Component - Voltage Reference V1.60

®
PSoC Creator™ Component Datasheet
Voltage Reference (Vref)
1.60
Features
 Voltage references and supplies
 Multiple options
 Bandgap principle to achieve temperature, and voltage stability
General Description
This component works with both PSoC 3 and PSoC 5 devices. The Voltage Reference (Vref)
component provides one of several voltage reference outputs. The 1.024-V and 0.256-V outputs
are temperature compensated using the bandgap principle to achieve excellent stability.
Note The Vref component is not intended to source or sink current. It has low drive strength. If
high drive strength is needed, buffer the Vref with an Opamp or PGA component.
Every Vref is associated with some analog resource. To enable a Vref, the associated resource
must be enabled. All Vrefs default their AutoEnable parameter to true. Since auto-enable Vrefs
automatically enable the associated analog resource, all Vrefs are automatically enabled by
default.
When to Use a Vref
Use Vref components for threshold detectors, reference inputs to analog-to-digital converters,
comparators, and programmable gain amplifiers. They can also be used whenever you need a
known voltage.
Input/Output Connections
The Vref component has a single output terminal that provides access to the selected voltage
reference.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-79279 Rev. **
Revised May 15, 2012
Voltage Reference (Vref)
®
PSoC Creator™ Component Datasheet
Component Parameters
Drag a Vref onto your design and double click it to open the Configure dialog.
Basic Tab
VRef Name
This is the Vref value. Options include:

1.024 V (default) – Based on bandgap; see DC and AC Electrical Characteristics section for
more information.


Vssa(GND) – Internal Vssa voltage.

Vdda/2 – Derived from Vdda with a resistive divider; see DC and AC Electrical
Characteristics section for more information.

Vdda(HiZ) – The Vdda voltage reference is provided with a resistive divider and so has high
impedance. Vdda(HiZ) cannot be used if Vdda/2 is used elsewhere. See the Precision
Reference chapter of the chip Technical Reference Manual (TRM) for details.
0.256 V – Derived from the 1.024 bandgap with a resistive divider; see DC and AC Electrical
Characteristics section for more information.
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Document Number: 001-79279 Rev. **
®
PSoC Creator™ Component Datasheet
Voltage Reference (Vref)

Vccd – Special 1.8-V reference that is only available for SIO pins. Available in Production
PSoC 3 or later only.



Vddd – Internal Vddd voltage. Available in Production PSoC 3 or later only.
Vbat – Internal Vbat voltage. Available in Production PSoC 3 or later only.
Vdda – Internal Vdda voltage. Available in Production PSoC 3 or later only.
Advanced Tab
AutoEnable
The AutoEnable parameter applies to the 1.024-V and 0.256 V-Vref components.
When AutoEnable is set to true (default), the Vref is enabled automatically when the device is
initialized and the static analog routes are established. The 1.024-V and 0.256-V Vref
components may need to consume a comparator when AutoEnable is true.
When a 1.024-V or 0.256-V Vref is connected to intended analog block connections such as the
comparator, the device automatically enables the Vref when the connected components are
enabled. AutoEnable is not necessary in these cases. See the Precision Reference chapter of
the chip Technical Reference Manual (TRM) for details.
Note Vref components that require AutoEnable set to true have reduced routing capability
because specific analog routing resources are required to supply the auto-enable Vref.
Document Number: 001-79279 Rev. **
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Voltage Reference (Vref)
®
PSoC Creator™ Component Datasheet
When AutoEnable is set to false, the 1.024-V and 0.256-V Vref components are only powered
up when the associated analog block is powered up. See the TRM for details.
Placement
For a design project, the list of available voltage references is determined by what is available
from the selected family or device.
If you place a Vref component in a library project schematic at the generic level, you do not see
any references available. In this case, you need to specify a family or device when creating the
schematic.
AutoEnable Vref Connecting to an Amux Switchable
Connection
The auto-enable 1.024-V or 0.256-V Vref component must be all by itself when connected to an
Amux switchable connection. This restriction is introduced so the software can handle the autoenable Vref feature without ambiguities.
In general, the software must split up signals connected to auto-enable Vrefs, but that is not
possible for Amux switchable connections.
In the following example, in order for Design 1 to work it must be converted to Design2.
If you choose to set the AutoEnable parameter of the Vref component to false, this restriction
does not apply.
Vrefs in low power mode
In low power mode, Vssa(GND) and Vdda(HiZ) are the only two vrefs that are available.
Functional Description
The Vref component provides one of the available voltage references. Connection is through a
single terminal. The Vref component may be shared among several components.
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Document Number: 001-79279 Rev. **
®
PSoC Creator™ Component Datasheet
Voltage Reference (Vref)
Resources
When AutoEnable is enabled for an unintended analog block, the 1.024-V Vref consumes a
comparator, which will be automatically removed from available comparator resources. A
comparator is required to satisfy device requirements of having the analog block associated with
the Vref powered up. So, a comparator is allocated to be able to control the power settings and
use that Vref.
DC and AC Electrical Characteristics
The following values indicate expected performance and are based on initial characterization
data. Note that the 1.024-V voltage reference calibration occurs for the buffered ADC_DelSig
reference. All of the other 1.024-V references (about 7 or 8 different ones) can be off by several
millivolts.
Vref Characteristics
Parameter
Vref
Description
Conditions
Precision reference voltage
Temperature drift
Initial trimming
1
Long term drift
Thermal cycling drift (stability)
1
Min
Typ
Max
Units
1.023
(–0.1%)
1.024
1.025
(+0.1%)
–
–
20
ppm/°C
–
100
–
ppm/Khr
–
100
–
ppm
V
Component Changes
This section lists the major changes in the component from the previous version.
Version
Description of Changes
Reason for Changes / Impact
1.60
Removed IgnoreSleep parameter from the
customizer.
1.50.c
Minor datasheet edits and updates
1.50.b
Updated description of Vdda(HiZ)
Description was unclear.
Updated AutoEnable section to include
quarter volt Vref
0.256-V Vref has the same AutoEnable properties as the
1.024-V Vref.
1.50.a
The Vref component can’t remain powered in low power
mode. The IgnoreSleep parameter has no effect.
Added characterization data to datasheet
Datasheet edits
1
Based on device characterization (Not production tested).
Document Number: 001-79279 Rev. **
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Voltage Reference (Vref)
Version
1.50
Description of Changes
®
PSoC Creator™ Component Datasheet
Reason for Changes / Impact
Added AutoEnable and IgnoreSleep
parameters to the customizer.
The AutoEnable and IgnoreSleep parameters provide
additional functionality and a more intuitive user
experience.
Added the special purpose Vccd Vref for
use with SIO pins.
The Vccd reference is used with SIO pins.
Added Vbat, Vddd, and Vdda references.
The Vbat, Vddd, and Vdda references were added to
provide additional functionality.
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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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Document Number: 001-79279 Rev. **
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