(625mA instead of 500mA).

- All electrical parameters of the device, con-

cerning the calculation, are at maximum val-

ues.

- Thermal shutdown threshold is at minimum

value.

Therefore:

ΘLim = 135°C

°C/W (Minidip); 90°C/W (SO20);

70

°C/W (SIP9)

It follows:

From equation 4, we can find:

°C (Minidip);

73.5

°C (SO20);

87.2

°C (SIP9).

Therefore, the IPS TDE1897/1898, although

guaranteed to operate up to 85

°C ambient tem-

perature, if used in the worst conditions, can meet

some limitations.

work at maximum operative current over the en-

tire ambient temperature range in the worst condi-

tions too. For other packages, it is necessary to

consider some reductions.

With the aid of equation 3, we can draw a derat-

ing curve giving the maximum current allowable

versus ambient temperature. The diagrams, com-

puted using parameter values above given, are

depicted in figg. 6 to 8.

If an increase of the operating area is needed,

e.g. by means of air cooling.

+

-

+IN

-IN

D1

D2

CONTROL

LOGIC

Ios

LOAD

OUTPUT

OUTPUT STATUS

GND

µP POLLING

+Vs

DC BUS 24V +/-25%

D93IN014

Figure 5: Application Circuit.

TDE1897R - TDE1898R

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