RT9293 datasheet(11/13 Pages) RICHTEK

11 / 13 page

RT9293

DS9293-01 April 2011

www.richtek.com

The maximum power dissipation depends on operating

ambient temperature for fixed TJ(MAX) and thermal

resistance

θJA. For RT9293 packages, the Figure 7 of

derating curves allows the designer to see the effect of

rising ambient temperature on the maximum power

allowed.

Figure 7. Derating Curves for RT9293 Packages

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

100

125

Ambient Temperature (

°C)

WDFN-8L 2x2

(

°C)

TSOT-23-6

Single Layer PCB

Layout Consideration

For best performance of the RT9293, the following

guidelines must be strictly followed.

}

Input and Output capacitors should be placed close to

the IC and connected to ground plane to reduce noise

coupling.

}

The GND and Exposed Pad should be connected to a

strong ground plane for heat sinking and noise protection.

}

Keep the main current traces as possible as short and

wide.

}

LX node of DC-DC converter is with high frequency

voltage swing. It should be kept at a small area.

}

Place the feedback components as close as possible

to the IC and keep away from the noisy devices.

RSET

VIN

GND

WLEDs

The inductor should be placed as close as

possible to the switch pin to minimize the

noise coupling into other circuits.

LX node copper area should be minimized

for reducing EMI.

FB node copper area should be

minimized and keep far away

from noise sources (LX pin) and

RS should be as close as

possible to FB pin.

CIN should be placed

as closed as possible

to VIN pin for good

filtering.

The COUT should be connected

directly from the output schottky

diode to ground rather than

across the WLEDs

VIN

VOUT

GND

CIN

COUT

Figure 8. The Layout Consideration of the RT9293

Reference

Qty

Part Number

Description

Manufacture

SR26

Schottky Diode

PANJIT

CIN

EMK107BJ225MA-T

Capacitor, Ceramic, 2.2

µF/16V X5R Taiyo Yuden

COUT

GMK107BJ105KA

Capacitor, Ceramic, 1

µF/50V X5R

Taiyo Yuden

RSET

RC0603FR

Resistor 15

Ω, 1%

YAGEO

NR4018T220M

Inductor, 22

µH

Taiyo Yuden

Table 1. Recommended Components for Typical Application Circuit

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