Component - PSoC 4 Voltage Reference V1.0

PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
1.0
Features
 Reference is based on either Bandgap or Vdda
 Each instantiation may be a different value
 Adjustable by 1/16 steps between Vss and Bandgap or Vdda
 Up to four individual references
 References may be changed during runtime
General Description
The PSoC 4 Programmable Voltage Reference (PVref_P4) component provides an adjustable
stable reference voltage for the analog resources in your design. Each component provides a
voltage reference that is based on either Vdda or the Bandgap voltage in 1/16 increments. This
reference may be connected to any high impedance input such as the input to an opamp or
comparator and cannot be routed to a GPIO unless it is buffered with an opamp.
When to Use a PVref_P4
Use the Programmable Reference any time a stable know voltage is required for comparison,
such as with comparators, VDACs, and ADCs.
Input/Output Connections
This section describes the various input and output connections for the PVref_P4 component. An
asterisk (*) in the following list indicates that it may not be shown on the component symbol for
the conditions listed in the description of that I/O.
Terminal Name
Vout
I/O Type
Analog Output
Description
Reference Voltage Output.
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Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 002-10611 Rev. *A
Revised May 4, 2016
PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
Component Parameters
Drag a PVref_P4 component onto your design and double click it to open the Configure dialog.
This dialog has the following tabs with different parameters.
Basic Tab
Parameter Name
Description
Reference Source
This option selects the reference source to be based on either the internal bandgap
voltage or the Vdda supply. The default is bandgap voltage.
Output Voltage
This parameter is used to select the desired output voltage from the voltage divider.
Default is the full reference source (16/16*Vref).
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PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
Application Programming Interface
API functions allow configuration of the component using the CPU.
By default, PSoC Creator assigns the instance name PVref_P4 to the first instance of a component in a
given design. You can rename it to any unique value that follows the syntactic rules for identifiers. The
instance name becomes the prefix of every global function name, variable, and constant symbol. For
readability, the instance name used in the following table is PVref_P4 .
Modules

General APIs
General APIs are used for run-time configuration of the component during active power mode.

Power Management APIs
Power management APIs perform the necessary configurations to the components to prepare it for entering low
power modes.
General APIs
General APIs are used for run-time configuration of the component during active power mode.
These include, initializing, starting, stopping, reading from registers and writing to registers.
Functions

void PVref_P4_Init(void)

void PVref_P4_Enable(void)

void PVref_P4_Start(void)

void PVref_P4_Stop(void)

void PVref_P4_SetTap(uint32 dividerTap)

void PVref_P4_SetVRefSrc(uint32 reference)
Function Documentation
void PVref_P4_Init (void )
Initialize/Restore the default Voltage Reference configuration as defined in the customizer. If the
reference is set to Vdda, it will enable all Vdda-based references.
Side Effects
If the reference is Vdda-based, the function will enable all Vdda-based references because they share the
same resistor tree.
void PVref_P4_Enable (void )
Enables the Voltage Reference.
void PVref_P4_Start (void )
Initializes all parameters required to setup the component as defined in the customizer. If the reference
is set to Vdda, it will enable all Vdda based references.
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PSoC 4 Programmable Voltage Reference (PVref_P4)
PSoC® Creator™ Component Datasheet
Global Variables
PVref_P4_initVar - This variable is used to indicate the initial configuration of this component. The variable
is initialized to zero and set to 1 the first time PVref_P4_Start() is called. This allows the component
initialization without re-initialization in all subsequent calls to the PVref_P4_Start() routine.
Side Effects
If the reference is Vdda-based, the function will enable all Vdda-based references because they share the
same resistor tree.
void PVref_P4_Stop (void )
Disables the Voltage Reference.
void PVref_P4_SetTap (uint32 dividerTap)
Selects which of the equally spaced resistor divider taps will be used for the reference. The output will
range in 1/16th steps between Vref/16 to Vref.
Parameters:
dividerTap
One of the 16-tap voltage dividers to select a voltage between 1/16 of
the reference source to the full reference source in steps of 1/16.

1 : 1/16 Vref

... : ...

16 : Vref
void PVref_P4_SetVRefSrc (uint32 reference)
Selects whether the reference at the top of the resistor divider is based on the bandgap or Vdda.
Parameters:
reference
The reference source.

PVref_P4_BANDGAP_REFERENCE : Bandgap reference

PVref_P4_VDDA_REFERENCE : Vdda reference
Side Effects
If the reference is based on Vdda, it will affect all Vdda-based references because they share the same
resistor tree.
Power Management APIs
Power management APIs perform the necessary configurations to the components to prepare it for entering
low power modes.
These APIs must be used if the intent is to put the chip to sleep, then to continue the component operation
when it comes back to active power mode.
Functions

void PVref_P4_Sleep(void)

void PVref_P4_Wakeup(void)
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PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
Function Documentation
void PVref_P4_Sleep (void )
Prepares the component to enter Sleep mode. If the reference is based on Vdda, the function will open
the switch at the bottom of the resistor tree to eliminate the current flow through the resistor. If the
reference is based on the bandgap, this function will do nothing.
Side Effects
If the reference is based on Vdda, it will affect all Vdda-based references because they share the same
resistor tree.
void PVref_P4_Wakeup (void )
Restores the component after exiting Sleep mode. By calling this function for any Vdda-based
reference, the function will enable all Vdda-based references because they all are based on the same
resistor divider. For bandgap-based references, nothing will happen.
Side Effects
If the reference is based on Vdda, it will affect all Vdda-based references because they share the same
resistor tree.
Global Variables
Global variables used in the component.
The following global variables are used in the component.
Variables

uint8 PVref_P4_initVar
PVref_P4_backup_struct Struct Reference
Data Fields

uint8 enableState
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PSoC 4 Programmable Voltage Reference (PVref_P4)
PSoC® Creator™ Component Datasheet
Code Examples and Application Notes
This section lists the projects that demonstrate the use of the component.
Code Examples
PSoC Creator provides access to code examples in the Code Example dialog. For componentspecific examples, open the dialog from the Component Catalog or an instance of the
component in a schematic. For general examples, open the dialog from the Start Page or File
menu. As needed, use the Filter Options in the dialog to narrow the list of projects available to
select.
Refer to the "Code Example" topic in the PSoC Creator Help for more information.
There are also numerous code examples that include schematics and example code available
online at the Cypress Code Examples web page. Examples that use this component include:

CE203972 - Comparator with Programmable Voltage Reference
Application Notes
Cypress provides a number of application notes describing how PSoC can be integrated into
your design. You can access the Cypress Application Notes search web page at
www.cypress.com/appnotes.
API Memory Usage
Shows the Flash, SRAM and stack usage of the component.
The component memory usage varies significantly depending on the compiler, device, number of
APIs used and component configuration. The following table provides the memory usage for all
APIs available in the given component configuration.
The measurements have been done with an associated compiler configured in Release mode
with optimization set for Size. For a specific design, the map file generated by the compiler can
be analyzed to determine the memory usage.
PSoC 4 (GCC)
PSoC Analog Coprocessor
Configuration
Default
Flash Bytes
SRAM Bytes
232
2
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PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
Functional Description
The PVref_P4 component provides an adjustable analog voltage reference in your design. You
can instantiate several PVref_P4 components on the schematic (particular number depends on
the selected device resources and can be obtained from the device datasheet) and set the
reference source to be either Vdda or the bandgap voltage. You may also select one tap of the
16-tap voltage divider to select a voltage between 1/16 of the reference source to the full
reference source in steps of 1/16. The PVref_P4 component output may be connected to any
high impedance input such as the input to an opamp or comparator. To route component output
to a GPIO - it should be buffered with an opamp.
Note There are general predefined settings for the Programmable Reference Block, such as
"Reference Source", "Voltage Reference Value", "Bandgap Gain", "Enable Vdda reference
during Deep Sleep", which are located under the System Editor of the Design-Wide Resources
file. For more details, refer to the PSoC Creator Help.
Note Changes to these settings will affect all PVref_P4 component instances. The general
settings in the System Editor can be tuned by System APIs as well. For more details refer, to
System Reference Guide.
Note The actual value of the Vdda-based reference is dependable on real value of the Vdda
voltage. The Vdda voltage is changeable and should be accurately treated to get precise
reference.
Low Power Mode Behavior
The bandgap reference will be automatically disabled in deep sleep. In case of Vdda reference
source to eliminate the current flow through the resistor it can be switched off by calling
PVref_P4_Sleep() API. There is an option to leave Vdda reference enabled in deep sleep. To do
this "Vdda reference active during deep sleep" option should be enabled in System tab at the
Design Wide Resources window and PVref_P4_Sleep() API shouldn't be called prior to enter
device into deep sleep mode.
Block Diagram and Configuration
A simplified diagram of the PVref_P4 hardware is shown in the component customizer. The
reference voltages are derived from a resistor string. There are 2 separate identical resistor
strings. The resistor string is made up of 16 resistor legs each with a poly taps. The top of the
first resistor string is connected to bandgap reference and the top of the second resistor is
connected to Vdda reference. The bottom of the first resistor string is connected to Vssa and the
bottom of the second resistor string is connected through a switch Vdda_enable to Vssa. Each
resistor string has four 16:1 muxes. This 16:1 mux selects one of 16 voltages from the resistor
string. The output reference voltages are not buffered and must be connected to only high
impedance nets.
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PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
Industry Standards
Lists the industry standard compliance of the PVref_P4 component.
MISRA Compliance
This section describes the MISRA-C:2004 compliance and deviations for the component. There
are two types of deviations defined:


project deviations – deviations that are applicable for all PSoC Creator components
specific deviations – deviations that are applicable only for this component
This section provides information on component-specific deviations. Project deviations are
described in the MISRA Compliance section of the System Reference Guide along with
information on the MISRA compliance verification environment.
The PVref_P4 component does not have any specific deviations.
Registers
Describes the UDB registers used in the PVref_P4 component.
For fixed-function blocks, refer to the chip Technical Reference Manual (TRM) for more
information about the registers.
Resources
The PVref_P4 component uses the dedicated PRB (Programmable Reference Block) IP in the
silicon.
DC and AC Electrical Characteristics
Specifications are valid for -40° C = TA = 85° C and TJ = 100° C, except where noted.
Specifications are valid for 1.71 V to 5.5 V, except where noted.
Note Final characterization data for PSoC 4000S, PSoC 4100S and PSoC Analog Coprocessor
devices is not available at this time. Once the data is available, the component datasheet will be
updated on the Cypress web site.
DC Specifications
Parameter
Description
Conditions
Total resistor string resistance
Min
Typ
Max
Units
-
86.45
-
kOhms
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PSoC® Creator™ Component Datasheet
PSoC 4 Programmable Voltage Reference (PVref_P4)
AC Specifications
Parameter
Description
Conditions
Min
Typ
Max
Units
Resistor
divider ratio
error
Deviation from 1/16 taps.
-
TBD
-
%
Bandgap
resistor
divider
current
Bandgap divided by the resistance
of the entire resistor divider string.
-
TBD
-
uA
Vdda
resistor
divider
current
Vdda divided by the resistance of
the entire resistor divider string.
-
TBD
-
uA
Component Changes
This section lists the major changes in the component from the previous version.
Version
Description of Changes
1.0.a
Edited datasheet.
1.0
Initial component version.
Reason for Changes / Impact
Final characterization data for PSoC 4000S,
PSoC 4100S and PSoC Analog Coprocessor devices
is not available at this time. Once the data is
available, the component datasheet will be updated
on the Cypress web site.
© Cypress Semiconductor Corporation, 2016. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
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Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in lifesupport systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application
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