PIC16C642-20/SO - 8-bit OTP MCU 7KB EPROM 22 I/O | Microchip
MPN: PIC16C642-20/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.45 | $7.45 |
| 10 | $6.7 | $67.00 |
| 100 | $5.95 | $595.00 |
| 500 | $5.3 | $2,650.00 |
| 1,000 | $4.85 | $4,850.00 |
PIC16C642-20/SO Overview
What is a PIC16C-series 8-bit microcontroller? The PIC16C family is Microchip's classic mid-range OTP (One-Time Programmable) microcontroller line, based on a RISC Harvard architecture with a small instruction set of only 35 single-word instructions. In the broader taxonomy: 8-bit microcontroller -> RISC MCU -> mid-range MCU -> PIC16C family -> embedded microcontroller. Each instruction completes in one instruction cycle (four clock periods), giving deterministic 200 ns execution at 20 MHz, and the architecture separates program and data buses so that program fetch and data access can overlap.
Key features of the PIC16C642-20/SO include: two on-chip analog comparators, a Brown-out Reset (BOR) circuit, a Watchdog Timer (WDT) with its own on-chip RC oscillator, power-saving SLEEP mode, and programmable code protection. The 22 I/O pins can be individually configured for digital input or output. An external oscillator is required (crystal, resonator, or RC), giving the designer flexibility over accuracy, cost, and start-up time versus the internal oscillator variants found on later PIC16F families.
Typical applications include appliance controls, simple sensor interfaces, low-cost motor control, automotive body electronics (non-safety), industrial control panels, and white-goods user interfaces. The 4-6 V operating range is compatible with 5 V regulated rails, and the 22 I/O count is enough to drive keypads, LED or LCD indicator panels, and a handful of analog signals via the on-chip comparators.
When designing in the PIC16C642-20/SO, remember that OTP memory cannot be erased - firmware must be correct on the first programming. The wide-body SOIC package is convenient for hand-prototyping and through-hole adapter boards, but for volume production the PIC16F equivalent with Flash memory is usually preferred. Always include decoupling (100 nF plus 10 uF) close to VDD/VSS and follow Microchip's recommended oscillator layout to avoid start-up failures. This page synthesizes distributor pricing, package-equivalent drop-in alternatives, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for PIC16C642-20/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 PIC16C642-20/SO (same form factor and footprint) — differing in Core Architecture, Program Memory Size, Program Memory Type, RAM Size, Maximum Clock Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C642-20I/SO
✅ Drop-In✓ In Stock
$2.3 / Unit
View Datasheet →PIC16C642-10/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C642-04/SO
✅ Drop-In✓ In Stock
$4.3 / Unit
View Datasheet →PIC16C642-20E/SO
✅ Drop-In✓ In Stock
$5.2 / Unit
View Datasheet →PIC16C622-20I/SO
✅ Drop-In✓ In Stock
$2.2 / Unit
View Datasheet →PIC16C642T-20I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C642-20/SO Maximum Ratings & Electrical Characteristics
| Core Processor | PIC |
| Core Size | 8-bit |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 7 KB (4K x 14) |
| RAM Size | 176 x 8 bytes |
| Number of I/O | 22 |
| Clock Speed | 20 MHz (max) |
| Instruction Execution Time | 200 ns |
| Number of Instructions | 35 single-word |
| Supply Voltage (Vcc/Vdd) | 4 V to 6 V |
| Oscillator Type | External |
| Package / Case | 28-SOIC (0.295 inch / 7.50 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature | 0 C to +70 C (commercial, /SO suffix) |
| Peripherals | Brown-out Detect, Watchdog Timer, 2 Analog Comparators |
| Connectivity | - |
| Data Converters | - |
PIC16C642-20/SO Pin Configuration
| Pin 1 | RA2/AN2 — Port A bit 2 / analog comparator input 2 |
| Pin 2 | RA3/AN3 — Port A bit 3 / analog comparator input 3 |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | RA5/AN4 — Port A bit 5 / analog comparator input 4 / SS |
| Pin 5 | GND — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt input |
| Pin 7 | RB1 — Port B bit 1 |
| Pin 8 | RB2 — Port B bit 2 |
| Pin 9 | RB3 — Port B bit 3 |
| Pin 10 | RB4 — Port B bit 4 |
| Pin 11 | RB5 — Port B bit 5 |
| Pin 12 | RB6 — Port B bit 6 |
| Pin 13 | RB7 — Port B bit 7 |
| Pin 14 | VDD — Positive supply (4 V to 6 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 16 | OSC1/CLKIN — Oscillator input / clock in |
| Pin 17 | RA0/AN0 — Port A bit 0 / analog comparator input 0 |
| Pin 18 | RA1/AN1 — Port A bit 1 / analog comparator input 1 |
| Pin 19 | RC0 — Port C bit 0 |
| Pin 20 | RC1 — Port C bit 1 |
| Pin 21 | RC2 — Port C bit 2 |
| Pin 22 | RC3 — Port C bit 3 |
| Pin 23 | RC4 — Port C bit 4 |
| Pin 24 | RC5 — Port C bit 5 |
| Pin 25 | RC6 — Port C bit 6 |
| Pin 26 | RC7 — Port C bit 7 |
| Pin 27 | GND — Ground reference (substrate tie) |
| Pin 28 | VDD — Positive supply (substrate tie) |
Typical Applications
PIC16C642-20/SO is suitable for 7 applications: Appliance Control Boards, Industrial Sensor Interface Modules, Automotive Body Electronics (Non-Safety), White-Goods User Interface Panels, HVAC Control Modules, Low-Cost Motor Control (BLDC / Stepper), Security and Access-Control Keypads.
Appliance Control Boards
The PIC16C642-20/SO fits appliance control boards thanks to its 22 I/O pins, 5 V operation, and 7 KB OTP program memory which holds appliance state machines (wash cycles, fan speeds, timer logic) with comfortable headroom. The 200 ns instruction cycle at 20 MHz easily drives keypad scan loops, LED multiplexing, and triac zero-crossing timing. The on-chip Brown-out Reset holds the MCU below 4 V to prevent EPROM corruption on brown-outs in mains-rail-powered boards. Two analog comparators handle sensor thresholds (water level, temperature NTC) without an external op-amp.
Recommended
Industrial Sensor Interface Modules
For industrial sensor-interface modules, the PIC16C642-20/SO's two analog comparators and 22 I/O let a single chip read multiple threshold sensors (level, pressure, proximity) and drive indicator LEDs or relays. The 4-6 V supply range tolerates regulated 5 V industrial rails, and the Watchdog Timer recovers the MCU from firmware lock-ups caused by EMI on long sensor cables. Industrial -40 to +85 C variants (PIC16C642-20I/SO) extend deployment to outdoor enclosures and unheated cabinets.
Recommended
Automotive Body Electronics (Non-Safety)
The PIC16C642-20/SO is widely used in non-safety automotive body electronics such as interior lighting controllers, mirror-adjust modules, and seat-position memories. Its 22 I/O drive multiple LED strings and H-bridge enable lines, while the 5 V operation and built-in Brown-out Reset ride through cranking transients on 12 V vehicle buses when paired with a 5 V regulator. The on-chip Watchdog Timer is essential for meeting automotive EMI robustness expectations, and the 28-SOIC package is well-suited to conformal-coated under-dash PCBAs.
Recommended
White-Goods User Interface Panels
White-goods UI panels (washing machines, dishwashers, ovens) use the PIC16C642-20/SO to scan 4x4 or 5x5 keypads and drive 7-segment or LCD indicator displays. The 22 I/O accommodate up to 20 key matrix points plus 2 to 4 display-driver lines, and the 20 MHz instruction rate keeps scan latency below 20 ms (per IEC 60335 UX guidance). OTP memory prevents field firmware tampering and reduces production cost relative to Flash equivalents when the firmware is mature and stable.
Recommended
HVAC Control Modules
HVAC control modules benefit from the PIC16C642-20/SO's 22 I/O, two analog comparators (for thermostat trip thresholds), and 7 KB OTP program memory that stores mode state machines (heat/cool/fan/auto) and EEPROM-emulated user settings. The 4-6 V supply rails directly off 5 V wall-adapter or 24 VAC-derived DC supplies. The 200 ns instruction cycle is fast enough to drive PWM outputs for triac phase-angle control of blower motors at 50/60 Hz line frequencies.
Recommended
Low-Cost Motor Control (BLDC / Stepper)
The PIC16C642-20/SO controls small brushless DC or bipolar stepper motors in pumps, fans, and small appliances, using its 22 I/O to drive 6-MOSFET three-phase bridges (high/low pairs) and 20 MHz throughput to generate 50 us commutation steps at moderate RPMs. The on-chip comparators provide back-EMF zero-crossing detection for sensorless BLDC trapezoidal commutation. The Brown-out Reset and Watchdog Timer ensure safe stop on undervoltage or firmware fault conditions.
Recommended
Security and Access-Control Keypads
Access-control keypads and simple alarm panels use the PIC16C642-20/SO to scan matrix keypads (3x4 or 4x4), debounce mechanical switches, validate PIN codes against the 7 KB OTP firmware, and drive relay or buzzer outputs on entry/exit events. The 22 I/O cover keypad rows/columns plus 4 to 6 status LEDs and a magnetic-door sensor input. OTP memory prevents code extraction via in-circuit programming attacks - a security advantage over Flash in low-cost access-control products.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C642-20/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C642-20I/SO | PIC16C642-10/SO | PIC16C642-04/SO | PIC16C642-20E/SO | PIC16C622-20I/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (7.50 mm) | 28-SOIC (7.50 mm) - same | 28-SOIC (7.50 mm) - same | 28-SOIC (7.50 mm) - same | 28-SOIC (7.50 mm) - same | 28-SOIC (7.50 mm) - same |
| Program Memory | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 3.5 KB OTP |
| RAM | 176 bytes | 176 bytes | 176 bytes | 176 bytes | 176 bytes | 128 bytes |
| Max Clock Speed | 20 MHz | 20 MHz | 10 MHz | 4 MHz | 20 MHz | 20 MHz |
| Number of I/O | 22 | 22 | 22 | 22 | 22 | 22 |
| Operating Temperature | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C | 0 C to +70 C | -40 C to +125 C | -40 C to +85 C |
| Analog Comparators | 2 | 2 | 2 | 2 | 2 | 2 |
| Memory Type | OTP (One-Time Programmable) | OTP | OTP | OTP | OTP | OTP |
Key Differentiators
- Higher throughput at same price point vs slower OTP siblings (vs PIC16C642-04/SO)
- Wider memory map than the PIC16C622 family (vs PIC16C622-20I/SO)
- Industrial temperature option without re-laying out the PCB (vs PIC16C642-20I/SO)
Design Notes
The PIC16C642-20/SO operates from a single 4 V to 6 V VDD. Place a 100 nF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 14) and a bulk 10 uF tantalum or aluminum electrolytic capacitor at the board power entry. The Brown-out Reset (BOR) holds the part in reset below ~4 V; design the upstream 5 V regulator to maintain VDD above the BOR threshold even at the minimum specified mains input. Add a TVS diode (e.g., 6.8 V) on VDD for industrial transient protection.
The 28-SOIC package is a wide-body 7.50 mm footprint with 1.27 mm pin pitch. Route all signal traces on the top layer with a continuous ground pour on the bottom layer; keep the OSC1/OSC2 traces short (under 10 mm) and surround them with ground pour to prevent crosstalk into the oscillator. The MCLR pin (not present in this OTP variant, internally tied) is not required, but reserve a 100 kohm pull-down footprint in case code-protection unlock is needed in production.
Because the PIC16C642 uses OTP memory, firmware errors cannot be corrected in-circuit. Always validate firmware on a Flash-based equivalent (PIC16F88, PIC16F628A) or on a windowed CERDIP variant (PIC16C642-20/JW) before committing the OTP order. The 22 I/O pins are shared with analog inputs and oscillator functions - misconfiguration of the PCON or TRIS registers can lock out the device. Always use Microchip's MPASM/MPLAB X IDE and the device programmer to verify configuration bits match your design.
OSC1 is the high-impedance clock input and is sensitive to noise coupling; keep the crystal or resonator within 10 mm of pins 15-16 and use a ground guard ring around the oscillator network. For 20 MHz operation, use a fundamental-mode crystal with 20 pF load capacitors, not an overtone crystal. If long cable connections to RB0/INT (pin 6) or RC ports are used in noisy environments, add a 100 pF capacitor and 10 kohm resistor in series to the input to form a hardware debounce/low-pass filter.
Compliance Information
Compliance status not stated in verified data. The /SO wide-body package is lead-finish, but Microchip generally ships /SO parts as matte-tin Pb-free for commercial temperature grade. The /I suffix designates industrial temperature and does not change lead-finish. AEC-Q100 not applicable since this is a commercial/industrial 8-bit MCU without explicit automotive qualification.