LED DRIVER. AL8843 Datasheet

AL8843 DRIVER. Datasheet pdf. Equivalent

AL8843 Datasheet
Recommendation AL8843 Datasheet
Part AL8843
Description 40V 3A STEP-DOWN LED DRIVER
Feature AL8843; NEW PRODUCT AL8843 40V 3A STEP-DOWN LED DRIVER Description The AL8843 is a hysteresis mode DC-DC s.
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Datasheet
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Diodes AL8843
AL8843
40V 3A STEP-DOWN LED DRIVER
Description
The AL8843 is a hysteresis mode DC-DC step-down converter,
designed for driving single or multiple series connected LEDs
efficiently from a voltage source higher than the LED voltage. The
device can operate from an input supply between 4.5V and 40V and
provide an externally adjustable output current up to 3A. Depending
upon supply voltage and external components, this converter can
provide up to 60W of output power.
The AL8843 integrates the power switch and a high-side output
current sensing circuit, which uses an external resistor to set the
nominal average output current.
Dimming can be realized by applying an external control signal to the
CTRL Pin. The CTRL Pin will accept either a DC voltage signal or a
PWM signal.
The soft-start time can be adjusted by an external capacitor from the
CTRL Pin to Ground. Applying a voltage of 0.3V or lower to the CTRL
Pin will shut down the power switch.
Features
Wide Input Voltage Range: 4.5V to 40V
Output Current up to 3A
Internal 40V NDMOS Switch
Typical 4% Output Current Accuracy
Single Pin for On/Off and Brightness Control by DC Voltage or
PWM Signal
Recommended Analog Dimming Range: 10% to 100%
Soft-Start
High Efficiency (Up to 97%)
LED Short Protection
Inherent Open-Circuit LED Protection
Over Temperature Protection (OTP)
Up to 1MHz Switching Frequency
SO-8EP Packages Available in Green Molding Compound (No
Br, Sb)
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Pin Assignments
(Top View)
GND 1
GND 2
SET 3
NC 4
EP
SO-8EP
8 SW
7 SW
6 VIN
5 CTRL
Applications
LED Retrofit for Low Voltage Halogen
Low Voltage Industrial Lighting
LED Backlighting
Illuminated Signs
External Driver with Multiple Channels
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated‘s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green‖ products are defined as those which contain <900ppm bromine, <900ppm chlorine
(<1500ppm total Br + Cl) and <1000ppm antimony compounds.
AL8843
Document number: DS40367 Rev. 1 - 2
1 of 18
www.diodes.com
December 2017
© Diodes Incorporated



Diodes AL8843
Typical Applications Circuit
VIN: 4.5-40V
RSET
AL8843
VIN SET
C1
CTRL
AL8843
D1
GND
SW
L1
Pin Descriptions
Pin Number
1,2
3
4
5
6
7,8
EP
Pin Name
GND
SET
NC
CTRL
VIN
SW
EP
Function
Ground of IC
Set Nominal Output Current Pin. Connect resistor RSET from this pin to VIN to define nominal average
output current.
No connection
Multi-function On/Off and brightness control pin:
Leave floating for normal operation.
Drive to voltage below 0.3V to turn off output current
Drive with DC voltage (0.4V < CTRL< 2.5V) to adjust output current from 10% to 100% of
IOUT_NOM
Drive with an analog voltage >2.6V output current will be 100% of IOUT_NOM
A PWM signal (Low level <0.3V, High level >2.6V, transition times less than 1us) allows the
output current to be adjusted over a wide range up to 100%
Connect a capacitor from this pin to ground to increase soft-start time.
(Default soft-start time = 0.1ms. Additional soft-start time is approx. 1.5ms/1nF)
Input voltage (4.5V to 40V). Decouple to ground with 10μF or higher X7R ceramic capacitor close to
device.
Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI.
Exposed pad/TAB connects to GND and thermal mass for enhanced thermal impedance.
AL8843
Document number: DS40367 Rev. 1 - 2
2 of 18
www.diodes.com
December 2017
© Diodes Incorporated



Diodes AL8843
Functional Block Diagram
SET
VIN 6
3
VDD
4.5V
Generator 4.5V_Drv
Current
Monitor
AL8843
SW
7, 8
AL8843
CTRL
5
BG &
Reference
Ref
Comp
Hysteresis
Control PWM
Logic &
Driver
PWM/DC PWM
Dimming
OTP
OTP
6
1, 2
GND
Absolute Maximum Ratings (Note 4)
Note:
Symbol
Parameter
Rating
Unit
VIN
VSW , VSET
VCTRL
TJ
TSTG
TLEAD
Input Voltage
SW, SET Pin Voltage
CTRL Pin Input Voltage
Operating Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10sec)
-0.3 to +42
-0.3 to +42
-0.3 to +6
-40 to +150
-65 to +150
+300
V
V
V
°C
°C
°C
4. Stresses greater than those listed under ―Absolute Maximum Ratings‖ 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 under ―Recommended Operating Conditions‖ is not
implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability.
ESD Ratings
Symbol
VESD
Human-Body Model (HBM)
Machine Model (MM)
Parameter
Rating
-2500 to 2500
-200 to 200
Unit
V
AL8843
Document number: DS40367 Rev. 1 - 2
3 of 18
www.diodes.com
December 2017
© Diodes Incorporated







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