A)
Over Voltage Protection Pin (top) (V)
1.142V
4
2
0
Time (4ms/div)
Figure 2: Over-Voltage Protection
Open Circuit Response (No LED).
When the rising OVP threshold is exceeded, switching is
stopped and the output voltage decays. Switching automatically restarts when the output drops below the
Output Voltage (middle) (V)
lower OVP hysteresis voltage (100mV typical) and, as a
result, the output voltage increases. The cycle repeats,
maintaining an average DC output voltage proportional
to the average of the rising and falling OVP levels (multiplied by the resistor divider scaling factor). High operating frequency and small output voltage ripple ensure
DC current and negligible flicker in the LED string(s).
The waveform in Figure 3 shows the output voltage and
LED current at cold temperature with a ten series white
LED string and V
rises as a result of the increased V
OVP constant voltage operation. Self heating of the
LEDs triggers a smooth transition back to constant current control.
V
= VFB + N · V
OUT
= 40V. As shown, the output voltage
OVP
FLED
which triggers the
FLED
1239-1.2008.10.1.2 11
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
V
OUT
(5V/div)
I
(200mA/div)
LED
Over-Voltage Protection
Self-RecoveryCold Temperature Apply
where:
V
= 0.4V when SEL = Low
FB(MAX)
V
= 0.6V when SEL = High
FB(MAX)
i.e., for a maximum LED current of 20mA (SEL = High):
R
BALLAST
VFB
= = = 30Ω ≈ 30.1Ω
I
LED(MAX)
0.6
0.020
Figure 3: Over-Voltage Protection
Constant Voltage Operation
(10 White LEDs; I
R
= 12kΩ; R3 = 374kΩ).
2
= 20mA;
LED
While OVP is active, the maximum LED current programming error (ΔI
an individual LED (ΔV
ΔV
To minimize the ΔI
(V
OUT(OVP_MIN)
increase in the maximum OVP voltage (V
) is proportional to voltage error across
LED
).
FLED
FLED
=
(N · V
FLED(TYP)
error, the minimum OVP voltage
LED
- V
OUT(OVP_MIN)
N
- VFB)
) may be increased, yielding a corresponding
OUT(OVP_MAX)
).
Measurements should confirm that the maximum switching node voltage (V
) is less than 45V under worst-
SW(MAX)
case operating conditions.
V
SW(MAX)
= V
OVP(MAX)
· + 1
⎝⎠
R
2
+ VF + V
RING
⎛⎞
R
3
VF = -Schottky Diode DS1 forward voltage at turn-OFF
V
= Voltage ring occurring at turn-OFF
RING
LED Selection and Current Setting
The AAT1239-1 is well suited for driving white LEDs with
constant current. Applications include main and sub-LCD
display backlighting, and color LEDs.
The LED current is controlled by the FB voltage and the
ballast resistor. For maximum accuracy, a 1% tolerance
resistor is recommended.
The ballast resistor (R
follows:
R
BALLAST
) value can be calculated as
BALLAST
=
V
I
FB(MAX)
LED(MAX)
Maximum I
LED
Current (mA)
30 20.0 13.3
25 24.3 16.2
20 30.1 20.0
15 40.2 26.7
10 60.4 40.2
5 121.0 80.6
Table 1: Maximum LED Current and R
R
SEL = High SEL = Low
BALLAST
(Ω)
BALLAST
Resistor Values (1% Resistor Tolerance).
Typical white LEDs are driven at maximum continuous
currents of 15mA to 20mA. The maximum number of
series connected LEDs is determined by the minimum
OVP voltage of the boost converter (V
the maximum feedback voltage (V
maximum LED forward voltage (V
FB(MAX)
FLED(MAX)
OUT(OVP_MIN)
) divided by the
). V
), minus
FLED(MAX)
can
be estimated from the manufacturers’ datasheet at the
maximum LED operating current.
V
OUT(OVP_MIN)
N =
= V
(V
OUT(OVP_MIN)
V
OVP(TYP)
- V
FLED(MAX)
· + 1
⎝⎠
R
3
)
FB(MAX)
⎛⎞
R
2
Figure 4 shows the schematic of using ten LEDs in series.
Assume V
@ 20mA = 3.5V (typical) from LW M673
FLED
(OSRAM) datasheet.
⎛⎞
374kΩ
V
OUT(OVP_MIN)
= 1.2V = 38.6V
· + 1
⎝⎠
10.4kΩ
38.6V
N =
- 0.6V
3.5V
≈ 10.9
Therefore, under these typical operating conditions, ten
LEDs can be used in series.
12 1239-1.2008.10.1.2
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
6
2.2μF
R1
30.1
DS1
R2
374K
R3
12K
D6
LED
D7
LED
D8
LED
D9
LED
D10
LED
D1
LED
D2
LED
D3
LED
D4
LED
D5
LED
C2
2.2μF
L1
2.2μH
V
CC
JP1
1
2
C1
Enable
JP2
Select
3
1
2
3
10K
R4
U1
1
VIN
2
EN
3
SEL
4
VP
5
N/C
6
SW
AAT1239-1 TSOP12JW
LIN
OVP
FB
GND
PGND
SW
12
11
10
9
8
7
C1 10V 0603 X5R 2.2μF GRM188R60J225KE01D
C2 50V 1206 X7R 2.2μF GRM31CR71H225KA88
L1 2.2μH SD3814-2R2 or SD3110-2R2
DS1 SS16L
D1-D10 LW M673 White LED
other alternatives:
more stability at 40V: C2 50V 1206 X7R 4.7μF GRM31CR71H475K
under 20V application: C2 25V 0805 X7R 2.2μF GRM21BR71E225KA73L
Figure 4: AAT1239-1 White LED Boost Converter Schematic.
LED Brightness Control
The AAT1239-1 uses S2Cwire programming to control
LED brightness and does not require PWM (pulse width
modulation) or additional control circuitry. This feature
greatly reduces the burden on a microcontroller or system IC to manage LED or display brightness, allowing
the user to “set it and forget it.” With its high-speed
serial interface (1MHz data rate), the output current of
the AAT1239-1 can be changed successively to brighten
or dim the LEDs in smooth transitions (i.e., to fade out)
or in abrupt steps, giving the user complete programmability and real-time control of LED brightness.
25
20
Default
15
10
SEL=HIGH
SEL=LOW
5
LED Current (mA)
0
14710131
S2Cwire Data Register
Figure 5: Programming AAT1239-1 LED Current
with R
BALLAST
= 30.1Ω.
1239-1.2008.10.1.2 13
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Alternatively, toggling the SEL logic pin from low to high
implements stepped or pulsed LED currents by increasing the FB pin voltage. Figure 6 illustrates the SELECT
pin scaling factor, defined as the LED current with
SEL=HIGH divided by the LED current with SEL=LOW. In
the AAT1239-1, the possible scaling factors are 3.0x to
1.5x with the internal default setting of 1.5x.
3. 5
3. 0
2. 5
2. 0
(Low to High)
Select Pin Scaling Factor
(Default)
1. 5
1. 0
14 7101316
S2Cwire Data Register
Figure 6: AAT1239-1 SEL Pin Scaling Factor:
I
(SEL = High) Divided by I
LED
(SEL = Low).
LED
S2Cwire Serial Interface
AnalogicTech’s S2Cwire single wire serial interface is a
proprietary high-speed single-wire interface available
only from AnalogicTech. The S
2
Cwire interface records
rising edges of the EN/SET input and decodes them into
16 individual states. Each state corresponds to a reference feedback voltage setting on the FB pin, as shown in
Table 2.
S2Cwire Serial Interface Timing
The S2Cwire single wire serial interface data can be
clocked-in at speeds up to 1MHz. After data has been
submitted, EN/SET is held high to latch the data for a
period T
. The FB pin voltage is subsequently changed
LAT
to the level as defined by the state of the SEL logic pin.
When EN/SET is set low for a time greater than T
OFF
, the
AAT1239-1 is disabled. When the AAT1239-1 is disabled,
the register is reset to its default value. In the AAT1239-1,
the FB pin voltage is set to 0.3V if the EN/SET pin is
subsequently pulled HIGH.
S2Cwire Feedback Voltage Programming
The FB pin voltage is set to the default level at initial
powerup. The AAT1239-1 is programmed through the
S2Cwire interface. Table 2 illustrates FB pin voltage programming for the AAT1239-1. The rising clock edges
applied at the EN/SET pin determine the FB pin voltage.
If a logic LOW is applied at the SEL pin of the AAT1239-1,
the default feedback voltage range becomes 0.4V to
0.1V and 0.6V to 0.3V for a logic HIGH condition at the
SEL pin.
T
HI
T
OFF
0
EN/SET
Data Reg
1
2 n-1 n ≤ 16
T
LO
0n-1
T
LAT
Figure 7: AAT1239-1 S2Cwire Timing Diagram to Program the Output Voltage.
14 1239-1.2008.10.1.2
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Rising Clock
Edges/Data
Register
1 0.4 (default) 13.29 0.6 (default) 19.93
2 0.38 12.62 0.58 19.27
3 0.36 11.96 0.56 18.60
4 0.34 11.30 0.54 17.94
5 0.32 10.63 0.52 17.28
6 0.30 9.97 0.50 16.61
7 0.28 9.30 0.48 15.95
8 0.26 8.64 0.46 15.28
9 0.24 7.97 0.44 14.62
10 0.22 7.31 0.42 13.95
11 0.20 6.64 0.40 13.29
12 0.18 5.98 0.38 12.62
13 0.16 5.32 0.36 11.96
14 0.14 4.65 0.34 11.30
15 0.12 3.99 0.32 10.63
16 0.10 3.32 0.30 9.97
Reference
Voltage (V)
SEL = Low SEL = High
LED Current (mA);
R
BALLAST
= 30.1Ω
Reference
Voltage (V)
LED Current (mA);
R
BALLAST
= 30.1Ω
Table 2: AAT1239-1 S2Cwire Reference Feedback Voltage Control Settings With R
(Assumes Nominal Values)*.
Selecting the Schottky Diode
To ensure minimum forward voltage drop and no recov-
The switching period is divided between ON and OFF
time intervals.
ery, high voltage Schottky diodes are considered the
best choice for the AAT1239-1 boost converter. The output diode is sized to maintain acceptable efficiency and
reasonable operating junction temperature under full
load operating conditions. Forward voltage (V
package thermal resistance (θ
) are the dominant fac-
JA
) and
F
tors to consider in selecting a diode. The diode non-repetitive peak forward surge current rating (I
) should
FSM
be considered for high pulsed load applications, such as
camera flash. I
rating drops with increasing conduc-
FSM
tion period. Manufacturers’ datasheets should be consulted to verify reliability under peak loading conditions.
During the ON time, the N-channel power MOSFET is
conducting and storing energy in the boost inductor.
During the OFF time, the N-channel power MOSFET is
not conducting. Stored energy is transferred from the
input battery and boost inductor to the output load
through the output diode.
Duty cycle is defined as the ON time divided by the total
switching interval.
The diode’s published current rating may not reflect
actual operating conditions and should be used only as a
D =
comparative measure between similarly rated devices.
40V rated Schottky diodes are recommended for outputs
less than 30V, while 60V rated Schottky diodes are recommended for outputs greater than 35V.
1
= TON + T
F
S
T
ON
= T
ON
TON
+ T
⋅ F
S
BALLAST
OFF
= 30.1Ω
OFF
*All table entries are preliminary and subject to change without notice.
1239-1.2008.10.1.2 15
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
The maximum duty cycle can be estimated from the
relationship for a continuous mode boost converter.
Maximum duty cycle (D
input voltage (V
IN(MIN)
) is the duty cycle at minimum
MAX
).
high efficiency under light load. The rectifier reverse current increases dramatically at elevated temperatures.
Selecting the Boost Inductor
V
=
OUT
V
OUT
D
MAX
- V
IN(MIN)
The average diode current is equal to the output
current.
I
AVG(TOT)
= I
OUT
The average output current multiplied by the forward
diode voltage determines the loss of the output diode.
P
LOSS(DIODE)
= I
= I
AVG(TOT)
· V
OUT
· V
F
F
For continuous LED currents, the diode junction temperature can be estimated.
T
J(DIODE)
= T
AMB
+ θ
· P
JA
LOSS(DIODE)
Output diode junction temperature should be maintained
below 110ºC, but may vary depending on application
and/or system guidelines. The diode θ
can be mini-
JA
mized with additional PCB area on the cathode. PCB
heat-sinking the anode may degrade EMI performance.
The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and
The AAT1239-1 controller utilizes hysteretic control and
the switching frequency varies with output load and input
voltage. The value of the inductor determines the maximum switching frequency of the boost converter.
Increased output inductance decreases the switching frequency and switching loss, but results in higher peak
currents and increased output voltage ripple. To maintain
2MHz maximum switching frequency and stable operation, an output inductor sized from 1.5H to 2.7H is
recommended. For higher efficiency in Li-ion battery
applications (V
from 3.0V to 4.2V) and stable operation,
IN
increasing the inductor size up to 10H is recommended.
Figure 15 and 16 show the special enhanced efficiency
application.
A better estimate of D
D
MAX
is possible once VF is known.
MAX
(V
=
+ VF - V
OUT
(V
OUT
+ VF)
IN(MIN)
)
Where VF is the Schottky diode forward voltage. If not
known, it can be estimated at 0.5V.
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 completed to
ensure that the inductor does not saturate or exhibit
excessive temperature rise.
Rated
Forward
Part
Manufacturer
Taiwan Semiconductor
Co., Ltd.
Diodes, Inc B340LA 3 70.0 40 25 5.59x2.92x2.30 SMA
Zetex ZHCS350 0.35 4.2 40 330 1.7x0.9x0.8 SOD523
Number
SS16L
SS15L 30 50 45 3.8x1.9x1.43 Sub SMA
SS14L 30 40 45 3.8x1.9x1.43 Sub SMA
Current
(A)
1.1
Non-Repetitive
Peak Surge
Current (A)
30 60 45 3.8x1.9x1.43 Sub SMA
Rated
Voltage
(V)
Thermal
Resistance
(θJA, °C/W)
Size (mm)
(LxWxH) Case
Table 3: Typical Surface Mount Schottky Rectifiers for Various Output Levels.
16 1239-1.2008.10.1.2
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
The output inductor (L) is selected to avoid saturation at
minimum input voltage, maximum output load conditions. Peak current may be estimated using the following equation, assuming continuous conduction mode.
Worst-case peak current occurs at minimum input voltage (maximum duty cycle) and maximum load. Switching
frequency (F
) can be estimated from the curves and
S
assumes a 2.2H inductor.
I
D
·
V
I
= +
PEAK
(1 - D
OUT
MAX)
MAX
(2
·
F
IN(MIN)
·
S
L)
be compared against the manufacturer’s temperature
rise, or thermal derating, guidelines.
RMS
3
I
PEAK
=
I
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.
At light load and low output voltage, the controller
reduces the operating frequency to maintain maximum
operating efficiency. As a result, further reduction in
output load does not reduce the peak current. Minimum
peak current can be estimated from 0.5A to 0.75A.
At high load and high output voltages, the switching frequency is somewhat diminished, resulting in higher I
PEAK
.
Bench measurements are recommended to confirm actual I
and ensure that the inductor does not saturate at
PEAK
maximum LED current and minimum input 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
Inductance
Manufacturer Part Number
CDRH2D14-2R2 2.2 1500 75 3.2x3.2x1.55 Shielded
Sumida
www.sumida.com
Cooper Electronics
www.cooperet.com
Taiyo Yuden
www.t-yuden.com
CDRH2D14-4R7 4.7 1000 135 3.2x3.2x1.55 Shielded
CDRH4D22/HP-4R7 4.7 2200 66 5.0x5.0x2.4 Shielded
CDRH3D18-100NC 10 900 164 4.0x4.0x2.0 Shielded
SD3814-2R2 2.2 1900 77 4.0x4.0x1.0 Shielded
SD3110-2R2 2.2 910 161 3.1x3.1x1.0 Shielded
SD3118-4R7 4.7 1020 162 3.1x3.1x1.8 Shielded
SD3118-100 10 900 295 3.1x3.1x1.8 Shielded
NP03SB-2R0M 2 1900 32 4.0x4.0x1.8 Shielded
NR3010T-2R2M 2.2 1100 95 3.0x3.0x1.0 Shielded
NP03SB4R7 4.7 1200 47 4.0x4.0x1.8 Shielded
NP03SB100M 10 800 100 4.0x4.0x1.8 Shielded
(μH)
P
LOSS(INDUCTOR)
= I
RMS
2
· DCR
To ensure high reliability, the inductor case temperature
should not exceed 100ºC. In some cases, PCB heatsinking applied to the LIN node (non-switching) can improve
the inductor’s thermal capability. PCB heatsinking may
degrade EMI performance when applied to the SW node
(switching) of the AAT1239-1.
Shielded inductors provide decreased EMI and may be
required in noise sensitive applications. Unshielded chip
inductors provide significant space savings at a reduced
cost compared to shielded (wound and gapped) inductors. In general, chip-type inductors have increased
winding resistance (DCR) when compared to shielded,
wound varieties.
Maximum DC I
Current (mA)
SAT
DCR
(mΩ)
Size (mm)
LxWxH Type
Table 4: Recommended Inductors for Various Output Levels (Select I
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PEAK
< I
SAT
).
Page 18
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Inductor Efficiency Considerations
The efficiency for different inductors is shown in Figure 8
for ten white LEDs in series. Smaller inductors yield
increased DCR and reduced operating efficiency.
75
CDRH5D16F-2R2 (29mΩ)
72
69
SD3814-2R2 (77mΩ)
recommended to ensure good capacitance stability over
the full operating temperature range.
The output capacitor is sized to maintain the output load
without significant voltage droop (ΔV
) during the
OUT
power switch ON interval, when the output diode is not
conducting. A ceramic output capacitor from 2.2F to
4.7F is recommended (see Table 5). Typically, 50V
rated capacitors are required for the 40V maximum
boost output. Ceramic capacitors sized as small as 0805
or 1206 are available which meet these requirements.
Efficiency (%)
66
MLC capacitors exhibit significant capacitance reduction
with applied voltage. Output ripple measurements should
confirm that output voltage droop and operating stability
63
25811141720
LED Current (mA)
are acceptable. Voltage derating can minimize this factor, but results may vary with package size and among
specific manufacturers.
Output capacitor size can be estimated at a switching
Figure 8: AAT1239-1 Efficiency for
Different Inductor Types (V
= 3.6V;
IN
Ten White LEDs in Series).
frequency (F
) of 500kHz (worst case).
S
I
· D
OUT
C
=
OUT
FS · ΔV
MAX
OUT
Selecting the Boost Capacitors
The high output ripple inherent in the boost converter
necessitates 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 AAT1239-1
boost regulator. MLC capacitors of type X7R or X5R are
Manufacturer Part Number Value (μF) Voltage Rating Temp Co Case Size
Murata GRM188R60J225KE19 2.2 6.3 X5R 0603
Murata GRM188R61A225KE34 2.2 10 X5R 0603
Murata GRM21BR71E225KA73L 2.2 25 X7R 0805
Murata GRM31CR71H225KA88 2.2 50 X7R 1206
Murata GRM31CR71H475K 4.7 50 X7R 1206
To maintain stable operation at full load, the output
capacitor should be sized to maintain ΔV
between
OUT
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.
Table 5: Recommended Ceramic Capacitors.
18 1239-1.2008.10.1.2
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
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 AAT1239-1
boost converter is shown in Figures 9 and 10. The following PCB layout guidelines should be considered:
1. Minimize the distance from Capacitor C1 and C2
negative terminal to the PGND pins. This is especially true with output capacitor C2, which conducts
high ripple current from the output diode back to the
PGND pins.
2. Minimize the distance between L1 to DS1 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 GND terminals of C1 and C2.
4. Consider additional PCB area on DS1 cathode to
maximize heatsinking capability. This may be necessary when using a diode with a high V
mal resistance.
5. To avoid problems at startup, add a 10kΩ resistor
between the VIN, VP and EN/SET pins (R4). This is
critical in applications requiring immunity from input
noise during “hot plug” events, e.g. when plugged
into an active USB port.
and/or ther-
F
Figure 9: AAT1239-1 Evaluation Figure 10: AAT1239-1 Evaluation
Board Top Side Layout (with ten LEDs Board Bottom Side Layout (with ten LEDs
and microcontroller). and microcontroller).
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AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
R8
330Ω
D12
Red
Select
Down
Up
S2
S3
S1
R7
1k
R61kR5
1k
JP2 JP3
R4
10k
U2
PIC12F675
1
VDD
2
GP5
3
GP4
4
GP3
VSS
GP0
GP1
GP2
2
S
VCC
Cwire
Microcontroller
C3
0.1μF
8
7
6
5
R9
330Ω
D11
Green
AAT1239-1
C
10μF
DC+DC-
123
VCC
JP1
C1
4.7μF
U1
AAT1239-1
1
VIN
2
EN
3
SEL
4
VP
5
N/C
6
SW
LIN
OVP
FB
GND
PGND
SW
L1
10μH
12
11
10
9
8
7
R1
30.1Ω
Schottky
D10
WLED
DS1
D9
WLED
WLED
D8
R2
374k
R3
12k
WLED
VOUT
JP4
D1
WLED
D2
WLED
D3
WLED
D4
WLED
D5
WLED
D7
D6
WLED
C2
2.2μF
White LED
Driver
Figure 11: AAT1239-1 Evaluation Board Schematic (with ten LEDs and microcontroller).
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20 1239-1.2008.10.1.2
20 1239-1.2008.10.1.2
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Page 21
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Additional Applications
0
Li-Ion
= 2.7V
V
IN
to 5.5V
Li-Ion
= 2.7V
V
IN
to 5.5V
C1
2.2μF
C1
2.2μF
PVIN
VIN
PGND
EN/SET
SEL
PVIN
VIN
PGND
EN/SET
SEL
AAT1239-1
AAT1239-1
LIN
SW
OVP
FB
AGND
Figure 12: Four LEDs In Series Configuration.
LIN
SW
OVP
FB
AGND
L1
2.2μH
L1
2.2μH
30.1
30.1Ω
Efficiency vs. LED Current
DS1
Schottky
R2
158k
R3
12k
R1
20mA
Ω
Up to 17V/
30mA max
C2
2.2μF
D1
LED
D2
LED
D3
LED
D4
LED
84
83
82
81
80
79
78
77
Efficiency (%)
76
75
74
(4 White LEDs; R
VIN = 5V
VIN = 4.2V
2 4 6 8 10 12 14 16 18 2
I
LED
BALLAST
(mA)
= 30.1ΩΩ)
VIN = 3.6V
Efficiency vs. LED Current
DS1
Schottky
R2
287k
R3
12k
R1
20mA
Up to 30V/
30mA max
C2
2.2μF
LEDD7LEDD8LED
D1
LED
D2
LED
D3
LED
D4
LED
D5
LED
D6
80
78
76
74
72
70
Efficiency (%)
68
66
2 4 6 8 10 12 14 16 18 20
(8 White LEDs; R
VIN = 5V
VIN = 4.2V
I
LED
BALLAST
(mA)
= 30.1ΩΩ)
VIN = 3.6V
Figure 13: Eight LEDs In Series Configuration.
Efficiency vs. LED Current
Li-Ion
= 2.7V
V
IN
to 5.5V
C1
2.2μF
PVIN
VIN
PGND
EN/SET
SEL
AAT1239-1
LIN
SW
OVP
FB
AGND
L1
2.2μH
30.1
DS1
Schottky
R2
324k
R3
12k
R1
20mA
Ω
Up to 34V/
30mA max
D1
LED
D2
C2
2.2μF
D9
LED
LED
D3
LED
D4
LED
D5
LED
D6
LEDD7LEDD8LED
78
76
74
72
70
Efficiency (%)
68
66
2 4 6 8 10 12 14 16 18 20
(9 White LEDs; R
VIN = 5V
VIN = 4.2V
I
LED
BALLAST
VIN = 3.6V
(mA)
= 30.1ΩΩ)
Figure 14: Nine LEDs In Series Configuration.
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1239-1.2008.10.1.2 21
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Page 22
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
90.0
Li-Ion
V
to 4.2V
C1 10V 0805 X5R 4.7μF GRM219R61A475KE19
C2 50V 1206 X7R 2.2μF GRM31CR71H225KA88
L1 1 0μH CDRH3D18-100NC
DS1 SS16L
= 3.0V
IN
C1
4.7
F
μ
PVIN
VIN
PGND
EN/SET
SEL
AAT1239 -1
SW
OVP
AGND
LIN
FB
L1
10
DS1
H
μ
D1
D2
C2
D3
F
2.2
μ
D4
D5
D6
30.1Ω
R2
374kΩ
R3
12kΩ
20mA
D10 D9 D8 D7
R1
87.5
85.0
82.5
80.0
77.5
Efficiency (%)
75.0
72.5
70.0
2 4 6 8 10 12 14 16 18 20
I
(mA)
OUT
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
Figure 15: Enhanced Efficiency Configuration for Li-ion Battery Ten WLEDs Series-Connected Application.
Li-Ion
V
to 4.2V
C1 10V 0805 X5R 4.7μF GRM219R61A475KE19
C2 50V 1206 X7R 2.2μF GRM31CR71H225KA88
L1 4.7μH CDRH4D22/HP-4R7
DS1 SS16L
IN
=3.0V
C1
4.7
F
μ
PVIN
VIN
PGND
EN/SET
SEL
AAT1239 -1
Figure 16: Enhanced Efficiency Configuration for Li-ion Battery, Two Branch,
OVP
AGND
LIN
SW
L1
4.7
FB
DS1
H
μ
R2
374kΩ
R3
12kΩ
R1
40mA
15Ω
D1
D11
D2
D3
D4
D10
D12
D13
D14
D5
D15
D6
D16
D7
D17
D8
D18
D9
D19
D20
C2
2.2
F
μ
85.0
82.5
80.0
77.5
75.0
72.5
Efficiency (%)
70.0
67.5
65.0
510152025303540
I
(mA)
OUT
VIN = 3.0V
VIN = 3.6V
V
= 4.2V
IN
Ten WLEDs Series-Connected Application.
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22 1239-1.2008.10.1.2
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Page 23
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDsSwitchReg
TM
PRODUCT DATASHEET
Ordering Information
Package Marking
TSOPJW-12 ZLXYY AAT1239ITP-1-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor
products that are in compliance with current RoHS standards, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. For more information, please visit our website at
http://www.analogictech.com/about/quality.aspx.
Package Information
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
3.00 ± 0.10
+ 0.10
0.20
- 0.05
1
TSOPJW-12
2.40 ± 0.10
2.85 ± 0.20
Part Number (Tape and Reel)
7° NOM
0.04 REF
2
0.0375
±
0.055 ± 0.045
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
0.9625
+ 0.10
1.00
- 0.065
0.010
0.15 ± 0.05
4° ± 4°
0.45 ± 0.15
2.75 ± 0.25
Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual
property rights are implied. AnalogicTech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
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