ADP225 Analog Devices, ADP225 Datasheet - Page 21
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ADP225
Manufacturer Part Number
ADP225
Description
Dual, 300 mA Adjustable Output, QOD, Low Noise, High PSRR Voltage Regulator
Manufacturer
Analog Devices
Datasheet
1.ADP222.pdf
(24 pages)
Data Sheet
The junction temperature of the ADP222/ADP223/ADP224/
ADP225
where:
T
P
where:
I
I
V
Power dissipation due to ground current is quite small and can
be ignored. Therefore, the junction temperature equation
simplifies to the following:
As shown in the simplified equation, for a given ambient
temperature, input- to-output voltage differential, and continuous
load current, there exists a minimum copper size requirement
for the PCB to ensure that the junction temperature does not rise
above 125°C. Figure 72 to Figure 75 show junction temperature
calculations for different ambient temperatures, power dissipation,
and areas of PCB copper.
LOAD
GND
A
D
IN
is the ambient temperature.
is the power dissipation in the die, given by
and V
is the ground current.
T
P
T
is the load current.
140
120
100
D
J
J
80
60
40
20
= T
= T
= [(V
0
0
can be calculated by
OUT
A
A
+ (P
+ {[(V
IN
are input and output voltages, respectively.
− V
0.2
D
Figure 72. 8-Lead LFCSP, T
× θ
IN
OUT
− V
TOTAL POWER DISSIPATION (W)
JA
) × I
)
0.4
OUT
LOAD
) × I
] + (V
LOAD
0.6
] × θ
IN
× I
A
0.8
JA
= 25°C
GND
}
)
1.0
6400mm
1000mm
500mm
100mm
25mm
JEDEC
T
J
MAX
2
2
2
2
2
1.2
Rev. B | Page 21 of 24
(2)
In the case where the board temperature is known, use the
thermal characterization parameter, Ψ
junction temperature rise (see Figure 75). Maximum junction
temperature (T
and power dissipation (P
The typical value of Ψ
T
140
120
100
140
120
100
J
140
120
100
80
60
40
20
80
60
40
20
80
60
40
20
= T
0
0
0
0
0
0
ADP222/ADP223/ADP224/ADP225
B
+ (P
J
) is calculated from the board temperature (T
0.2
1
0.2
D
Figure 73. 8-Lead LFCSP, T
Figure 74. 8-Lead LFCSP, T
Figure 75. 8-Lead LFCSP, T
× Ψ
TOTAL POWER DISSIPATION (W)
TOTAL POWER DISSIPATION (W)
JB
TOTAL POWER DISSIPATION (W)
JB
is 18.2°C/W for the 8-lead LFCSP package.
2
)
0.4
0.4
D
) using the following formula:
3
0.6
0.6
4
JB
A
A
A
, to estimate the
0.8
0.8
= 50°C
= 85°C
= 85°C
5
1.0
1.0
6400mm
1000mm
500mm
100mm
25mm
JEDEC
T
6400mm
1000mm
500mm
100mm
25mm
JEDEC
T
T
T
T
T
J
J
B
B
B
J
6
MAX
MAX
MAX
= 25°C
= 50°C
= 85°C
2
2
2
2
2
2
2
2
2
2
1.2
1.2
7
B
(3)
)