MIC4826 datasheet(11/22 Pages) MICROCHIP

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2019 -2022 Microchip Technology Inc.

DS20006134B-page 11

MIC4826

5.0

APPLICATION INFORMATION

5.1

Inductor

In general, smaller value inductors, which can handle

more current, are more suitable to drive larger size

lamps. As the inductor value decreases, the switching

frequency (controlled by RSW) should be increased to

avoid saturation or the input voltage should be

increased. Typically, inductor values ranging from

220 µH to 560 µH can be used. Murata offers the

LQH3C series up to 560 µH and LQH4C series up to

470 µH, with low DC resistance. A 220 µH Murata

(LQH4C221K04) inductor is recommended for driving

a lamp size of 3 square inches. It has a maximum DC

resistance of 4.0Ω.

5.2

Diode

The diode must have a high reverse voltage (100V)

since the output voltage at the CS pin can reach up to

100V. A fast switching diode with lower forward voltage

and higher reverse voltage (100V), such as BAV19WS,

can be used to enhance efficiency.

5.3

Output Capacitor

Low ESR capacitors should be used at the regulated

boost output (CS pin) of the MIC4826 to minimize the

switching output ripple voltage. Selection of the

capacitor value will depend upon the peak inductor

current, inductor size, and the load. MuRata offers the

GRM40 series with up to 0.015 µF at 100V, with a X7R

temperature coefficient in 0805 surface mount

package. Typically, values ranging from 0.01 µF to

0.1 µF at 100V can be used for the regulated boost

output capacitor.

5.4

Pre-Designed Application Circuits

FIGURE 5-1:

100 Hz EL Driver for 3in2

Lamp.

FIGURE 5-2:

Typical Characteristics for

100 Hz EL Driver for 3in2 Lamp.

322k

3.32M

Li-Ion Battery

VIN

3.0V to 4.2V

0.22 F/10V

Murata

GRM39X7R 224K10

COUT

0.01 F/100V

GRM40X7R103K

Vishay Telefunken

BAV19WS

220 H

Murata

LQH4C221K04

3in2 LAMP

VDD

RSW

REL

GND

MIC4826

10 F/6.3V

Murata

GRM42-6X5R106K6.3

VIN

IIN

VA-VB

FEL

Lamp Size

3.3V

20 mA

160VPP

100 Hz

3in2

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