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MIC3263 Evaluation Board

Six-Channel WLED Driver for

Backlighting Applications with

Flicker-Free Dimming

Bringing the Power to Light™

MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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

March 2010 M9999-032410-B

General Description

This evaluation board (EVB) is designed for the MIC3263.

The MIC3263 is a high-efficiency Pulse Width Modulation

(PWM) boost switching regulator that is optimized for

constant-current WLED driver backlighting applications.

The MIC3263 drives six channels of up to ten low-power

WLEDs per channel. Each channel is matched in current

to within ±3% for constant brightness across the screen

and can be programmed from 15mA to 30mA.

The MIC3263 provides a very flexible dimming control

scheme with high accuracy and noise immunity. The

dimming frequency can be set to any value between

100Hz and 20kHz by an external resistor. The dimming

ratio is determined by the duty-cycle of a dimming ratio

control input signal and can be set to one of 16 levels with

a minimum ratio of 1%. The LED dimming current is set by

an external resistor to allow programming of LED current

between 15mA and 30mA.

The dimming ratio of the MIC3263 is fixed to 16

logarithmic levels to better match the sensitivity of the

human eye. Each of the dimming levels has hysteresis to

avoid skipping between levels resulting in Flicker-Free

operation.

The MIC3263 has a programmable PWM switching

frequency from 400kHz to 1.8MHz to allow small inductor

sizes. The 6V to 40V wide-input voltage range of MIC3263

allows direct operation from 6V or high cell count Li-Ion

batteries commonly found in notebook computers.

Precautions

The MIC3263 evaluation board operates as a boost

converter, which requires the output voltage to be greater

than the input voltage. Connect a PWM dimming signal to

the DRC pin. The DRC pin needs an input signal to

operate.

Requirements

1. Voltage source capable of supplying 10W

2. Load: Six LED strings

3. Scope

4. Function generator for PWM Dimming

Getting Started

1. Set the LED current of all six channels by one resistor

RISET (noted as R9 on the EVB). Use 2kΩ for 30mA

and 3kΩ for 20mA. Use the following equation to find

RISET:

LED

R =

ISET I

Ω

2. Connect six strings of LEDs from LED out to LED-

RTN. Each one of the six LED strings needs to

connect to one of the LED RTN. The cathode end of

each LED string connects to one of the six LED RTN

pins. The anode end of all the LED strings connects to

LED OUT (VOUT). The number of LEDs in each string

should be from 4 to 10.

3. Connect 12V (or other input voltage) to VIN and GND.

4. Use a current probe to measure the load current and

monitor the switch node with a scope to view the

switching waveform

5. PWM Dimming:

a. Connect a function generator to the

dimming input (DRC pin) 0V to 5V at

100Hz to 40kHz.

b. Adjust the duty-cycle of the function

generator for PWM dimming. The

MIC3263 converts the duty-cycle at the

DRC to one of sixteen dimming ratios

(DR) according to Table 1.

c. Follow the power-on sequence to ensure

all channels turn on.

d. The EVB is set for 30mA LED current. For

a different LED current, change R9 using

the given equation.

Produktspecifikationer

Varumärke:	Microchip
Kategori:	Inte kategoriserad
Modell:	MIC3263YML
Färg på produkten:	Black, Grey
Vikt:	1450 g
Bredd:	335 mm
Djup:	111 mm
Höjd:	295 mm
Typ av strömkälla:	DC
Antal USB 2.0-portar:	3
VGA (D-Sub) port(ar):	1
HDMI-kontakttyp:	Volledige grootte
Antal Ethernet LAN (RJ-45)-portar:	2
DC-spänningsingång:	19 V
Certifiering:	FCC, CE, MIL-STD 810G, SAE J1455
HDMI:	Ja
Hållbarhetscertifikat:	RoHS
RS-232:	Ja
Varumärkeskompatibilitet:	Getac
Antal portar USB 3.2 Gen 1 (3.1 Gen 1) Typ A:	3
Extern anpassning:	Ja
Kompatibilitet:	K120
Adapter medföljer:	Ja
Standard enhetstyp:	Tablet