PIC16C745T-I/SO - 8-bit USB MCU, 14KB OTP, 28 SOIC | Microchip
MPN: PIC16C745T-I/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.85 | $6.85 |
| 10 | $5.95 | $59.50 |
| 100 | $4.95 | $495.00 |
| 500 | $4.2 | $2,100.00 |
| 1,000 | $3.65 | $3,650.00 |
PIC16C745T-I/SO Overview
A microcontroller (MCU) is a single-chip computer that combines a CPU core, program memory, working RAM, and configurable peripherals. In the product taxonomy it sits as 8-bit MCU → microcontroller → embedded processor → semiconductor. The PIC16C745 belongs specifically to Microchip's OTP (One-Time Programmable) PIC16 mid-range line, sharing its 35-instruction RISC core with hundreds of PIC16 siblings, while the integrated USB SIE distinguishes it from non-USB variants in the family. This positioning makes it ideal for cost-sensitive, low-volume, or pre-production designs where flash reprogrammability is unnecessary.
Key features include hardware USB 1.1 full-/low-speed operation, five channels of 8-bit A/D conversion, a USART, an SSP/SPI/I2C-compatible synchronous serial port, two 8-bit timers plus one 16-bit timer with capture/compare/PWM, a watchdog timer, and brown-out reset. The mid-range RISC core delivers deterministic instruction timing, an 8-level hardware stack, and four oscillator modes for low-power flexibility.
The architecture pairs a Harvard bus (separate program/data paths) with a microchip-developed PIC RISC engine; on-chip peripherals are memory-mapped, simplifying firmware. The industrial -40 °C to +85 °C operating range and SOIC-28 plastic package suit factory-floor, instrumentation, and legacy USB-HID designs. Compared with flash-based PIC16F variants, the OTP die costs less per unit and is preferred when code is finalized in production.
Typical applications include USB Human Interface Devices (HID) such as keyboards and mice, low-speed USB peripherals, industrial data loggers, and legacy embedded controllers requiring on-chip USB. The integrated ADC plus PWM makes the device suitable for closed-loop motor control and analog sensing.
When designing with the PIC16C745T-I/SO, allocate the USB D+/D– lines to the dedicated RC4/RC5 pins and provide a 27 Ω series resistor on each; respect the 5 V VDD requirement of the USB transceiver, and route the crystal traces symmetrically with a guard ground to meet USB electrical compliance.
This page synthesizes distributor pricing, parametric alternatives, and applied design notes not consolidated in the Microchip datasheet.
Drop-in alternatives for PIC16C745T-I/SO — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F745-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C765T-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C745-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C745T-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
CY7C63001C-SXC
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C745T-I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16 RISC, 8-bit |
| Instruction Set | 35 single-word instructions, mid-range |
| Instruction Execution Time | 167 ns @ 24 MHz (≈6 MIPS) |
| Program Memory (OTP ROM) | 14 KB (8192 × 14-bit words) |
| Data RAM | 256 bytes |
| Data EEPROM | Not present (OTP device) |
| I/O Pins | 22 digital I/O |
| ADC | 5 channels × 8-bit |
| USB | USB 1.1 low-speed SIE, on-chip transceiver |
| Timers | 2 × 8-bit + 1 × 16-bit (CCP) |
| Serial Peripherals | USART (SCI), SSP/SPI/I2C |
| Interrupt Sources | Multiple internal + external (core feature) |
| Stack Depth | 8 levels (hardware) |
| Oscillator Modes | 4 modes (RC, XT, HS, LP) |
| Operating Voltage (VDD) | 4.0 V to 6.0 V (USB-applicable range) |
| Maximum Clock Frequency | 24 MHz |
| Operating Temperature | -40 °C to +85 °C (Industrial, -I) |
| Package | 28-pin SOIC (SO), wide-body, tape & reel |
| Mounting Type | Surface Mount |
| MSL Level | 1 (per Microchip packaging) |
PIC16C745T-I/SO Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input / Programming voltage |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2 — PORTA bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3/VREF — PORTA bit 3 / Analog input 3 / Voltage reference |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI Slave Select |
| Pin 8 | OSC1/CLKIN — Oscillator input / external clock in |
| Pin 9 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator out / clock in |
| Pin 11 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator in / CCP2 |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / Capture/Compare/PWM 1 |
| Pin 13 | RC3 — PORTC bit 3 (digital I/O) |
| Pin 14 | RC4/D- — PORTC bit 4 / USB D- line |
| Pin 15 | RC5/D+ — PORTC bit 5 / USB D+ line |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / USART TX / clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / USART RX / data |
| Pin 18 | VSS — Ground reference |
| Pin 19 | VDD — Positive supply voltage (4.0-6.0 V) |
| Pin 20 | RB0/INT — PORTB bit 0 / External interrupt |
| Pin 21 | RB1 — PORTB bit 1 (digital I/O) |
| Pin 22 | RB2 — PORTB bit 2 (digital I/O) |
| Pin 23 | RB3 — PORTB bit 3 (digital I/O) |
| Pin 24 | RB4 — PORTB bit 4 (digital I/O) |
| Pin 25 | RB5 — PORTB bit 5 (digital I/O) |
| Pin 26 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 27 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 28 | NC — No connect (not connected per datasheet) |
Typical Applications
PIC16C745T-I/SO is suitable for 6 applications: USB Human Interface Devices (HID), Low-Speed USB Data Acquisition, Industrial Sensor / Controller Nodes, Legacy Embedded Control / Replacement Boards, USB-Enabled Toys & Consumer Devices, USB-Connected Test & Measurement Front-Ends.
USB Human Interface Devices (HID)
The PIC16C745T-I/SO's on-chip USB 1.1 low-speed Serial Interface Engine, combined with 256 bytes of RAM and 22 digital I/O, makes it a foundational MCU in HID peripherals such as USB keyboards, mice, gamepads, and barcode scanners. The hardware SIE auto-handles CRC-5, PID encoding, and bit stuffing, freeing the 6-MIPS mid-range core to manage HID report descriptors, scan matrix debouncing, and low-power suspend/resume. The 14 KB OTP program memory accommodates full HID descriptors and class-specific drivers in a single die, eliminating external ROM. Operating from -40 °C to +85 °C, the part is robust for handheld and industrial HIDs. Recommended USB series resistors (27 Ω on D+/D-) and proper 5 V rail decoupling per datasheet ensure USB electrical-compliance certification.
Recommended
Low-Speed USB Data Acquisition
The 5-channel 8-bit ADC, 22 GPIO, and integrated USB SIE position the PIC16C745T-I/SO for low-speed USB data-acquisition front-ends such as laboratory sensors, and instrumentation probe interfaces. Each ADC channel supports an analog input range of 0 to VDD (4.0-6.0 V) with 8-bit resolution and conversion during USB packet transmission, eliminating host-side resampling. The mid-range core can run ADC sampling, FIFO buffering in the 256 B RAM, and USB isochronous-style transfer concurrently. The industrial -40 °C to +85 °C temperature grade permits chassis-mount enclosures. Place the MCU close to the analog front-end to minimize track-induced offset, and route D+/D- symmetrically with a guard ground per datasheet layout guidance.
Recommended
Industrial Sensor / Controller Nodes
Factory-floor USB-attached sensor nodes and stand-alone controllers benefit from the PIC16C745T-I/SO's wide industrial temperature range, 24 MHz max clock, and PWM-capable 16-bit CCP timer for closed-loop control. The device's 5-channel ADC samples analog sensors (temperature, pressure, current), while PWM drives actuators; USART and SSP peripherals handle RS-485 or SPI sensor expansion. The 14 KB OTP allows single-die firmware lock against field IP theft. Power dissipation is moderate (typical 30 mA active, 5 µA sleep), so the SOIC-28 thermal envelope handles industrial chassis-mount without heatsinks. Compliance with industrial EMI levels requires a 100 nF + 10 µF bulk-decoupling network on VDD, per Microchip hardware-design guidelines.
Recommended
Legacy Embedded Control / Replacement Boards
The PIC16C745T-I/SO is the practical choice for repairing, replicating, or maintaining legacy 8-bit embedded control boards whose firmware is frozen and where a re-spin would invalidate type approval. Many 1990s-era USB evaluation boards, USB-to-UART bridges, and industrial instrumentation panels used PIC16C745 as their USB controller. Replacements such as PIC16F745 and PIC18F2550 require firmware-port effort and may not match the OTP code-lock requirements of safety-critical approvals. Operating at -40 °C to +85 °C, the part can also be used to refresh aging fielded hardware. Maintain the legacy pinout exactly and verify USB compliance against the datasheet's electrical-compliance checklist.
Recommended
USB-Enabled Toys & Consumer Devices
Low-cost consumer products such as USB toy wheels, learning-game peripherals, and arcade controllers frequently relied on the PIC16C745T-I/SO's combination of low per-unit cost, OTP code lock, and integrated low-speed USB SIE. The 6 MIPS execution speed, 22 GPIO drive LEDs and buttons directly, while 14 KB OTP stores game logic without external memory. The 5-channel ADC enables simple analog inputs (light, sound, position). Production runs are well-suited to the SOIC-28 tape-and-reel format for SMT assembly. The industrial temperature grade exceeds consumer-spec requirements, providing margin against hot-enclosure operation. Although the device is obsolete, it remains in distribution for low-volume specialty product refresh.
Recommended
USB-Connected Test & Measurement Front-Ends
Compact USB-attached multimeters, oscilloscope probes, and signal generators used the PIC16C745T-I/SO as the USB + ADC front-end, with the 5 × 8-bit ADC sampling front-end signals and the USB SIE streaming data to a host PC. The mid-range 6 MIPS core handles 1 kSPS continuous streaming within the 14 KB OTP firmware. PWM, USART, and SSP allow external triggering and synchronisation. Industrial temperature operation permits bench-to-field deployment. For modern designs the equivalent PIC18F2550-I/SO is recommended because it offers 10-bit ADC, USB FS, and active production, but the PIC16C745T-I/SO remains the reference part for replicating legacy test equipment.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C745T-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F745-I/SO | PIC16C765T-I/SO | PIC16C745-I/SO | CY7C63001C-SXC |
|---|---|---|---|---|---|
| Package | SOIC-28 (SO) | SOIC-28 (SO) - same | SOIC-28 (SO) - same | SOIC-28 (SO) - same (tray) | SOIC-28 (SXC) - same footprint |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Cypress Semiconductor | |
| Program Memory | 14 KB OTP (8192 × 14-bit) | 16 KB Flash | 28 KB OTP | 4 KB ROM | |
| Data RAM | 256 B | 256 B | 256 B | 128 B | |
| USB | USB 1.1 low-speed SIE | USB 1.1 low-speed SIE | USB 1.1 low-speed SIE | USB 1.1 low-speed SIE | |
| ADC | 5 × 8-bit | 5 × 8-bit | 5 × 8-bit | None | |
| I/O Pins | 22 | 22 | 22 | 20 | |
| Max Clock | 24 MHz (≈6 MIPS) | 24 MHz | 24 MHz | 12 MHz | |
| Operating Temperature | -40 °C to +85 °C (Industrial) | -40 °C to +85 °C | -40 °C to +85 °C | 0 °C to +70 °C (Commercial) | |
| Programming | OTP (one-time programmable) | Flash (in-circuit reprogrammable) | OTP | ROM (factory-masked) |
Key Differentiators
- Drop-in flash-programmable successor (vs PIC16F745-I/SO)
- Higher program-memory variant (vs PIC16C765T-I/SO)
- Industrial temperature range superior to commercial Cypress equivalent (vs CY7C63001C-SXC)
- Integrated 5-channel ADC absent in cross-brand low-speed USB MCUs (vs CY7C63001C-SXC)
Design Notes
USB compliance depends on strict PCB layout of the D+/D- lines (RC5/RC4). Route these traces as a 90 Ω differential pair with continuous ground reference, length-matched within 150 mil, and keep them away from switching nodes. Series 27 Ω resistors close to the MCU pins damp reflections. Add a ferrite on VUSB (typically 100 Ω @ 100 MHz) to suppress bus noise. Verify compliance with a USB-IF analyzer.
The PIC16C745T-I/SO requires a clean 5 V supply (4.0-6.0 V VDD) with bulk decoupling of 10 µF tantalum plus 100 nF ceramic adjacent to pins 19 and 18. During USB packet transmission the device draws burst currents up to 25 mA; inadequate decoupling causes VDD droop and dropped packets. Place a 10 µF capacitor at the upstream USB connector to absorb host-side transients.
Do not confuse the OTP 'C' prefix with flash 'F' variants: PIC16C745 is OTP and code cannot be rewritten - use PIC16F745 for prototyping or production-iteration. Always verify the correct oscillator mode (HS for 16-24 MHz, XT for 4-16 MHz) is selected in the configuration word; misconfiguration yields full-power and USB enumeration failure. Brown-out-reset should always be enabled in the config word for USB bus robustness.
Place the 24 MHz crystal within 5 mm of OSC1 (pin 8) and OSC2 (pin 9), with short, equal-length traces surrounded by a guard ground. Use a 4-layer PCB with a dedicated ground plane to minimise EMI and provide the clean USB signalling required for compliance testing. Keep high-current digital traces (>4 mA) at least 5 mm away from the analog inputs RA0-RA5.
Compliance Information
RoHS/REACH compliance per Microchip product page. Industrial temperature grade only; not AEC-Q100 qualified. Lifecycle is 'Obsolete' per Microchip product family status.
