RT7294A
2.0
1.6
1.2
0.8
0.4
0.0
maximum power dissipation can be calculated by the
following formula :
Four-Layer PCB
PD(MAX) = (TJ(MAX) − TA) / θJA
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
TSOT-23-6 (FC) package, the thermal resistance, θJA, is
70°C/W on a standard four-layer thermal test board. The
maximum power dissipation at TA = 25°C can be calculated
by the following formula :
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 7. Derating Curve of Maximum PowerDissipation
PD(MAX) = (125°C − 25°C) / (70°C/W) = 1.429W for
TSOT-23-6 (FC) package
Layout Considerations
For best performance of the RT7294A, the following layout
guidelines must be strictly followed.
The maximum power dissipation depends on the operating
ambient temperature for fixed TJ(MAX) and thermal
resistance, θJA. The derating curve in Figure 7 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
Input capacitor must be placed as close to the IC as
possible.
SW should be connected to inductor by wide and short
trace. Keep sensitive components away from this trace.
SW should be connected to inductor by Wide and
short trace. Keep sensitive components away from
this trace. Suggestion layout trace wider for thermal.
C
OUT
V
OUT
Keep sensitive components away
from this trace. Suggestion layout
trace wider for thermal.
C
OUT
GND
SW
C
S*
R
S*
Suggestion layout trace
wider for thermal.
BOOT
GND
FB
6
5
4
SW
VIN
EN
C
C
IN
IN
2
3
R
EN
V
IN
Input capacitor must be placed as close
to the IC as possible. Suggestion layout
trace wider for thermal.
V
OUT
R1
R2
The R component must
EN
The feedback components must be
connected as close to the device as
possible.
be connected to V
Suggestion layout trace
wider for thermal.
.
IN
Figure 8. PCB Layout Guide
Copyright 2016 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS7294A-05 October 2016
www.richtek.com
13
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
