APPLICATIONS RECOMMENDATIONS

OPERATION LIMITS

The STM901-30 power module should never be op-

erated under any condition which exceeds the Ab-

solute Maximum Ratings presented on this data

sheet. Nor should the module be operated continu-

ously at any of the specified maximum ratings. If

the module is to be operated under any condition

such that it may be subjected to one or more of the

maximum rating conditions, care must be taken to

monitor other parameters which may be affected.

DECOUPLING

Failure to properly decouple any of the voltage sup-

ply pins will result in oscillations at certain operating

frequencies. Therefore, it is recommended that

these pins be bypassed as indicated in the Module

DC and Test Fixture Configuration drawing of this

data sheet.

MODULE MOUNTING

To insure adequate thermal transfer from the mod-

ule to the heatsink, it is recommended that a satis-

factory thermal compound such as Dow Corning

340, Wakefield 120-2 or equivalent be applied be-

tween the module flange and the heatsink.

The heatsink mounting surface under the module

should be flat to within +/- 0.05 mm (+/- 0.002

inch). The module should be mounted to the

heatsink using 3 mm (or 4-40) or equivalent screws

torqued to 5-6 kg-cm (4-6 in-lb).

The module leads are attached to the equipment

PC board using 180

°C solder applied to the leads

with a properly grounded soldering iron tip, not to

exceed 195

°C, applied a minimum of 2 mm (0.080

inch) from the body of the module for a duration not

to exceed 15 seconds per lead. It is imperative that

no other portion of the module, other than the

leads, be subjected to temperatures in excess of

100

°C (maximum storage temperature), for any pe-

riod of time, as the plastic moulded cover, internal

components and sealing adhesives may be ad-

versely affected by such conditions.

Due to the construction techniques and the materi-

als used within the module, reflow soldering of the

flange heatsink or the leads, is not recommended.

THERMAL CONSIDERATIONS

It will be necessary to provide a suitable heatsink in

order to maintain the module flange temperature at

or below the maximum case operating temperature.

In a case where the module output power will be

limited to +44.7 dBm (30W PEP) and designing for

the worst case double-tone efficiency of 25%, the

power dissipated by the module will be 48 watts.

The heatsink must be designed such that the ther-

mal rise will be less than the difference between

the maximum ambient temperature at which the

module will operate and the maximum operating

case temperature of the module while dissipating

48 watts.

+44.7dBm PEP, maximum junction temperatures for

the individual transistors should be below the fol-

lowing values:

Q1 = 115

°C

Q2 = 130

°C

Q3 = 125

°C

Q4 = 145

°C

STM901-30

October 31, 1997

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