AD8240YRM Analog Devices Inc, AD8240YRM Datasheet

AD8240YRM

Manufacturer Part Number

AD8240YRM

Description

IC LED DRIVER PWM CONTROL 8-MSOP

Manufacturer

Analog Devices Inc

Type

PWM Controlr

Datasheet

1.AD8240YRMZ.pdf (12 pages)

Specifications of AD8240YRM

Constant Current

Yes

Topology

Linear, PWM

Number Of Outputs

Internal Driver

Type - Primary

Automotive

Frequency

500Hz

Voltage - Supply

9 V ~ 27 V

Voltage - Output

12V

Mounting Type

Surface Mount

Package / Case

8-MSOP, Micro8™, 8-uMAX, 8-uSOP,

Operating Temperature

-40°C ~ 125°C

Current - Output / Channel

15mA

Internal Switch(s)

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

Efficiency

Available stocks

Company

Part Number

Manufacturer

Quantity

Price

Company:

Meier Automation Equipment Co., Limited

Part Number:

AD8240YRMZ

Manufacturer:

ADI/亚德诺

Quantity:

20 000

Current page: 1 of 12
Download datasheet (218Kb)

FEATURES

PWM input for LED brightness control

Open LED detection

Latch-off overcurrent protection

Constant voltage regulated output

Supply range: 9 V to 27 V

Regulated voltage range: 12.5 V to 27 V

Operating current: 300 µA

Shutdown current: 10 µA

Temperature range −40°C to +125°C

8-lead MSOP package

GENERAL DESCRIPTION

The AD8240 LED driver/monitor, in combination with an

external transistor, supplies a constant 12 V to drive LED

lamps. This allows cost-effective LED lamp monitoring and

short-circuit protection. The output is regulated at 12 V when

the supply voltage is between 12.5 V and 27 V.

A CMOS compatible, level-dependent, digital input can be used

for PWM control of the LED brightness. V

the PWM input is high and turned off when the input is low.

The AD8240 is designed to work with a PWM frequency up

to 500 Hz, and a typical PWM range from 5% to 95%.

Open LED detection is accomplished by measuring the change

in LED lamp current caused by an open LED(s) through the use

of an internal high-side current-sense amplifier that amplifies

the voltage across an external current shunt. The voltage across

the shunt resistor is amplified to a level that can be measured by

a microcontroller A/D converter or a comparator. The ability to

measure the change in LED lamp current is the key benefit of

constant-voltage LED lamp driving.

The output is current-limited by latching off the output voltage

when the current reaches a preset level. The current limit is set

by selecting the value of the external current shunt that causes

the output of the sense amplifier to slightly exceed the 5 V

reference level when the current exceeds a maximum level.

When the sense amplifier output exceeds 5 V, it trips an internal

comparator that causes the driver to latch off the output voltage.

The latch is reset during the next PWM cycle. The overcurrent

condition can also be detected by a microcontroller or external

comparator by measuring the sense amplifier output.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.

However, no responsibility is assumed by Analog Devices for its use, nor for any

infringements of patents or other rights of third parties that may result from its use.

Specifications subject to change without notice. No license is granted by implication

or otherwise under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

is turned on when

PRODUCT HIGHLIGHTS

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

Fax: 781.326.8703

REFERENCE

Partial LED lamp failure detection.

Allows for compliance with automotive regulations

for turn signal functionality detection and minimum

brightness, as well as running/brake light minimum

brightness compliance.

Current limiting/latch-off protection.

Limiting and latching off the LED current protects vehicle

wiring and prevents lamp damage

PWM input.

Provides brightness control.

Constant voltage output.

Saves cost by minimizing wiring and system design

complexity.

Drives an external transistor for low power operation.

Providing for an external power transistor allows the

AD8240 to be a low cost solution in a small package. A

more efficient design is made possible when the system

designer can select a power device with specifications

that match the application requirements.

Linear regulation.

Minimizes EMI, which allows faster system integration,

qualification, and time to market. Additionally, costs are

reduced by eliminating the inductor required for a

switching design. Because of the power-saving nature of

LED lamps as compared to incandescent lamps, a

switching driver is typically not required.

SENSE

PWM

FUNCTIONAL BLOCK DIAGRAM

AD8240

10k Ω

SENSE

Figure 1.

LED Driver/Monitor

SHUNT

LATCH-OFF

DRIVER

BASE

www.analog.com

GND

AD8240

350k Ω

250k Ω

Related parts for AD8240YRM

AD8240YRM Summary of contents

Page 1

FEATURES PWM input for LED brightness control Open LED detection Latch-off overcurrent protection Constant voltage regulated output Supply range Regulated voltage range: 12 Operating current: 300 µA Shutdown current: 10 µA ...

Page 2

AD8240 TABLE OF CONTENTS Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 Product Description......................................................................... 5 Linear Regulator (Block A) ......................................................... 5 High-Side Current-Sense Amplifier with Open LED Detection (Block B)...................................................................... 5 Comparator with Latch-off OverCurrent Protection (Block C)........................................................................................ 5 Intelligent Driver (Block ...

Page 3

SPECIFICATIONS T = operating temperature range PLUS Table 1. Parameter Regulation at 25° Regulation -40°C to 125° OUT V Rise Time O V Gain SENSE V Accuracy SENSE ...

Page 4

AD8240 ABSOLUTE MAXIMUM RATINGS Table 2. Parameters Rating Supply Voltage, Continuous 27 V Supply Voltage, Transient 30 V Reverse Supply Protection −0.3 V Operating Temperature 125°C Storage Temperature −65°C to +150°C 1 Output Short-Circuit Duration Indefinite 1 Output short circuits ...

Page 5

PRODUCT DESCRIPTION The AD8240 consists of four functional blocks labeled A through D, as shown in Figure 2. V SHUNT BASE PLUS B V SENSE C 5V REFERENCE D PWM AD8240 Figure 2. Simplified Functional Block Diagram Table 3 briefly ...

Page 6

AD8240 USING/EVALUATING THE AD8240 LED DRIVER MONITOR Figure 3 shows a connection diagram for a typical application. SETUP In order to set up and evaluate the AD8240, the following components and equipment are needed: • A shunt resistor (typically 0.1 ...

Page 7

CONTROLLING THE LED LAMP The LEDs are turned on and off depending on the CMOS compatible digital voltage level present at the PWM pin (Pin 3). This voltage can be continuous for a simple on/off function, or PWM for dimming ...

Page 8

AD8240 ADVANTAGES OF DRIVING LED LAMPS WITH CONSTANT VOLTAGE The advantages of driving LED lamps with constant voltage are • Low system cost • Accurate monitoring • Proven strategy BACKGROUND A great variety of LED lamps are being used in ...

Page 9

As a result, the constant voltage driving/monitoring method is the lowest cost and least-prone-to-failure method for driving and monitoring LEDs from a system perspective. This is primarily because the number of wires and connections can be minimized. By using a ...

Page 10

AD8240 OUTLINE DIMENSIONS 3.00 BSC 8 5 4.90 3.00 BSC BSC 4 PIN 1 0.65 BSC 1.10 MAX 0.15 0.00 8° 0.38 0.23 0° 0.22 0.08 COPLANARITY SEATING 0.10 PLANE COMPLIANT TO JEDEC STANDARDS MO-187AA Figure 4. 8-Lead Mini Small ...

Page 11

... ORDERING GUIDE Model Temperature Range AD8240YRM −40°C to +125°C AD8240YRM-REEL −40°C to +125°C AD8240YRM-REEL7 −40°C to +125°C Package Description Package Option 8-Lead MSOP RM-8 MSOP, 13” Tape and Reel RM-8 MSOP, 7” Tape and Reel RM-8 Rev Page ...

Page 12

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