|
|
PDF AAT3123ITP-20-T1 Data sheet ( Hoja de datos )
| Número de pieza | AAT3123ITP-20-T1 | |
| Descripción | High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications | |
| Fabricantes | ETC | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AAT3123ITP-20-T1 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
|
No Preview Available !
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
General Description
The AAT3123/24 is a low noise, constant frequen-
cy 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 to drive up to 6 LEDs from a
2.7V to 5.5V input. Outputs may be operated indi-
vidually or paralleled for driving higher-current
LEDs. Low external parts counts (two 1µF flying
capacitors and two small 1µF capacitors at VIN,
and OUT) make the AAT3123/24 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 with a 32 level loga-
rithmic scale LED brightness control. The
AAT3123/24 has a thermal management system to
protect the device in the event of a short circuit
condition at the output pin. Built-in soft-start circuit-
ry 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 quiescent current to less
than 1µA. The AAT3123 is available in very small
12 pin TSOPJW package. The six output AAT3124
is available in a 16 pin 4x4mm QFN package.
Features
ChargePump™
• Dual Mode 1x and 1.5x Charge Pump for
Maximum Efficiency
• Drives Low-VF & High-VF Type LEDs
• Up to 6 20mA Outputs
• 32 Position Logarithmic Scale with Digital
Control
• Simple Serial Control™ (S2Cwire™) interface
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• Small Application Circuit
• Regulated Output Current
• Automatic Soft-Start
• VIN Range: 2.7V to 5.5V
• No Inductors
• Iq < 1µA in Shutdown
• Temperature Range -40 to 85°C.
• 16 pin 4x4 QFN package (AAT3124)
• 12 pin TSOPJW-12 package (AAT3123)
Applications
• White LED Backlighting
• White Photo-Flash for DSCs
• Color (RGB) Lighting
• Programmable Current Source
Typical Application
VBATTERY
VIN C1+
CIN
1µF
COUT
1µF
EN/SET
VOUT
C1-
C2+
AAT3124
C2-
EN/SET
GND
D1
D2
D3
D4
D5
D6
C1
1µF
C2
1µF
D6 D5 D4 D3 D2 D1
3123.2003.09.1.1
1
1 page  
AAT3123/4
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)
Efficiency vs. VIN (4x20mA)
Efficiency vs. VIN (4x10mA)
100%
95%
90%
VDIODE = 3.2V
VDIODE = 3.4V
85%
80%
VDIODE = 3.0V
75%
70%
65%
60%
55%
50%
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1
VIN (V)
100%
95%
90%
VDIODE = 3.2V
VDIODE = 3.4V
85%
80%
VDIODE = 3.0V
75%
70%
65%
60%
55%
50%
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1
VIN (V)
IDIODE vs. VIN (4x20mA)
85
VDIODE = 3.2V
VDIODE = 3.4V
80
75 VDIODE = 3.0V
70
65
60
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1
VIN (V)
IDIODE vs. VIN (4x10mA)
45
VDIODE = 3.2V
VDIODE = 3.4V
40
VDIODE = 3.0V
35
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1
VIN (V)
Quiescent Current vs. VIN
VIH and VIL vs. VIN
2.6 0.850
2.4 0.825
2.2
2.0 0.800
1.8 0.775
1.6 0.750
1.4
1.2
1.0
VDIODE = 3.4V
0.725
0.700
0.8
0.6 VDIODE = 3.0V
0.4
0.2
VDIODE = 3.2V
0.675
0.650
0.625
0.0 0.600
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1
2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)
VIN (V)
3123.2003.09.1.1
5
5 Page 
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
Capacitor Selection
Careful selection of the four external capacitors
CIN, C1, C2, COUT is important because they will
affect turn on time, output ripple and transient per-
formance. Optimum performance will be obtained
when low ESR (<100mΩ) ceramic capacitors are
used. In general, low ESR may be defined as less
than 100mΩ. A capacitor value of 1µF for all four
capacitors is a good starting point when choosing
capacitors. If the LED current sources are only
programmed for light current levels, then the
capacitor size may be decreased.
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use
with the AAT3123/24. Ceramic capacitors offer
many advantages over their tantalum and alu-
minum electrolytic counterparts. A ceramic capac-
itor 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 capaci-
tors are non-polarized, they are not prone to incor-
rect connection 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.
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 sta-
ble over temperature. Large capacitor values are
typically composed of X7R, X5R, Z5U or Y5V
dielectric materials. Large ceramic capacitors, typ-
ically greater than 2.2 F are often available in low
cost Y5V and Z5U dielectrics, but capacitors
greater than 1µF are typically not required for
AAT3123/24 applications.
3123.2003.09.1.1
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 AAT3123/24 has a thermal protection circuit
that will shut down the internal LDO and charge
pump if the die temperature rises above the ther-
mal limit as is the case during a short circuit of the
OUT pin.
Driving Multiple LED's, White LED
display module back lights and
individual LED's connected in parallel
The AAT3123/24 D1 to D6 outputs are true con-
stant current sources capable of driving up to
20mA each over the operation input voltage range.
Since these outputs are true constant current
sources, they may be connected in parallel to drive
a single power output. Any combination of outputs
(D1 to D6) may be connected in parallel. The max-
imum total output current is a sum of how many
current sources are parallel connected. This fea-
ture is particularly useful to power pre-manufac-
tured display modules which are pre-wired with
white LED backlights connected in a parallel circuit
configuration. Any combination of outputs may be
connected in parallel to drive groups of LED's. The
AAT3123 internal current source reference circuit
bases feedback from current sensed on the D1
output. The AAT3124 internal current source refer-
ence circuit bases feedback from current sensed
on the D1 and D5 outputs. For best operation, the
only requirement for this type of application is the
output D1 (and or D5 for the AAT3124) should
always be connected to the load circuit.
The AAT3124 may be used to drive multiple LED's
having differing forward voltages. Using feedback
techniques, the current in D1 to D4 output currents
sources are referenced to the current in the LED
connected to D1. In AAT3124 (six output version),
the D5 and D6 output current sources are refer-
enced to the current in D5, not to D1. If all six LED's
are of similar type, the diodes will be matched in
current, maintaining uniform LED brightness
despite variations in manufacturer, production, etc.
11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet AAT3123ITP-20-T1.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AAT3123ITP-20-T1 | High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications | ETC |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |