ADP1720-3.3-EVALZ Analog Devices Inc, ADP1720-3.3-EVALZ Datasheet - Page 12

• Manufacturer Part Number: ADP1720-3.3-EVALZ
• Description: BOARD EVAL FOR ADP1720-3.3
• Manufacturer: Analog Devices Inc

Specifications of ADP1720-3.3-EVALZ

• Design Resources: 4 mA-to-20 mA Loop-Powered Temperature Monitor Using ADuC7060/1 (CN0145)
• Channels Per Ic: 1 - Single
• Voltage - Output: 3.3V
• Current - Output: 50mA
• Voltage - Input: 4 ~ 28V
• Regulator Type: Positive Fixed
• Operating Temperature: -40°C ~ 125°C
• Board Type: Fully Populated
• Utilized Ic / Part: ADP1720
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADP1720
THERMAL CONSIDERATIONS
To guarantee reliable operation, the junction temperature of the
ADP1720 must not exceed 125°C. To ensure the junction tem-
perature stays below this maximum value, the user needs to be
aware of the parameters that contribute to junction temperature
changes. These parameters include ambient temperature, power
dissipation in the power device, and thermal resistances between
the junction and ambient air (θ
on the package assembly compounds used and the amount of
copper to which the GND pins of the package are soldered on the
PCB. Table 5 shows typical θ
for various PCB copper sizes.
Table 5.
Copper Size (mm
0
50
100
300
500
1
The junction temperature of the ADP1720 can be calculated
from the following equation:
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 Equation 5, 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 22 to Figure 27 show junction temperature
calculations for different ambient temperatures, load currents,
V
LOAD
GND
Device soldered to minimum size pin traces.
1
D
A
IN
IN
is the power dissipation in the die, given by
is the ambient temperature.
and V
to V
is the ground current.
T
P
T
is the load current.
J
D
J
= T
= T
= [(V
OUT
OUT
A
A
differentials, and areas of PCB copper.
+ (P
+ {[(V
IN
are input and output voltages, respectively.
– V
D
2
× θ
)
IN
OUT
– V
JA
) × I
)
OUT
LOAD
) × I
JA
values of the 8-lead MSOP package
] + (V
JA
LOAD
). The θ
] × θ
IN
× I
JA
JA
GND
number is dependent
}
θ
118
99
77
75
74
JA
)
(°C/W)
Rev. A | Page 12 of 16
(3)
(4)
(5)
140
120
100
140
120
100
140
120
100
80
60
40
20
80
60
40
20
80
60
40
20
0
0
0
0
0
0
MAX T
MAX T
MAX T
Figure 22. 300 mm
Figure 23. 100 mm
Figure 24. 0 mm
1mA
5mA
1mA
5mA
1mA
5mA
4
4
4
J
J
J
(DO NOT OPERATE ABOVE THIS POINT)
(DO NOT OPERATE ABOVE THIS POINT)
(DO NOT OPERATE ABOVE THIS POINT)
8
8
8
10mA
20mA
10mA
20mA
10mA
20mA
2
2
2
of PCB Copper, T
V
V
V
12
IN
of PCB Copper, T
12
IN
of PCB Copper, T
12
IN
– V
– V
– V
OUT
OUT
OUT
30mA
40mA
30mA
40mA
30mA
40mA
16
16
16
(V)
(V)
(V)
(LOAD CURRENT)
(LOAD CURRENT)
(LOAD CURRENT)
A
20
A
20
A
20
= 25°C
= 25°C
= 25°C
50mA
50mA
50mA
24
24
24
28
2
2
8
8