SA303

SA303U

3

P r o d u c t I n n o v a t i o n F r o m

FIgURE0.TImINgDIAgRAmS

3.POWERDISSIPATION

The thermally enhanced package of the SA303 al-

lows several options for managing the power dissi-

pated in the three output stages. Power dissipation

in traditional PWM applications is a combination

of output power dissipation and switching losses.

Output power dissipation depends on the quadrant

of operation and whether external flyback diodes

are used to carry the reverse or commutating cur-

rents. Switching losses are dependent on the fre-

quency of the PWM cycle as described in the typi-

cal performance graphs.

The size and orientation of the heatsink must be

selected to manage the average power dissipation

of the SA303. Applications vary widely and various

thermal techniques are available to match the re-

quired performance. The patent pending mounting

technique shown in Figure 12, with the SA303 in-

verted and suspended through a cutout in the PCB

is adequate for power dissipation up to 17W with

the HS33, a 1.5 inch long aluminum extrusion with

four fins. In free air, mounting the PCb perpendicular to the ground, such that the heated air flows upward along the

channels of the fins can provide a total Θ

the ground impedes the flow of heated air and provides a Θ

in which higher power dissipation is expected or lower junction or case temperatures are required, a larger heatsink

or circulated air can significantly improve the performance.

4.ORDERINgANDPRODUCTSTATUSINFORmATION

MODEL

TEMPERATURE

PACKAGE

PRODUCTION STATUS

SA303-IHZ

-25 to 85ºC

64 pin Power QFP (HQ package drawing)

Samples Available 1Q09

TOP INPUT

BOTTOM INPUT

DELAY TIMING

OUTPUT

DISABLE

td(fall)

td(dis)

td(rise)

td(dis)

td(dis)

td(dis)

TOP INPUT

BOTTOM INPUT

OUTPUT

t(fall)

t(rise)

20%

80%

FIgURE.OUTPUTRESPONSE