VP503 View Datasheet(PDF) - SANYO -> Panasonic
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VP503 Datasheet PDF : 11 Pages
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VP503
Thermal Design for the VP503
We recommended that the VP503 be used with the operating case temperature, Tc, under 100°C. Since the VP503
includes three channels, we first consider a single channel. The chip temperature of each transistor under actual operating
conditions is determined using the following formula.
Tj = (Tri) = θj-c (Tri) × Pc (Tri) + ∆Tc + Ta [°C] .................................. (1)
θj-c (Tri): Thermal resistance of an individual transistor
Pc (Tri): Collector loss for an individual transistor
∆Tc: Case temperature rise
Ta:
Ambient temperature
The θj-c(Tri) for each chip is:
θj-c (Tr2) to (Tr4) = 30°C/W.................................................................. (2)
Although the loss for each transistor in a Video Pack varies with frequency and is not uniform, if we assume that the
maximum operating frequency, f = 85 MHz (clock), then the chips with the largest loss will be transistor 3 and that loss
will be about 1/4 of the total loss.Thus from the Pd for a single channel we have:
Pc (Tr3) f = 85 MHz = Pd (1CH) f = 85 MHz × 0.25 [W] ..................... (3)
Here, we must select a heat sink with a capacity θh such that the Tj of these transistors does not exceed 150°C. Equation
(4) below gives the relationship between θh and ∆Tc.
∆Tc = Pd (TOTAL) × θh ........................................................................ (4)
The required θh is calculated using this equation and equation (1).
No. 4933-8/11
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