Inverting Amplifier Datasheet AMPINV V 4.3
001-13255 Rev. *H
Inverting Amplifier
Copyright © 2002-2015 Cypress Semiconductor Corporation. All Rights Reserved.
PSoC® Blocks
Resources
Digital
Analog CT
API Memory (Bytes)
Analog SC
Flash
RAM
Pins (per
External I/O)
CY8C29/27/24/23/22xxx, CY8CLED04/08/16, CY8CLED0xD, CY8CLED0xG, CY8CTST120, CY8CTMG120,
CY8CTMA120, CY8C28x45, CY8CPLC20, CY8CLED16P01, CY8C28x43, CY8C28x52
0
1
0
64
0
1
For one or more fully configured, functional example projects that use this user module go to
www.cypress.com/psocexampleprojects.
Features and Overview
18 user-programmable gain options with a maximum gain of -47.0 for the
CY8C29/27/24/23/22xxxdevice family
16 user-programmable gain options with a maximum gain of -15.0 for the CY8C26/25xxxdevice family
Single-ended output referenced to analog ground
The AMPINV User Module implements a single opamp inverting amplifier. The gain, source and output
enable are set by the user from tables of values in the Device Editor.
Figure 1.
AMPINV Block Diagram
Cypress Semiconductor Corporation
Document Number: 001-13255 Rev. *H
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San Jose, CA 95134-1709
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Revised March 12, 2015
Inverting Amplifier
Functional Description
The AMPINV User Module amplifies an internal signal referenced to the analog ground. The gain of the
inverting amplifier is set by programming the selectable resistor array tap in a continuous time analog
PSoC block. The gain, input, and analog output bus connection are set by the user from tables of values in
the Device Editor. The amplifier has the following transfer function:
Equation 1
In Equation 1, VAGND is the user selected analog ground, typically 2*VBandGap or Vdd/2. Vss cannot be
used as analog ground, as input and output voltages are limited to values above Vss. The input and output
voltage ranges of the amplifier do not extend to the power supplies (that is, they are not "rail-to-rail"
opamps). The allowed input range is a combination of input limit, output limit, power supply voltage, and
selected gain. This is illustrated in the DC and AC Electrical Characteristics section of this user module.
The user selects the Gain (the value for -Rb/Ra) from the values in the Device Editor. The Device Editor
then programs appropriate resistor taps in the PSoC block. API routines are provided for Start, Stop,
SetPower, and SetGain functions.
DC and AC Electrical Characteristics
The following values are indicative of expected performance and based on initial characterization data.
Unless otherwise specified in the tables following, TA = 25°C, Vdd= 5.0V, Power HIGH, Op-Amp Bias
LOW, output referenced to Analog Ground = 2*VBandGap.
Table 1.
5.0V AMPINV DC Electrical Characteristics, CY8C29/27/24/23/22xxx Family of PSoC Devices
Parameter
Typical
Limit
Units
Conditions and Notes
Gain
Deviation from Nominal at G=-47
9.0
--
%
Deviation from Nominal at G=-23
4.8
--
%
Deviation from Nominal at G=-15
3.8
--
%
Deviation from Nominal at G=-4.33
1.1
--
%
Deviation from Nominal at G=-1
0.3
--
%
7.8
--
mV
--
Vss to Vdd
V
Leakage1
1
--
nA
Input Capacitance1
3
--
pF
Output Swing
0.05 to Vdd-0.05
--
V
PSRR
60
--
dB
Input
Input Offset Voltage
Input Voltage Range
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Inverting Amplifier
Parameter
Typical
Limit
Units
Conditions and Notes
Operating Current
Low Power
141
--
µA
Med Power
535
--
µA
High Power
2062
--
µA
Table 2.
5.0V AMPINV AC Electrical Characteristics, CY8C29/27/24/23/22xxxFamily of PSoC Devices
Typical4
Parameter
Limit4
Units
Conditions and Notes
Slew Rate (20% to 80%) 2
Low Power
0.4
V/µs
Med Power
1.5
V/µs
High Power
6.0
V/µs
Low Power
10.6
µs
Med Power
3.4
µs
High Power
3.2
µs
Gain=-1.00, 2.0V step at input
Settling Time2
To 0.1%, Gain = -1.00
Referred to input
Noise2
Low Power
250
Med Power
79
nV/√Hz OpAmp bias low except at
High Power.
nV/√Hz
High Power
70
nV/√Hz
The following values are indicative of expected performance and based on initial characterization data.
Unless otherwise specified in the following tables, TA = 25°C, Vdd = 3.3V, Power HIGH, Op-Amp Bias
LOW, output referenced to Analog Ground = Vdd/2.
Table 3.
3.3V AMPINV DC Electrical Characteristics, CY8C29/27/24/23/22xxxFamily of PSoC Devices
Parameter
Typical
Limit
Units
Conditions and Notes
Gain
Deviation from Nominal at G=-47
10.3
--
%
Deviation from Nominal at G=-23
5.4
--
%
Deviation from Nominal at G=-15
4.0
--
%
Deviation from Nominal at G=-4.33
1.3
--
%
Deviation from Nominal at G=-1
0.2
--
%
Input
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Inverting Amplifier
Parameter
Input Offset Voltage
Typical
Limit
Units
6.9
--
mV
--
Vss to Vdd
V
Leakage1
1
--
nA
Input Capacitance1
3
--
pF
Output Swing
0.05 to Vdd-0.05
--
V
PSRR
60
--
dB
Low Power
136
--
µA
Med Power
519
--
µA
High Power
1986
--
µA
Input Voltage Range
Conditions and Notes
Operating Current
Table 4.
3.3V AMPINV AC Electrical Characteristics, CY8C29/27/24/23/22xxxFamily of PSoC Devices
Typical4
Parameter
Limit4
Units
Conditions and Notes
Slew Rate (20% to 80%) 2
Low Power
0.4
V/µs
Med Power
1.4
V/µs
High Power
5.7
V/µs
Low Power
10.1
µs
Med Power
3.3
µs
High Power
3.0
µs
Gain=-1.00, 2.0V step at input
Settling Time2
To 0.1%, Gain = -1.00
Referred to input
Noise2
Low Power
250
Med Power
79
nV/√Hz OpAmp bias low except at
High Power.
nV/√Hz
High Power
70
nV/√Hz
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Inverting Amplifier
Note
Electrical Characteristics Notes
1. To provide a direct comparison with other user modules, these specifications Include I/O pin measurements. In practice, however, the input connects only to other PSoC blocks, and not directly to the
device pins.
2. Based on device simulation.
3. PSRR typical value is for input signal referenced to analog ground.
4. PSRR limit value is for input signal referenced to Vss, where VAGND error algebraically adds to input
offset voltage.
5. Output swing is for internal signals. External output swing (at pins) is limited by analog output buffer.
6. AC specifications are for internal signals. Slew rate and settling time (at pins) are limited by analog output buffer.
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Inverting Amplifier
Figure 2.
AMPINV Typical Gain Deviation from Nominal
Figure 3.
AMPINV Vin Range at Vcc = 5V
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Inverting Amplifier
Figure 4.
AMPINV Vin Range at Vcc = 3.3V
Power supply rejection is determined by variation in the analog ground reference. At low gains, the ground
variation adds as a fixed offset and may be larger than the input signal.
Figure 5.
AMPINV Power Supply Rejection Ratio
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Inverting Amplifier
Placement
The AMPINV maps freely onto any of the continuous time PSoC blocks in the device. However, if the
AnalogBus output is enabled onto the bus, ensure that no other user module tries to drive the same bus.
Parameters and Resources
Gain
The Gain is selected from values ranging from -0.067 to -47.00, using PSoC Designer or the SetGain
routine provided in the API. Gain accuracy is dependent on gain value and power level. High power
offers the greatest accuracy at high gain values.
Input
The inputs to the inverting amplifier are driven only by the outputs of adjacent PSoC blocks. When
selecting the input, it is important to know the input-signal integrity with respect to the source and
sampling clock. The input from a switched capacitor analog block is connected to the non-sampled
and held output of the source. When the source is a DAC User Module, this signal is auto-zero and
valid only during one phase of the analog clock. When the source is a Filter User Module, the signal
is not auto-zero and valid all of the time. You can select the specific input in the Device Editor.
Reference
The gain of the AMPINV is referenced to the analog ground selected in the global resources window.
Choices include 2*VBandGap, Vdd/2, and the voltage applied on Port 2[4]. Vss cannot be used because
the input and output voltage ranges do not include the range below ground.
AnalogBus
The output may be routed through the analog PSoC block array’s network of local interconnections
and/or through an analog output bus. Setting the AMPINV User Module AnalogBus parameter to
Disable, the default value, restricts the set of possible connections to the local network. Choosing
Enable extends the set of possible connections to an associated analog output buffer that can drive
a pin and to some additional input multiplexers not afforded by the local network.
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Inverting Amplifier
Application Programming Interface
The Application Programming Interface (API) routines are provided as part of the user module to allow the
designer to deal with the module at a higher level. This section specifies the interface to each function
together with related constants provided by the “include" files.
Note
In this, as in all user module APIs, the values of the A and X register may be altered by calling an API
function. It is the responsibility of the calling function to preserve the values of A and X before the call if
those values are required after the call. This “registers are volatile" policy was selected for efficiency
reasons and has been in force since version 1.0 of PSoC Designer. The C compiler automatically takes
care of this requirement. Assembly language programmers must ensure their code observes the policy,
too. Though some user module API function may leave A and X unchanged, there is no guarantee they
may do so in the future.
For Large Memory Model devices, it is also the caller's responsibility to perserve any value in the
CUR_PP, IDX_PP, MVR_PP, and MVW_PP registers. Even though some of these registers may not be
modified now, there is no guarantee that will remain the case in future releases.
The following are the API programming routines provided for the AMPINV User Module.
AMPINV_Start
Description:
Performs all required initialization for this user module and sets the power level for the continuous time
PSoC block. The user module output is driven.
C Prototype:
void
AMPINV_Start(BYTE bPowerSetting)
Assembler:
mov
A, bPowerSetting
lcall AMPINV_Start
Parameters:
bPowerSetting: One byte that specifies the power level to the analog PSoC block. Following reset and
configuration, the PSoC block assigned to the instrumentation amplifier is powered down. Symbolic
names provided in C and assembly, and their associated values, are listed in the following table:
Symbolic Name
Value
AMPINV_OFF
0
AMPINV_LOWPOWER
1
AMPINV_MEDPOWER
2
AMPINV_HIGHPOWER
3
Return Value:
None
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Inverting Amplifier
Side Effects:
The A and X registers may be altered by this function.
AMPINV_SetPower
Description:
Sets the power level for the continuous time PSoC blocks. May be used to turn the blocks off and on.
When the power level is set for any power except off, the output is driven.
C Prototype:
void
AMPINV_Start(BYTE bPowerSetting)
Assembler:
mov
bPowerSetting
lcall AMPINV_SetPower
Parameters:
bPowerSetting: Same as the bPowerSetting used for the Start entry point.
Return Value:
None
Side Effects:
The A and X registers may be altered by this function.
AMPINV_SetGain
Description:
Sets the gain for the continuous time PSoC block.
C Prototype:
void
AMPINV_SetGain(BYTE bGain)
Assembler:
mov
A, bGain
lcall AMPINV_SetGain
Parameters:
bGain: Symbolic names provided in C and assembly, and their associated values are given in the
following table. Programmed gain of -15.0 uses declared name of ....G15_0.
Table 5.
CY8C29/27/24/23/22xxx Gain Parameters
Symbolic Name
Value
Symbolic Name
Value
AMPINV_G47_0
04h
AMPINV_G1_00
70h
AMPINV_G23_0
14h
AMPINV_G0_78
80h
AMPINV_G15_0
00h
AMPINV_G0_60
90h
AMPINV_G7_00
10h
AMPINV_G0_46
A0h
AMPINV_G4_33
20h
AMPINV_G0_33
B0h
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Inverting Amplifier
Symbolic Name
Value
Symbolic Name
Value
AMPINV_G3_00
30h
AMPINV_G0_23
C0h
AMPINV_G2_20
40h
AMPINV_G0_14
D0h
AMPINV_G1_67
50h
AMPINV_G0_06
E0h
AMPINV_G1_27
60h
Return Value:
None
Side Effects:
In the CY8C29/27/24/23/22xxxfamily of PSoC devices, there may be a gain glitch while changing
between a low gain setting (less than 23) and a high gain setting (23 or 47). This glitch should be less
than 1usec when the CPU clock is set to 12 MHz. The A and X registers may be altered by this function.
AMPINV_Stop
Description:
Powers the user module off.
C Prototype:
void
AMPINV_Stop(void)
Assembler:
lcall
AMPINV_Stop
Parameters:
None
Return Value:
None
Side Effects:
The A and X registers may be altered by this function.
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Inverting Amplifier
Sample Firmware Source Code
The sample code initializes and starts an amplifier with the gain fixed to -7.00, over-riding the gain value
set in the PSoC Designer configuration screen.
;;----------------------------------------------------------------;;Sample Code for the AMPINV.
;; Turn on power and set gain to -7.00.
;;----------------------------------------------------------------include "m8c.inc"
include "memory.inc"
include "PSoCAPI.inc"
; part specific constants and macros
; Constants & macros for SMM/LMM and Compiler
; PSoC API definitions for all User Modules
export _main
_main:
mov A, AMPINV_G7_00
; Specify amplifier gain
call AMPINV_SetGain
; Set amplifier gain
mov A, AMPINV_HIGHPOWER ; Specify amplifier power level
call AMPINV_Start
; Start the amplifier operation
.terminate:
jmp .terminate
; Repeat in this loop forever
The following C sample code has the same functionality as the assembly code:
//-----------------------------------------------------------------------// This sample C code sets and Inverting Amplifier user module's gain to
// -7.00 and then starts the user module operation.
//-----------------------------------------------------------------------#include <m8c.h>
#include "PSoCAPI.h"
// part specific constants and macros
// PSoC API definitions for all User Modules
void main(void)
{
AMPINV_SetGain(AMPINV_G7_00);// Set AMPINV gain at -7.00
AMPINV_Start(AMPINV_HIGHPOWER);// Start AMPINV in HIGH power mode
while(1);// Repeat forever
}
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Inverting Amplifier
Configuration Registers
The topology of inverting amplifier user module sets most of the bits in the configuration registers for the
chosen Analog CT PSOC block. These include values for opamp compensation, comparator mode, and
feedback connection.
Table 6.
INVAMP PSoC Block Registers for the CY8C29/27/24/23/22xxxFamily of PSoC Devices
Register
7
6
5
4
CR0
Gain
CR1
AnalogBus 0
1
0
CR2
0
0
1
CR3
0
0
0
3
2
1
1
Input
0
0
1
0
0
0
Power
0
0
0
0
0
1
EXGAIN
Gain sets the gain value per selection. Reference sets the reference point (effective "ground") for gain.
Input is established by the selection of a value for the Input parameter in the device editor.
AnalogBus determines whether the GAIN PSoC block drives the bus. The value of this bit-field is
determined by the choice made for the parameter of the same name in user module Interconnect View of
the Device Editor. Input is the value selected in PSoC Designer.
Power is set to ‘Off’ following device reset and configuration. It is modified by calling Start, SetPower, or
Stop entry points in the API.
The EXGAIN bit is automatically set whenever a gain of -23 or -47 is selected.
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Inverting Amplifier
Version History
Version Originator
4.3
Note
DHA
Description
Added Version History
PSoC Designer 5.1 introduces a Version History in all user module datasheets. This section documents high level descriptions of the differences between the current and previous user module versions.
Document Number: 001-13255 Rev. *H
Revised March 12, 2015
Page 14 of 14
Copyright © 2002-2015 Cypress Semiconductor Corporation. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility
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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 life-support 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.