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Número de pieza | AS3833 | |
Descripción | 6 channel high-precision LED controller | |
Fabricantes | austriamicrosystems | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de AS3833 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
No Preview Available ! Datasheet
AS3833
6 channel high-precision LED controller for 3D-LCD backlight with
integrated step-up controller
1 General Description
The AS3833 is a 6 channel high precision LED controller with PWM
input for driving external bipolar transistors in LCD-backlight panels,
optimized for 2D and 3D operation.
The integrated step-up controller provides the necessary output
voltage for the LED string supply.
The SMPS feedback control optimizes the power efficiency by
adjusting the LED string supply voltage.
Build in safety features include under-voltage and thermal shutdown
as well as open and short LED detection.
2 Key Features
6 channel LED controller
Step-up controller optimized for 2D/3D mode
Supply voltage range: 12V to 50V
Output current up to 250mA per channel
Absolute current accuracy +/- 0.8%
Channel to channel accuracy+/- 0.6%
1 PWM input with internal phase shift
Open LED detection and disconnect
Short LED protection and auto-turnoff
Undervoltage shutdown
Temperature shutdown
Temperature supervision of external BJT
BJT Beta compensation
SMPS feedback control
DCDC Softstart Function
Over Voltage Protection (OVP)
Package SOIC-28
Package TQFP-32
Figure 1. AS3833
3 Applications
LED backlighting for 3D-LCD backlight TV sets and monitors
www.austriamicrosystems.com/AS3833
Revision 1.8
1 - 20
1 page AS3833
Datasheet - Absolute Maximum Ratings
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 6 is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 2. Absolute Maximum Ratings
Parameter
Electrical Parameters
Min Max Units
Comments
VDDH to VSS, VDDH_HC to VSS
-0.3 55 V
VDDM to VSS, GATE to VSS
-0.3 25 V
xFAULT to VSS
-0.3 7 V
VDDL to VSS
-0.3 5 V
Analog Pin Voltage to VSS1
-0.3 5 V
Digital Pin Voltage to VSS2
-0.3 5 V
Input Current (latch-up immunity)
Electrostatic Discharge
-100 100 mA
Norm: JEDEC 78
Electrostatic Discharge HBM
+/- 1500
V
Norm: MIL 883 E method 3015
Electrostatic Discharge MM
Continuos Power Dissipation (TA = +70°C)
Continuos Power Dissipation
+/- 200
1.5
V
W
Norm: JESD22-A115C
PT3 for SOIC-28 Package
Continuos Power Dissipation Derating Factor
Temperature Ranges and Storage Conditions
13 mW / °C
PDERATE4
Junction to ambient thermal resistance
SOIC-28 Package.
76 ºC/W For more information about thermal metrics, see
application note AN01 Thermal Characteristics.
Junction Temperature (TJmax)
Storage Temperature Range
+150 ºC
-55 +150 ºC
Package Body Temperature
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020“Moisture/Reflow Sensitivity
+260 ºC Classification for Non-Hermetic Solid State Surface
Mount Devices”.
The lead finish for Pb-free leaded packages is matte
tin (100% Sn).
Humidity non-condensing
5 85 %
Moisture Sensitive Level
1
Represents a max. floor life time of unlimited
1. Pins Vth, UVLO, Comp, Sense, FB, Iset, Ex, Bx
2. Pins PWMx
3. Depending on actual PCB layout and PCB used.
4. PDERATE derating factor changes the total continuous power dissipation (PT) if the ambient temperature is not 25ºC. Therefore for e.g.
TA=85ºC calculate PT at 85ºC = PT - PDERATE x (85ºC - 25ºC)
Revision 1.8
5 - 20
5 Page AS3833
Datasheet
8.2 VDDH_HC resistor
Figure 11. VDDH_HC resistor
Pin VDDH_HC is connected to an internal 3.3V voltage regulator. In order to keep the power dissipation of this regulator low, it is recommended
to connect pin VDDH_HC to the power supply Vin with a resistor. The resistor should guarantee sufficient voltage drop so that the remaining
voltage at pin VDDH_HC is approximately 5V. The power dissipation of the RVDDH_HC hat to be considered.
RVDDH_HC
=
-V---i--n---–-----5---V--
75mA
(EQ 2)
PRVDDH_HC = (75 mA )2 × RVDDH_HC
Typical values for RVVDH2 are:
VIN = 13V: RVDDH_HC= 100Ω / 1W
VIN = 24V: RVDDH_HC= 250Ω / 2W
(EQ 3)
8.3 Safety features
8.3.1 Undervoltage lockout
In order to avoid startup of the Boost controller at low supply voltage an undervoltage lockout function is implemented. The boost controller only
turns on when the voltage at pin UVLO exceeds VUVLO. Once the boost controller is turned on a current source IUVLO_Hyst is activated which
increases the UVLO voltage and so shifts the turn off voltage level.
Figure 12. Undervoltage lockout
www.austriamicrosystems.com/AS3833
Revision 1.8
11 - 20
11 Page |
Páginas | Total 20 Páginas | |
PDF Descargar | [ Datasheet AS3833.PDF ] |
Número de pieza | Descripción | Fabricantes |
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