CY8C21634, CY8C21534CY8C21434, CY8C21334, CY8C21234
Document Number: 38-12025 Rev. *O Page 3 of 45

The Analog System

The Analog System consists of 4 configurable blocks that allow
the creation of complex analog signal flows. Analog peripherals
are very flexible and may be customized to support specific
application requirements. Some of the common PSoC analog
functions for this device (most available as user modules) are:
■Analog-to-digital converters (single or dual, with 8-bit or 10-bit
resolution)
■Pin-to-pin comparator
■Single-ended comparators (up to 2) with absolute (1.3V)
reference or 8-bit DAC reference
■1.3V reference (as a System Resource)
In most PSoC devices, analog blocks are provided in columns of
three, which includes one CT (Continuous Time) and two SC
(Switched Capacitor) blocks. The CY8C21x34 devices provide
limited functionality Type “E” analog blocks. Each column
contains one CT Type E block and one SC Type E block. Refer
to the PSoC Programmable System-on-Chip™ Technical
Reference Manual for detailed information on the CY8C21x34’s
Type E analog blocks.
Figure 2. Analog System Block Diagram
The Analog Multiplexer System
The Analog Mux Bus can connect to every GPIO pin. Pins may
be connected to the bus individually or in any combination. The
bus also connects to the analog system for analysis with
comparators and analog-to-digital converters. An additional 8:1
analog input multiplexer provides a second path to bring Port 0
pins to the analog array.
Switch control logic enables selected pins to precharge
continuously under hardware control. This enables capacitive
measurement for applications such as touch sensing. Other
multiplexer applications include:
■Track pad, finger sensing.
■Chip-wide mux that allows analog input from any IO pin.
■Crosspoint connection between any IO pin combinations.
When designing capacitive sensing applications, refer to the
signal-to-noise system level requirement found in Application
Note AN2403 on the Cypress web site at
http://www.cypress.com.

Additional System Resources

System Resources, some of which are listed in the previous
sections, provide additional capability useful to complete
systems. Additional resources include a switch mode pump, low
voltage detection, and power on reset. Brief statements
describing the merits of each system resource follow.
■Digital clock dividers provide three customizable clock
frequencies for use in applications. The clocks may be routed
to both the digital and analog systems. Additional clocks can
be generated using digital PSoC blocks as clock dividers.
■The I2C module provides 100 and 400 kHz communication over
two wires. Slave, master, and multi-master modes are all
supported.
■Low Voltage Detection (LVD) interrupts can signal the
application of falling voltage levels, while the advanced POR
(Power On Reset) circuit eliminates the need for a system
supervisor.
■An internal 1.3 voltage reference provides an absolute
reference for the analog system, including ADCs and DACs.
■An integrated switch mode pump (SMP) generates normal
operating voltages from a single 1.2V battery cell, providing a
low cost boost converter.
■Versatile analog multiplexer system.
ACOL 1MU X
ACE00 ACE01
Array
Array Input
Configuration
ASE10 ASE11
X
X
X
X
X
Ana l og Mux Bus
All IO
ACI0[1:0] ACI1[1:0]
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