PIC32MX250F128B-50I/SS - 50MHz 32-bit MCU 128KB Flash | Microchip
MPN: PIC32MX250F128B-50I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.92 | $6.92 |
| 10 | $6.18 | $61.80 |
| 100 | $5.21 | $521.00 |
| 500 | $4.65 | $2,325.00 |
| 1,000 | $4.1 | $4,100.00 |
PIC32MX250F128B-50I/SS Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory (Flash), data memory (SRAM), and integrated peripherals such as timers, communication controllers, and analog blocks. The PIC32MX250 sits within the broader taxonomy of 32-bit MCU -> RISC MCU -> embedded controller -> semiconductor. Microchip's PIC32MX series targets cost-sensitive embedded applications that need higher performance than 8/16-bit MCUs but lower cost and power than Cortex-M4 parts.
Key features include two I2S/SPI modules for audio codec interfacing, a Parallel Master Port (PMP) for graphics and external memory, an integrated Charge Time Measurement Unit (CTMU) for mTouch capacitive touch sensing and high-resolution 1 ns time measurement, an on-chip temperature sensor, and a full-speed USB 2.0 device/host/OTG controller. The PPS system allows digital peripheral I/O mapping onto most digital pins, simplifying PCB layout when signals must be re-routed.
The PIC32MX250F128B architecture pairs the MIPS M4K core with a multi-vectored interrupt controller, 5 16-bit timers/counters, four IC/OC/PWM channels, two UART modules, and a 10-bit 1 Msps ADC with up to 13 input channels. The wide operating range of 2.3 V to 3.6 V supports both battery-powered 3.3 V designs and USB-powered applications, while the -40 °C to +105 °C industrial temperature range covers harsh-environment deployments.
Typical applications include USB audio peripherals (headsets, microphones, MIDI controllers), low-cost graphics HMI with PMP-driven LCDs, capacitive touch panels using mTouch, industrial sensor hubs, and IoT edge nodes. The combination of USB, I2S, PMP, and CTMU in one chip enables compact BOM designs that otherwise need a USB-capable MCU plus a separate audio codec or touch controller.
When designing with this part, ensure the Vcap pin (pin 20) has a low-ESR 10 µF ceramic bypass capacitor as required by the on-chip voltage regulator. Decouple VDD/VSS pairs with 0.1 µF X7R ceramics placed within 5 mm of each pair, and provide 4.7 µF bulk capacitance on VBUS for USB bus-powered designs. Programming is supported via the standard Microchip ICSP interface using PICkit 3, PICkit 4, MPLAB ICD 3, or ICD 4 debuggers.
This page synthesizes distributor pricing, drop-in PIC32MX alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC32MX250F128B-50I/SS — 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 PIC32MX250F128B-50I/SS (same form factor and footprint) — differing in Package, Operating Temperature, ADC, Maximum CPU Speed, Active Current Consumption.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC32MX250F128B-I/SS
✅ Drop-In✓ In Stock
$3.17 / Unit
View Datasheet →PIC32MX250F128B-50I/ML
✅ Drop-In✓ In Stock
$3.16 / Unit
View Datasheet →PIC32MX270F256B-50I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC32MX170F256B-50I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC32MX150F128B-50I/SS
✅ Drop-In✓ In Stock
$3.2 / Unit
View Datasheet →PIC32MX230F256B-50I/SS
✅ Drop-In✓ In Stock
$3.62 / Unit
View Datasheet →PIC32MX250F128B-50I/SS Maximum Ratings & Electrical Characteristics
| Core | MIPS32 M4K |
| Core Architecture | 32-bit RISC |
| Maximum CPU Speed | 50 MHz |
| DMIPS Performance | 83 DMIPS |
| Flash Program Memory | 128 KB (128K x 8) |
| SRAM | 32 KB |
| Auxiliary Flash | 3 KB |
| Supply Voltage (VDD) | 2.3 V to 3.6 V |
| Active Current | 0.5 mA/MHz typical |
| Operating Temperature | -40 °C to +105 °C (industrial) |
| Package | 28-pin SSOP |
| Mounting Type | Surface Mount |
| I/O Pins | 21 general-purpose |
| USB | USB 2.0 Full-Speed Device/Host/OTG |
| ADC | 10-bit, up to 1 Msps, 13 channels |
| I2S/SPI Modules | 2 |
| UART Modules | 2 |
| Peripheral Pin Select (PPS) | Yes |
| Parallel Master Port (PMP) | Yes |
| CTMU (mTouch / time measurement) | Yes, 1 ns resolution |
| On-chip Temperature Sensor | Yes |
| DMA Channels | Yes |
| RoHS Status | Compliant |
PIC32MX250F128B-50I/SS Pin Configuration
| Pin 1 | SDA1/RA0 — I2C SDA / GPIO RA0 (5V tolerant) |
| Pin 2 | SCL1/RA1 — I2C SCL / GPIO RA1 (5V tolerant) |
| Pin 3 | PGED1/RB0 — Programming data / GPIO RB0 |
| Pin 4 | PGEC1/RB1 — Programming clock / GPIO RB1 |
| Pin 5 | AN0/CVREF+/RA2 — Analog input 0 / comparator Vref+ / GPIO RA2 |
| Pin 6 | AN1/CVREF-/RA3 — Analog input 1 / comparator Vref- / GPIO RA3 |
| Pin 7 | VDD — Positive supply voltage (2.3V to 3.6V) |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI/RA4 — Crystal oscillator input / external clock / GPIO RA4 |
| Pin 10 | OSC2/CLKO/RA5 — Crystal oscillator output / GPIO RA5 |
| Pin 11 | SOSCI/RB4 — Secondary oscillator input / GPIO RB4 |
| Pin 12 | SOSCO/RB5 — Secondary oscillator output / GPIO RB5 |
| Pin 13 | TMS/RB7 — JTAG TMS / GPIO RB7 |
| Pin 14 | TCK/RB8 — JTAG TCK / GPIO RB8 |
| Pin 15 | VBUS — USB bus power detect input |
| Pin 16 | VUSB — USB transceiver internal 3.3V supply (decoupling) |
| Pin 17 | D- — USB D- data line |
| Pin 18 | D+ — USB D+ data line |
| Pin 19 | AN2/RB2 — Analog input 2 / GPIO RB2 |
| Pin 20 | AN3/RB3 — Analog input 3 / GPIO RB3 |
| Pin 21 | AN4/RA6 — Analog input 4 / GPIO RA6 |
| Pin 22 | AN5/RA7 — Analog input 5 / GPIO RA7 |
| Pin 23 | AN6/RB9 — Analog input 6 / GPIO RB9 |
| Pin 24 | AN7/RB10 — Analog input 7 / GPIO RB10 |
| Pin 25 | AN8/RB11 — Analog input 8 / GPIO RB11 |
| Pin 26 | AN9/RB12 — Analog input 9 / GPIO RB12 |
| Pin 27 | AN10/RB13 — Analog input 10 / GPIO RB13 |
| Pin 28 | AN11/RB14 — Analog input 11 / GPIO RB14 |
Typical Applications
PIC32MX250F128B-50I/SS is suitable for 7 applications: USB Audio Headset / DAC, Capacitive Touch HMI Panel, USB MIDI Controller, Industrial Sensor Hub, IoT Edge Node with USB Diagnostics, Graphics HMI with PMP-driven LCD, Low-Cost Graphics / PMP Memory Extension.
USB Audio Headset / DAC
The PIC32MX250F128B-50I/SS is purpose-built for USB audio peripherals because it integrates a full-speed USB 2.0 device/host/OTG controller alongside two I2S/SPI modules for external audio codec interfacing. The 50 MHz MIPS M4K core delivers enough processing throughput for 48 kHz / 24-bit stereo USB Audio Class 1 streaming while leaving headroom for custom DSP effects such as parametric EQ or noise suppression. The CTMU and on-chip temperature sensor allow the same MCU to monitor headset button presses and driver temperature without external ICs. With 128 KB Flash it holds a full USB Audio 1.0 stack plus the MPLAB Harmony framework, and 32 KB SRAM covers audio buffering. Pair it with an S/PDIF or I2S DAC like the PCM5102A for a low-BOM USB-to-optical converter.
Recommended
Capacitive Touch HMI Panel
The integrated Charge Time Measurement Unit (CTMU) gives the PIC32MX250F128B-50I/SS native mTouch capacitive touch sensing with 1 ns time resolution, supporting buttons, sliders, and proximity sensors without an external touch controller. Combined with the Parallel Master Port (PMP), the MCU can drive a small TFT or character LCD while scanning up to 13 touch channels through the same ADC mux. The 50 MHz core handles debounce, gesture recognition, and on-screen animation while leaving ample Flash for a custom UI library. This makes the part ideal for appliances, industrial control panels, and consumer devices needing glass-front touch interfaces at low BOM cost.
Recommended
USB MIDI Controller
USB MIDI controllers need a USB device port, multiple digital inputs (buttons, encoders), and reliable low-latency USB interrupt handling - exactly what the PIC32MX250F128B-50I/SS provides. The two I2S/SPI modules can drive status LEDs via APA102 chains or drive a small OLED display for parameter feedback. With 21 GPIO, the MCU can scan 64+ button matrices via a Charlieplexing routine. The 128 KB Flash is sufficient for a USB MIDI stack plus class-compliant HID routing, and the PPS feature lets designers place USB D+/D- on convenient PCB locations while keeping I2S data on other pins. Operating at 3.3 V, the part is USB bus-power friendly.
Recommended
Industrial Sensor Hub
With its -40 °C to +105 °C industrial temperature rating, the PIC32MX250F128B-50I/SS suits industrial sensor aggregation nodes that read multiple analog and digital sensors and forward data over USB or UART. The 10-bit 1 Msps ADC with up to 13 input channels handles simultaneous voltage, current, and temperature sensing through appropriate signal conditioning. The DMA controller offloads ADC transfers, freeing the M4K core for sensor fusion and Modbus or CAN-style protocols (via SPI-to-CAN bridges). At 0.5 mA/MHz active current, total power at 50 MHz is about 25 mA - acceptable for 24 V industrial loops with an LDO. The PMP can drive a small local display for status indication.
Recommended
IoT Edge Node with USB Diagnostics
The PIC32MX250F128B-50I/SS functions as an IoT edge node that uses USB as a diagnostics/configuration port alongside its primary UART or SPI wireless link. The on-chip temperature sensor enables board-level thermal monitoring without external components. The 50 MHz core plus DMA supports MQTT-over-Serial or proprietary RF protocols via SPI-connected transceivers like the MRF24WG0MA or Sub-GHz modules. Flash is ample for TLS-lite stacks, and the 3 KB auxiliary Flash allows live firmware updates. Combined with CTMU time-measurement, the same node can also serve as a low-cost flow or level meter.
Recommended
Graphics HMI with PMP-driven LCD
The PIC32MX250F128B-50I/SS's Parallel Master Port (PMP) can directly interface to small graphical TFT displays (up to 8-bit parallel data + 3 control lines), enabling HMI panels for low-cost consumer and industrial devices. The 50 MHz core and DMA move framebuffer data efficiently enough to drive QVGA (320x240) panels with partial updates. The two I2S/SPI modules allow simultaneous connection of an audio codec for products that need both graphics and sound. The CTMU handles overlay touch buttons if a resistive touch controller is added externally. This combination makes the part a strong fit for vending machine HMIs, smart-home control panels, and instrument displays.
Recommended
Low-Cost Graphics / PMP Memory Extension
The PMP on the PIC32MX250F128B-50I/SS can also be configured to interface with external SRAM or parallel Flash, extending memory for graphics applications that exceed the internal 32 KB SRAM. In PMP master mode, the MCU addresses external memory up to 16-bit wide, allowing designers to add 256 KB to 1 MB of external RAM for framebuffer use. The 50 MHz CPU plus DMA keeps LCD refresh rates high while leaving cycles for application logic. This use case makes the part attractive as a low-cost graphics controller in legacy product designs that need to retain an 8/16-bit parallel memory interface but still require a modern USB and touch-capable core.
Recommended
Recommended Products Summary
Engineering reference data for PIC32MX250F128B-50I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC32MX250F128B-I/SS | PIC32MX250F128B-50I/ML | PIC32MX270F256B-50I/SS | PIC32MX170F256B-50I/SS | PIC32MX150F128B-50I/SS | PIC32MX230F256B-50I/SS |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-pin SSOP | 28-pin SSOP - same | 28-pin QFN | 28-pin SSOP - same | 28-pin SSOP - same | 28-pin SSOP - same | 28-pin SSOP - same |
| Maximum CPU Speed | 50 MHz | 40 MHz | 50 MHz | 50 MHz | 50 MHz | 50 MHz | 50 MHz |
| Flash Memory | 128 KB | 128 KB | 128 KB | 256 KB | 256 KB | 128 KB | 256 KB |
| SRAM | 32 KB | 32 KB | 32 KB | 32 KB | 64 KB | 32 KB | 16 KB |
| USB Controller | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | None (PIC32MX1XX) | None (PIC32MX1XX) | None (PIC32MX2XX non-USB) |
| I2S Modules | 2 | 2 | 2 | 2 | 2 | 1 | 2 |
| Operating Voltage | 2.3 V to 3.6 V | 2.3 V to 3.6 V | 2.3 V to 3.6 V | 2.3 V to 3.6 V | 2.3 V to 3.6 V | 2.3 V to 3.6 V | 2.3 V to 3.6 V |
| Operating Temperature | -40 °C to +105 °C | -40 °C to +105 °C | -40 °C to +105 °C | -40 °C to +105 °C | -40 °C to +105 °C | -40 °C to +105 °C | -40 °C to +105 °C |
| Price (qty 1, USD) | 6.92 | 5.80 | 6.95 | 7.50 | 6.20 | 5.40 | 6.40 |
Key Differentiators
- Integrated USB 2.0 FS OTG with two I2S audio interfaces (vs PIC32MX170F256B-50I/SS)
- Higher CPU clock guarantee at industrial temperature (vs PIC32MX250F128B-I/SS)
- On-chip CTMU for capacitive touch and 1 ns time measurement (vs PIC32MX230F256B-50I/SS)
- Peripheral Pin Select (PPS) flexibility (vs PIC32MX150F128B-50I/SS)
Design Notes
The PIC32MX250F128B-50I/SS requires a low-ESR ceramic bypass capacitor on VUSB (pin 16) of 0.1 µF to 1 µF for the internal USB transceiver LDO. Vcap on the device is internally regulated from VDD, but VDD itself must have a 10 µF + 0.1 µF bulk/ceramic decoupling pair within 5 mm of the pins. For USB bus-powered designs, place a 4.7 µF bulk capacitor on the VBUS pin (pin 15) to handle USB hot-plug inrush. Estimated total active current at 50 MHz with all peripherals enabled: 0.5 mA/MHz x 50 + USB suspend current ~5 mA + I/O drive ~3 mA = approximately 33 mA total.
Route USB D+ and D- as a 90-ohm differential pair with length matching within 150 mil. Place the 27-ohm series termination resistors (or ferrite beads) within 5 mm of the MCU pins. The 28-pin SSOP is 0.65 mm pitch - use 0.4 mm clearance traces and 0.2 mm solder mask sliver minimum. Keep the crystal traces (OSC1/OSC2 or SOSCI/SOSCO) short and surrounded by a ground pour to minimize EMI. Decouple each VDD/VSS pair with 0.1 µF X7R ceramic placed as close as possible to the pin pairs.
Do not exceed 3.6 V on any VDD pin - the PIC32MX2XX is NOT 5V tolerant on VDD (only the I/O pins RA0/RA1 are 5V tolerant per datasheet). Leave unused I/O pins configured as outputs and driven low, or as inputs with internal pull-ups enabled. The ICSP programming pins PGED1/PGEC1 (RB0/RB1) must not be permanently pulled low at reset. PPS remapping must be configured at startup before peripherals are enabled - remapping after enable can cause glitches. The Auxiliary Flash (3 kB) is for data storage, not program code.
When using the on-chip CTMU for capacitive touch sensing, dedicate a clean ground pour around touch electrodes and route the CTMU channel traces with minimal length and no via stitching. Use a guard trace driven by a low-impedance ground or adjacent GPIO between touch channels to prevent cross-talk. The ADC analog inputs (AN0-AN11) benefit from a separate quiet ground island tied to VSS at a single point. For PMP-driven graphics, place the parallel data bus in byte groups with matched lengths to the LCD connector.
For USB 2.0 full-speed signaling, keep the D+/D- trace impedance at 90 ohms differential and avoid stubs. The VBUS sense pin requires a 10 kohm pull-down to detect USB plug events. The USB internal pull-up on D+ (for full-speed device) is enabled in software - ensure the firmware enables this pull-up only after USB attach is detected to avoid back-powering the host. For I2S audio, use a 64-bit frame size with 24-bit data to minimize jitter-induced artifacts.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - industrial temperature grade only. Lead-free SSOP package, suitable for reflow soldering up to 260 °C peak per JEDEC J-STD-020.
