MCP6S91-E/P - SPI Programmable Gain Amplifier | Microchip
MPN: MCP6S91-E/P ✓ NakahandaMCP6S91-E/P Ulas
A programmable gain amplifier is a type of operational amplifier whose closed-loop voltage gain is set digitally rather than by a single feedback resistor. Because the gain is selected through a serial register, a PGA replaces the resistor ladder, rotary switch, or multi-amplifier chain normally required to cover a wide signal range. In the signal-chain hierarchy a PGA sits above the plain operational amplifier and below the application-level front end, and it belongs to the broader family of amplifier ICs used in analog and mixed-signal signal conditioning.
Key specifications of the MCP6S91 include a programmable gain range of +1 V/V to +32 V/V in eight steps, rail-to-rail input and output capability, and a serial peripheral interface (SPI) capable of operating at 10 MHz, which allows fast gain re-selection between measurements. Because gain is set over the serial bus rather than by analog switching, the amplifier adds no relay or switch contact noise, and the internal gain network avoids the gain-error and temperature drift problems of external resistor dividers.
Internally, the MCP6S91 combines a precision bandgap-referenced gain-setting network, a low-noise input stage, and the SPI shift register that latches the gain code. The serial port also controls a shutdown bit, letting the system place the amplifier in a low-power state when it is not actively measuring, which is valuable in battery-operated instrumentation. The 8-pin PDIP (0.300 inch / 7.62 mm body) package is a legacy-style through-hole format favored for prototyping, educational use, and industrial serviceability.
Typical applications include multichannel sensor signal conditioning, battery monitoring with programmable scaling of cell voltage, gain-programmable instrumentation amplifiers, portable medical and test equipment, and general analog front ends where one amplifier must handle signals spanning millivolts to volts.
A key design consideration is that the gain must be written over the SPI bus before the signal path is valid, so firmware must sequence gain changes and discard the settling interval after each write. Decoupling close to pins 5 and 6, and keeping the SPI clock lines away from the high-impedance input pins, are important for accurate measurements.
This page adds practical engineering context that a datasheet alone does not provide: a parameter-by-parameter comparison against pin-compatible alternatives, guidance on gain-step settling and layout, and a selection guide covering when a different PGA in the same family is the better fit.
Mga alternatibo na pwedeng ilagay na MCP6S91-E/P — parehas na package, pin-to-pin na katugmang. Hindi kasama ang mga bahagi ng iba't-ibang package na nangangailangan ng pagpapaayos ng PCB.
MCP6S92-E/P
✅ Drop-In📋 Alternatibo na Reference (hindi sa katalogo)
MCP6S93-E/P
✅ Drop-In ⚠️ Mga Talaan Hindi Naiwerikmo📋 Alternatibo na Reference (hindi sa katalogo)
MCP6S91-I/P
✅ Drop-In ⚠️ Mga Talaan Hindi Naiwerikmo📋 Alternatibo na Reference (hindi sa katalogo)
MCP6S92-I/P
✅ Drop-In ⚠️ Mga Talaan Hindi Naiwerikmo📋 Alternatibo na Reference (hindi sa katalogo)
MCP6S93-I/P
✅ Drop-In ⚠️ Mga Talaan Hindi Naiwerikmo📋 Alternatibo na Reference (hindi sa katalogo)
MCP6S91-E/P Mga Pinakamataas na Rating at Electrical Characteristics
| Amplifier Type | Programmable Gain Amplifier (PGA) |
| Number of Circuits | 1 |
| Gain Range | +1 V/V to +32 V/V |
| Interface | SPI (Serial Peripheral Interface) |
| SPI Clock Frequency | 10 MHz |
| Slew Rate | 22 V/us |
| Input Type | Rail-to-Rail |
| Type ng Output | Rail-to-Rail |
| Number of Input Channels | 2 (via input multiplexer) |
| Power-Down Control | Yes, via SPI shutdown bit |
| Hanay ng Temperature na Operasyon | -40C to +125C (E grade) |
| Packhaging | 8-DIP (0.300 in / 7.62 mm) |
| Uri ng Pagpapasok | Through Hole |
| Packaging | Tube |
Pin Configuration ng MCP6S91-E/P
| Pin 1 | CS — SPI chip select / serial interface control |
| Pin 2 | SCK — SPI serial clock input |
| Pin 3 | SDI — SPI serial data in (gain and shutdown codes) |
| Pin 4 | SDO — SPI serial data out |
| Pin 5 | VSS — Ground / negative supply |
| Pin 6 | VDD — Positive supply |
| Pin 7 | IN+ — Non-inverting signal input (channel 0) |
| Pin 8 | IN- — Inverting signal input (channel 0) |
Tipikal na mga Gamit
MCP6S91-E/P ay nararapat para sa 6 aplikasyons: Battery Cell Monitoring and Scaling, Multichannel Sensor Signal Conditioning, Programmable Gain Instrumentation Front End, Portable Medical and Diagnostic Devices, Test and Measurement Equipment, Industrial Process Control Loops.
Battery Cell Monitoring and Scaling
The MCP6S91-E/P fits battery monitoring because its +1 V/V to +32 V/V programmable gain lets a single amplifier scale a small cell-sense voltage up into the useful range of the system ADC, replacing a wide-range resistor divider and the noise it introduces. The amplifier is placed between the sense tap and the converter input, with the gain code written over SPI so the same analog path can handle a 2 V cell, a 12 V pack tap or a precision reference. Because the SPI port also carries a shutdown command, the host can park the amplifier between measurement bursts and cut standby current in a battery-powered pack. The trade-off is that the gain is only changed digitally, so each new scale factor needs a settling interval after the SPI write before the ADC sample is valid.
Inirekomenda
Multichannel Sensor Signal Conditioning
For multichannel sensor front ends, the MCP6S91-E/P combines a digitally selected gain with an input multiplexer, so a single amplifier can scale several dissimilar sensors - a thermocouple millivolt signal, a thermistor bridge and a strain-gauge output - into one common ADC range. The gain code is written over SPI at 10 MHz, so the acquisition loop can re-range between channels in microseconds rather than waiting on relays or analog switches that would add contact noise and drift. The key design consideration is the settling time after each gain write: the host should discard the first conversion after a range change and validate that the multiplexer settles before the sample is taken.
Inirekomenda
Programmable Gain Instrumentation Front End
The MCP6S91-E/P is well suited to instrumentation amplifier front ends where the input magnitude is unknown at design time - load cells, pressure transducers and bridge sensors all produce outputs that vary by orders of magnitude. The +1 V/V to +32 V/V range lets the system authorise the amplifier to normalise the signal into the 0 to 3.3 V or 0 to 5 V domain of the downstream converter, which maximises the converter's resolution without a passive attenuator. The rail-to-rail input and output capability preserves signal headroom close to the supply rails, and the SPI shutdown bit keeps the front end powered down between force readings. Designers should confirm that the input common-mode range covers the sensor's swing at the lowest gain step.
Inirekomenda
Portable Medical and Diagnostic Devices
In portable diagnostic equipment the MCP6S91-E/P gives a compact way to normalise bio-sensor outputs - pulse-oximeter photodiode signals, impedance measurements, electrochemical electrodes - whose amplitudes vary widely between patients and test conditions. The programmable gain replaces a mechanical switch or multi-gain resistor network, shrinking board area and eliminating switch-contact noise in the sensitive analog path. Because the shutdown command is a single serial bit, the device can be powered down between measurement bursts to extend battery life in handheld units. Design guidance: keep the SPI bus physically separated from the high-impedance electrode inputs, and verify the amplifier's noise performance against the smallest signal of interest before fixing the gain range.
Inirekomenda
Test and Measurement Equipment
Programmable gain amplifiers are a staple of laboratory and bench instrumentation, and the MCP6S91-E/P fits automatic test equipment where the DUT output level varies widely across units. Instead of an operator selecting a range with a front-panel switch, the instrument firmware programs the gain over SPI for each measurement point and records the scale factor alongside the reading, which removes human error and speeds up the test cycle. The 22 V/us slew rate lets the output move quickly after a range change, keeping the measurement cycle short, and the through-hole 8-pin PDIP package is convenient for instrument builders and for field service replacement. Verify the settling window in the datasheet before assuming the first post-switch sample is valid.
Inirekomenda
Industrial Process Control Loops
In industrial process control the MCP6S91-E/P normalises 4-20 mA, 0-10 V or resistive sensor signals so that a single downstream controller and ADC can serve several measurement ranges. The digital gain selection means the plant operator or a recipe-driven controller can re-range a loop at runtime without mechanical intervention, which reduces mechanical wear and improves repeatability. The rail-to-rail input stage keeps the usable signal span wide, and the SPI shutdown bit supports power-conscious field nodes. Engineering cautions apply: the analog input path must stay away from the SPI clock and data routing, and the device should be mounted away from high-temperature process areas or protected with an appropriate thermal package in hot environments.
Inirekomenda
Buod ng mga Inirekomendang Produkto
Impormasyon ng Talumpati sa Engineering for MCP6S91-E/P — ikabit, gabay sa disenyo, at impormasyon ng pagsunod sa kautusan.
Paunawang Hanapin
Ikabit sa Mga Alternatibo
| Parametro | Ito ang Producto | MCP6S92-E/P | MCP6S93-E/P | MCP6S91-I/P | MCP6S92-I/P | MCP6S93-I/P |
|---|---|---|---|---|---|---|
| Package | 8-DIP (0.300 in / 7.62 mm) | 8-DIP (0.300 in / 7.62 mm) - same | 8-DIP (0.300 in / 7.62 mm) - same | 8-DIP (0.300 in / 7.62 mm) - same | 8-DIP (0.300 in / 7.62 mm) - same | 8-DIP (0.300 in / 7.62 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Gain Range | +1 V/V to +32 V/V | +1 V/V to +32 V/V | +1 V/V to +32 V/V | +1 V/V to +32 V/V | +1 V/V to +32 V/V | +1 V/V to +32 V/V |
| Number of Input Channels | 2 (via input multiplexer) | Up to 4 (wider multiplexer) | Up to 8 (widest multiplexer) | 2 (same configuration) | Up to 4 (wider multiplexer) | Up to 8 (widest multiplexer) |
| Serial Interface | SPI, 10 MHz | SPI, 10 MHz | SPI, 10 MHz | SPI, 10 MHz | SPI, 10 MHz | SPI, 10 MHz |
| Temperature Grade | -E extended temperature | -E extended temperature | -E extended temperature | -I industrial temperature | -I industrial temperature | -I industrial temperature |
| Power-Down / Shutdown Control | Yes, via SPI shutdown bit | Yes, via SPI shutdown bit | Yes, via SPI shutdown bit | Yes, via SPI shutdown bit | Yes, via SPI shutdown bit | Yes, via SPI shutdown bit |
| Number of Circuits | 1 | 1 | 1 | 1 | 1 | 1 |
Pangunahing mga Pagkakaiba
- Digital gain selection removes analog switch and relay noise from the signal path (kumpara saMCP6S92-E/P)
- Same 8-pin PDIP footprint and gain range as the wider-multiplexer family members (kumpara saMCP6S93-E/P)
- Temperature-grade flexibility within an identical die and pinout (kumpara saMCP6S91-I/P)
Talaan ng Disenyo
Route the SPI clock, data and chip-select traces away from pins 7 and 8, and keep the input pair short and symmetric. The MCP6S91 inputs are high-impedance, so shared copper with digital switching nets can inject charge that appears as gain-dependent error. If the SPI bus must cross the analog area, guard the trace with ground and terminate the clock with a source-series resistor near the driver. This matters most at the +32 V/V gain step, where a 1 mV pickup on the input appears as 32 mV at the output.
A gain written over SPI does not take effect at the output instantly. Firmware should write the gain code, allow the internal gain network and any output filter to settle, and only then start the ADC conversion. A practical sequence is: write the gain, discard one conversion, then take the sample that is used. Forgetting this step is the single most common reason a PGA measurement reads slightly high or low right after a range change.
Place the supply bypass capacitor immediately between pins 5 (VSS) and pin 6 (VDD), with a short, low-inductance return path, because the SPI write current spikes on the same supply. In an 8-pin PDIP layout, keep the amplifier at the board edge away from switching regulators and digital processors, and provide a solid ground plane region under the analog section. For through-hole prototype boards, solder the capacitor on the component side rather than the solder side to keep the loop area minimal.
Impormasyon ng Pagsunod sa Kautusan
The MCP6S91 family is an industrial/analog PGA; the AEC-Q100 automotive qualification does not apply to the -E/P industrial-temperature ordering code. RoHS, REACH, lead-free and halogen-free declarations are not stated on the pages consulted for this part - confirm the current material declaration with the manufacturer before release.
