ADP225 Analog Devices, ADP225 Datasheet - Page 21

• Manufacturer Part Number: ADP225
• Description: Dual, 300 mA Adjustable Output, QOD, Low Noise, High PSRR Voltage Regulator
• Manufacturer: Analog Devices

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)
)