RT9515 데이터 시트보기 (PDF) - Richtek Technology
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RT9515 Datasheet PDF : 11 Pages
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RT9515
For recommended operating conditions specification,
where TJ(MAX) is the maximum junction temperature of the
die (125°C) and TA is the ambient temperature. The junction
to ambient thermal resistance θJA is layout dependent.
For WDFN-10L 3x3 packages, the thermal resistance θJA
is 60°C/W on the standard JEDEC 51-7 four layers thermal
test board. The maximum power dissipation at TA = 25°C
can be calculated by following formula :
PD(MAX) = (125°C − 25°C) / (60°C/W) = 1.667W for
WDFN-10L 3x3 packages
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For WDFN-10L 3x3 package, the Figure 4
of derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
1.8
Four Layers PCB
1.6
1.4
1.2
WDFN-10L 3x3
1.0
0.8
0.6
0.4
0.2
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 4. Derating Curves for RT9515 Package
` Connect the GND and Exposed Pad to a strong ground
plane for maximum thermal dissipation and noise
protection.
` The TS's capacitor should be placed close to TS (Pin 9)
and connected to ground plane. If the PCB layout is
poor, it is recommended to use a 10uF at C2 to prevent
noise.
The capacitor should be
placed close to IC pin and
connected to ground plane.
C1
ACIN 1
NC 2
CHG_S 3
PGOOD 4
GND 5
GND
10 BATT
9 TS
8 EN
7 NC
ISETA
RSETA
C3
Battery
C2
The TS's capacitor should be
placed close to TS(Pin 9) and
connected to ground plane.
GND
The GND should be connected to a
strong ground plane for heat sinking
and noise protection.
The connection of RSET should be
isolated from other noisy traces.
The short wire is recommended to
prevent EMI and noise coupling.
Figure 5. PCB Layout Guide
Layout Considerations
For the best performance of the RT9515, the following
PCB layout guidelines must be strictly followed.
` Place the input and output capacitors as close as
possible to the input and output pins respectively for
good filtering.
` Keep the main power traces as wide and short as
possible.
` The connection of RSETA should be isolated from other
noisy traces. The short wire is recommended to prevent
EMI and noise coupling.
www.richtek.com
10
DS9515-01 April 2011
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