PIC16C642-04/SO - 4MHz 8-bit OTP MCU, 7KB Flash, 22 I/O | Microchip
MPN: PIC16C642-04/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.45 | $6.45 |
| 10 | $5.95 | $59.50 |
| 100 | $5.4 | $540.00 |
| 500 | $4.85 | $2,425.00 |
| 1,000 | $4.3 | $4,300.00 |
PIC16C642-04/SO Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program and data memory, and programmable I/O peripherals. The PIC16C642 belongs to the PIC16C family of OTP-based 8-bit microcontrollers, which sit at the entry level of the PIC architecture hierarchy: MCU -> 8-bit MCU -> PIC16 family -> PIC16C sub-family. These MCUs use a RISC (Reduced Instruction Set Computer) architecture that executes most instructions in a single 200 ns instruction cycle (with program branches taking two cycles).
Key features of the PIC16C642 include 35 single-word instructions for fast code development, a wide 4V to 5.5V supply voltage range, integrated Brown-out Reset (BOR) and Power-on Reset (POR), an external oscillator interface, and 22 general-purpose I/O pins. The device is offered in commercial and industrial temperature grades.
The 8-bit RISC core uses a Harvard architecture with separate program and data buses. Code is executed from OTP program memory; the 176-byte RAM provides data storage. This older-generation OTP architecture is suitable for cost-sensitive embedded applications that require code security (one-time programming prevents firmware readout) and low per-unit cost.
Typical applications include appliance controls, simple sensor interfaces, hobby and educational projects, and low-volume industrial controllers. Modern designs often migrate to flash-based PIC16F equivalents for reprogrammability. When designing with this part, ensure the chosen oscillator crystal or external clock meets the 4 MHz maximum, and follow Microchip's in-circuit serial programming (ICSP) guidelines for OTP programming. This page synthesizes distributor pricing, parametric specifications, and pin-compatible alternatives from Microchip's PIC16C lineup not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C642-04/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 PIC16C642-04/SO (same form factor and footprint) — differing in Program Memory Type, Package, Timers, Program Memory Size, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C622A-04I/SO
✅ Drop-In✓ In Stock
$2.72 / Unit
View Datasheet →PIC16C621A-04I/SO
✅ Drop-In✓ In Stock
$1.98 / Unit
View Datasheet →PIC16C620A-04I/SO
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →PIC16F648A-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C642-04E/SO
✅ Drop-In✓ In Stock
$3.62 / Unit
View Datasheet →PIC16C642-04/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Core Size | 8-bit |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns |
| Program Memory Size | 7 KB (4K x 14) |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Data RAM Size | 176 x 8 bytes |
| Number of I/O Pins | 22 |
| Supply Voltage Range | 4 V to 5.5 V |
| Oscillator Type | External |
| Brown-out Reset | Yes |
| Power-on Reset | Yes |
| Package Type | SOIC-28 (SO), 7.50 mm body width |
| Mounting Type | Surface Mount |
| Instruction Set | 35 single-word instructions |
| Lifecycle Stage | ACTIVE |
PIC16C642-04/SO Pin Configuration
| Pin 1 | RA2 — PORTA I/O bit 2 / AN2 analog input |
| Pin 2 | RA3 — PORTA I/O bit 3 / AN3 analog input |
| Pin 3 | RA4 — PORTA I/O bit 4 / T0CKI timer0 clock input |
| Pin 4 | RA5 — PORTA I/O bit 5 / AN4 analog input / SS |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — PORTB I/O bit 0 / INT external interrupt |
| Pin 7 | RB1 — PORTB I/O bit 1 |
| Pin 8 | RB2 — PORTB I/O bit 2 |
| Pin 9 | RB3 — PORTB I/O bit 3 |
| Pin 10 | RB4 — PORTB I/O bit 4 |
| Pin 11 | RB5 — PORTB I/O bit 5 |
| Pin 12 | RB6 — PORTB I/O bit 6 / PGC ICSP clock |
| Pin 13 | RB7 — PORTB I/O bit 7 / PGD ICSP data |
| Pin 14 | VSS — Ground reference |
| Pin 15 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 16 | OSC2/CLKOUT — Oscillator crystal output / clock output |
| Pin 17 | RC0 — PORTC I/O bit 0 |
| Pin 18 | RC1 — PORTC I/O bit 1 |
| Pin 19 | RC2 — PORTC I/O bit 2 |
| Pin 20 | RC3 — PORTC I/O bit 3 |
| Pin 21 | RC4 — PORTC I/O bit 4 |
| Pin 22 | RC5 — PORTC I/O bit 5 |
| Pin 23 | RC6 — PORTC I/O bit 6 |
| Pin 24 | RC7 — PORTC I/O bit 7 |
| Pin 25 | VSS — Ground reference |
| Pin 26 | VDD — Positive supply voltage (4V to 5.5V) |
| Pin 27 | RA0 — PORTA I/O bit 0 / AN0 analog input |
| Pin 28 | RA1 — PORTA I/O bit 1 / AN1 analog input |
Typical Applications
PIC16C642-04/SO is suitable for 7 applications: Appliance Control Systems, Industrial Sensor Interfaces, Hobby and Educational Electronics, LED Display and Signage Controllers, Remote Control and RF Encoders, Automotive Interior Electronics (Legacy), Battery Charger Controllers (Simple).
Appliance Control Systems
The PIC16C642-04/SO fits appliance control applications where OTP firmware security and low per-unit cost outweigh reprogrammability. With 7 KB of program memory and 22 I/O pins, the MCU can drive relays, read keypad inputs, multiplex LED or seven-segment displays, and interface with sensors for washing machines, microwave ovens, and HVAC controllers. The 4 MHz clock is sufficient for typical control loops at 1-10 ms response times. Brown-out Reset ensures clean recovery from supply glitches common in motor-driven loads. Migration to flash-based PIC16F648A is straightforward if field updates become necessary.
Recommended
Industrial Sensor Interfaces
The PIC16C642-04/SO suits simple industrial sensor interfaces requiring analog signal conditioning, threshold detection, and digital output. With 22 I/O pins, the MCU can interface multiple digital sensors, drive indicator LEDs, communicate via UART to a host controller, and implement simple state machines. The 4 MHz clock provides adequate throughput for polling sensor arrays at 100 Hz-1 kHz rates. The 176-byte RAM is sufficient for buffering readings and the 7 KB OTP holds calibration tables and protocol stacks. Industrial-grade temperature versions support factory automation environments.
Recommended
Hobby and Educational Electronics
The PIC16C642-04/SO is widely used in hobby projects, maker platforms, and educational electronics courses teaching embedded programming fundamentals. The 35-instruction RISC architecture is simple enough for beginners to learn assembly language within a single semester, while the 7 KB OTP holds substantial student projects including PWM motor control, LCD interfacing, and basic communication protocols. The 4 MHz clock simplifies timing calculations. Programming via Microchip's ICSP interface using PICkit programmers is straightforward, and the SOIC-28 package fits standard breadboard breakout boards.
Recommended
LED Display and Signage Controllers
The PIC16C642-04/SO drives LED matrix displays, scrolling signs, and simple alphanumeric indicators. With 22 I/O pins, the MCU can drive 8x8 LED matrices directly using charlieplexing or shift register expansion for larger displays. The 4 MHz instruction rate provides enough throughput for multiplexing 8-16 digit displays at 100+ Hz refresh rates without visible flicker. The 7 KB OTP stores font tables and animation sequences. Brown-out Reset prevents display corruption during power dips. Commercial temperature grade suits indoor signage applications.
Recommended
Remote Control and RF Encoders
The PIC16C642-04/SO is used in simple RF remote control transmitters and IR encoder applications. With 22 I/O pins, the MCU can read multiple button inputs, encode them into protocols like Manchester or PWM-modulated signals, and drive an RF transmitter module or IR LED. The 4 MHz clock provides precise timing for sub-microsecond pulse generation needed for 38 kHz IR carrier modulation. The 176-byte RAM handles button debounce buffers and protocol state. Low power consumption makes it suitable for battery-powered remote controls.
Recommended
Automotive Interior Electronics (Legacy)
The PIC16C642-04/SO extended-temperature grade variant (-04E/SO) is suitable for non-safety automotive interior applications such as simple dashboard indicators, lighting controllers, and HVAC auxiliary controls. The wide operating temperature range (-40C to +125C) handles cabin and under-dash thermal conditions. The 22 I/O pins drive LED indicators, switches, and small relays. The 7 KB OTP holds diagnostic logic and switch debouncing code. Modern designs typically migrate to AEC-Q100-qualified flash-based PIC MCUs, but the PIC16C642 family remains in legacy automotive product lines.
Recommended
Battery Charger Controllers (Simple)
The PIC16C642-04/SO implements simple battery charger controllers for lead-acid, NiMH, and Li-ion packs below 1C charge rates. With 22 I/O pins, the MCU monitors voltage and current via ADC channels, drives MOSFET switches through PWM, and implements charge termination algorithms (delta-V, timer, temperature). The 4 MHz clock is sufficient for switching frequencies up to 20 kHz. The 7 KB OTP stores charge profile tables and safety logic. Brown-out Reset prevents incorrect charging state on power-up. Commercial-grade parts suit consumer chargers; industrial variants serve backup power systems.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C642-04/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C622A-04I/SO | PIC16C621A-04I/SO | PIC16C620A-04I/SO | PIC16F648A-I/SS | PIC16C642-04E/SO |
|---|---|---|---|---|---|---|
| Package | SOIC-28 | SOIC-28 | SOIC-28 | SOIC-28 | SSOP-28 | SOIC-28 |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 7 KB (4K x 14) OTP | 3.5 KB OTP | 1.75 KB OTP | 0.875 KB OTP | 7 KB Flash | 7 KB (4K x 14) OTP |
| Maximum Clock | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz (with internal osc 4 MHz) | 4 MHz |
| RAM Size | 176 bytes | 128 bytes | 80 bytes | 80 bytes | 256 bytes | 176 bytes |
| I/O Pins | 22 | 22 | 13 | 13 | 22 | 22 |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash | OTP EPROM |
| Operating Temperature | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +125C (extended) |
| Supply Voltage | 4.0V to 5.5V | 2.5V to 5.5V (extended range parts) | 2.5V to 5.5V (extended range parts) | 2.5V to 5.5V (extended range parts) | 2.0V to 5.5V | 4.0V to 5.5V |
Key Differentiators
- Larger program memory in the PIC16C62x family (vs PIC16C622A-04I/SO)
- Reprogrammable flash memory (vs PIC16F648A-I/SS)
- Full I/O count preserved (vs PIC16C621A-04I/SO)
- Extended temperature grade option (vs PIC16C642-04E/SO)
Design Notes
Place a 100 nF decoupling capacitor as close as possible to the VDD pin (pin 26) and a 10 uF bulk capacitor on the supply rail to suppress switching noise. The PIC16C642-04/SO has multiple VSS pins (5, 14, 25) - connect ALL of them to the ground plane for proper thermal and electrical performance. The integrated Brown-out Reset (BOR) and Power-on Reset (POR) eliminate the need for an external reset supervisor in most designs.
Route the OSC1/OSC2 traces short and symmetric when using a crystal oscillator, keeping them away from high-current switching traces to minimize EMI coupling. Place load capacitors (typically 15-33 pF for 4 MHz crystals) adjacent to the crystal pins. If using an external clock source, the OSC1 pin is the clock input and OSC2 can be left floating per the Microchip datasheet. The 28-SOIC package requires standard reflow profiles (peak 250-260C).
Do not exceed the 4 MHz maximum clock frequency for the PIC16C642-04 speed grade - higher clock requires the -10 or -20 variant. OTP (One-Time Programmable) memory cannot be erased - verify your firmware thoroughly using a flash-equivalent emulator or development part (PIC16F648A with same pinout) before committing to OTP programming. The configuration word (oscillator selection, watchdog timer, BOR enable) MUST be programmed correctly or the part may appear dead.
When driving LEDs or relays directly from PORTB or PORTC pins, ensure total pin current stays within the 25 mA per-pin and 200 mA per-port limits specified in the datasheet. For higher drive requirements, use a MOSFET driver like the MCP1407 or TPIC6B595 shift register. PORTB pins have weak internal pull-ups that can be enabled in software - useful for keypad scanning without external resistors. Analog inputs (RA0-RA5) require the A/D converter to be configured properly or they may inject noise into digital operations.
Compliance Information
RoHS and REACH compliant per Microchip product environmental compliance information. Not AEC-Q100 qualified - choose PIC16C642-04E/SO for extended temperature, or AEC-Q100-qualified PIC16F variants for automotive safety applications.
