PA13 • PA13A

PA13U

7

For certain applications, foldover current limit adds a slope to the current limit which allows more power to be deliv-

ered to the load without violating the SOA. For maximum foldover slope, ground pin 4 and use equations 3 and 4.

0.65 + (V

I

R

CL

(3)

0.65 + (V

R

I

CL

(4)

Where:

V

Most designers start with either equation 1 to set R

the maximum output voltage. Equation 3 should then be used to plot the resulting foldover limits on the SOA graph.

If equation 3 results in a negative current limit, foldover slope must be reduced. This can happen when the output

voltage is the opposite polarity of the supply conducting the current.

In applications where a reduced foldover slope is desired, this can be achieved by adding a resistor (R

pin 4 and ground. Use equations 4 and 5 with this new resistor in the circuit.

V

O

* 0.14

I

R

CL

0.65 +

10.14 + R

FO

(5)

V

O

* 0.14

R

I

CL

0.65 +

10.14 + R

FO

(6)

Where:

R

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

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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 2012

PA13U REVU