General Description
The AAT3119 is a general purpose high efficiency
voltage regulated charge pump IC that can produce
output current levels up to 150mA. As a voltage
regulated output device, it may be used for general
voltage boost applications or to power white, RGB,
or flash type LEDs from a 2.7V to 5.5V input.
The voltage doubling charge pump architecture of
the AAT3119 provides for a low external part count;
just three small ceramic capacitors are needed.
This makes the AAT3119 ideally suited for small
battery-powered applications. This device oper-
ates from a fixed high frequency 1.2MHz oscillator
which enables the use of very small external
capacitors, one 1F flying capacitor, and two 1F
bypass capacitors at IN and OUT.
The AAT3119 has a thermal management system to
protect the device in the event of a short-circuit con-
dition at the output pin. Built-in soft-start circuitry pre-
vents excessive inrush current from the source sup-
ply during startup. A low-current shutdown feature
disconnects the load from V
IN
and reduces quies-
cent current to less than 1.0A when the device is
disabled. The AAT3119 is available in an 8-pin
SC70JW package and is rated over the -40C to
+85C temperature range.
Features
V
IN
Range: 2.7V to 5.5V
150mA of Output Current
Peak Current up to 250mA
Regulated Output Voltage
1.2MHz Switching Frequency
Low Noise Constant Frequency Operation
<1.0A of Shutdown Current
Automatic Soft Start
Small Application Circuit
Inductorless Boost
8-Pin SC70JW Package
-40C to +85C Temperature Range
Applications
Cellular Phones
Digital Cameras
Handheld Electronics
PDAs
White LED Backlighting
White LED Camera Flash
AAT3119
High Efficiency 2X Charge Pump
Typical Application
AAT3119
IN
GND
EN
OUT
C
OUT
C
IN
1F
1F
1F
C+
C-
C
FLY
Enable
V
IN
V
OUT
Preliminary Information
3119.2004.12.0.92
1
ChargePump
TM
Pin Descriptions
Pin Configuration
SC70JW-8
IN
OUT
C+
GND
GND
GND
C-
EN
1
2
3
4
5
6
7
8
Pin #
Symbol
Function
1
EN
Enable input control pin. When low, the device is disabled and consumes
less than 1A of current. This pin should not be left floating.
2
IN
Input power supply. A 1F capacitor should be connected between this pin
and ground.
3
OUT
Charge pump output. Connect a 1F capacitor between this pin and
ground.
4
C+
Flying capacitor + terminal. Connect a 1F capacitor between C+ and C-.
5
C-
Flying capacitor - terminal.
6
GND
Ground connection.
7
GND
Ground connection.
8
GND
Ground connection.
AAT3119
High Efficiency 2X Charge Pump
2
3119.2004.12.0.92
Absolute Maximum Ratings
1
Note 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.
Thermal Information
Note 1: Mounted on an FR4 board.
Note 2: Derate 6.25mW/C above 25C.
Electrical Characteristics
1
V
IN
= 3.3V; C
IN
= C
OUT
= C
FLY
= 1.0F; T
A
= -40C to 85C, unless otherwise noted. Typical values are T
A
= 25C.
Note 1: The AAT3119 is guaranteed to meet performance specifications from 0C to 70C. Specification over the -40C to +85C operat-
ing temperature range is assured by design, characterization, and correlation with statistical process controls.
Symbol
Description
Conditions
Min Typ Max Units
AAT3119-5.0
Power Supply
V
IN
Input Voltage Range
2.7
5.5
V
V
OUT
Output Voltage Tolerance
2.7V < V
IN
< 5V, I
OUT
=50mA
4
%
Output Voltage
3.0V < V
IN
< 5V, I
OUT
=100mA
4.8
5.0
5.2
V
I
CC
Operating Current
V
IN
=
5.0V, Active, No Load Current
2.0
4.5
mA
I
SHDN
Shutdown Current
EN = 0
1.0
A
I
OUT
Maximum Output Current
3.0
V
IN
5.5
150
mA
Efficiency
V
IN
= 3.0V, I
OUT
= 100mA
82
%
EN
V
EN(L)
Enable Threshold Low
0.4
V
V
EN(H)
Enable Threshold High
EN = 5.5V
1.4
V
I
i
Enable Input Current
-1.0
1.0
A
Charge Pump
T
SS
Soft-Start Time
200
s
F
CLK
Clock Frequency
1200
kHz
Symbol
Description
Value
Units
JA
Thermal Resistance
1
160
C/W
P
D
Maximum Power Dissipation
1, 2
625
mW
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6.0
V
V
OUT
Charge Pump Output
-0.3 to 6.0
V
V
EN
EN to GND Voltage
-0.3 to 6.0
V
V
EN(MAX)
Maximum EN to Input Voltage
0.3
V
I
OUT
Maximum DC Output Current
250
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
T
LEAD
Maximum Soldering Temperature (at leads, 10 sec)
300
C
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
3
Electrical Characteristics
1
V
IN
= 3.3V; C
IN
= C
OUT
= C
FLY
= 1.0F; T
A
= -40C to 85C, unless otherwise noted. Typical values are T
A
= 25C.
Note 1: The AAT3119 is guaranteed to meet performance specifications from 0C to 70C. Specification over the -40C to +85C operat-
ing temperature range is assured by design, characterization, and correlation with statistical process controls.
Symbol
Description
Conditions
Min Typ Max Units
AAT3119-4.5
Power Supply
V
IN
Input Voltage Range
2.7
5.5
V
V
OUT
2.7V < V
IN
< 5V, I
OUT
=50mA
4
%
Output Voltage
3.0V < V
IN
< 5V, I
OUT
=100mA
4.32
4.5
4.68
V
I
CC
Operating Current
V
IN
= 4.5V, Active, No Load Current
2.0
4.5
mA
I
SHDN
Shutdown Current
EN=0
1.0
A
I
OUT
Maximum Output Current
3.0
V
IN
5.5
150
mA
Efficiency
V
IN
= 2.7V, I
OUT
= 100mA
82
%
EN
V
EN(L)
Enable Threshold Low
0.4
V
V
EN(H)
Enable Threshold High
EN = 5.5V
1.4
V
I
i
Enable Input Current
-1.0
1.0
A
Charge Pump
T
SS
Soft-Start Time
200
s
F
CLK
Clock Frequency
1200
kHz
AAT3119
High Efficiency 2X Charge Pump
4
3119.2004.12.0.92
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
5
Typical Characteristics _ AAT3119-5V
Oscillator Frequency vs. Supply Voltage
Supply Voltage (V)
Oscillator Frequency (MHz)
1.10
1.15
1.20
1.25
1.30
2.7
3.2
3.7
4.2
4.7
-40
C
+85
C
+25
C
Efficiency vs. Load Current
Load Current (mA)
Efficiency (%)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.1
1.0
10.0
100.0
1000.0
V
IN
= 2.7V
V
IN
= 3.0V
V
IN
= 3.3V
V
IN
= 3.6V
Efficiency vs. Supply Voltage
Supply Voltage (V)
Efficiency (%)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2.7
3.0
3.3
3.6
3.9
4.2
4.5
50mA
100mA
150mA
Supply Current vs. V
EN
V
EN
Control Voltage (V)
Supply Current (mA)
0
1
2
3
4
5
0
1
3
4
2
5
6
I
OUT
= 0
A
V
IN
= 3.3V
V
IN
= 2.8V
V
IN
= 5.5V
Supply Current vs. Supply Voltage
Supply Voltage (V)
Supply Current (mA)
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
2.5
3.0
3.5
4.0
4.5
5.0
I
OUT
= 0
A
C
FLY
= 1
F
V
EN
= V
IN
Output Voltage vs. Output Current
Output Current (mA)
Output Voltage (V)
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
0
40
80
120
160
200
V
IN
= 2.7
V
IN
= 3.0
V
IN
= 3.3
V
IN
= 3.6
AAT3119
High Efficiency 2X Charge Pump
6
3119.2004.12.0.92
Typical Characteristics _ AAT3119-5V
Output Ripple Voltage
I
OUT
= 100mA @ V
IN
= 3.5V
V
IN
10mV/DIV
V
OUT
20mV/DIV
I
IN
10mA/DIV
500ns/div
Output Ripple Voltage
I
OUT
= 50mA @ V
IN
= 3.5V
V
IN
10mV/DIV
V
OUT
10mV/DIV
I
IN
10mA/DIV
500ns/div
Load Response
100mA Load
V
OUT
10mV/DIV
I
OUT
50mA/DIV
5ms/div
V
IN
=3.5V
Load Response
50mA Load
V
OUT
10mV/DIV
I
OUT
20mA/DIV
5ms/div
V
IN
=3.5V
Startup Time with 100mA Load
Time (100
S/div)
V
OUT
(1V/div)
ENABLE
(1V/div)
Startup Time with 50mA Load
Time (100
S/div)
V
OUT
(1V/div)
ENABLE
(1V/div)
Typical Characteristics _ AAT3119-4.5V
Oscillator Frequency vs. Supply Voltage
Supply Voltage (V)
Oscillator Frequency (MHz)
-40
C
+85
C
+25
C
1.10
1.15
1.20
1.25
1.30
2.7
3.0
3.3
3.6
3.9
4.2
4.5
Efficiency vs. Load Current
Load Current (mA)
Efficiency (%)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.1
1.0
10.0
100.0
1000.0
V
IN
= 2.7V
V
IN
= 3.0V
V
IN
= 3.3V
V
IN
= 3.6V
Efficiency vs. Supply Voltage
Supply Voltage (V)
Efficiency (%)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2.7
3.0
3.3
3.6
3.9
4.2
4.5
50mA
100mA
150mA
Supply Current vs. V
EN
V
EN
Control Voltage (V)
Supply Current (mA)
0
1
2
3
4
5
0
1
2
3
4
5
6
I
OUT
= 0
A
V
IN
= 5.5
V
IN
= 3.3V
V
IN
= 2.8V
Supply Current vs. Supply Voltage
Supply Voltage (V)
Supply Current (mA)
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
2.5
2.9
3.3
3.7
4.1
4.5
I
OUT
= 0
A
C
FLY
= 1
F
V
EN
= V
IN
Output Voltage vs. Output Current
Output Current (mA)
Output Voltage (V)
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
0
40
80
120
160
200
V
IN
=3.3
V
IN
=3.6
V
IN
= 2.7
V
IN
= 3.0
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
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AAT3119
High Efficiency 2X Charge Pump
8
3119.2004.12.0.92
Typical Characteristics _ AAT3119-4.5V
Startup
Time (100
S/div)
V
OUT
(1V/div)
ENABLE
(1V/div)
I
LOAD
= 100mA @ V
IN
= 3.0V
I
LOAD
= 150mA @ V
IN
= 3.3V
I
LOAD
= 150mA @ V
IN
= 3.3V
Maximum Current Pulse vs. Supply Voltage
Supply Voltage (V)
Maximum Current Pulse (mA)
0
100
200
300
400
500
600
3.0
3.2
3.4
3.6
3.8
4.0
4.2
One-shot pulse duration = 250ms
V
OUT
> 4.0V
Output Ripple Voltage
I
OUT
= 100mA @ V
IN
= 3.5V
V
IN
10mV/DIV
V
OUT
20mV/DIV
I
IN
10mA/DIV
500ns/div
Output Ripple Voltage
I
OUT
= 50mA @ V
IN
= 3.5V
V
IN
10mV/DIV
V
OUT
10mV/DIV
I
IN
10mA/DIV
500ns/div
Load Response
100mA Load
V
OUT
10mV/DIV
I
OUT
50mA/DIV
5ms/div
V
IN
=3.5V
Load Response
50mA Load
V
OUT
10mV/DIV
I
OUT
20mA/DIV
5ms/div
V
IN
=3.5V
Typical Characteristics _ AAT3119
Normalized Output Voltage vs. Temperature
Temperature (
C)
Normalized Output Voltage (%)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
-50
-30
-10
10
30
50
70
90
I
OUT
= 25mA
V
EN
Threshold vs. Supply Voltage
Supply Voltage (V)
V
EN
Threshold (V)
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
V
IL
V
IH
V
IN
vs. V
IL
Supply Voltage (V)
V
IL
(V)
+85
C
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
+25
C
-40
C
V
IN
vs. V
IH
Supply Voltage (V)
V
IH
(V)
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40
C
+25
C
+85
C
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
9
AAT3119
High Efficiency 2X Charge Pump
10
3119.2004.12.0.92
Functional Block Diagram
OUT
Voltage
Reference
Soft Start
1MHz
Oscillator
Charge
Pump
C1+
C1-
GND
EN
IN
Functional Description
The AAT3119 is a 5.0V or 4.5V regulated voltage
doubling charge pump device intended for general
applications that require low noise voltage boost
function from input supplies ranging from 2.7V to
5.5V. The charge pump is capable maintaining the
regulated voltage output for continuous output cur-
rent loads up to 150mA. This makes the AAT3119
ideal for general purpose voltage boost applica-
tions, driving white and RGB color LEDs as well as
USB OTG V
BUS
supplies in portable products. The
AAT3119 charge pump and regulation circuit is
also capable of supplying peak pulse currents up to
250mA for 500ms. This makes the device suitable
for many photo flash LED applications.
The AAT3119 accomplishes the voltage boost func-
tion by utilizing a voltage doubling (2X) charge
pump. The charge pump block within the device
uses low R
DS
MOSFET switches to transfer charge
from the input to output via a "flying" capacitor
(C
FLY
). This switching process is performed over
two phases of each clock cycle which is set by the
fixed 1.2MHz internal oscillator. On the first phase
of each clock cycle, the flying capacitor is placed in
parallel with the input (IN) and is charged to the
level of the input voltage across C
IN
. On the second
phase of the switching cycle, the flying capacitor is
reconfigured by the internal switches and placed in
series with the input capacitor. C
IN
and C
FLY
are
then placed across the output capacitor (C
OUT
).
The voltage seen on C
OUT
is then two times that of
C
IN
. The AAT3119 contains an internal reference
and feedback system that senses the charge pump
output and controls the charge pump function to
maintain an accurate regulated output voltage.
Because of the fixed 1.2MHz high frequency inter-
nal oscillator, the input, output, and flying capaci-
tors are very small. This circuit architecture
requires only one 1F ceramic capacitor for the
charge pump flying capacitor (C
FLY
), and one 1F
ceramic capacitor for both C
IN
and C
OUT
.
The AAT3119 has a soft-start circuit to prohibit in-
rush current when the device is enabled. This fea-
ture guarantees a smooth transition to the desired
output voltage when the device is turned on. The
system soft-start circuit is particularly useful in
white LED backlight applications where the use of
a PWM signal is employed as an LED dimming
function. In limiting the input in-rush current each
time the device is turned on, the soft-start circuit
helps minimize back-injected switching noise and
transient supply current.
To protect the AAT3119 as well as the system
application, this device has a thermal protection
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
11
circuit that will shut down the charge pump if the
die temperature rises above the preset internal
thermal limit. This not only protects the device if
the ambient temperature exceeds the operating
limits, but can also protect the system in the event
of a short circuit on the OUT pin.
In the operating state, the AAT3119 typically con-
sumes 2mA of quiescent operating current. The
enable pin (EN) is an active high input. When
pulled low, the AAT3119 is shut down, the quies-
cent current drops to less than 1A, and the output
is disconnected from the input.
Charge Pump Efficiency
The core of the AAT3119 is a regulated output volt-
age doubling charge pump. The efficiency (
) for
an ideal voltage doubling charge pump can typical-
ly be expressed as the output power divided by the
input power:
In addition, with an ideal voltage doubling charge
pump, the output current may be expressed as half
the input current. The expression to define the ideal
efficiency (
) can be rewritten as:
-or-
For a charge pump with an output of 5.0 volts and
a nominal input of 3.0 volts, the theoretical efficien-
cy is 83.3%. Due to internal switching losses and
IC quiescent current consumption, the actual effi-
ciency can be measured at approximately 82%.
Efficiency will decrease as the level of V
IN
approaches that of the regulated V
OUT
. Refer to
the device typical characteristics curves for expect-
ed actual efficiency based on either input voltage or
load current.
Capacitor Selection
Careful selection of the three external capacitors
C
IN
, C
FLY
, and C
OUT
is important because they will
affect turn-on time, output ripple, efficiency, and
load transient response. Optimum performance will
be obtained when low equivalent series resistance
(ESR) ceramic capacitors are used. In general, low
ESR may be defined as less than 100m
. A value
of 1F for all three capacitors is a good starting
point when designing with the AAT3119. This not
only provides for a very small printed circuit board
area, but cost is further reduced by the minimized
bill of materials.
Input Capacitor
A 1F multilayer ceramic chip capacitor is suggest-
ed for the input. This capacitor should be connect-
ed between the IN pin and ground. 1F should be
suitable for most applications. Even though the
AAT3119 switching ripple and noise are very low,
back-injected line noise may be further reduced by
increasing the value of C
IN
. Other types of capaci-
tors may be used for C
IN
at the cost of compro-
mised circuit performance.
Output Capacitor
The output capacitor (C
OUT
) should be connected
between the OUT pin and ground. A 1F ceramic
capacitor is also suggested in this position.
Switching noise and ripple seen on the charge
pump output increases with load current. Typically
1F is sufficient for minimizing output ripple seen
by the load circuit. If the load current in an appli-
cation is low, or if higher levels of switching ripple
can be tolerated, C
OUT
can be reduced as low as
0.33F. If application circuits with greater load cur-
rent demands require lower switching ripple ampli-
tudes, C
OUT
may be increased to values above
1F. Capacitor types other than ceramic capaci-
tors can be used for C
OUT
. However, types of
capacitors other than ceramic material will typically
have a greater value of ESR resulting in increased
output switching ripple.
(%) = 100
V
OUT
2V
IN
=
P
OUT
=
V
OUT
I
OUT
=
V
OUT
P
IN
V
IN
2I
OUT
2V
IN
=
P
OUT
P
IN
AAT3119
High Efficiency 2X Charge Pump
12
3119.2004.12.0.92
Flying Capacitor
Due to the switching operation of the voltage dou-
bling circuit topology, current flow through the flying
capacitor is bi-directional. The flying capacitor
selected must be a non-polarized type. A 1F low
ESR ceramic capacitor is ideal for this application.
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use with
the AAT3119. Ceramic capacitors offer many advan-
tages over their tantalum and aluminum electrolytic
counterparts. A ceramic capacitor typically has very
low ESR, is lowest cost, has a smaller PCB footprint,
and is non-polarized. Low ESR ceramic capacitors
help maximize charge pump transient response.
Since ceramic capacitors are non-polarized, they are
not prone to incorrect connection damage.
Equivalent Series Resistance: ESR is an impor-
tant characteristic to consider when selecting a
capacitor. ESR is a resistance internal to a capaci-
tor that is determined by the leads, internal con-
nections, size or area, material composition, and
ambient temperature. Capacitor ESR is typically
measured in milliohms for ceramic capacitors and
can range to more than several ohms for tantalum
or aluminum electrolytic capacitors.
Ceramic Capacitor Materials: Ceramic capacitors
less than 0.1F are typically made from NPO or
COG materials. NPO and COG materials typically
have tight tolerance and are stable over tempera-
ture. Large capacitor values are typically com-
posed of X7R, X5R, Z5U, or Y5V dielectric materi-
als. Large ceramic capacitors, typically greater
than 2.2F, are often available in low-cost Y5V and
Z5U dielectrics, but large capacitors are not
required in most AAT3119 applications. Capacitor
area is another contributor to ESR. Capacitors that
are physically large will have a lower ESR when
compared to an equivalent material smaller capac-
itor. These larger devices can improve circuit tran-
sient response when compared to an equal value
capacitor in a smaller package size.
Applications Information
White LED Backlight Driver
LED Selection: In applications where the AAT3119
is utilized as a white LED backlight driver, LEDs
with forward voltages up to 5.0V may be used. The
AAT3119 is available in two regulated output volt-
age versions: 4.5V and 5.0V. The output voltage
option selected will determine the maximum LED
forward voltage that can be driven. The trade off
for the lower 4.5V output voltage version is the
device's ability to supply greater output current.
Refer to the "Output Voltage vs. Output Current"
curves in the Typical Characteristics section of this
datasheet to determine the best AAT3119 output
voltage option based on the requirements of a
given application.
LED Ballast Resistors: To set the maximum
brightness of white LEDs connected in parallel from
a voltage source supply, a ballast resistor connect-
ed between each LED cathode and ground is
required. Refer to the application schematic in
Figure 1. The maximum brightness is determined
by the forward current (I
F
) through the respective
LED for a given forward voltage (V
F
). The typical
forward voltage of a specific LED is usually stated in
the typical characteristics of the given LED manu-
facturer's datasheet. The correct ballast resistor
value can be determined by the following equation:
Where:
R
B
=
Ballast resistor value in ohms (
)
V
OUT
=
Regulated charge pump output voltage
V
F
=
LED forward voltage at the desired
forward current
I
F
=
Desired LED forward current (I
F
)
R
B
=
(V
OUT
- V
F
)
I
F
Flash LED Driver
The AAT3119 can source 250mA for pulsed loads
up to 500ms from an input supply as low as 3.3V.
This makes the device well suited for low-cost flash
LED driver applications in portable products.
Typically the 4.5V output version of the AAT3119
should be selected for photo flash LED applica-
tions, as it can maintain better voltage regulation at
higher pulsed load current levels (refer to Figure 2).
The limitation of this option is that the greatest flash
LED forward voltage (V
F
) that can be driven is 4.5V
at the maximum set forward current (I
F
) for the
application. Flash LEDs with forward voltage (V
F
)
levels up to 5.0V can be driven by the AAT3119
5.0V output option. However, the maximum cur-
rent for a 500ms pulse will be reduced. Refer to
the Typical Characteristics curves for peak output
current levels for a given minimum input voltage.
The forward current (I
F
) through the flash LED may
be determined with the use of a series ballast resis-
tor. The typical forward voltage (V
F
) for the flash
LED in a given application should be derived from
the LED manufacturer's datasheet for the desired
forward current (I
F
) of the flash application. Once
the forward current has been determined, the flash
ballast resistor can be calculated using the follow-
ing equation:
Where:
R
F
= Flash ballast resistor value in ohms (
)
V
OUT
= Regulated charge pump output voltage
(typically 4.5V)
V
F
= Flash LED forward voltage at the
desired forward current
I
F
= Desired flash LED forward current (I
F
)
The flash LED function can be controlled by the
AAT3119 enable pin in most applications. The
device start-up time into a maximum load is about
200s, thus eliminating the need for pre-flash con-
trol synchronization.
R
F
=
(V
OUT
- V
F
)
I
F
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
13
Figure 1: White LED Driver.
AAT3119
IN
GND
EN
OUT
C
OUT
C
IN
1F
1F
1F
C1+
C1-
D1
D2
D3
D4
D5
D6
C
FLY
R
B2
R
B3
R
B4
R
B5
R
B1
R
B6
V
BATTERY
Enable
If a "light" or "movie" mode is also needed along
with the flash function, this can be accomplished
with the addition of a second ballast resistor with a
flash function gating MOSFET switch as shown in
Figure 3. Refer to the following equations for the
calculation of flash and light resistors, R
F
and R
L
.
Where:
R
L
= Light mode ballast resistor value in
ohms (
)
V
OUT
= Regulated charge pump output voltage
(typically 4.5V)
V
F
= Flash LED forward voltage at the
desired forward current
I
F
= Desired flash LED forward current (I
F
)
in the "light" mode
Where:
R
F
= Flash ballast resistor value in ohms (
)
R
DS
= Flash gating mosfet on resistance
V
OUT
= Regulated charge pump output voltage
(typically 4.5V)
V
F
= Flash LED forward voltage at the
desired forward current
I
F
= Desired flash LED forward current (I
F
)
R
F
=
- R
DS
(V
OUT
- V
F)
I
F
R
L
=
(V
OUT
- V
F
)
I
F
AAT3119
High Efficiency 2X Charge Pump
14
3119.2004.12.0.92
Figure 2: Flash LED Application.
AAT3119
IN
GND
EN
OUT
4.5V
C
OUT
C
IN
R
F
1F
1F
1F
C
FLY
V
IN
Enable
Flash LED
Layout Considerations
For the AAT3119, the high charge pump switching
frequencies and large peak transient currents
require careful printed circuit board layout. As a
general rule for charge pump boost converters, the
three external capacitors should be located as
closely as possible to the device package with min-
imum length trace connections. Maximize ground
plane around the AAT3119 charge pump and make
sure all external capacitor are connected to the
immediate power ground plane. A local component
side ground plane is recommended. If this is not
possible due the layout area limitations, assure
good ground connections by the use of large or
multiple printed circuit board vias.
Refer to the following basic AAT3119 evaluation
board shown in Figures xxx for an example of the
recommended charge pump layout design.
AAT3119
High Efficiency 2X Charge Pump
3119.2004.12.0.92
15
Figure 3: Flash LED Driver with Gated Flash Application.
AAT3119
IN
GND
EN
OUT
4.5V
C
OUT
C
IN
R
L
R
F
1F
1F
1F
C
FLY
V
IN
Enable
Flash Enable
Flash LED
Ordering Information
Note: Sample stock is held on part numbers listed in BOLD.
Note 1: XYY = assembly and date code.
Package Information
SC70JW-8
0.225
0.075
0.45
0.10
0.05
0.05
2.10
0.30
2.00
0.20
7
3
4
4
1.75
0.10
0.85
0.15
0.15
0.05
1.10 MAX
0.100
2.20
0.20
0.048REF
0.50 BSC 0.50 BSC 0.50 BSC
Package
Marking
1
Part Number (Tape and Reel)
SC70JW-8
MUXYY
AAT3119IJS-4.5-T1
SC70JW-8
MVXYY
AAT3119IJS-5.0-T1
AAT3119
High Efficiency 2X Charge Pump
16
3119.2004.12.0.92
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
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