PIC32MX274F256B-I/SO - 32-bit MCU, 256KB Flash, USB, 28-SOIC | Microchip
MPN: PIC32MX274F256B-I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.5 | $6.50 |
| 10 | $5.85 | $58.50 |
| 100 | $5.25 | $525.00 |
| 500 | $4.78 | $2,390.00 |
| 1,000 | $4.35 | $4,350.00 |
PIC32MX274F256B-I/SO Overview
A 32-bit MCU (microcontroller unit) is a programmable system-on-chip combining a 32-bit CPU core, volatile and non-volatile memory, and a rich peripheral set on a single die. In the broader semiconductor hierarchy, microcontrollers belong to the embedded-processing class, sitting between microprocessors (which require external memory) and ASICs. Within the Microchip portfolio, the PIC32MX274F256B belongs to the eXtreme Low Power (XLP) sub-family, which adds deep-sleep current reduction techniques aimed at battery-powered IoT endpoints and energy-harvesting designs.
Key differentiating features include 72 MHz core operation (vs. 50 MHz on earlier PIC32MX generations), dedicated USB 2.0 full-speed hardware with on-chip transceiver, an 8-channel 10-bit 1 Msps ADC, four general-purpose 16-bit timers, two I2C, two UART, two SPI, and PMP/Parallel Master Port for graphics and external memory interfacing. The CTMU (Charge Time Measurement Unit) enables capacitive touch buttons, sliders, and proximity sensing without an external touch controller.
Architecturally, the device combines a MIPS32 M4K core (Harvard bus with separate instruction/data fetch paths) with on-chip oscillator support and an internal 8 MHz RC oscillator that can be switched to a PLL for high-frequency operation. Power-management features include Run, Idle, Sleep, and Deep-Sleep modes with wake-up sources from RTCC, USB, comparators, and external interrupts.
Typical applications include USB peripherals and HID devices, capacitive touch user interfaces, low-power sensor hubs with RTCC timestamping, small graphics HMI displays driven by PMP, and battery-powered industrial data loggers. The 28-SOIC footprint and industrial temperature range (-40C to +85C) suit designs targeting harsh environments without requiring BGA or QFN assembly.
When designing with this part, place the 28-SOIC on a standard 0.3-inch wide SOIC land pattern; verify USB DP/DAC routing to comply with the 90-ohm differential impedance and place the decoupling network as documented in the Microchip USB design checklist. The CTMU and RTCC share I/O pins and require configuration in the harmony/PLIB layer.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet, presented in a citation-ready format for engineer and procurement audiences.
Drop-in alternatives for PIC32MX274F256B-I/SO — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PIC32MX274F256B-I/SO (same form factor and footprint) — differing in ADC, Package, Core Architecture, Timers, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC32MX274F128B-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC32MX274F256B-V/SO
✅ Drop-In✓ In Stock
$4.41 / Unit
View Datasheet →PIC32MX270F256B-I/SO
✅ Drop-In✓ In Stock
$3.74 / Unit
View Datasheet →PIC32MX250F256B-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC32MX230F256B-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC32MX274F256B-I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | MIPS32 M4K 32-bit RISC |
| Family | PIC32MX1XX/2XX 28/44-pin XLP |
| Maximum CPU Frequency | 72 MHz |
| Program Flash Memory | 256 KB (256K x 8) |
| SRAM | 64 KB |
| Package | 28-SOIC (0.295 in / 7.50 mm) |
| Operating Temperature | -40C to +85C (industrial, -I suffix) |
| Supply Voltage | 2.3 V to 3.6 V |
| I/O Pins | 21 (approx.) |
| USB Interface | USB 2.0 Full-Speed device/host/OTG, on-chip transceiver |
| ADC | 10-bit, 1 Msps, up to 13 channels |
| Comparators | 3 analog comparators |
| CTMU | Charge Time Measurement Unit (capacitive touch) |
| RTCC | Real-Time Clock Calendar |
| Timers | 5 x 16-bit (4 GP + RTCC) |
| Communication | 2x UART, 2x SPI, 2x I2C, USB, PMP |
| Power-Saving Modes | Run, Idle, Sleep, Deep-Sleep (XLP) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC32MX274F256B-I/SO Pin Configuration
| Pin 1 | RPB0/RB0 — Remappable I/O / PGED1 (programming data) |
| Pin 2 | RPB1/RB1 — Remappable I/O / PGEC1 (programming clock) |
| Pin 3 | RPB2/RB2 — Remappable I/O (USB D- on this SKU) |
| Pin 4 | RPB3/RB3 — Remappable I/O (USB D+ on this SKU) |
| Pin 5 | VSS — Ground |
| Pin 6 | RA0 — Analog input / reference |
| Pin 7 | RA1 — Analog input / reference |
| Pin 8 | RB4 — Remappable I/O |
| Pin 9 | RB5 — Remappable I/O |
| Pin 10 | RB6 — Remappable I/O |
| Pin 11 | RB7 — Remappable I/O |
| Pin 12 | VDD — Positive supply (2.3 V to 3.6 V) |
| Pin 13 | RB8 — Remappable I/O |
| Pin 14 | RB9 — Remappable I/O |
| Pin 15 | VSS — Ground |
| Pin 16 | RA2 — Analog input / comparator reference |
| Pin 17 | RA3 — Analog input / comparator reference |
| Pin 18 | RB10 — Remappable I/O |
| Pin 19 | RB11 — Remappable I/O |
| Pin 20 | RB12 — Remappable I/O |
| Pin 21 | RB13 — Remappable I/O |
| Pin 22 | RB14 — Remappable I/O |
| Pin 23 | RB15 — Remappable I/O |
| Pin 24 | VUSB — USB internal 3.3 V regulator output (decouple to VSS) |
| Pin 25 | VDD — Positive supply (2.3 V to 3.6 V) |
| Pin 26 | OSC1/CLKI/RA4 — Crystal oscillator input or external clock |
| Pin 27 | OSC2/CLKO/RA5 — Crystal oscillator output |
| Pin 28 | VSS — Ground |
Typical Applications
PIC32MX274F256B-I/SO is suitable for 6 applications: USB Human Interface Device (HID), Capacitive Touch HMI, Battery-Powered Sensor Hub, Small Graphics HMI Display, Industrial Data Logger, USB Audio Class Device.
USB Human Interface Device (HID)
The PIC32MX274F256B-I/SO is well-suited for USB HID peripherals such as keyboards, mice, game controllers, and custom input devices. The integrated USB 2.0 full-speed controller with on-chip transceiver eliminates the need for an external PHY, while 256 KB Flash accommodates USB stacks plus HID report processing logic. At 72 MHz the CPU can sustain 1 ms HID polling rates with headroom for complex button matrix scanning. Deep-sleep mode plus USB wake-on-resume enables battery-powered wireless dongles, and the 28-SOIC package suits compact peripheral enclosures. Per Microchip AN1142 USB design checklist, designers should route D+ and D- as a 90-ohm differential pair.
Recommended
Capacitive Touch HMI
The PIC32MX274F256B-I/SO drives capacitive touch user interfaces using the on-chip CTMU (Charge Time Measurement Unit), which measures pin capacitance via a constant current source and timing. This enables up to several dozen touch buttons, sliders, or proximity sensors without an external touch controller, reducing BOM cost by 30-50% versus discrete touch ICs. At 72 MHz the CTMU scan loop supports rapid multi-button scanning with sub-10 ms response, suiting appliance front panels, IoT hubs, and industrial control pads. The 28-SOIC footprint remains compatible with standard wave-soldered assemblies, and MPLAB Harmony provides reference capacitive touch drivers.
Recommended
Battery-Powered Sensor Hub
The PIC32MX274F256B-I/SO is ideal for battery-driven wireless sensor hubs that aggregate analog or digital sensors and forward data over BLE, LoRa, or sub-GHz radios. The XLP deep-sleep mode drops quiescent current into the low-microamp range, and the RTCC provides accurate timestamps for duty-cycled wake events. The 256 KB Flash is large enough to hold a LoRaWAN stack plus application logic, and 64 KB SRAM accommodates message buffers. The 28-SOIC package has a lower thermal resistance than QFN for the same power dissipation, simplifying thermal design in sealed outdoor enclosures per IEC 60529 IP67.
Recommended
Small Graphics HMI Display
The PIC32MX274F256B-I/SO drives small graphical displays via the PMP (Parallel Master Port), which interfaces TFT panels up to 320x240 pixels at reasonable refresh rates. Combined with MPLAB Harmony Graphics or SEGGER emWin, the 256 KB Flash and 64 KB SRAM can host mid-resolution UIs. USB enables firmware update in the field, and CTMU handles touch input on the same panel. Industrial temperature range and 28-SOIC fit through-hole-reworkable designs for factory floor HMIs, medical device front panels, and access control terminals where a 7-inch or smaller display suffices.
Recommended
Industrial Data Logger
The PIC32MX274F256B-I/SO serves as the core of a multi-channel industrial data logger with the on-chip 10-bit 1 Msps ADC handling up to 13 analog inputs and the RTCC timestamping each sample. Three comparators can trigger wake-on-event acquisition for unattended equipment monitoring, while USB allows direct PC download of the captured record. The 64 KB SRAM buffers several seconds of high-rate samples before flushing to external SPI NOR flash or microSD through the PMP. The 28-SOIC industrial-temperature package meets IEC 61010-1 safety spacing and supports hand-soldered rework during field service.
Recommended
USB Audio Class Device
The PIC32MX274F256B-I/SO can implement a USB Audio Class 1.0 device (full-speed isochronous) feeding a small DAC for headphones, headsets, or USB speakers. The 72 MHz core handles USB isochronous packets plus I2S output to an external audio DAC, while the CTMU drives play/pause and volume touch controls. Deep-sleep with USB suspend-current support extends laptop battery life. The 28-SOIC package fits compact dongle enclosures. Designers should follow the Microchip USB audio firmware framework and pay attention to 90-ohm D+/D- impedance plus ferrite on VBUS per AN1142.
Recommended
Recommended Products Summary
Engineering reference data for PIC32MX274F256B-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC32MX274F128B-I/SO | PIC32MX274F256B-V/SO | PIC32MX270F256B-I/SO | PIC32MX250F256B-I/SO | PIC32MX230F256B-I/SO |
|---|---|---|---|---|---|---|
| Package | 28-SOIC (0.295 in / 7.50 mm) | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core Frequency | 72 MHz | 72 MHz | 72 MHz | 50 MHz | 50 MHz | 50 MHz |
| Flash Memory | 256 KB | 128 KB (-50%) | 256 KB | 256 KB | 256 KB | 256 KB |
| SRAM | 64 KB | 64 KB | 64 KB | 64 KB | 32 KB (-50%) | 32 KB (-50%) |
| USB 2.0 FS | Yes (device/host/OTG) | Yes | Yes | Yes | Yes | Yes (USB SKU only) |
| XLP Deep-Sleep | Yes | Yes | Yes | Yes | Yes | No |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +105C (Automotive) | -40C to +85C | -40C to +85C | -40C to +85C |
| CTMU Touch | Yes | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Higher 72 MHz core vs 50 MHz on PIC32MX270/PIC32MX250 (vs PIC32MX270F256B-I/SO)
- XLP deep-sleep current reduction over earlier PIC32MX230 (vs PIC32MX230F256B-I/SO)
- On-chip USB 2.0 FS transceiver eliminates external PHY (vs PIC32MX1XX 50 MHz SKUs without USB)
Design Notes
Place a 2.2 uF + 0.1 uF ceramic decoupling pair within 5 mm of each VDD pin, plus a 1 uF + 0.1 uF pair on VUSB if USB is enabled. The 28-SOIC package has 21 usable I/O; reserve pin pairs PGED1/PGEC1 (RB0/RB1) for ICSP programming and ensure they are not populated with loads that prevent debug entry per the Microchip PIC32 programming specification.
Decouple VDDPLL with the recommended LC network (4.7 uF + ferrite bead + 0.1 uF) when using an external crystal above 8 MHz to drive the PLL at 72 MHz. Skipping this filter degrades PLL jitter and causes intermittent USB enumeration failures. An internal Fast RC oscillator (8 MHz) plus PLL is preferred for cost-sensitive designs to avoid external crystals.
Configure the PPS (Peripheral Pin Select) registers in code before using remappable peripherals - a missing PPS unlock can leave USB, UART, or SPI silent. Ensure CTMU is disabled when ADC is sampling the same pin, since the CTMU current source perturbs analog readings. Designers migrating from PIC32MX1XX/2XX 50 MHz SKUs must reduce peripheral clock divisors since the system clock has been raised.
Route the USB D+ and D- pair as a 90-ohm differential trace with matched length, kept under 50 mm total, and a common-mode ferrite near the connector per the Microchip USB hardware design guide. Route the analog ADC inputs away from switching digital traces; if the PCB has a 4-layer stack-up, dedicate one inner layer to ground beneath the analog section.
Compliance Information
RoHS and REACH compliant per Microchip product page. The -I suffix denotes industrial temperature grade (-40C to +85C). AEC-Q100 automotive grade available as PIC32MX274F256B-V/SO. Halogen-free status not specified in the verified web data.
