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參數(shù)資料
| 型號： | QPI-6LZ-01 |
| 廠商： | Vicor Corporation |
| 文件頁數(shù)： | 7/13頁 |
| 文件大小： | 0K |
| 描述： | IC INTERFACE FILTER |
| 標(biāo)準(zhǔn)包裝： | 20 |
| 系列： | Picor®, QUIETPOWER® |
| 其它名稱： | 1102-1100-5 |
Picor Corporation picorpower.com
QPI-6
Rev 2.6, Page 3 of 13
QPI-6
QUIETPOWER
Applications Information
EMI Sources
Many of the components in today’s power conversion
modules are sources of high-frequency EMI noise generation.
Diodes, high-frequency switching devices, transformers and
inductors, and circuit layouts passing high dv/dt or di/dt
signals are all potential sources of EMI.
EMI is propagated either by radiated or conductive means.
Radiated EMI can be sourced from these components as well
as by circuit loops that act like antennas and broadcast the
noise signals to neighboring circuit paths. This also means
that these loops can act as receivers of a broadcasted signal.
This radiated EMI noise can be reduced by proper circuit
layout and by shielding potential sources of EMI transmission.
There are two basic forms of conducted EMI that typically
need to be filtered; namely common-mode (CM) and
differential-mode (DM) EMI. Differential-mode resides in the
normal power loop of a power source and its load; where the
signal travels from the source to the load and then returns to
the source. Common-mode is a signal that travels through
both leads of the source and is returned to earth via parasitic
pathways, either capacitively or inductively coupled.
Figure 8 to Figure 11 are the resulting EMI plots, after filtering
by the QPI-6, of the total noise, both common and differential
mode, of a Vicor Brick and a DOSA (Distributed-power Open
Standards Alliance) compliant converter. These converters
are mounted on a QPI-6 evaluation board and tested under
various loads. The red and blue traces represent the positive
and negative branches of total noise, as measured using an
industry standard LISN setup, as is shown in Figures 6 and 7.
Differential-mode EMI is typically larger in magnitude than
common-mode, since common-mode is produced by the
physical imbalances in the differential loop path. Reducing
differential EMI will cause a reduction in common-mode EMI.
Passive EMI Filtering
The basic premise of filtering EMI is to insert a high-
impedance, at the EMI’s base frequency, in both the
differential and common-mode paths as it returns to the
power source.
Passive filters use common-mode chokes and “Y” capacitors
to filter out common-mode EMI. These chokes are designed
to present a high-impedance at the EMI frequency in series
with the return path, and a low impedance path to the earth
signal via the “Y” caps. This network will force the EMI signals
to re-circulate within a confined area and not to propagate to
the outside world. Often two common-mode networks are
required to filter EMI within the frequency span required to
pass the EN55022 class B limits.
The other component of the passive filter is the differential
LC network. Again, the inductor is chosen such that it will
present a high-impedance in the differential EMI loop at the
EMI’s base frequency. The differential capacitor will then
shunt the EMI back to its source. The QPI-6 was specifically
designed to work with conventional switching frequency
converters like Vicor’s Brick products; Micro, Mini and Maxi
modules; as well as converters from various vendors.
Active EMI Filtering
PICOR’s QPI-6 active EMI filter uses the same basic principles
for filtering as the passive approach, but its active common-
mode filter can perform as well as a passive filter, when
filtering lower frequencies, in much less board area.
Figure 3 – Simplified Active EMI filter circuit.
Typically, the lower the frequency the greater the needed
inductance would be to properly filter the EMI signal. This
means either a larger core or a greater number of turns on a
smaller core. A larger core requires more board space, where
a smaller core with more turns has a greater amount of
unwanted parasitics that can affect the filters ability to
attenuate EMI signals.
Figure 3 is a simplified schematic of the QPI-6’s active and
passive circuitry used for EMI filtering. The QPI-6’s active
filter uses a small high-frequency common-mode transformer
to filter the higher frequencies and adds a sensing element to
it so that the lower frequency common mode signal can be
sensed and a correction signal can be generated and inserted
into the shield connection.
By this means, the QPI-6 is
capable of providing EMI filtering of converters in far less
space than standard passive filters and can provide filtering
over the entire EN55022 class B range.
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| QPI-8-CB1 | 功能描述:EVAL BOARD QPI-8LZ DOSA STYLE RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估演示板和套件 系列:Picor®, QUIETPOWER® 標(biāo)準(zhǔn)包裝:1 系列:PSoC® 主要目的:電源管理，熱管理 嵌入式:- 已用 IC / 零件:- 主要屬性:- 次要屬性:- 已供物品:板，CD，電源 |
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