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PDF AAT3134ISN-T1 Data sheet ( Hoja de datos )
| Número de pieza | AAT3134ISN-T1 | |
| Descripción | High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications | |
| Fabricantes | ETC | |
| Logotipo |  |
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AAT3134
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
General Description
The AAT3134 is a low noise, constant frequency
charge pump DC/DC converter that uses a dual
mode Load Switch (1X) and fractional (1.5X) con-
version to maximize efficiency for White LED appli-
cations. The device can be used to produce current
levels up to 20mA in each of its six outputs to drive
LED's from a 2.7V to 5.5V input. Outputs may be
operated individually or paralleled for driving high-
er-current LED's. Low external parts counts (two
1µF flying capacitors and two small 1µF capacitors
at VIN, and OUT) make the AAT3134 ideally suited
for small battery-powered applications.
AnalogicTech's Simple Serial Control (S2Cwire™)
interface is used to enable, disable and set the
LED drive current in two groups of four outputs and
two outputs with multiple level independently con-
trolled brightness scales. The AAT3134 has a ther-
mal management system to protect the device in
the event of a short circuit condition at the output
pin. Built-in soft-start circuitry prevents excessive
inrush current during start-up. A high charge pump
switching frequency enables the use of very small
external capacitors. A low current shutdown feature
disconnects the load from VIN and reduces quies-
cent current to less than 1µA. The AAT3134 is
available in a 16-pin quad QFN package.
Features
ChargePump™
• VIN Range: 2.7 - 5.5 Volts
• < 1.0µA of Shutdown
• 1 MHz Switching Frequency
• Fully Independent Display Lighting
• Dual Mode 1x and 1.5x Charge Pump for
Maximum Efficiency
• Drives Low-VF & High-VF Type LED's
• Up to Six 20mA Outputs
• Multi Position Brightness Scale with Digital
Control
• Low Noise Constant Frequency Operation
• Small Application Circuit
• Regulated Output Current
• Automatic Soft-Start
• No Inductors
• 16-pin QFN package
• -40 to +85°C Temperature range
Applications
• White LED Backlighting
• White Photo-Flash for DSC's
• Color (RGB) Lighting
• Programmable Current Source
Typical Application
VBATTERY
VIN C1+
CIN COUT
1µF 1µF
EN/SET
VOUT
C1-
C2+
AAT3134
EN/SET
C2-
D1
D2
D3
D4
D5
D6
GND
3134.2004.04.1.0
C1
1µF
C2
1µF
D4 D3 D2 D1
D6 D5
Sub
Display
Main
Display
1
1 page  
AAT3134
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
Typical Characteristics
(Unless otherwise noted, VIN = 3.5V, CIN = COUT = C1 = C2 = 1µF, TA = 25°C)
Turn-On to Full Scale Charge-Pump
Turn-On to Full Scale Load-Switch
ENSET
(1V/div)
OUT
(2V/div)
VDIODE
(1V/div)
IIN
(200mA/div)
50µs/div
ENSET
(1V/div)
OUT
(2V/div)
VDIODE
(2V/div)
IIN
(100mA/div)
50µs/div
Charge Pump to Load Switch (80mA)
VIN
(10mV/div)
OUT
(2V/div)
VDIODE
(2V/div)
IIN
(100mA/div)
50µs/div
ENSET
(1V/div)
VDIODE
(2V/div)
IIN
(100mA/div)
Turn-Off
200µs/div
Load Switch to Charge Pump (80mA)
VIN
(20mV/div)
OUT
(1V/div)
VDIODE
(1V/div)
IIN
(200mV/div)
50µs/div
80mA Load Characteristics
VIN
OUT
VDIODE
1µs/div
3134.2004.04.1.0
5
5 Page 
AAT3134
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use
with the AAT3134. Ceramic capacitors offer many
advantages over their tantalum and aluminum elec-
trolytic 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 con-
nection damage.
Equivalent Series Resistance (ESR)
ESR is an important characteristic to consider when
selecting a capacitor. ESR is a resistance internal
to a capacitor, which is caused by the leads, inter-
nal connections, size or area, material composition
and ambient temperature. Capacitor ESR is typi-
cally measured in milliohms for ceramic capacitors
and can range to more than several ohms for tanta-
lum or aluminum electrolytic capacitors.
Additional Application Circuits
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1µF are typically
made from NPO or COG materials. NPO and COG
materials typically have tight tolerance and are stable
over temperature. Large capacitor values are typi-
cally composed of X7R, X5R, Z5U or Y5V dielectric
materials. Large ceramic capacitors, typically greater
than 2.2µF are often available in low cost Y5V and
Z5U dielectrics, but capacitors greater than 1µF are
typically not required for AAT3134 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 capacitor. These larger devices can improve
circuit transient response when compared to an
equal value capacitor in a smaller package size
Thermal Protection
The AAT3134 has a thermal protection circuit that
will shut down the internal LDO and charge pump if
the die temperature rises above the thermal limit as
is the case during a short circuit of the OUT pin.
VBATTERY
VIN C1+
CIN COUT
1µF 1µF
EN/SET
VOUT
C1-
C2+
AAT3134
C2-
EN/SET
GND
D1
D2
D3
D4
D5
D6
C1
1µF
C2
1µF
D1 D2 D3 D4
RB* RB* RB* RB*
Resistor R is optional
D5 D6
RR
Resistor R is optional
*In some applications, white LED forward voltages (VF) can vary significantly. Ballast resistors between the LED cathodes and ground are recommended
for balancing the forward voltage differences. The ballast resistor value may be approximated by the following equation:
RB
=
VSOURCE
IF
-
VF
3134.2004.04.1.0
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet AAT3134ISN-T1.PDF ] | |
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