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4

OPERATING

CONSIDERATIONS

PA52 • PA52A

GENERAL

Please read Application Note 1 "General Operating Con-

siderations" which covers stability, supplies, heat sinking,

mounting, current limit, SOA interpretation, and specification

interpretation. Visit www.apexmicrotech.com for design tools

that help automate tasks such as calculations for stability,

internal power dissipation, current limit; heat sink selection;

Apex’s complete Application Notes library; Technical Seminar

Workbook; and Evaluation Kits.

CURRENT LIMIT

There is no internal circuit provision for current limit in the

PA52. However, the PA52 circuit board in the PA52 evaluation

kit does provide a means whereby the output current can be

sensed. An external circuit current limit can thereby be imple-

mented if needed. See EK27 data sheet for more details.

BOOST OPERATION

With the V

amplifier are operated at higher supply voltages than the

amplifier’s high current output stage. +V

–V

the amplifier. +V

the high current output stage. An additional 10V on the V

BOOST

pins is sufficient to allow the small signal stages to drive the

output transistors into saturation and improve the output voltage

swing for extra efficient operation when required. When close

swings to the supply rails is not required the +V

pins must be strapped together as well as the –V

pins. The boost voltage pins must not be at a voltage lower

than the V

This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specifications are subject to change without notice.

PA52U REV D APRIL 2003 © 2003 Apex Microtechnology Corp.

COMPENSATION

Compensation is internally fixed for a gain of 3 or more and

is not adjustable by the user. The PA52 therefore is not unity

gain stable.

POWER SUPPLY BYPASSING

Proper and sufficient power supply bypassing is crucial to

proper operation of the PA52. Bypass the +Vb and -Vb supply

pins with a minimum .1µF ceramic capacitors directly at the

supply pins. On the +Vs and -Vs pins use a combination of

ceramic and electrolytic capacitors. Use 1µF ceramic capaci-

tors and an electrolytic capacitor at least 10µF for each amp

of output current required.