Component - Comparator (Comp) V2.0

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PSoC Creator™ Component Datasheet
Comparator (Comp)
2.0
Features
 Low input offset
 User controlled offset calibration
 Multiple speed modes
 Low-power mode
 Output routable to digital logic blocks or pins
 Selectable output polarity
 Configurable operation mode during Sleep
General Description
The Comparator (Comp) component provides a hardware solution to compare two analog input
voltages. The output can be sampled in software or digitally routed to another component. Three
speed levels are provided to allow you to optimize for speed or power consumption. A reference
or external voltage can be connected to either input.
You can also invert the output of the comparator using the Polarity parameter.
When to Use a Comparator
The Comparator can provide a fast comparison between two voltages, compared to using an
ADC. Although an ADC can be used with software to compare multiple voltage levels,
applications requiring fast response or little software intervention are good candidates for this
comparator. Some example applications include CapSense ®, power supplies, or simple
translation from an analog level to a digital signal.
A common configuration is to create an adjustable comparator by connecting a voltage DAC to
the negative input terminal.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-84985 Rev. **
Revised December 3, 2012
®
Comparator (Comp)
PSoC Creator™ Component Datasheet
Input/Output Connections
This section describes the input and output connections for the Comp. An asterisk (*) in the list of
I/Os states that the I/O may be hidden on the symbol under the conditions listed in the
description of that I/O.
Positive Input – Analog
This input is usually connected to the voltage that is being compared. This input can be routed to
GPIOs or to a selection of internal references.
Negative Input – Analog
This input is usually connected to the reference voltage. This input can be routed to GPIOs or to
a selection of internal references.
Comparator Out – Digital Output
The output of the comparison. For noninverting configuration, this output goes high when the
positive input voltage is greater than the negative input voltage. If the polarity is set to inverting,
the output will go high when the negative input voltage is greater than the positive input voltage,
in this case one inverter from an UDB block is used in order to inverts the comparator’s output
signal. The output can be routed to other component digital inputs such as interrupts, timers, etc.
clock – Digital Input *
The clock input synchronizes the comparator output to the rising edge of the clock when the
Sync parameter is set to Normal. This forces the comparator output to be sampled on the rising
edge of the clock.
When the Sync parameter is set to Bypass, the output is not synchronized with bus clock on
rising edge and synchronized to the bus clock on falling edge. In this case the clock input
terminal no longer displayed on the component symbol.
Sync: Normal
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Sync: Bypass
Document Number: 001-84985 Rev. **
PSoC® Creator™ Component Datasheet
Comparator (Comp)
Component Parameters
Drag a Comparator onto your design and double-click it to open the Configure dialog.
The Comparator provides the following parameters.
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Comparator (Comp)
PSoC Creator™ Component Datasheet
Hysteresis
This parameter allows you to add approximately 10 mV of hysteresis to the comparator. This
helps to ensure that slowly moving voltages or slightly noisy voltages will not cause the output of
the comparator to oscillate when the two input voltages are near equal.
Hysteresis Disabled
Hysteresis Enabled
Speed
This parameter provides a way for the user to optimize speed verses power consumption.
Speed Options
Description
Ultra Low Power
Use this setting for very low power applications.
Slow (default)
Use this setting for signals requiring response times slower than 80 ns.
Fast
Use this setting for signals requiring response times faster than 80 ns.
PowerDownOverride
Enabling the power down override parameter causes the comparator to stay active during Sleep
mode. When the PowerDownOverride option is enabled, the customizer automatically sets the
power mode to Ultra Low Power and remaining power options become unavailable. This is
because Ultra Low Power is the only valid power mode for the comparator in Sleep mode.
Note Don't use the inverted output in this mode.
Note This parameter is not valid for PSoC 5 silicon and the GUI option is unavailable. For PSoC
3 and PSoC 5 LP silicon, this feature is supported and the GUI option is available.
Polarity
This parameter allows you to invert the output of the comparator. This is useful for peripherals
that require an inverted signal from the comparator. The sampled signal state returned by the
software API and the comparator output seen by the power manager (see the System Reference
Guide section on Alt Active and Sleep) is not affected by this parameter.
Note Inversion logic for comparator is implemented using UDBs.
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PSoC® Creator™ Component Datasheet
Comparator (Comp)
Polarity Options
Description
Inverting
Output goes high when positive input is less than the negative input
Non-Inverting (default)
Output goes high when positive input is greater than negative input
Sync
This parameter selects between synchronizing the output with a clock and connecting through
asynchronous set/synchronous to the bus clock reset flop. When Norm is selected, the output
will change on the rising edge of the clock input. When Bypass is selected, the output will set
immediately and reset on the rising edge of the bus clock.
Sync Options
Description
Norm (default)
Sync the comparator output with the clock input.
Bypass
Connect the analog comparator output through asynchronous
set/synchronous to the bus clock reset flop.
Application Programming Interface
Application Programming Interface (API) routines allow you to configure the component using
software. The following table lists the interface to each function. The subsequent sections cover
each function in more detail.
By default, PSoC Creator assigns the instance name “Comp_1” to the first instance of a
component in a given design. You can rename the instance 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 “Comp.”
Function
Description
Comp_Start()
Initializes the Comparator with default customizer values.
Comp_Stop()
Turns off the Comparator.
Comp_SetSpeed()
Sets speed of the Comparator.
Comp_ZeroCal()
Zeros the input offset of the Comparator.
Comp_GetCompare()
Returns compare result.
Comp_LoadTrim()
Writes a value to the Comparator trim register.
Comp_Sleep()
Stops Comparator operation and saves the user configuration.
Comp_Wakeup()
Restores and enables the user configuration.
Comp_Init()
Initializes or restores default Comparator configuration.
Comp_Enable()
Enables the Comparator.
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Comparator (Comp)
PSoC Creator™ Component Datasheet
Function
Description
Comp_SaveConfig()
Empty function. Provided for future use.
Comp_RestoreConfig()
Empty function. Provided for future use.
Comp_PwrDwnOverrideEnable()
Enables Comparator operation in sleep mode. Only valid for PSoC 3 silicon.
Comp_PwrDwnOverrideDisable()
Disables Comparator operation in sleep mode. Only valid for PSoC 3 silicon.
Global Variables
Variable
Comp_initVar
Description
Indicates whether the Comparator has been initialized. The variable is initialized to 0 and set to 1
the first time Comp_Start() is called. This allows the component to restart without reinitialization
after the first call to the Comp_Start() routine.
If reinitialization of the component is required, then the Comp_Init() function can be called before
the Comp_Start() or Comp_Enable() function.
void Comp_Start(void)
Description:
This is the preferred method to begin component operation. Comp_Start() sets the initVar
variable, calls the Comp_Init() function, and then calls the Comp_Enable() function.
Parameters:
None
Return Value:
None
Side Effects:
If the initVar variable is already set, this function only calls the Comp_Enable() function.
void Comp_Stop(void)
Description:
Disables and powers down the comparator.
Note This API is not recommended for use on PSoC 3 ES2 and PSoC 5 silicon. These
devices have a defect that causes connections to several analog resources to be unreliable
when not powered. The unreliability manifests itself in silent failures (for example,
unpredictably bad results from analog components) when the component using that resource
is stopped. When using this silicon, all analog components in a design should be powered up
(by calling their respective _Start() APIs, for instance Comp_Start()) at all times. Do not call
the Comp_Stop() APIs.
Parameters:
None
Return Value:
None
Side Effects:
None
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PSoC® Creator™ Component Datasheet
Comparator (Comp)
void Comp_SetSpeed(uint8 speed)
Description:
This function selects one of three speed modes for the comparator. The comparator power
consumption increases for the faster speed modes.
Parameters:
uint8 speed: Speed parameter, see the following table for valid settings.
Speed Options
Description
Comp_LOWPOWER
Use this setting for very low power applications
Comp_SLOWSPEED
Use this setting for signals requiring response times slower
than 80 ns
Comp_HIGHSPEED
Use this setting for signals requiring response times faster
than 80 ns
Return Value:
None
Side Effects:
None
uint16 Comp_ZeroCal(void)
Description:
Performs custom calibration of the input offset to minimize error for a specific set of
conditions: comparator reference voltage, supply voltage, and operating temperature.
A reference voltage in the range at which the comparator will be used must be applied to the
negative input of the comparator while the offset calibration is performed. The comparator
component must be configured for Fast or Slow operation when calibration is performed. The
calibration process will not work correctly if the comparator is configured in Low Power mode.
Parameters:
None
Return Value:
uint16: The value from the comparator trim register after the offset calibration is complete.
This value has the same format as the input parameter for the Comp_LoadTrim() API
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routine. Refer to the PSoC 3, PSoC 5 Architecture TRM for a description of the comparator
trim register.
Side Effects:
During the calibration procedure, the comparator output may behave erratically.
During the calibration procedure, the analog routing switches for the comparator positive
input are reconfigured. This reconfiguration may affect the analog signal routing for other
components that are connected to the comparator positive input.
When calibration is complete, all routing and comparator configuration registers are restored
to the state they were in before calibration occurred.
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Comparator (Comp)
PSoC Creator™ Component Datasheet
uint8 Comp_GetCompare(void)
Description:
This function returns a nonzero value when the voltage connected to the positive input is
greater than the negative input voltage. This value is not affected by the Polarity parameter.
This value always reflects a noninverted state.
Parameters:
None
Return Value:
uint8: Comparator output state. Nonzero value when the positive input voltage is greater than
the negative input voltage; otherwise, the return value is zero.
Side Effects:
None
void Comp_LoadTrim(uint16 trimVal)
Description:
This function writes a value into the comparator trim register.
Parameters:
uint16 trimVal: Value to be stored in the comparator trim register.
This value has the same format as the parameter returned by the Comp_ZeroCal() API
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routine. Refer to the PSoC 3, PSoC 5 Architecture TRM for a description of the comparator
trim register.
Return Value:
None
Side Effects:
None
void Comp_SaveConfig(void)
Description:
This function saves the component configuration and nonretention registers. It also saves the
current component parameter values, as defined in the Configure dialog or as modified by
appropriate APIs. This function is called by the Comp_Sleep() function.
Parameters:
None
Return Value:
None
Side Effects:
Empty function. Implemented for future usage. No effect by calling this function.
void Comp_RestoreConfig(void)
Description:
This function restores the component configuration and nonretention registers. It also
restores the component parameter values to what they were prior to calling the
Comp_Sleep() function.
Parameters:
None
Return Value:
None
Side Effects:
Empty function. Implemented for future use. No effect by calling this function.
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Document Number: 001-84985 Rev. **
PSoC® Creator™ Component Datasheet
Comparator (Comp)
void Comp_Sleep(void)
Description:
This is the preferred routine to prepare the component for sleep. The Comp_Sleep() routine
saves the current component state. Then it calls the Comp_Stop() function and calls
Comp_SaveConfig() to save the hardware configuration.
Call the Comp_Sleep() function before calling the CyPmSleep() or the CyPmHibernate()
function. Refer to the PSoC Creator System Reference Guide for more information about
power management functions.
Parameters:
None
Return Value:
None
Side Effects:
In the inverting mode of comparator, the output is implemented using UDB. Hence, the
comparator output level is high when this sleep API is called and it does not go to sleep.
void Comp_Wakeup(void)
Description:
This is the preferred routine to restore the component to the state when Comp_Sleep() was
called. The Comp_Wakeup() function calls the Comp_RestoreConfig() function to restore the
configuration. If the component was enabled before the Comp_Sleep() function was called,
the Comp_Wakeup() function will also re-enable the component.
Parameters:
None
Return Value:
None
Side Effects:
Calling the Comp_Wakeup() function without first calling the Comp_Sleep() or
Comp_SaveConfig() function may produce unexpected behavior.
void Comp_PwrDwnOverrideEnable(void)
Description:
This is the power-down override feature. This function allows the component to stay active
during sleep mode. Before calling this API, the Comp_SetPower() API should be called with
the Comp_LOWPOWER parameter to set the comparator power mode to Ultra Low Power.
This is because Ultra Low Power is the only valid power mode for the comparator in Sleep
mode.
The Comp_PwrDwnOverrideEnable() function is not valid for PSoC 5 silicon. It is available
for PSoC 3 and PSoC 5 LP silicon.
Parameters:
None
Return Value:
None
Side Effects:
None
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Comparator (Comp)
PSoC Creator™ Component Datasheet
void Comp_PwrDwnOverrideDisable(void)
Description:
This is the power-down override feature. This function allows the comparator to stay
inactive during sleep mode. This API is not valid for PSoC 5 silicon. It is available for PSoC
3 and PSoC 5 LP silicon.
Parameters:
None
Return Value:
None
Side Effects:
None
void Comp_Init(void)
Description:
Initializes or restores the component according to the customizer Configure dialog settings. It
is not necessary to call Comp_Init() because the Comp_Start() routine calls this function and
is the preferred method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
All registers will be set to values according to the customizer Configure dialog.
void Comp_Enable(void)
Description:
Activates the hardware and begins component operation. It is not necessary to call
Comp_Enable() because the Comp_Start() routine calls this function, which is the preferred
method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
None
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 Comp component does not have any specific deviations.
This component has no embedded components.
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PSoC® Creator™ Component Datasheet
Comparator (Comp)
Sample Firmware Source Code
PSoC Creator provides numerous example projects that include schematics and example code
in the Find Example Project dialog. For component-specific 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 “Find Example Project” topic in the PSoC Creator Help for more information.
Functional Description
The Comparator is functionally a high-gain high-bandwidth differential amplifier (an opamp with
the compensation removed). The comparator is trimmed at the factory to achieve low input offset
voltage. It can be trimmed at runtime in the customer’s code to achieve improved input offset
voltage precision at a specific point. Hysteresis is enabled by adding offsetting currents to the
input stage. The nominal hysteresis is 10 mV (33 mV maximum), which is enough to be
significantly larger than the sum of any input self noise of the comparator and internal routing
interference.
Input offset voltage is normally specified as the absolute value of the difference between the two
inputs when the output of the Comparator switches state.
Resources
The analog comparator component uses one analog comparator block.
API Memory Usage
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 the 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 3 (Keil_PK51)
Configuration
Default
PSoC 5 (GCC)
PSoC 5LP (GCC)
Flash
SRAM
Flash
SRAM
Flash
SRAM
Bytes
Bytes
Bytes
Bytes
Bytes
Bytes
512
2
540
12
584
5
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Comparator (Comp)
PSoC Creator™ Component Datasheet
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.
Comparator DC Specifications
Parameter
VIOFF
VIOFF
Description
Conditions
Max
Units
Factory trim
–
2.0
10
mV
Input offset voltage in slow mode
Factory trim
–
2.0
10
mV
1
Custom trim
–
1.0
4.0
mV
Custom trim
–
1.0
4.0
mV
–
12
–
mV
mV
Input offset voltage in fast mode
1
VIOFF
Input offset voltage in ultra lowpower mode
VHYST
Hysteresis
Hysteresis enable mode
–
10
33
VICM
Input common mode voltage
High current / fast mode
0
–
VDDA – 0.1
V
Low current / slow mode
0
–
VDDA
V
Ultra low power mode
0
–
VDDA – 0.9
V
30
50
–
dB
2
–
250
400
µA
2
–
40
100
µA
–
6.0
–
µA
CMRR
Common mode rejection ratio
ICMP
High current mode/fast mode
Low current mode/slow mode
Ultra low-power mode
2
Typ
Input offset voltage in fast mode
Input offset voltage in slow mode
1
Min
2
The recommended procedure for using a custom trim value for the on-chip comparators can be found in the TRM.
Based on device characterization (Not production tested).
Comparator AC Specifications
Parameter
TRESP
1
Description
Conditions
Min
Typ
Max
Units
Response time, high current
1
mode
50-mV overdrive,
measured pin-to-pin
–
80
110
ns
Response time, low current
1
mode
50-mV overdrive,
measured pin-to-pin
–
155
200
ns
Response time, ultra low-power
50-mV overdrive,
–
55
–
µs
Based on device characterization (Not production tested).
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PSoC® Creator™ Component Datasheet
Parameter
Comparator (Comp)
Description
mode
1
Conditions
Min
Typ
Max
Units
measured pin-to-pin
Component Changes
This section lists the major changes in the component from the previous version.
Version
Description of Changes
Reason for Changes / Impact
2.0
Added MISRA Compliance section.
The component does not have any specific deviations.
1.90
Updated ZeroCal() API.
In order to decrease function execution time.
Updated comparator trim register masks for
PSoC3, PSoC5LP or later.
To support zero calibration procedure for this chips.
Adding support Panther LP silicon.
1.80
1.70
1.60
Per creator 2.0 public release requirement.
Comp_Stop() API changes for PSoC 5.
Change required to prevent the component from
impacting unrelated analog signals when stopped,
when used with PSoC 5.
Fixed an issue with using comparator as
wakeup source for Sleep and Alt Active
modes.
Comparator was not configured correctly in previous
version to use it as a wakeup source for Sleep and Alt
Active modes.
Changed Comp_SetSpeed() API to set the
comparator trim values based on the speed
settings.
Comparator Trim values were not properly set based
on the speed settings in the previous version of the
component.
Comparator GUI updates
To force the power mode to Ultra Low power when
PowerDownOverride option is enabled.
Updated configuration window with an
accurate waveform including hysteresis.
Previous configuration window did not provide enough
information for ease of use.
Corrected Hysteresis enable bit setting
implementation
The meaning of the enable hysteresis bit was flipped.
This has been corrected to correctly enable hysteresis
on all versions of silicon
Added characterization data to datasheet.
Minor datasheet edits and updates.
1.50.a
Added Known Problems and Solutions to
datasheet
To provide a workaround for hysteresis problem in
PSoC 3 ES2 silicon.
1.50
Added Sleep/Wakeup and Init/Enable APIs.
To support low power modes, as well as to provide
common interfaces to separate control of initialization
and enabling of most components.
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Comparator (Comp)
Version
PSoC Creator™ Component Datasheet
Description of Changes
Reason for Changes / Impact
Updated Configure dialog with customized
interface.
The updated Configure dialog makes it easier to use.
There is also a preview of how the component will
change based on various selections.
Added Power Down Override parameter to
the Configure dialog.
To allow configuration of Comparator to operate during
sleep mode.
Added Comp_PwrDwnOverrideEnable()/
Comp_PwrDwnOverrideDisable() APIs.
To allow the component to stay active/inactive during
sleep mode.
© Cypress Semiconductor Corporation, 2012. 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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