CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
431
23. Switched Capacitor PSoC
®
Block
This chapter presents the Analog Switched Capacitor Block and its associated registers. The analog Switched Capacitor (SC)
blocks are built around a low offset, low noise operational amplifier. For a complete table of the Switched Capacitor PSoC
®
Block registers, refer to the
“Summary Table of the Analog Registers” on page 389
. For a quick reference of all PSoC regis-
ters in address order, refer to the
Register Details chapter on page 125
.
23.1
Architectural Description
The Analog Switched Capacitor blocks are built around a
rail-to-rail, input and output, low offset and low noise opamp.
(Refer to
.) There are several
analog multiplexers (muxes) controlled by register bit set-
tings in the control registers that determine the signal topol-
ogy inside the block. There are four user-selectable
capacitor arrays inside this block connected to the opamp.
There are four analog arrays. Three of the four arrays are
input arrays and are labeled A Cap Array, B Cap Array, and
C Cap Array. The fourth array is the feedback path array and
is labeled F Cap Array. All arrays have user-selectable unit
values: one array is in the feedback path of the opamp and
three arrays are in the input path of the opamp. Analog
muxes, controlled by bit settings in control registers, set the
capacitor topology inside the block. A group of muxes are
used for the signal processing and switch synchronously to
clocks PHI1 and PHI2, with behavior that is modified by con-
trol register settings. There is also an analog comparator
that converts the opamp output (relative to the local analog
ground) into a digital signal.
There are two types of Analog Switched Capacitor blocks
called Type C and Type D. Their primary differences relate
to connections of the C Cap Array and the block’s position in
a two-pole filter section. The Type D block also has greater
flexibility in switching the B Cap Array.
There are three discrete outputs from this block. These out-
puts connect to the following buses:
1. The analog output bus (ABUS), which is an analog bus
resource shared by all of the analog blocks in the analog
column. This signal may also be routed externally
through the output buffer. The ABUS of each column has
a 1.4 pF capacitor to GND. This capacitor may be used
to hold a sampled value on the ABUS net. Although
there is only one capacitor per column, it is shown in
both
to allow visualization
of the sample and hold function. See the description of
the ClockPhase bit in the ASCxxCR0 and ASDxxCR0
registers in section
.
2. The comparator bus (CBUS), which is a digital bus
resource shared by all of the analog blocks in the analog
column.
3. The local output bus (OUT), which is an analog node, is
routed to neighboring block inputs.
Содержание CY8C28 series
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Страница 93: ...92 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G External Crystal Oscillator ECO ...
Страница 97: ...96 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Phase Locked Loop PLL ...
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Страница 425: ...424 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Analog Reference ...
Страница 461: ...460 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Two Column Limited Analog System ...
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Страница 533: ...532 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G I O Analog Multiplexer ...
Страница 537: ...536 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Real Time Clock RTC ...
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