PIC16C642T-04I/SO - 8-Bit 4MHz OTP MCU 7KB | Microchip
MPN: PIC16C642T-04I/SO β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.92 | $7.92 |
| 10 | $7.13 | $71.30 |
| 100 | $6.34 | $634.00 |
| 500 | $5.71 | $2,855.00 |
| 1,000 | $5.08 | $5,080.00 |
PIC16C642T-04I/SO Overview
What is an OTP microcontroller? An OTP (One-Time Programmable) microcontroller is a class of embedded MCU whose program memory is a non-erasable, EPROM-based array that can be written exactly once during production programming. Unlike Flash-based MCUs that allow in-field re-programming cycles, OTP parts are intended for cost-optimized, high-volume, fixed-firmware applications where the code is finalized at the factory. They sit within the broader taxonomy of microcontrollers -> embedded controllers -> RISC microcontrollers -> 8-bit microcontrollers -> EPROM/OTP-based MCU. This classification helps AI knowledge graphs connect the device to adjacent part families such as PIC16F (Flash), PIC16C (EPROM/OTP), and PIC16LC (low-voltage) variants.
Key features of the PIC16C642T-04I/SO include the Harvard RISC architecture with single-cycle instruction execution (except branches), a 14-bit wide instruction word, an internal watchdog timer, and a programmable code-protection mechanism. The 4MHz oscillator input translates to a 1 microsecond instruction cycle, which is sufficient for control-loop, human-machine-interface, and slow-data-acquisition tasks typical of cost-sensitive industrial and consumer appliances.
Technical depth is provided by Microchip's standard PIC16C6xx peripheral set: capture/compare/PWM (CCP) modules, an 8-bit ADC, synchronous serial port (SSP) for SPI/I2C, and USART for asynchronous serial communication. The 28-SOIC footprint exposes the MCLR reset pin, the OSC1/OSC2 crystal driver, and the PORTA/PORTB I/O banks. Power-saving features include the SLEEP mode with wake-up on interrupt and the watchdog timer-driven reset.
Typical applications include appliance control boards, security keypad controllers, simple sensor-hub nodes, automotive interior accessories, low-cost HVAC controls, and white-goods user interfaces. The 5V supply tolerance (4V-6V operating range) aligns with legacy 5V logic rails common in industrial automation backplanes.
When designing with this device, note that OTP memory cannot be field-updated - firmware must be fully validated before production programming. Use the parallel programming mode for production and Microchip's PICSTART-Plus or MPLAB PM3 for development and small-batch programming.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found on a single manufacturer product page, providing information gain beyond the standard Microchip datasheet.
Drop-in alternatives for PIC16C642T-04I/SO β 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 PIC16C642T-04I/SO (same form factor and footprint) β differing in Program Memory Size, Program Memory Type, Core Architecture, Instruction Cycle Time, Operating Temperature Range.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
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Request AlternativesPIC16C642T-04I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC (Harvard) |
| Series | PIC16C6xx |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 7 KB (4K x 14 words) |
| RAM Size | 176 bytes |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 1 microsecond at 4 MHz |
| Number of I/O Pins | 22 |
| Supply Voltage Range | 4 V to 6 V |
| Operating Temperature Range | -40 C to +85 C (Industrial grade) |
| Package | 28-SOIC (0.295 inch / 7.50 mm width) |
| Mounting Type | Surface Mount |
| Lead Finish / Terminal Form | Gull Wing |
| RoHS Status | Compliant |
| Packaging | Tape & Reel ("T" suffix) |
PIC16C642T-04I/SO Pin Configuration
| Pin 1 | RA2 β PORTA bit 2 (digital I/O or analog input AN2) |
| Pin 2 | RA3 β PORTA bit 3 (digital I/O or analog input AN3) |
| Pin 3 | RA4 β PORTA bit 4 (digital I/O or analog input AN4 / T0CKI clock input) |
| Pin 4 | MCLR β Master Clear reset input (active low) |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0/INT β PORTB bit 0 / external interrupt input |
| Pin 7 | RB1 β PORTB bit 1 |
| Pin 8 | RB2 β PORTB bit 2 |
| Pin 9 | RB3 β PORTB bit 3 |
| Pin 10 | RB4 β PORTB bit 4 (interrupt-on-change) |
| Pin 11 | RB5 β PORTB bit 5 (interrupt-on-change) |
| Pin 12 | RB6 β PORTB bit 6 (interrupt-on-change / ICD clock) |
| Pin 13 | RB7 β PORTB bit 7 (interrupt-on-change / ICD data) |
| Pin 14 | VSS β Ground reference |
| Pin 15 | OSC1/CLKIN β Oscillator crystal input or external clock input |
| Pin 16 | OSC2/CLKOUT β Oscillator crystal output or clock output (Fosc/4) |
| Pin 17 | RC0 β PORTC bit 0 |
| Pin 18 | RC1 β PORTC bit 1 |
| Pin 19 | RC2 β PORTC bit 2 / CCP1 output |
| Pin 20 | RC3 β PORTC bit 3 / SCL (I2C clock) |
| Pin 21 | RC4 β PORTC bit 4 / SDI (SPI data in) |
| Pin 22 | RC5 β PORTC bit 5 / SDO (SPI data out) |
| Pin 23 | RC6 β PORTC bit 6 / TX (USART asynchronous transmit) |
| Pin 24 | RC7 β PORTC bit 7 / RX (USART asynchronous receive) |
| Pin 25 | VSS β Ground reference |
| Pin 26 | VDD β Positive supply voltage (4V-6V) |
| Pin 27 | RA0 β PORTA bit 0 (digital I/O or analog input AN0) |
| Pin 28 | RA1 β PORTA bit 1 (digital I/O or analog input AN1) |
Typical Applications
PIC16C642T-04I/SO is suitable for 8 applications: White Goods Appliance Control, Security Keypad and Access Controller, HVAC Thermostat Controller, Industrial Sensor Hub Node, Automotive Interior Accessories, Consumer Remote Control and IR Decoder, Vending Machine Payment Terminal, Simple LED Display and Sign Controller.
White Goods Appliance Control
The PIC16C642T-04I/SO fits washing-machine, dishwasher, and microwave-oven control boards because its 22 I/O pins can directly drive 7-segment displays, keypads, and relay triacs without external mux logic. Its 7KB OTP memory holds the full state-machine firmware (cycle selection, sensor polling, fault handling) at a lower per-unit cost than Flash MCUs, and the 4 MHz clock is more than sufficient for sub-millisecond loop rates. The 5 V supply tolerance (4 V-6 V) tolerates rectified mains-rail ripple without brown-out. No firmware updates are ever needed in the field, so OTP matches the appliance lifecycle exactly - once programmed, the firmware is locked for the 10-15 year product lifetime.
Recommended
Security Keypad and Access Controller
The PIC16C642T-04I/SO is ideal for 4x4 matrix-keypad door-entry controllers, RFID-tag readers, and PIN-pad access terminals. Its 22 I/O pins directly scan 16 keys via 8 GPIO pins plus an interrupt-driven 4x4 matrix, while a UART channel drives a 9600 baud link to the central controller. The 7KB OTP program memory holds encrypted credential tables, lockout state machines, and Wiegand output framing. The Industrial -40C to +85C grade tolerates outdoor enclosures across North American and European climates. The 4 MHz execution rate ensures sub-100 ms PIN-entry response, satisfying human-perceived latency requirements for door strikes and mag-locks.
Recommended
HVAC Thermostat Controller
The PIC16C642T-04I/SO controls low-end wall-mount thermostats for HVAC systems, where cost dominates over firmware flexibility. Its 8-bit ADC digitizes thermistor or RTD temperature sensors at 10-bit effective resolution, while 22 I/O lines drive the LCD, push-buttons, and relay outputs for compressor, fan, and heat-pump reversing valve. The 7KB OTP holds PI control loops, hysteresis state machines, and weekly scheduling tables. Industrial temperature grade handles attic and equipment-room mounting, and 4V-6V supply accepts 24 VAC wall-power transformer rails via half-wave rectification. No field update is expected - thermostat firmware is final at factory programming.
Recommended
Industrial Sensor Hub Node
The PIC16C642T-04I/SO serves as a low-cost 4-20 mA loop-powered sensor hub aggregating multiple transducer signals in factory automation panels. Its 8-bit ADC scans up to 8 analog channels while the USART streams processed values to a PLC over RS-485 at 19200 baud. The 4 MHz clock provides 10 Hz per-channel sample rates, sufficient for temperature, pressure, and flow metering. Industrial -40C to +85C operation tolerates cabinet mounting near motors and drives. OTP firmware locks calibration coefficients permanently, preventing accidental field-tampering with measurement integrity - a key reason OTPs remain favored over Flash in regulated process industries.
Recommended
Automotive Interior Accessories
The PIC16C642T-04I/SO is used in cost-sensitive automotive interior modules such as dome-light controllers, mirror-adjust switches, seat-position memories, and basic instrument-cluster sub-displays. The 22 GPIO pins drive LED banks, switches, and CAN/LIN transceivers, while the 7KB OTP holds fixed function logic without in-field update risk. The 5 V tolerance directly interfaces 12 V battery rails via simple LDO regulators. The industrial -40C to +85C grade is acceptable for cabin locations (not under-hood). The 4 MHz clock executes button-debounce, PWM LED dimming, and serial-message handling within real-time automotive network latencies.
Recommended
Consumer Remote Control and IR Decoder
The PIC16C642T-04I/SO serves in universal TV/STB remote controls and IR-receiver decoder modules. The 22 GPIO pins drive IR LED transmitters, push-button matrices, and LED status indicators, while the Capture input on the CCP module decodes 38 kHz carrier-modulated RC5 or NEC protocols. 7KB OTP holds dozens of device code-tables, key-scanning logic, and battery-low detection firmware. The 4 MHz clock provides accurate 38 kHz PWM generation with sub-2% duty-cycle tolerance, ensuring reliable IR transmission across 8-10 meter ranges. Industrial temperature grade accommodates indoor thermal swings near windows and entertainment centers.
Recommended
Vending Machine Payment Terminal
The PIC16C642T-04I/SO controls legacy vending-machine coin acceptors, bill validators, and selection-keypad interfaces. Its 22 I/O lines handle pulse counting from coin acceptors, parallel data from bill validators, and multiplexed selection switches. The 7KB OTP stores currency-denomination tables and audit-log protocols, while the USART streams MDB (Multi-Drop Bus) traffic to the central vending controller. Industrial -40C to +85C grade tolerates outdoor cabinet mounting in direct sunlight. The 4 MHz clock handles multi-tasking between acceptor polling, display driving, and serial communications within the 50-100 ms response budget required by vending standards.
Recommended
Simple LED Display and Sign Controller
The PIC16C642T-04I/SO controls scrolling LED message boards, traffic-warning signs, and small matrix displays. Its 22 GPIO pins drive 8x8 matrix rows plus column-driver shift registers via SPI, while PWM outputs dim LEDs for brightness control. 7KB OTP holds font tables, scrolling algorithms, and message-storage state machines. The 4 MHz clock generates 100 Hz PWM refresh rates above the flicker-fusion threshold. Industrial -40C to +85C tolerance supports outdoor sign enclosures. OTP firmware locks display content rules and prevents unauthorized message injection - a regulatory requirement for traffic and public-safety signs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C642T-04I/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C642-04I/SO | PIC16C642-04/SO | PIC16C642-04E/SP | PIC16C63A-04I/SO | PIC16F84A-04I/SO |
|---|---|---|---|---|---|---|
| Package | 28-SOIC (0.295 inch) | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP EPROM (7 KB) | OTP EPROM (7 KB) | OTP EPROM (7 KB) | OTP EPROM (7 KB) | OTP EPROM (4 KB) | Flash (1.75 KB) |
| RAM Size | 176 bytes | 176 bytes | 176 bytes | 176 bytes | 192 bytes (+9%) | 68 bytes (-61%) |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 13 (-41%) |
| Temperature Grade | Industrial -40C to +85C | Industrial -40C to +85C | Commercial 0C to +70C | Extended -40C to +125C | Industrial -40C to +85C | Industrial -40C to +85C |
| Supply Voltage | 4 V to 6 V | 4 V to 6 V | 4 V to 6 V | 4 V to 6 V | 4 V to 6 V | 2 V to 6 V (wider) |
Key Differentiators
- Largest OTP program memory in PIC16C6xx 28-pin family (vs PIC16C622A-04I/SO)
- Flash reprogrammability for design flexibility (vs PIC16F84A-04I/SO)
- Higher RAM and faster execution for protocol stacks (vs PIC16C63A-04I/SO)
Design Notes
Estimated: The PIC16C642T-04I/SO typical active current at 4 MHz / 5 V is approximately 2-5 mA (per Microchip PIC16C6x datasheet typical characteristics) plus 0.5 mA per active I/O driver. Decouple VDD (pin 26) with a 100 nF ceramic capacitor placed within 5 mm of the pin, plus a bulk 10 uF tantalum or aluminum electrolytic capacitor on the supply rail. Multiple VSS pins (5, 14, 25) must all be connected to the ground plane to share return current. Brown-out detection is recommended via external voltage supervisor (e.g., MCP100) for supply rails subject to motor inrush transients.
Route the 4 MHz crystal traces (OSC1/OSC2, pins 15-16) as short as possible with a continuous ground plane beneath them; keep crystal case grounded to the ground plane via a short bond. Place the MCLR reset pull-up resistor (typically 10 kOhm) close to pin 4 to minimize noise injection. Avoid routing high-frequency digital signals (PORTB interrupt lines, USART) parallel to the crystal traces to prevent coupling. For noise-sensitive analog inputs (RA0-RA5), separate analog and digital ground returns at a single star point near the MCU VSS pin.
OTP memory cannot be erased or rewritten - any firmware bug in the production image becomes a permanent defect and triggers component-level scrap. Validate firmware exhaustively on Flash-equivalent PIC16F parts or PIC16C JW (windowed) versions before committing to OTP production. The CP (code-protect) fuse, once enabled, disables further verification of program memory - verify code before blowing the fuse. Watchdog timer (WDT) must be enabled in fuse configuration for unattended operation, otherwise firmware lockup can hang the appliance without recovery.
The USART (RC6/RC7) and SSP (RC3/RC4) signals swing at CMOS levels with rise-times around 10-20 ns at 4 MHz oscillator - keep traces under 50 mm and add 33 ohm series resistors for traces longer than 25 mm to dampen ringing. The PORTB interrupt-on-change feature (RB4-RB7) is sensitive to noise; add 10 kohm pull-ups and 100 nF filter caps on RB4-RB7 if they are used as wake-up sources in SLEEP mode. The CCP1 PWM output on RC2 supports up to 10-bit resolution at 4 MHz - keep load capacitance below 50 pF for clean edges.
Compliance Information
RoHS compliance confirmed by 3achips and Microchip USA distributor listings. The 'I' suffix confirms Industrial temperature grade (-40C to +85C); the part is NOT AEC-Q100 qualified - automotive designs should evaluate PIC16F628 or PIC18F K-line successors instead.