AN331 Silicon Laboratories, AN331 Datasheet

no-image

AN331

Manufacturer Part Number
AN331
Description
Manufacturer
Silicon Laboratories
Datasheet

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
AN331
Quantity:
5 510
Part Number:
AN331
Manufacturer:
SUNLORD
Quantity:
5 510
Part Number:
AN3316K
Manufacturer:
OKI
Quantity:
80
Part Number:
AN3317K
Manufacturer:
PANASONIC/松下
Quantity:
20 000
Part Number:
AN3317SB
Manufacturer:
NS
Quantity:
6
Part Number:
AN3317SB
Manufacturer:
SANYO/三洋
Quantity:
20 000
C
Si3400
1. Introduction
The Si3400 and Si3401 reference designs are available for many output voltages (e.g., 3.3, 5, 9, 12 V) and output
capacitor types. In general, Silicon Laboratories strongly recommends using these standard designs to minimize
risk and ensure robust performance. Refer to the design databases posted on the Si3400/01 documentation page
on the Silicon Labs website for more information:
However, some designers may want to consider other cases of output filtering, input filtering, inductors, etc. for a
variety of reasons (cost, footprint, availability, etc.).
While it would be desirable to use circuit simulation to optimize the feedback loop, it is very difficult to get reliable
information about important factors such as capacitor ESR. Also, the stabilizing effect of the input side hot-swap
switch and input filter ESR must be taken into account, which is not straightforward for commonly available SPICE
implementations. For these reasons, the feedback loop must be experimentally optimized if a known reference
design is not used.
The application note outlines the general process for compensating the feedback loop experimentally. In case a
predefined compensation and output filter is not used, it is strongly recommended that this procedure be followed
to ensure robust performance.
1.1. Breaking the feedback loop
The feedback loop is broken and a transformer is used to inject an ac signal across the break. Using a transformer
allows the loop stability to be measured in a closed loop system with whatever load a filtering is present. The loop
is broken at the output and at the point sensing the output voltage. The transformer ac and dc impedance must be
small compared to the impedance sensing the output voltage.
Figures 1 and 2 show the recommended transformer placement for the non-isolated and isolated reference
designs.
Rev. 0.1 9/07
O M P E N S A T I N G T H E
EVB Data Sheets
EVB Reference Design Databases (Schematics and Layout)
Si3400-EVB
Si3401-EVB
Si3400ISO-EVB
Si3401ISO-EVB
Si3400-EVB
Si3401-EVB
Si3400ISO-EVB
Si3401ISO-EVB
A N D
S i 3 4 0 1
Copyright © 2007 by Silicon Laboratories
F
E E D B A C K
L
O O P F O R T H E
AN331
AN331

Related parts for AN331

AN331 Summary of contents

Page 1

... The transformer ac and dc impedance must be small compared to the impedance sensing the output voltage. Figures 1 and 2 show the recommended transformer placement for the non-isolated and isolated reference designs. Rev. 0.1 9/ Copyright © 2007 by Silicon Laboratories AN331 AN331 ...

Page 2

... AN331 Vstim Vstim 22uF 22uF 2.87K 2.87K NP NP C20 C20 R5 R5 0.33u C9 0.33u 8.66K 8.66K R6 R6 1000u 1000u C5 C5 3.3n 3. 12uF 12uF ...

Page 3

... C16 C16 D13 D13 C11 C11 S1B S1B D9 D9 1000p 1000p C15 C15 D14 D14 C10 C10 S1B S1B D10 D10 1000p 1000p C14 C14 D15 D15 S1B S1B D11 D11 Rev. 0.1 AN331 3 ...

Page 4

... AN331 A commercially available phase gain meter optimized for power supply analysis is available from Venable Inc. The Venable meter can be used with an injection transformer from Venable ordinary transformer can be used as long as it keeps a low ac and dc impedance. Good results have also been achieved with a Bode 100 phase gain meter from Omicron Labs and using Coilcraft BU15-7521ROBL common mode choke hooked transformer (input on 1,2 output on 3,4). When terminated with a 50 Ω ...

Page 5

... The R7-C7 zero should be placed at somewhat less than the desired loop bandwidth in order to contribute the most phase boost. For example, in the 1000 2000 5000 10000 phase(Gain) in ° 1000 2000 5000 10000 phase(Gain) in ° Rev. 0.1 AN331 ° 150 100 50 0 -50 -100 -150 -200 20000 f/Hz ° ...

Page 6

... AN331 non-isolated reference design the R7-C7 zero is at 1.6 kHz and the loop bandwidth is about 4 kHz. C19 introduces a final pole which is required to filter noise that can be coupled to the ERout node. If used, the C20-R6 zero is placed at about the loop bandwidth (not below maximize the phase boost prior to the pole from C20-R5// R6 ...

Page 7

... N : OTES Rev. 0.1 AN331 7 ...

Page 8

... AN331 C I ONTACT NFORMATION Silicon Laboratories Inc. 400 West Cesar Chavez Austin, TX 78701 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Email: PoEinfo@silabs.com Internet: www.silabs.com The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. ...

Related keywords