Microchip MIC4801 Handleiding

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MIC4801

High Efficiency 600mA Single Channel

Linear WLED Driver with

Ultra Fast PWM™ Control

Ultra Fast PWM is a trademark of Micrel, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

January 2011 M9999-011811-A

General Description

The MIC4801 is a high efficiency White LED (WLED)

driver designed to drive a single LED up to 600mA. The

MIC4801 constant current driver is designed to drive high

power LED’s in various lighting applications. The MIC4801

provides the highest possible efficiency as this architecture

has no switching losses present in traditional charge

pumps or inductive boost circuits. It features a typical

dropout of 130mV at 400mA. This allows the LEDs to be

driven directly from the voltage source eliminating

switching noise/losses present with the use of boost

circuitry. The high accuracy (±1% typical) current regulated

WLED channel ensures uniform display illumination under

all conditions. The brightness is controlled through an Ultra

Fast PWM™ Control interface operating down to less than

1% duty cycle.

The MIC4801 is available in an 8-pin SOIC package with a

junction temperature range of -40° °C to +125 C.

Datasheets and support documentation can be found on

Micrel’s web site at: www.micrel.com.

Features

• High Efficiency (no Voltage Boost losses)

• Ultra Fast PWM™ control (200Hz to 500kHz)

• Input voltage range: 3.0V to 5.5V

• Dropout of 130mV at 400mA

• Programmable LED current with external resistor

• Current accuracy of ±1% typical

Applications

• Bill board displays

• Marquee displays

• Instrument displays

• Architectural lighting

____________________________________________________________________________________________________________

Typical Application

High Current Lighting Schematic

Micrel Inc. MIC4801

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Ordering Information

Part Number Temperature Range Package

MIC4801YM –40°C to +125°C 8-Pin SOIC

Pin Configuration

8-Pin SOIC (M)

(Top View)

Pin Description

Pin Number Pin Name Pin Function

1 VIN Voltage Input. Connect at least 2.2µF ceramic capacitor between VIN and GND.

2 EN Enable LED drivers. This pin can be used as a PWM input for dimming of WLEDs. Do not leave

floating.

3 RSET An internal 1.27V reference sets the nominal maximum WLED current. Example, apply a 12.1kΩ

resistor between RSET and GND to set LED current to 416mA at 100% duty cycle.

4 GND Ground.

5 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be

connected to the LED.

6 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be

connected to the LED.

7 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be

connected to the LED.

8 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be

connected to the LED.

Micrel Inc. MIC4801

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Absolute Maximum Ratings(1)

Main Input Voltage (VIN) .................................. –0.3V to +6V

Enable Input Voltage (VEN).............................. –0.3V to +6V

LED Driver Voltage (VD1) ................................ –0.3V to +6V

Power Dissipation .....................................Internally Limited

Lead Temperature (soldering, 10sec.)....................... 260°C

Storage Temperature (Ts) .........................–65°C to +150°C

Operating Ratings(2)

Supply Voltage (VIN)..................................... +3.0V to +5.5V

Enable Input Voltage (VEN) .................................... 0V to V

LED Driver Voltage (VD1) ....................................... 0V to VIN

Junction Temperature (TJ) ........................ –40°C to +125°C

Junction Thermal Resistance

SOIC-8L (θJA)..................................................98.9°C/W

Electrical Characteristics

VIN = VEN = 5V, RSET = 12.1kΩ; VD1 = 1.2V; TJ = 25° °C, bold values indicate –40 C ≤ TJ ≤ 125°C; unless noted.

Parameter Conditions Min Typ Max Units

Current Accuracy(3) 374 416 458 mA

Drop-out Where ILED = 90% of LED current seen at

VDROPNOM = 1.2V, 100% brightness level 130 250 mV

Ground/Supply Bias Current IOUT = 416mA 2.2 2.9 mA

Shutdown Current VEN = 0V 0.01 1 µA

PWM Dimming

Logic Low 0.2 V Enable Input Voltage (V

EN)

Logic High 1.2 V

Enable Input Current VIH > 1.2V 0.01 1 µA

Current Source Delay

(50% levels)

Shutdown to on

Standby to on

On to Standby

0.3

60 µs

µs

Current Source Transient Time

(10%-90%)

TRISE

TFALL

0.3

µs

Stand-by to Shutdown Time VEN = 0V 10 20 40 ms

Notes:

1. Exceeding the absolute maximum rating may damage the device.

2. The device is not guaranteed to function outside its operating rating.

3. As determined by average current based on R

SET resistance.

Micrel Inc. MIC4801

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MIC4801 Typical Application Circuit

Bill of Materials

Item Part Number Manufacturer Description Qty.

C1608X5R0J225K TDK(1)

06036D225KAT2A AVX

(2)

GRM188R60J225KE19D Murata(3)

VJ0603G225KXYAT Vishay(4)

Ceramic Capacitor, 2.2µF, 6.3V, X5R, Size 0603 1

LED R42180 Seoul Semiconductor(5) 3.8W High Power WLED 1

R1 CRCW060312K1FKEA Vishay(4) Resistor, 1%, 1/16W, Size 0603 1

U1 MIC4801YM Micrel, Inc.(6) 600mA Single Channel Ultra Fast PWM™

Linear WLED Driver 1

Notes:

1. TDK: www.tdk.com

2. AVX: www.avx.com

3. Murata: www.murata.com

4. Vishay: www.vishay.com

5. Seoul Semi: http://www.acriche.com/en

6. Micrel, Inc.: www.micrel.com

Micrel Inc. MIC4801

January 2011 12 M9999-011811-A

Package Information

8-Pin SOIC (M)

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This

information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,

specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual

property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability

whatsoever, and Micrel disclaims any express or implied warranty of Micrel products including lrelating to the sale and/or use iability or warranties

relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

can reasonably be expected to result in personal injury. Life support devices or system ended for surgical implant s are devices or systems that (a) are int

into the body or (b) support or sustain life, and whose failure t injury to the user. A to perform can be reasonably expected to result in a significan

Purchaser’s use or sale of Micrel Produc Purchaser agrees to fully ts for use in life support appliances, devices or systems is a Purchaser’s own risk and

indemnify Micrel for any damages resulting from such use or sale.