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SMM105/205/605/665
ADOC Tutorial and Performance
Summary
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TEST
RESULT SUMMARY AND CONCLUSIONS:
Use of the ADOC function with both the LDO and the
DC-DC converter results in improvements by actively
controlling the DC output levels. The LDO DC
accuracy with the ADOC engaged and testing with a
5A load, showed significant improvement from 4.7%
to 0.11%.
Pulsed loads do not change the ADOC's high accuracy
performance as shown in the oscilloscope photos.
Although some step voltage changes occurred on the
LDO output, this is expected because of the step
response of the 2.0V DC-DC converter supplying the
LDO circuit. Board layout is critical, connecting
the ADOC device ground to the load ground improves
step response. The device ground, external
reference ground and the load ground should be all
connected together.
Voltage drops between these ground connections can
cause errors in accuracy. Also, the VM pins should
be used the same as a power supply "Sense" pin by
tying it at the POL
Long-term accuracy of an external supply is
guaranteed using the ADOC alone or with a higher
accuracy (0.1% or better) external reference.
Initial checking or trimming of converter or LDO
circuits is not required using the
SMM105/205/605/665. The closed loop operation and
user programmable ADOC voltage allow wide
variations in initial supply voltage tolerance
making it unnecessary to specify high accuracy set
points of board level DC-DC converters, discrete
switching regulators or LDOs.
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SUMMIT
Microelectronics, Inc. reserves the right
to make changes to the products contained
in this publication in order to improve
design, performance or reliability. SUMMIT
Microelectronics, Inc. assumes no
responsibility for the use of any circuits
described herein, conveys no license under
any patent or other right, and makes no
representation that the circuits are free
of patent infringement. Charts and
schedules contained herein reflect
representative operating parameters, and
may vary depending upon a user's specific
application. While the information in this
publication has been carefully checked,
SUMMIT Microelectronics, Inc. shall not be
liable for any damages arising as a result
of any error or omission.
SUMMIT Microelectronics, Inc. does not
recommend the use of any of its products
in life support or aviation applications
where the failure or malfunction of the
product can reasonably be expected to
cause any failure of either system or to
significantly affect their safety or
effectiveness. Products are not authorized
for use in such applications unless SUMMIT
Microelectronics, Inc. receives written
assurances, to its satisfaction, that: (a)
the risk of injury or damage has been
minimized; (b) the user assumes all such
risks; and (c) potential liability of
SUMMIT Microelectronics, Inc. is
adequately protected under the
circumstances.
Revision 1.0 - This document supersedes
all previous. Please check the Summit
Microelectronics, Inc. web site at
www.summitmicro.com
for updates.
I2C is a trademark of Philips
Corporation.
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Copyright
© 2003 SUMMIT MICROELECTRONICS, Inc.
Power Management for Communications™
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