STM32H5 OPAMP
Presentation of the STM32H5 embedded operational amplifier, covering its features for conditioning analog signals.
Features
- 1x OPAMP in STM32H503
- PGA gain 2,4,8,16
- Offset calibration
- High speed mode
The STM32H503 integrates one OPAMP module, which is not present in the STM32H573. This general-purpose analog amplifier reduces the need for an external OPAMP. It can be configured in stand-alone mode with all terminals available for the user, enabling its use as a voltage follower, non-inverting and inverting amplifiers, and analog filters (low- or high-pass). It can also serve as a pre-amplifier for the ADC input.
The table below shows performance parameters for the STM32H5's OPAMP:
| SYMBOL | Parameter | Typical | Unit |
|---|---|---|---|
| VDDA | Analog supply voltage | 2.0~3.6 | V |
| CMIR | Common mode input range | 0~VDDA | V |
| Vos | Offset voltage | 2.5 (max) | mV |
| Gain bandwidth (GBW) | Normal mode | 7.3 | MHz |
| SlewRate | High speed mode | 24 | V/μs |
| Normal mode | 3 | V/μs | |
| Low power mode | 0.25 | V/μs | |
| Output Current | Normal mode | 500 | μA |
| Power supply rejection Ratio (PSRR) | Normal mode | 66 | dB |
| WakeUp Time | Normal mode | 3.2 (max) | μs |
| High Speed mode | 2.8 (max) | μs |
The gain bandwidth is 7.3 MHz typical. The OPAMP module present in the STM32H503 supports a high speed mode, activated by a control bit, which improves slew rate characteristics. Using an internal feedback resistor, the OPAMP can function as a Programmable Gain Amplifier (PGA). A spice simulation model is available upon demand for PCB design.
OPAMP Input/Output Configuration
The table below shows the internal and external connections for the OPAMP inputs and outputs:
| OPAMP | VINPx | VINMx | VOUTx | |||
|---|---|---|---|---|---|---|
| External | Internal | External | Internal | External | Internal | |
| OPAMP1 | PA0, PB0 | dac1_out1 | PC5, PB1 | PGA feedback | PA7 | ADC1_IN7 |
The OPAMP module has two inputs (inverting and non-inverting) and one output. The non-inverting inputs can connect to a GPIO pad or internally to a DAC output. The inverting input is used for feedback in PGA mode or can connect to a GPIO pad. The output connects to a GPIO pad and then to an ADC input.
Related Presentations
In addition to this presentation, refer to the following for peripherals connected to the STM32H5's operational amplifiers:
- Analog-to-digital converter (ADC) and Digital-to-analog converter (DAC).
- General purpose input output (GPIO).
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