PA340

PA340U

7

3.4 HEATSINKING

The PA340CC 7-pin DDPAK surface mountable package has a large exposed integrated copper heatslug to which

the monolithic amplifier is directly attached. The PA340CC requires surface mount techniques of heatsinking. A sol-

der connection to a copper foil area as defined in Note 5 of Page 3 is recommended for circuit board layouts. This

may be adequate heatsinking but the large number of variables suggests temperature measurements to be made

on the top of the package. Do not allow the temperature to exceed 85°C.

3.5 OVERVOLTAGE PROTECTION

Although the PA340 can withstand differential input voltages up to 16V, in

some applications additional external protection may be needed. Differen-

tial inputs exceeding 16V will be clipped by the protection circuitry. How-

ever, if more than a few milliamps of current is available from the overload

source, the protection circuitry could be destroyed. For differential sources

above 16V, adding series resistance limiting input current to 1mA will pre-

vent damage. Alternatively, 1N4148 signal diodes connected anti-parallel

across the input pins is usually sufficient. In more demanding applications

where bias current is important, diode connected JFETs such as 2N4416

will be required. See Q1 and Q2 in Figure 5. In either case the differential

input voltage will be clamped to 0.7V. This is sufficient overdrive to produce

the maximum power bandwidth.

In the case of inverting circuits where the +IN pin is grounded, the diodes

mentioned above will also afford protection from excessive common mode

voltage. In the case of non-inverting circuits, clamp diodes from each input to each supply will provide protection.

Note that these diodes will have substantial reverse bias voltage under normal operation and diode leakage will

produce errors.

Some applications will also need over-voltage protection devices connected to the power supply rails. Unidirectional

zener diode transient suppressors are recommended. The zeners clamp transients to voltages within the power

supply rating and also clamp power supply reversals to ground. Whether the zeners are used or not the system

power supply should be evaluated for transient performance including power-on overshoot and power-off polarity

reversals as well as line regulation. See Z1 and Z2 in Figure 5.

+Vs

-Vs

OUT

+Vs

-Vs

Z1

Z2

-IN

+IN

Q1

Q2

FIGURE 5. Overvoltage Protection

NEED TECHNICAL HELP? CONTACT APEX SUPPORT!

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For inquiries via email, please contact apex.support@apexanalog.com.

International customers can also request support by contacting their local Apex Microtechnology Sales Representative.

To find the one nearest to you, go to www.apexanalog.com

IMPORTANT NOTICE

Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information is subject to change

without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the right to make changes without further

notice to any specifications or products mentioned herein to improve reliability. This document is the property of Apex Microtechnology and by furnishing this informa-

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property rights. Apex Microtechnology owns the copyrights associated with the information contained herein and gives consent for copies to be made of the informa-

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APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR

LIFE SUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDER-

STOOD TO BE FULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK.

Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnolgy, Inc. All other corporate names noted herein may be trademarks

of their respective holders.

Copyright © Apex Microtechnology, Inc. 2012

(All Rights Reserved)

www.apexanalog.com

OCT 2013

PA340U REVC