NCP1422LEDGEVB ON Semiconductor, NCP1422LEDGEVB Datasheet

NCP1422LEDGEVB

Manufacturer Part Number

NCP1422LEDGEVB

Description

EVAL BOARD FOR NCP1422LED

Manufacturer

ON Semiconductor

Datasheets

1.NCP1422MNR2G.pdf (14 pages)

2.NCP1421LEDEVB.pdf (6 pages)

3.NCP1422LEDGEVB.pdf (1 pages)

Specifications of NCP1422LEDGEVB

Design Resources

NCP1422LEDGEVB BOM NCP1422LEDGEVB Schematic NCP1422LEDEVB Gerber Files

Current - Output / Channel

800mA

Outputs And Type

1, Non-Isolated

Voltage - Output

500 ~ 700 mV

Voltage - Input

3.6V

Utilized Ic / Part

NCP1421

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Features

Lead Free Status / Rohs Status

Lead free / RoHS Compliant

Other names

NCP1422LEDEVBOS
NCP1422LEDEVBOS
NCP1422LEDGEVBOS

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AND8171/D

NCP1421/2 Reference

Designs for High−Power

White LED Flash

Applications

Prepared by: Jim Hill

ON Semiconductor

Abstract

converters can be configured as a current regulator for

biasing high current white LED’s. Typical boost converters,

such as these, have a reference voltage of 1.2 V. Since this

is a current sourcing application, the more straightforward

approach of directly sensing the boost converter’s reference

voltage (V

dissipate too much power at the currents required to drive

high−power White LED’s. Also, the lot−to−lot forward

voltage variation is too high to simply regulate at a fixed

voltage with a current limiting resistor. Therefore, this paper

describes a technique that reduces both the power loss in the

sense resistor and the lot−to−lot variation effect of the LED.

This applications shows two implementations of this

concept. Figure 1 shows a simple boost converter configured

at various current levels and uses the Lumileds LXHL−

WW06 white LED. Figure 5 shows a circuit that switches

between a low current for focus lighting and high current for

the flash and uses the Lumileds LXCL−PWF1 white LED.

Overview

converter IC’s uniquely suited to power higher current

portable applications (600 − 800 mA maximum). Their high

switching frequency (up to 1.2 MHz) allows for a low

November, 2004 − Rev. 0

The attached design illustrates how the NCP1421/2 boost

The NCP1421 and NCP1422 are monolithic boost

Semiconductor Components Industries, LLC, 2004

ref

), which is 1.2 V, across a sense resistor would

22 mF

Figure 1. NCP1422 Configured to Drive High Current White LED

50 ms Pulse

100k

OFF

220 nF

LBI/EN

LBO

REF

NCP1422

GND 6

BAT 5

OUT

profile, small sized inductor and output capacitor to be used.

Also an integrated disconnect switch provides “true cutoff”

by isolating the output from the battery during shutdown.

The NCP1421 comes in the 3x5 mm Micro−8 package, and

the NCP1422 comes in the 3x3 mm DFN package. Because

of these features the NCP1421/2 are well suited to provide

current regulation for biasing high current white LED’s in

portable flash applications. Figure 1 illustrates this circuit.

current sense resistor, R4, and a divided down voltage from

the white LED with resistors R2 and R3. This helps remove

some of the dependence of the NCP1421/2’s output voltage,

and thus current, on the LED’s forward voltage, V

also helps prevent lot−to−lot V

brightness.

Materials shown in Table 1, can provide LED currents of 200,

600 and 800 mA. The 200 mA design uses the NCP1422

because of its smaller footprint, and the 600 mA and 800 mA

designs use the NCP1421 and NCP1422 respectively to

showcase the load current limits of each device.

LED will be pulsed and not run at steady state. 50 ms pulses

on the LBI/EN were used in the analysis of these circuits.

The NCP1421/2 takes 1.5 ms (nominal) to turn on after the

LBI/EN pin is driven high.

LX 7

In summary the reference voltage is split between the

Figure 1 shows a typical circuit which, with the Bill of

The higher currents (600 and 800 mA) assume that the

6.8 mH

APPLICATION NOTE

http://onsemi.com

variation affecting the LED

Publication Order Number:

22 mF

AND8171/D

. This

Related parts for NCP1422LEDGEVB

NCP1422LEDGEVB Summary of contents

Page 1

... NCP1421/2 Reference Designs for High−Power White LED Flash Applications Prepared by: Jim Hill ON Semiconductor Abstract The attached design illustrates how the NCP1421/2 boost converters can be configured as a current regulator for biasing high current white LED’s. Typical boost converters, such as these, have a reference voltage of 1.2 V. Since this is a current sourcing application, the more straightforward approach of directly sensing the boost converter’ ...

Page 2

V 0 3.0 3.2 3.4 3.6 INPUT VOLTAGE (V) Figure 2. Output Current vs. Input Voltage 100 200 mA 80 600 ...

Page 3

Finally, Figure 5 shows a Focus/Flash application where the NCP1422 drives one LED at 200 and 600 mA R4a Q1 ON R4b OFF 50 ms Pulse Figure 5. 200/600 mA Focus/Flash Application V = 3.6 ...

Page 4

... V (X5R Ceramic) 0805 6.3 V (X5R Ceramic) 0805 http://onsemi.com 4 Manufacturer ON Semiconductor Lumileds TDK Vishay Vishay Vishay Vishay TDK TDK TDK ON Semiconductor Lumileds TDK / Coilcraft Vishay Vishay Vishay Vishay TDK TDK TDK ON Semiconductor Lumileds TDK Vishay Vishay Vishay Vishay TDK TDK TDK ...

Page 5

... SC−88 6.8 mH Inductor (5.6 x 5.0 x 1.0 mm) 100 kW 0402 475 kW 0402 100 kW 0402 1.0 W 1206 2.0 W 1206 220 nF 0603 6.3 V (X5R Ceramic) 0805 6.3 V (X5R Ceramic) 0805 http://onsemi.com 5 ON Semiconductor Lumileds ON Semiconductor TDK Vishay Vishay Vishay Vishay Vishay TDK TDK TDK ...

Page 6

... Fax: 480−829−7709 or 800−344−3867 Toll Free USA/Canada Email: orderlit@onsemi.com AND8171/D N. American Technical Support: 800−282−9855 Toll Free USA/Canada Japan: ON Semiconductor, Japan Customer Focus Center 2−9−1 Kamimeguro, Meguro−ku, Tokyo, Japan 153−0051 Phone: 81−3−5773−3850 http://onsemi.com 6 ON Semiconductor Website: http://onsemi ...

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