|
|
PDF AX2021 Data sheet ( Hoja de datos )
| Número de pieza | AX2021 | |
| Descripción | 0.45A Step-down High Brightness LED Driver | |
| Fabricantes | AXElite | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AX2021 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
|
No Preview Available !
AX2021
32V, 0.45A Step-down High Brightness
LED Driver with 5000:1 Dimming
GENERAL DESCRIPTION
The AX2021 is a continuous conduction mode inductive step-down converter, designed
for driving single or multiple series connected LED efficiently from a voltage source higher
than the total LED chain voltage. The device operates from an input supply between 8V and
32V and provides an externally adjustable output current of up to 0.45A. Depending upon
the supply voltage and external components, the AX2021 can provide more than 15 watts of
output power. The AX2021 includes the power switch and a high-side output current sensing
circuit, which uses an external resistor to set the nominal average output current, and a
dedicated DIM input accepts a wide range of pulsed dimming. Applying a voltage of 0.3V or
lower to the DIM pin turns the output off and switches the device into a low current standby
state.
The AX2021 is available in TSOT-23-5L package.
FEATURES
- Simple low parts count
- Wide input voltage range: 8V to 32V
- Up to 0.45A output current
- Single pin on/off and brightness control using PWM
- Up to 1MHz switching frequency
- Typical 5% output current accuracy
- High-Side Current Sense
- Hysteretic Control: No Compensation
- Adjustable Constant LED Current
1/11
1 page  
AX2021
APPLICATION INFORMATION
OPERATION DESCRIPTION
The device, in conjunction with the coil (L1) and current sense resistor (RS), forms a
self oscillating continuous-mode buck converter.
When input voltage VIN is first applied, the initial current in L1 and RS is zero and there
is no output from the current sense circuit. Under this condition, the output of CS comparator
is high. This turns on an internal switch and switches the SW pin low, causing current to flow
from VIN to ground, via RS, L1 and the LED(s). The current rises at a rate determined by VIN
and L1 to produce a voltage ramp (VCSN) across RS. When (VIN-VCSN) > 150mV, the output of
CS comparator switches low and the switch turns off. The current flowing on the RS
decreases at another rate. When (VIN-VCSN) < 110mV, the switch turns on again and the
mean current on the LED is determined by ( 110 + 150 mV) / RS= 130mV / RS.
2
The high-side current-sensing scheme and on-board current-setting circuitry minimize
the number of external components while delivering LED current with ±5% accuracy, using a
1% sense resistor.
The AX2021 allow dimming with a PWM signal at the DIM input. A logic level below
0.3V at DIM forces AX2021 to turn off the LED and the logic level at DIM must be at least
2.0V to turn on the full LED current. The frequency of PWM dimming ranges from 100Hz to
more than 20 kHz.
The DIM pin is pulled high current approximately 70μA. It can be floated at normal
working. When a voltage applied to DIM falls below the threshold (0.3V nom.), the output
switch is turned off. The internal regulator and voltage reference remain powered during
shutdown to provide the reference for the shutdown circuit.
Additionally, to ensure the reliability, the AX2021 is built with a thermal shutdown (TSD)
protection and a thermal pad. The TSD protests the IC from over temperature (150°C). Also
the thermal pad enhances power dissipation. As a result, the AX2021 can handle a large
amount of current safely.
Setting nominal average output current with external resistor RS
The nominal average output current in the LED(s) is determined by the value of the
external current sense resistor (RS) connected between VIN and CSN and is given by:
IOUT = 0.130/RS (RS ≧ 0.16Ω)
This equation is valid when DIM pin is float. Actually, RS sets the maximum average
current which can be adjusted to a less one by dimming.
5/11
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Oct.06, 2010
5 Page 
PACKAGE OUTLINES
D
AX2021
θ
R
e
e1
b
C
L2
y
Symbol
Dimensions in Millimeters
Min. Nom. Max.
A-
- 1.10
A1 0.00
-
0.10
A2 0.70
0.90
1.00
b 0.30 0.40 0.50
C 0.08 0.14
0.20
D 2.80 2.90
3.00
E 2.60 2.80 3.00
E1 1.50
1.60
1.70
e 0.95 BSC.
e1 1.90 BSC.
L 0.30 0.45 0.60
L1 0.60 REF.
L2 0.25 BSC.
y-
- 0.10
R 0.10
-
-
θ 0o
-
8o
JECED outline: MO-193 AB
Dimensions in Inches
Min. Nom. Max.
- - 0.043
0 - 0.004
0.028
0.035
0.039
0.012
0.016
0.020
0.003
0.006
0.008
0.110
0.114
0.118
0.102
0.110
0.118
0.059
0.063
0.067
0.037 BSC.
0.075 BSC.
0.012
0.018
0.024
0.024 REF.
0.010 BSC.
- - 0.004
0.004
-
-
0o - 8o
11/11
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Oct.06, 2010
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet AX2021.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AX2020 | 1A Step-down High Brightness LED Driver | AXElite |
| AX2021 | 0.45A Step-down High Brightness LED Driver | AXElite |
| 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 |