OPAMP - Operational Amplifier#
Operational Amplifier (OPAMP) peripheral API.
This module contains functions to:
OPAMP_Enable() Configure and enable OPAMP.
OPAMP_Disable() Disable OPAMP.
All OPAMP functions assume that the DAC clock is running. If DAC is not used, the clock can be turned off when OPAMPs are configured.
If the available gain values don't suit the application at hand, the resistor ladders can be disabled and external gain programming resistors used.
A number of predefined OPAMP setup macros are available for configuration of the most common OPAMP topologies (see figures below).
Note
The terms POSPAD and NEGPAD in the figures are used to indicate that these pads should be connected to a suitable signal ground.
Unity gain voltage follower.
Use predefined macros OPA_INIT_UNITY_GAIN and OPA_INIT_UNITY_GAIN_OPA2.
|\
___________|+\
| \_______
___|_ / |
| | / |
| |/ |
|___________|
Non-inverting amplifier.
Use predefined macros OPA_INIT_NON_INVERTING and OPA_INIT_NON_INVERTING_OPA2.
|\
___________|+\
| \_______
___|_ / |
| | / |
| |/ |
|_____R2____|
|
R1
|
NEGPAD
Inverting amplifier.
Use predefined macros OPA_INIT_INVERTING and OPA_INIT_INVERTING_OPA2.
_____R2____
| |
| |\ |
____R1_|___|_\ |
| \____|___
___| /
| |+/
| |/
|
POSPAD
Cascaded non-inverting amplifiers.
Use predefined macros OPA_INIT_CASCADED_NON_INVERTING_OPA0, OPA_INIT_CASCADED_NON_INVERTING_OPA1 and OPA_INIT_CASCADED_NON_INVERTING_OPA2.
|\ |\ |\
___________|+\ OPA0 ___________|+\ OPA1 ___________|+\ OPA2
| \_________| | \_________| | \_______
___|_ / | ___|_ / | ___|_ / |
| | / | | | / | | | / |
| |/ | | |/ | | |/ |
|_____R2____| |_____R2____| |_____R2____|
| | |
R1 R1 R1
| | |
NEGPAD NEGPAD NEGPAD
Cascaded inverting amplifiers.
Use predefined macros OPA_INIT_CASCADED_INVERTING_OPA0, OPA_INIT_CASCADED_INVERTING_OPA1 and OPA_INIT_CASCADED_INVERTING_OPA2.
_____R2____ _____R2____ _____R2____
| | | | | |
| |\ | | |\ | | |\ |
____R1_|___|_\ | ____R1_|___|_\ | ____R1_|___|_\ |
| \____|____| | \____|___| | \____|__
___| / ___| / ___| /
| |+/ OPA0 | |+/ OPA1 | |+/ OPA2
| |/ | |/ | |/
| | |
POSPAD POSPAD POSPAD
Differential driver with two opamp's.
Use predefined macros OPA_INIT_DIFF_DRIVER_OPA0 and OPA_INIT_DIFF_DRIVER_OPA1.
__________________________
| +
| _____R2____
|\ | | |
___________|+\ OPA0 | | |\ OPA1 |
| \_________|____R1_|___|_\ | _
___|_ / | | \____|______
| | / | ___| /
| |/ | | |+/
|________________| | |/
|
POSPAD
Differential receiver with three opamp's.
Use predefined macros OPA_INIT_DIFF_RECEIVER_OPA0, OPA_INIT_DIFF_RECEIVER_OPA1 and OPA_INIT_DIFF_RECEIVER_OPA2.
|\
__________|+\ OPA1
_ | \_________
___|_ / | | _____R2____
| | / | | | |
| |/ | | | |\ |
|___________| |____R1_|___|_\ |
| \____|___
|\ ____R1_ ___| /
+__________|+\ OPA0 | | |+/ OPA2
| \_________| | |/
___|_ / | R2
| | / | |
| |/ | NEGPAD OPA0
|___________|
Modules#
Enumerations#
OPAMP negative terminal input selection values.
OPAMP positive terminal input selection values.
OPAMP output terminal selection values.
OPAMP gain values.
OPAMP resistor ladder input selector values.
Functions#
Disable an Operational Amplifier.
Configure and enable an Operational Amplifier.
Macros#
Configuration of OPA0/1 in unity gain voltage follower mode.
Configuration of OPA2 in unity gain voltage follower mode.
Configuration of OPA0/1 in non-inverting amplifier mode.
Configuration of OPA2 in non-inverting amplifier mode.
Configuration of OPA0/1 in inverting amplifier mode.
Configuration of OPA2 in inverting amplifier mode.
Configuration of OPA0 in cascaded non-inverting amplifier mode.
Configuration of OPA1 in cascaded non-inverting amplifier mode.
Configuration of OPA2 in cascaded non-inverting amplifier mode.
Configuration of OPA0 in cascaded inverting amplifier mode.
Configuration of OPA1 in cascaded inverting amplifier mode.
Configuration of OPA2 in cascaded inverting amplifier mode.
Configuration of OPA0 in two-opamp differential driver mode.
Configuration of OPA1 in two-opamp differential driver mode.
Configuration of OPA0 in three-opamp differential receiver mode.
Configuration of OPA1 in three-opamp differential receiver mode.
Configuration of OPA2 in three-opamp differential receiver mode.
Enumeration Documentation#
OPAMP_TypeDef#
OPAMP_TypeDef
OPAMP selector values.
Enumerator | |
---|---|
OPA0 | Select OPA0. |
OPA1 | Select OPA1. |
OPA2 | Select OPA2. |
OPAMP_NegSel_TypeDef#
OPAMP_NegSel_TypeDef
OPAMP negative terminal input selection values.
Enumerator | |
---|---|
opaNegSelDisable | Input disabled. |
opaNegSelUnityGain | Unity gain feedback path. |
opaNegSelResTap | Feedback resistor ladder tap. |
opaNegSelNegPad | Negative pad as input. |
OPAMP_PosSel_TypeDef#
OPAMP_PosSel_TypeDef
OPAMP positive terminal input selection values.
Enumerator | |
---|---|
opaPosSelDisable | Input disabled. |
opaPosSelDac | DAC as input (not OPA2). |
opaPosSelPosPad | Positive pad as input. |
opaPosSelOpaIn | Input from OPAx. |
opaPosSelResTapOpa0 | Feedback resistor ladder tap from OPA0. |
OPAMP_OutMode_TypeDef#
OPAMP_OutMode_TypeDef
OPAMP output terminal selection values.
Enumerator | |
---|---|
opaOutModeDisable | OPA output disabled. |
opaOutModeMain | Main output to pin enabled. |
opaOutModeAlt | Alternate output(s) enabled (not OPA2). |
opaOutModeAll | Both main and alternate enabled (not OPA2). |
OPAMP_ResSel_TypeDef#
OPAMP_ResSel_TypeDef
OPAMP gain values.
Enumerator | |
---|---|
opaResSelDefault | Default value when resistor ladder is unused. |
opaResSelR2eq0_33R1 | R2 = 0.33 * R1. |
opaResSelR2eqR1 | R2 = R1 |
opaResSelR1eq1_67R1 | R2 = 1.67 R1 |
opaResSelR2eq2R1 | R2 = 2 * R1 |
opaResSelR2eq3R1 | R2 = 3 * R1 |
opaResSelR2eq4_33R1 | R2 = 4.33 * R1. |
opaResSelR2eq7R1 | R2 = 7 * R1 |
opaResSelR2eq15R1 | R2 = 15 * R1 |
OPAMP_ResInMux_TypeDef#
OPAMP_ResInMux_TypeDef
OPAMP resistor ladder input selector values.
Enumerator | |
---|---|
opaResInMuxDisable | Resistor ladder disabled. |
opaResInMuxOpaIn | Input from OPAx. |
opaResInMuxNegPad | Input from negative pad. |
opaResInMuxPosPad | Input from positive pad. |
opaResInMuxVss | Input connected to Vss. |
Function Documentation#
OPAMP_Disable#
void OPAMP_Disable (DAC_TypeDef * dac, OPAMP_TypeDef opa)
Disable an Operational Amplifier.
Type | Direction | Argument Name | Description |
---|---|---|---|
DAC_TypeDef * | [in] | dac | A pointer to the DAC peripheral register block. |
OPAMP_TypeDef | [in] | opa | Selects an OPA, valid values are OPA0, OPA1, and OPA2. |
OPAMP_Enable#
void OPAMP_Enable (DAC_TypeDef * dac, OPAMP_TypeDef opa, const OPAMP_Init_TypeDef * init)
Configure and enable an Operational Amplifier.
Type | Direction | Argument Name | Description |
---|---|---|---|
DAC_TypeDef * | [in] | dac | A pointer to the DAC peripheral register block. |
OPAMP_TypeDef | [in] | opa | Selects an OPA, valid values are OPA0, OPA1, and OPA2. |
const OPAMP_Init_TypeDef * | [in] | init | A pointer to a structure containing OPAMP initialization information. |
Note
The value of the alternate output enable bit mask in the OPAMP_Init_TypeDef structure should consist of one or more of the DAC_OPA[opa#]MUX_OUTPEN_OUT[output#] flags (defined in <part_name>_dac.h) OR'ed together.
For OPA0:DAC_OPA0MUX_OUTPEN_OUT0
DAC_OPA0MUX_OUTPEN_OUT1
DAC_OPA0MUX_OUTPEN_OUT2
DAC_OPA0MUX_OUTPEN_OUT3
DAC_OPA0MUX_OUTPEN_OUT4
For OPA1:
DAC_OPA1MUX_OUTPEN_OUT0
DAC_OPA1MUX_OUTPEN_OUT1
DAC_OPA1MUX_OUTPEN_OUT2
DAC_OPA1MUX_OUTPEN_OUT3
DAC_OPA1MUX_OUTPEN_OUT4
For OPA2:
DAC_OPA2MUX_OUTPEN_OUT0
DAC_OPA2MUX_OUTPEN_OUT1
E.g:
init.outPen = DAC_OPA0MUX_OUTPEN_OUT0 | DAC_OPA0MUX_OUTPEN_OUT4;