ADD8708WCPZ-REEL7 AD [Analog Devices], ADD8708WCPZ-REEL7 Datasheet - Page 12

• Manufacturer Part Number: ADD8708WCPZ-REEL7
• Description: 18-Channel Gamma Buffer with Regulator
• Manufacturer: AD [Analog Devices]

ADD8708
OPERATING TEMPERATURE RANGE
The junction temperature is as follows:
where:
T
θ
P
For the ADD8708, P
where:
In this example, T
values in Table 6.
Table 6.
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
JA
DIS
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
AMB
T
P
V
I
power dissipation (current comes from V
−I
dissipation (current goes to GND).
(V
= junction-to-ambient thermal resistance, in °C/watt.
Σ(I
OUT X(+)
DIS
J
DD
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
= power dissipated in the device, in watts.
OUT X(−)
= T
= ambient temperature.
DD
OUT X(+)
= V
× I
– V
AMB
Σ(−I
DQ
× (V
DD
REG OUT
× V
× (V
+ θ
= nominal system power requirements.
× I
V
14.400
11.405
10.627
10.397
10.195
10.080
9.821
9.130
8.611
6.480
6.077
5.098
4.810
4.694
4.435
4.205
3.398
0.202
OUT X(−)
DD
OUT X
OUT X
JA
DD
DQ
× P
− V
) × I
− V
AMB
+ Σ(I
(V)
= negative-current amplifier load power
DIS
DIS
× V
OUT X
OUT X
LOAD
= 95°C. To calculate P
can be calculated by this equation:
OUT X(+)
)) + Σ(−I
OUT X
)= positive-current amplifier load
= regulator load power dissipation.
) + (V
× (V
OUT X(−)
I
4.3
5.2
−4.4
7.3
7.6
−3.9
8.3
7.9
−4.5
−4.2
5.6
−3.3
−6.9
5.7
3.5
9.6
−9.5
−7.2
OUT X
DD
DD
– V
− V
(mA)
× V
REG OUT
OUT X
OUT X
DIS
DD
)
)) +
).
, assume the
) × I
P (W)
0.00688
0.0239
0.0468
0.0409
0.0441
0.0393
0.0513
0.0543
0.0389
0.0272
0.0556
0.0168
0.0332
0.0644
0.0405
0.113
0.0323
0.00145
0.731
LOAD
Rev. 0 | Page 12 of 16
Example 1
Exposed pad soldered down with via θ
where 150°C is the maximum junction temperature that is
guaranteed before the part breaks down. The maximum process
limit is 125°C. Because T
demonstrates a condition where the part should perform within
process limits.
Example 2
Exposed pad not soldered down θ
In this example, T
should not exhibit any damage in this situation, the process
limits have been exceeded. The part may no longer operate
as intended.
These examples show that soldering down the exposed pad is
important for proper heat dissipation. Under the same power-
up and loading conditions, the unsoldered part has a higher
temperature than the soldered part. Therefore, it is strongly
advised that the exposed pad be soldered to V
part integrity.
T
T
V
(V
P
DIS
J
J
DD
= 95°C + (28.3°C/W) × (0.979 W) = 122.7°C
= 95°C + (47.7°C/W) × (0.979 W) = 141.7°C
DD
= 0.240 W + 0.731 W + 0.008 W =0.979 W
× I
– V
DQ
REG OUT
= 16 V × 15 mA = 0.240 W
) × I
J
is < 150°C but > 125°C. Although the part
LOAD
J
= (16 V – 14.4 V) × 5 mA = 0.008 W
is < 150°C and < 125°C, this example
JA
= 47.7°C/W:
JA
= 28.3°C/W:
DD
to maintain