RT9004 데이터 시트보기 (PDF) - Richtek Technology
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RT9004 Datasheet PDF : 12 Pages
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RT9004
Preliminary
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
power dissipation definition in device is :
PD = (VIN-VOUT) x IOUT + VIN x IQ
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient. The maximum power dissipation can
be calculated by following formula :
PD(MAX) = ( TJ(MAX) - TA ) /θJA
Where TJ(MAX) is the maximum operation junction
temperature 125°C, TA is the ambient temperature and the
θJA is the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9004, where TJ(MAX) is the maximum junction
temperature of the die (125°C) and TA is the maximum
ambient temperature. The junction to ambient thermal
resistance θJA is layout dependent. For VDFN-10L 3x3
and WDFN-10L 3x3 packages, the thermal resistance θJA
is 105°C/W on the standard JEDEC 51-3 single-layer 1s
thermal test board and 70°C/W on the standard JEDEC
51-7 4-layers 2S2P thermal test board. The maximum
power dissipation at TA = 25°C can be calculated by
following formula :
PD(MAX) = ( 125°C - 25°C ) / 105 = 0.952 W for single-layer
1s board
PD(MAX) = ( 125°C - 25°C ) / 70 = 1.428 W for 4-layers
2S2P board
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For RT9004 packages, the Figure 3 of
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
1500
1350
1200
1050
900
750
600
450
300
150
0
0
4-Layers Board
Single-Layer Board
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curves for RT9004 Package
www.richtek.com
10
DS9004-00 February 2008
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