RT9301 Datasheet, PDF (8/9 Pages) Richtek Technology Corporation – 3-Channel Low Dropout RGB LED Driver

RT9301
The maximum power dissipation depends on operating
ambient temperature for fixed T_{J (MAX)} and thermal resistance
θ_JA . For RT9301 packages, the Figure 6 of derating curves
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
500
Single Layer PCB
450
400
350
300
250
200
150
100
50
0
0
20 40 60 80 100 120 140
Ambient Temperature (°C)
Figure 6. Derating Curves for RT9301 Packages
Layout Consideration
For best performance, careful PCB layout is necessary.
Place all peripheral components as close to the IC as
possible. A short connection is highly recommended. The
following guidelines should be strictly followed when
designing a PCB layout for the RT9301.
1. All the traces of LED and VIN pin running from chip to
LEDs should be wide and short to reduce the parasitic
connection resistance.
2. Input capacitor (C_IN) must be placed close to LEDs and
connected to ground plane. The anodes of LEDs must
be connected to C_IN, not battery directly.
3. Current setting resistors R_SET should be placed as close
to the chip as possible.
4. The GND should be connected to a strong ground plane
for heat sinking and noise protection.
5. The current setting resistors should be placed as close
to the IC as possible.
All the traces of LED and V_IN running from
chip to LEDs should be wide and short to
reduce the parasitic connection resistance.
Input capacitor (C_IN) should
be placed close to LEDs
Pin and connected to
ground plane. The Anodes
of LEDs must connect to
C_IN, not battery directly.
Battery
LED3 ¹
GND 2
VIN ³
ISET3 ⁴
8 LED2
7 LED1
6 ISET1
5 ISET2
Ground Plane
The GND should be connected to a strong
ground plane for heat sinking and noise
protection.
Figure 7. PCB Layout Guide
www.richtek.com
8
DS9301-02 March 2007