Bode Plot

267 Pages·2000·6.44 MB·English

by  Granger Scofield

M I C R O T E C H N O L O G Y
ECHNICAL
seminar
Designed to Help You Boost Your Analog Design Power
REVISION 5 JANUARY, 2000
NOTES:
APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: [phone]
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Table of Contents
Welcome to Apex…………….……… 585 The packages………………………….. 650
Where we live………………………….. 586 Linear basics…………………………… 651
Quality at Apex………………………… 587 Class C outputs……………………….. 652
DC-DC Converters……………………. 588 Class AB outputs…………………………. 654
The packages………………………….. 589 Complex construction……………………. 656
Linear power delivery………………….. 590 Monolithic types………………………….. 658
PWM power delivery…………………… 591 Selector guides…………………………… 659
Basic converter block…………………. 592 Amplifier selection……………………….. 661
Basic converter operation…………….. 593 Electrical limitations……………………… 663
Defining Apex converters……………… 594 Non-linear model…………………………. 664
What’s inside…………………………… 595 Common non-linear cases………………. 665
Shorted output response……………… 596 False summing node ……………………. 668
Ceramic capacitors……………………. 598 Reading the specs……………………….. 669
Shutdown Plus pin…………………….. 600 Common mode voltage………………….. 670
DHC 6W singles………………………… 601 Op amp protection……………………… 671
DHC 6W duals……….………………… 604 Input protection networks……………….. 672
DB 20W family…………………………. 607 Gain switching……………………………. 674
Triplets are coming……………………. 610 To invert or not with I/P protection……… 676
PWM Amplifiers………………………. 612 Flyback diodes……………………………. 677
The packages………………………….. 613 Transient voltage protection…………….. 678
Linear vs. PWM power delivery….……. 614 SOA……………………………………….. 679
The H-Bridge……………………………. 617 SOA graph………………………………… 680
Switching concerns…………….………. 619 Output transistors………………………… 681
Evaluation kits…………….….…………. 620 Load fault to consider……………………. 682
What’s inside………………….………… 621 What’s current limit……………………… 683
Block diagrams………………………… 622 Thermal modeling………………………… 688
Transfer function……………………….. 626 Where to set Tj max……………………… 689
The integrator…………………………… 627 What is the internal power………………. 691
Samples at work…………………….…. 628 DC vs. AC vs. reactance………………… 693
The frequencies involved………………. 631 Calculating the power……………………. 694
Filter design……………………………. 632 When to sweep the frequency………….. 700
Response with real parts………………. 636 Thermal capacity & averaging………….. 701
Fllter termination required…………….. 637 Proper mounting or not………………….. 702
What is -3db…………………………… 638 Motor reversal…………………………….. 705
Matching networks….…………………. 640 Single Supply Operation……………… 706
Half bridges…………………………….. 643 Internal limitations……………………….. 707
Heatsinking PWMs……………………. 644 Basic techniques…………………………. 708
Selector guide………………………….. 648 Taking care of CMV………………………. 709
The Apex Linear World…………….. 649 PA21 is ideal……………………………… 712
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PA21 protection alternatives…………… 713 Valve control……………………………. 790
Asymmetrical supplies…………………. 714 Programmable torque drive…………… 791
Basic Stability…………………………… 715 Howland single Vs bridge torquer……. 792
Eliminate coupling………………………. 716 ATE……………………………………… 793
Ground loops………………………………717 Low drift PZT tester……………………. 794
Supply wire impedance………………… 718 Linear high power PPS……………….. 799
Supply bypassing………………………… 719 A PWM alternative…………….……….. 800
Output stages vs. stability……………… 720 Remote sensing……………………….. 801
Loop Stability…………………………… 722 Driven ground…………………………… 802
Feedback theory………………………… 723 Very high voltage PPS………………… 803
External phase compensation…………. 725 High power AC PPS…………………… 804
Open, closed and loop gains…………. 726 Signal Sources……………………….. 806
Inductors in the feedback loop……….. 728 PB58 voltage regulator………………… 807
Capacitive loading……………………… 734 400Hz servo supply…………………… 811
Stability Testing……………………… 746 Low power telephone ringer……………… 812
Ringing test…………………………….. 747 High power telephone ringer…………….. 813
Peaking test……………………………. 748 Thermo-electric cooler…………………… 814
High Speed Techniques……………. 749 Deflection………………………………… 815
Techniques and strays………………… 750 Magnetic deflection waveforms…………. 816
Slew rate vs. power bandwidth……….. 751 Basic magnetic deflection………………. 817
Effects of compensation………………. 752 V-to-I bridge……………………………….. 822
Cable loads…………………………….. 753 Electrostatic deflection………………….. 823
High Power Techniques……………. 754 Dynamic focusing………………………… 824
This is no laughing matter……………. 755 PZT Drive…………………………………. 825
Bridge basics…………………………… 757 860Vp-p single Vs bridge……………….. 826
Bridge power calculations…………….. 759 ±1KV bridge………………………………. 827
A weird & dangerous bridge………….. 760 Composite amplifier………………………. 828
External current buffers……………….. 761 Audio/Noise Cancellation…………………837
Parallel operation………………………. 765 Fast and low distortion…………………… 838
Parallel and bridge together………….. 769 Foldover can help………………………… 839
Current Outputs………………………. 770 PWM aircraft audio………………………. 840
Inductance concerns………………….. 771 SA51 PWM audio………………………… 841
PWM current output…………………… 772 Sonar transducer…………………………. 842
Op amp current output………………… 773 Tools for you………………………………. 843
Howland for grounded loads………….. 774 Beat the discrete…………………………. 844
Motion Control……………………….. 781 Top of the line is on line…………………. 845
Z-axis position…………………………. 782
Brush motor specifications…………… 783
Fitting the op amp to the motor………. 784
Simple speed control………………….. 788
PWM antenna position ………………. 789
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APEX MICROTECHNOLOGY CORPORATION
DC-DC Converters ¤ PWM Amplifiers ¤ Power Op Amps
Power Integrated Circuits with Technical Support
Since 1981, Apex has been designing and manufacturing hybrid (chip and wire) power
amplifiers. Careful attention to process development and control has made Apex the world
leader in hybrid power. The products consistently perform per the data sheet. The product
line now boasts the highest current, the highest voltage and highest wattage hybrids to be
found anywhere in the industry.
The expertise in handling large power levels electrically and thermally has been adapted to
high reliability DC-DC converters. Unique construction techniques make these converters
especially impervious to demanding environmental conditions. The Apex design
philosophy provides converters with no de-rating over their entire operating temperature
range.
Pulse Width Modulation (PWM) amplifiers share the same reliability as their linear
counterparts but utilize switching technology to greatly extend the delivered power range
while keeping wasted heat in the same area as the linears.
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The present Apex facility is 55,000 sq. ft. on ten acres zoned such that we can double our
size. Current sales are about $14M and we can do $25M in this building. Almost half the
area and third the cost of the building are clean room related. This class 100,000 clean
room keeps the ICs clean.
Apex extends an invitation to you all to visit us and take a tour of our home to see first
hand how we design and manufacture the world’s best power integrated circuits.
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(cid:127) Total Quality Management
(cid:127) Certified Mil-Std-1772 in 1989
(cid:127) Certified ISO9001 in 1994
Sigma Plus has led to consistent increases in quality and performance for Apex and our
customers. Sigma Plus, our Total Quality Management program, continues to produce
measurable quality improvements, a culture based on teamwork, and increased value for
our customers.
In alignment with Sigma Plus, we have instituted training and development in the
fundamentals or our business, further supporting Apex teams with the tools they need to
perform at high productivity and quality levels. With a firm foundation of Sigma Plus quality
tools that solve the “how” of continuous improvement, team members are now learning the
“why” with Open Book Management. As a result, Apex teams are gaining greater
understanding of their personal impact on organizational systems and how they can
directly improve organizational performance. By giving team members a stake in the
outcome, they gain personal satisfaction and ownership of the products and services they
provide to you, our customers.
We will continue to improve our systems and processes to exceed our customers’
expectations. Feedback systems that identify internal and external customers’ needs and
expectations keep Team Apex focused on customer value. Team members have
increased their job skills and have become functionally cross-trained to quickly adapt to
changes that anticipate customer needs.
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DC-DC Converters
Transform
Isolate
Regulate
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As you can see, these welded all steel packages are rugged. This is the first indicator that
these converters are no ordinary breed. They are designed from top to bottom to give
reliable performance in the most demanding environments.
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LINEAR POWER DELIVERY
Pass Element
Vs
Load
DRIVER
The most popular DC-DC converter application vividly demonstrates why the DC-DC
converter is the only reasonable choice compared to a linear regulator. This function is
providing 5V for logic or computer circuits from a 28V bus.
Let us assume the load requires 1A @ 5V or 5W. A linear regulator would pass the 1A
while having 23V across it, thus wasting 23W. With an input power of 28W, efficiency is
less than 18%! Unless the application also just happens to need a 23W heater, you pay
twice; once to generate the 23W and again to get rid of it. Typical efficiencies of these DC-
DC converters reduce this waste heat by better than an order of magnitude.
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