Component - Programmable Gain Amplifier (PGA) V1.90 Datasheet.pdf

®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
1.90
Features
 Gain steps from 1 to 50
 High input impedance
 Selectable input reference
 Adjustable power settings
General Description
The PGA implements an opamp-based, noninverting amplifier with user-programmable gain.
This amplifier has high input impedance, wide bandwidth and selectable input voltage reference.
It is derived from the switched capacitor/continuous time (SC/CT) block.
The gain can be between 1 (0 dB) and 50 (+34 dB). The gain can be selected using the
configuration window or changed at run time using the provided API. The maximum bandwidth is
limited by the gain-bandwidth product of the opamp and is reduced as the gain is increased. The
input of the PGA operates from rail to rail, but the maximum input swing (difference between Vin
and Vref) is limited to VDDA/Gain. The output of the PGA is class A, and is rail to rail for
sufficiently high load resistance.
The PGA is used when an input signal has insufficient amplitude. A PGA can be put in front of a
comparator, ADC, or mixer to increase the amplitude of the signal to these components. The
PGA can be used as a unity gain amplifier to buffer the inputs of lower impedance blocks,
including Mixers or inverting PGAs. A unity gain PGA can also be used to buffer the output of a
VDAC or reference.
Input/Output Connections
This section describes the various input and output connections for the PGA. An asterisk (*) in
the list of I/Os indicates that the I/O may be hidden on the symbol under the conditions listed in
the description of that I/O.
Vin – Analog
Vin is the input signal terminal.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-80699 Rev. **
Revised June 20, 2012
Programmable Gain Amplifier (PGA)
®
PSoC Creator™ Component Datasheet
Vref – Analog *
Vref is the input terminal for a reference signal.
The reference input can be connected to an external (to the component) reference or internal (to
the component) VSS (ground). When the reference is connected externally, the routing resistance
is added to the internal resistors, slightly decreasing the gain and increasing the gain tolerance.
Vout – Analog
Vout is the output voltage signal terminal. Vout is a function of (Vin – Vref) times the specified
Gain:
Vout = Vref + (Vin – Vref) × Gain
Component Parameters
Drag a PGA component onto your design and double-click it to open the Configure dialog.
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Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
Gain
This parameter sets the initial gain of the PGA. You can select the gain from the following set of
allowed values: 1 (default), 2, 4, 8, 16, 24, 32, 48, and 50.
The following table shows the gain selection using Internal Resisters Ra and Rb
Gain
Rb
Ra
1
0
40k
2
40k
40k
4
120k
40k
8
280k
40k
16
600k
40k
24
460k
40k
32
620k
20k
48
470k
10k
50
490k
10k
Power
This parameter sets the initial drive power of the PGA. The power determines how fast the PGA
reacts to changes in the input signal. There are four power settings: Minimum Power, Low
Power (default), Medium Power, and High Power. A Minimum Power setting results in the
slowest response time and a High Power setting results in the fastest response time.
Vref_Input
This parameter is used to select the input voltage reference. The options include:


Internal Vss – A ground signal internal to the component provides the amplifier reference.
External (default) – A signal on the Vref terminal provides the amplifier reference.
The symbol displayed in PSoC Creator changes depending on the reference input selected.
Document Number: 001-80699 Rev. **
Page 3 of 17
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Programmable Gain Amplifier (PGA)
PSoC Creator™ Component Datasheet
Figure 1. PGA Configurations
Application Programming Interface
Application Programming Interface (API) routines allow you to configure the component using
software. The following table lists and describes the interface to each function. The subsequent
sections cover each function in more detail.
By default, PSoC Creator assigns the instance name “PGA_1” 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
“PGA.”
Function
Description
PGA_Start()
Starts the PGA
PGA_Stop()
Powers down the PGA
PGA_SetGain()
Sets gain to predefined constants
PGA_SetPower()
Sets drive power to one of four settings
PGA_Sleep()
Stops and saves the user configurations
PGA_Wakeup()
Restores and enables the user configurations
PGA_Init()
Initializes or restores default PGA configuration
PGA_Enable()
Enables the PGA
PGA_SaveConfig()
Empty function. Provided for future use.
PGA_RestoreConfig()
Empty function. Provided for future use.
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Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
Global Variables
Variable
PGA_initVar
Description
Indicates whether the PGA has been initialized. The variable is initialized to 0 and set to 1 the
first time PGA_Start() is called. This allows the component to restart without reinitialization after
the first call to the PGA_Start() routine.
If reinitialization of the component is required, then the PGA_Init() function can be called before
the PGA_Start() or PGA_Enable() function.
void PGA_Start(void)
Description:
This is the preferred method to begin component operation. This function turns on the
amplifier with the power and gain based on the settings provided during the configuration or
the current values after PGA_Stop() has been called.
Parameters:
None
Return Value:
None
Side Effects:
None
void PGA_Stop(void)
Description:
This function turns off PGA and enables its lowest power state.
Note This API is not recommended for use on PSoC 5 silicon. This device has 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 PGA_Start()) at all times. Do not call the PGA_Stop() APIs.
Parameters:
None
Return Value:
None
Side Effects:
None. Does not affect power or gain settings.
Document Number: 001-80699 Rev. **
Page 5 of 17
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Programmable Gain Amplifier (PGA)
PSoC Creator™ Component Datasheet
void PGA_SetPower(uint8 power)
Description:
This function sets the drive power to one of four settings; minimum, low, medium, or high.
Parameters:
uint8 power: See the following table for valid power settings.
Power Setting
Notes
PGA_MINPOWER
Minimum active power and slowest reaction time
PGA_LOWPOWER
Low power and speed
PGA_MEDPOWER
Medium power and speed
PGA_HIGHPOWER
Highest active power and fastest reaction time
Return Value:
None
Side Effects:
None
void PGA_SetGain(uint8 gain)
Description:
This function sets the amplifier gain to a value between 1 and 50.
Parameters:
uint8 gain: See the following table for valid gain settings.
Gain Setting
PGA_GAIN_01
Gain = 1
PGA_GAIN_02
Gain = 2
PGA_GAIN_04
Gain = 4
PGA_GAIN_08
Gain = 8
PGA_GAIN_16
Gain = 16
PGA_GAIN_24
Gain = 24
PGA_GAIN_32
Gain = 32
PGA_GAIN_48
Gain = 48
PGA_GAIN_50
Gain = 50
Return Value:
None
Side Effects:
None
Page 6 of 17
Notes
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
void PGA_Sleep(void)
Description:
This is the preferred API to prepare the component for sleep. The PGA_Sleep() API saves
the current component state. Then it calls the PGA_Stop() function and calls
PGA_SaveConfig() to save the hardware configuration.
Call the PGA_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:
None
void PGA_Wakeup(void)
Description:
This is the preferred API to restore the component to the state when PGA_Sleep() was
called. The PGA_Wakeup() function calls the PGA_RestoreConfig() function to restore the
configuration. If the component was enabled before the PGA_Sleep() function was called,
the PGA_Wakeup() function will also re-enable the component.
Parameters:
None
Return Value:
None
Side Effects:
Calling the PGA_Wakeup() function without first calling the PGA_Sleep() or
PGA_SaveConfig() function may produce unexpected behavior.
void PGA_Init(void)
Description:
This function initializes or restores the component according to the customizer Configure
dialog settings. It is not necessary to call PGA_Init() because the PGA_Start() API 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 PGA_Enable(void)
Description:
This function activates the hardware and begins component operation. It is not necessary to
call PGA_Enable() because the PGA_Start() API calls this function, which is the preferred
method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
None
Document Number: 001-80699 Rev. **
Page 7 of 17
Programmable Gain Amplifier (PGA)
®
PSoC Creator™ Component Datasheet
void PGA_SaveConfig(void)
Description:
Empty function. Provided for future use.
Parameters:
None
Return Value:
None
Side Effects:
None
void PGA_RestoreConfig(void)
Description:
Empty function. Provided for future use.
Parameters:
None
Return Value:
None
Side Effects:
None
Sample Firmware Source Code
PSoC Creator provides many 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 PGA is constructed from a generic SC/CT block. You can find details about this block in the
applicable device datasheet and TRM, available on the Cypress website. The gain is selected by
adjusting two resistors, Ra and Rb (see Figure 2. PGA Schematic). Ra may be set to either 10
kΩ, 20 kΩ, or 40 kΩ. Rb is set between 0 kΩ and 1000 kΩ to generate the gain values selectable
in either the parameter dialog or the PGA_SetGain() function.
The block has a programmable capacitor in parallel with the feedback resistor, Rb. The value of
the capacitor is configured for each gain selection to achieve guaranteed stability. Reassigning
Rb values without also selecting the appropriate feedback capacitor value can result in PGA
instability. Cypress strongly recommends that you use the provided APIs for gain changes.
Page 8 of 17
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
Figure 2. PGA Schematic
Vin
Vout
Vref
Ra
Rb
The bandwidth of the PGA is determined by gain and power setting. Because of compensation
capacitor and stability requirements, the bandwidth is somewhat reduced from the absolute
maximum expected from the opamp's open loop gain-bandwidth.
Registers
The PGA component configuration is implemented in registers SC[0..3]_CR0, SC[0..3]_CR1,
and SC[0..3]_CR2. These can be accessed in your code by referring to the instantiated
component name, for example, PGA_1_CR0_REG. You can review the register contents in the
PSoC Creator component debug window. See the applicable TRM, available on the Cypress
website, for a detailed description of each register. The following registers are displayed in the
PGA component debug window.
Register:
PGA_1_CR0_REG
Name:
Switched Capacitor Control Register 0
Description:
Register bits 3:1 configure the switch capacitor block operating mode. This field is set to 110b
for the PGA component.
Register:
PGA_1_CR1_REG
Name:
Switched Capacitor Control Register 1
Description:
Register fields configure drive mode, compensation capacitor values, and gain setting of the
switch capacitor block.
Register:
PGA_1_CR2_REG
Name:
Switched Capacitor Control Register 2
Description:
Register fields configure the input impedance, feedback impedance, and the reference ground
selection for the switch capacitor block.
Register:
PGA_1_PM_ACT_CFG_REG
Name:
Active Power Mode Configuration Register 9
Description:
Register bits 3:0 enable power to each of the four switch capacitor blocks.
Document Number: 001-80699 Rev. **
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Programmable Gain Amplifier (PGA)
PSoC Creator™ Component Datasheet
Resources
The PGA component uses one SC/CT analog 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
PSoC 5 (GCC)
PSoC 5LP (GCC)
Flash
SRAM
Flash
SRAM
Flash
SRAM
Bytes
Bytes
Bytes
Bytes
Bytes
Bytes
228
22
388
12
332
5
Default
DC and AC Electrical Characteristics for PSoC 3
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. Typical values are for TA =
25 °C.
DC Characteristics
Parameter
Description
Conditions
Min
Typ
Max
Units
Vssa
-
Vdda
V
Vin
Input voltage range
Power Mode = minimum
VOS
Input offset voltage
Power mode = high, gain = 1
-
-
10
mV
TCVOS
Temp. coeff. input
offset voltage,
absolute value
Power mode = high, gain = 1
-
-
±30
µV/°C
Vonl
DC output
nonlinearity
-
-
±0.01
% of
FSR
CIN
Input capacitance
-
-
7
pF
Voh
Output voltage swing
VDDA0.15
-
-
V
-
-
VSSA+
0.15
V
Gain = 1
Power mode = high,
gain = 1, Rload = 100 kΩ to VDDA / 2
Vol
Output voltage swing
Power mode = high,
gain = 1, Rload = 100 kΩ to VDDA / 2
Page 10 of 17
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Parameter
Programmable Gain Amplifier (PGA)
Description
Min
Typ
Max
Units
-
-
300
mV
G = 1, Vref internally connected to VSS
–
0.01
0.15
+/-%
G = 2, Vref internally connected to VSS
–
0.1
1.0
Ge4
G = 4, Vref internally connected to VSS
–
0.5
1.35
Ge8
G = 8, Vref internally connected to VSS
–
0.6
1.6
Ge16
G = 16, Vref internally connected to VSS
–
0.7
2.5
Ge32
G = 32, Vref internally connected to VSS
–
0.85
5.0
Ge50
G = 50, Vref internally connected to VSS
–
2.1
5.0
G = 1, Vref internally connected to VSS
N/A
1.2
2.5
G = 2, Vref internally connected to VSS
–
8.6
20
Gd4
G = 4, Vref internally connected to VSS
–
13
29
Gd8
G = 8, Vref internally connected to VSS
–
15
35
Gd16
G = 16, Vref internally connected to VSS
–
18
40
Gd32
G = 32, Vref internally connected to VSS
–
38
75
Gd50
G = 50, Vref internally connected to VSS
–
167
400
48
-
-
–
1.5
1.65
Vsrc
Conditions
Iload = 250 μA, Vdda ≥
Output voltage under
load
Ge1
2.7V, power mode = high
Gain accuracy,
deviation from
nominal
Ge2
Gd1
Gain change versus
temperature
Gd2
PSSR
Power supply
rejection ratio
IDD
Operating current
Power mode = high
ppm/°C
dB
mA
Figures
Histogram Input Offset Voltage
18
Occurance
16
14
12
10
8
6
4
2
6.0
4.0
2.0
0.0
-2.0
-4.0
-6.0
0
Vos mV
Document Number: 001-80699 Rev. **
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Programmable Gain Amplifier (PGA)
PSoC Creator™ Component Datasheet
AC Characteristics
Conditions
Min
Typ
Ma
x
Units
Power mode = high,
gain = 1, input = 100 mV
6.7
8
-
MHz
20 - 80%, Gain = 1, P = High
3.0
4.8
N/A
V/µs
SR_G16
20 - 80%, Gain = 16, P = High
0.5
0.8
7
N/A
V/µs
SR_G50
20 - 80%, Gain = 50, P = High
0.2
5
0.8
4
N/A
V/µs
-
43
-
nV/sqrtH
z
Parameter
Description
BW1
-3dB Bandwidth
peak-to-peak
SR_G1
Slew rate
en
Input noise
density
f = 100 kHz, P = High , Vdda = 5V
Figures
Bandwidth versus Temperature, at Different Gain Settings,
Power = High
1000
10
nV/rtHz
Gain = 1
BW, MHz
Voltage noise, VDDA = 5.0V, Power = High
Gain = 24
1
100
Gain = 48
0.1
-40
-20
0
20
40
Temperature, °C
Page 12 of 17
60
80
10
0.01
0.1
1
kHz
10
100
1000
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
DC and AC Electrical Characteristics for PSoC 5
Specifications are valid for –40 °C ≤ TA ≤ 85 °C and TJ ≤ 100 °C, except where noted.
Specifications are valid for 2.7 V to 5.5 V, except where noted. Typical values are for TA = 25 °C.
DC Characteristics
Parameter
Description
Conditions
Min
Typ
Max
Unit
s
VSSA
–
VDDA
V
Vin
Input voltage
range
Power mode =
minimum
VOS
Input offset voltage
Power mode = high,
gain = 1
–
–
20
mV
TCVOS
Input offset voltage
drift with
temperature
Power mode = high,
gain = 1
–
–
±30
µV/°
C
Ge1
Gain error, gain =
1
–
–
±2
%
Ge16
Gain error, gain =
16
–
–
±8
%
Ge50
Gain error, gain =
50
–
–
±10
%
VONL
DC output
nonlinearity
–
–
±0.1
%of
FSR
CIN
Input capacitance
–
–
7
pF
VOH
Output swing
Power mode = high,
gain = 1, RLOAD = 100
kΩ to VDDA/2
VDDA –
0.15
–
–
V
VOL
Output swing
Power mode = high,
gain = 1, RLOAD = 100
kΩ to VDDA/2
–
–
VSSA +
0.15
V
VSRC
Output voltage
under load
–
–
300
mV
IDDA
Operating current
–
1.5
1.65
mA
PSRR
Power supply
rejection ratio
48
–
–
dB
Gain =1
ILOAD = 250 μA,
power mode = high
Power mode = high
Figures
PGA Voffset Histogram, 4096 samples/1024 parts
Document Number: 001-80699 Rev. **
Page 13 of 17
Programmable Gain Amplifier (PGA)
Page 14 of 17
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PSoC Creator™ Component Datasheet
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Programmable Gain Amplifier (PGA)
AC Characteristics
Parameter
Description
Conditions
BW1
–3 dB bandwidth
Power mode = high, gain = 1,
noninverting mode, 300 mV ≤ VIN ≤
VDDA – 1.2 V, CL ≤ 25 pF
SR1
Slew rate
Power mode = high, gain = 1, 20% to
80%
en
Input noise density Power mode = high, VDDA = 5 V at
100 kHz
Min
Typ
Max
Units
6
8
–
MHz
3.0
–
–
V/µs
–
43
nV/sqrtHz
Figures
Bandwidth versus Temperature, Gain = 1, Power
Mode = High
Noise versus Frequency, VDDA = 5 V, Power Mode =
High
1000
nV/rtHz
100
10
0.01
Document Number: 001-80699 Rev. **
0.1
1
kHz
10
100
1000
Page 15 of 17
Programmable Gain Amplifier (PGA)
®
PSoC Creator™ Component Datasheet
Component Changes
This section lists the major changes in the component from the previous version.
Version
1.90
Description of Changes
Reason for Changes / Impact
For low voltage VDDA operation
Reduces the number of analog clocks required in the system for
uses a boost clock shared by all the boost clocks. With this change a single boost clock is shared
SC/CT based components.
instead of using a separate clock for each SC/CT based
component.
Added PSoC 5LP support
1.80
Changed resistor combination for
Gain = 24
Resistor values were incorrect
Added all component APIs with the
CYREENTRANT keyword
Minor GUI updates
Added DC and AC Electrical
characteristics data for PSoC 5
1.70.a
Changed PGA_Stop() API for
PSoC 5
Change required to prevent the component from impacting
unrelated analog signals when stopped, when using PSoC 5.
1.70
Updated PGA response graph
Change required to dynamically resize graph to fit window and to
add horizontal and vertical grids.
Removed VDDA parameter from
component customizer
VDDA setting in the component is redundant and unnecessary for
multiple components. The parameter was removed and the
component queries the global setting for minimum VDDA in the
DWR and automatically enables the pump when necessary.
Created configuration window to
include frequency response graphs
for an easier to use GUI.
Previous configuration window did not provide enough information
for ease of use.
Corrected SetGain constants in the
header file
The constants provided for the SetGain API had incorrect values.
These have been corrected.
1.60
Added characterization data to
datasheet
Minor datasheet edits and updates
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.
Removed Gain setting of 25.
The gain of 25 was too close to other values and therefore offered
no value.
Updated the symbol image and
These were updated to comply with corporate standards.
Page 16 of 17
Document Number: 001-80699 Rev. **
®
PSoC Creator™ Component Datasheet
Version
Description of Changes
Programmable Gain Amplifier (PGA)
Reason for Changes / Impact
Configure dialog.
Changed the names of the registers Updated to comply with coding guidelines.
by adding "_REG."
Added specification table and
graphic placeholders
Data to be provided when characterization is complete.
© Cypress Semiconductor Corporation, 2012. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used
for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for
use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in lifesupport systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
PSoC® is a registered trademark, and PSoC Creator™ and Programmable System-on-Chip™ are trademarks of Cypress Semiconductor Corp. All other trademarks or registered trademarks
referenced herein are property of the respective corporations.
Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide patent protection (United States and
foreign), United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license to copy, use, modify, create
derivative works of, and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in
conjunction with a Cypress integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source Code except as
specified above is prohibited without the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein.
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
implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
Document Number: 001-80699 Rev. **
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