Thermalloy #2328B Pin-fin Heat Sink
(25 x 28 x 15 mm)
8
7
6
5
4
3
2
1
0
0.5
1
1.5
2
2.5
3
3.5
Approach Air Velocity (m/s)
Figure 22. Thermalloy #2328B Pin-Fin Heat Sink-to-Ambient Thermal Resistance Versus Air flow
Velocity
Assu m in g an air velocity of 0.5 m / s, we h ave an effective θ of 7 °C/ W, th u s
sa
Tj = 30°C + 5°C + (2.2 °C/W +1.0°C/W + 7 °C/W) * 4.5 W,
resu ltin g in a ju n ction tem peratu re of approxim ately 81 °C wh ich is well with in th e
m axim u m operatin g tem peratu re of th e com pon en t.
Oth er h eat sin ks offered by Ch ip Coolers, IERC, Th erm alloy, Aavid, an d Wakefield
En gin eerin g offer differen t h eat sin k-to-am bien t th erm al resistan ces, an d m ay or m ay
n ot n eed air flow.
Th ou gh th e ju n ction -to-am bien t an d th e h eat sin k-to-am bien t th erm al resistan ces are
a com m on figu re-of-m erit u sed for com parin g th e th erm al perform an ce of variou s
m icroelectron ic packagin g tech n ologies, on e sh ou ld exercise cau tion wh en on ly u sin g
th is m etric in determ in in g th erm al m an agem en t becau se n o sin gle param eter can ade-
qu ately describe th ree-dim en sion al h eat flow. Th e fin al ch ip-ju n ction operatin g tem per-
atu re is n ot on ly a fu n ction of th e com pon en t-level th erm al resistan ce, bu t th e system -
level design an d its operatin g con dition s. In addition to th e com pon en t's power dissipa-
tion , a n u m ber of factors affect th e fin al operatin g die-ju n ction tem peratu re. Th ese fac-
PPC740 and PPC750 Hardware Specifications
42 of 44
Preliminary and subject to change without notice
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