點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
DM11A
Power Dissipation
The power dissipation of a semiconductor chip is limited to its package and ambient
temperature, in which the device requires the maximum output current calculated for given
operating conditions. The maximum allowable power consumption can be calculated by the
following equation:
Tj(junction temperature)(max)(°C)– Ta(ambient temperature)(°C)
Pd(max)(Watt) =
Rth(junction-to-air thermal resistance)(°C/Watt)
The relationship between power dissipation and operating temperature can be referred to the figure
below:
2
Rth(SOP16)=81.2°C/W
SOP16
PDIP16
Rth(PDIP16)=85.0°C/W
Rth(SOP16B)=90°C/W
Rth(SSOP16)=115.9°C/W
1.5
1
SOP16B
SSOP16
0.5
0
0
20
40
60
80
100
120
140
160
Ambient Temperature Ta(℃)
The power consumption of IC can be determined by the following equation and should be less than
the maximum allowable power dissipation:
Pd(max)(W)
+ Vout7 Iout7 Duty7 <
Pd(W) = VCC(V) IDD(A) + Vout0 Iout0 Duty0 +
8-bit Constant Current LED Driver
Version:A.003
Page 13
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