No. 5209-4/4

VPS10

VPS10 Thermal Design Example

Consider the case where the maximum clock frequency is 100 MHz, taking into account the fact that this class of monitor

can be operated at ambient temperatures up to Ta = 60°C.

As mentioned previously, the chips with the largest loss are the transistors in the emitter-follower stage. Determining

those values gives:

We determine

∆Tj by substituting the value for θj-c in equation (5).

∆Tj = 1.44 × 30 = 43.2 [°C]

Therefore, Tj (max) will be 43.2 + Tc (max) = 43.2 + 100. Since this will be under 100°C, it suffices to design a heat sink

that guarantees that Tc will be under 100°C.

Therefore, a heat sink such that Tc < 100°C will have the following thermal resistance:

θh = ∆Tc ÷ Pd (TOTAL) = (Tc – Ta) ÷ [Pd (1ch) × 3] = 40 ÷ (7.2 × 3) = 1.85°C/W

Thus the thermal resistance in this case is

θh = 1.8°C/W.

In actual practice, the ambient temperature and operating conditions will allow a heat sink smaller than that indicated by

this calculation to be used. Therefore, design optimization taking the actual conditions into account is also required.

This catalog provides information as of December, 1997. Specifications and information herein are subject to

change without notice.

s No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace

equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of

which may directly or indirectly cause injury, death or property loss.

s Anyone purchasing any products described or contained herein for an above-mentioned use shall:

ΠAccept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and

distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all

damages, cost and expenses associated with such use:

 Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on

SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees

jointly or severally.

s Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for

volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied

regarding its use or any infringements of intellectual property rights or other rights of third parties.

Item

1

90

10

50

50

2

80

10

40

45