TDA8357J Datasheet, PDF (11/16 Pages) NXP Semiconductors – Full bridge vertical deflection output circuit in LVDMOS

Philips Semiconductors
Full bridge vertical deflection output circuit
in LVDMOS
Preliminary specification
TDA8357J
Heatsink calculation
The value of the heatsink can be calculated in a standard
way with a method based on average temperatures.
The required thermal resistance of the heatsink is
determined by the maximum die temperature of 150 °C.
In general we recommend to design for an average die
temperature not exceeding 130 °C.
EXAMPLE
Measured or given values: P_tot = 3 W; T_amb = 40 °C;
T_j = 110 °C; R_th(j-c) = 5 K/W; R_th(c-h) = 2 K/W.
The required heatsink thermal resistance is given by:
R_{th(h – a)} = ^T----j---^–-P----T_t--_o-^a-_t--^m----^b- – (R_{th(j – c)} + R_{th(c – h)})
When we use the values given we find:
R_{th(h – a)} = ^{1----1---0-3---.-–}-0----4---0-- – (5 + 2) = 16 K/W
The heatsink temperature will be:
T_h = T_amb + (R_th(h-a) × P_tot) = 40 + (3 × 16) = 90 °C
1999 Nov 10
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