PIC16C558-20/SO - 8-Bit 20MHz 3.5KB OTP MCU 18-SOIC | Microchip
MPN: PIC16C558-20/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.18 | $3.18 |
| 10 | $2.85 | $28.50 |
| 100 | $2.55 | $255.00 |
| 500 | $2.28 | $1,140.00 |
| 1,000 | $2.05 | $2,050.00 |
PIC16C558-20/SO Overview
An 8-bit OTP microcontroller is a small single-chip computer built around an 8-bit data path with non-volatile program memory that can be written exactly once (One-Time-Programmable), commonly used in low-cost, high-volume products. PIC microcontrollers belong to the broader family of microcontrollers -> embedded processors -> semiconductors, and the PIC16C series specifically targets mid-range applications requiring moderate I/O count (13-33 pins), modest memory (a few KB), and deterministic real-time response.
Key features of the PIC16C558-20/SO include a Harvard architecture with separate program and data buses, 8-level hardware stack, integrated power-on reset, brown-out reset, watchdog timer, and an 8-bit timer/counter. The 18-pin SOIC package provides 13 digital I/O pins, each capable of sinking/sourceing up to 25 mA, plus dedicated oscillator and reset pins. The CMOS process yields low power consumption suitable for battery-operated or line-powered industrial equipment.
The PIC16C558 uses a RISC instruction set where all 35 instructions are single-word (14-bit) and execute in a single instruction cycle (4 clock periods), giving 5 MIPS throughput at 20MHz. The OTP program memory allows code to be written during manufacturing test, ideal for mature products. The architecture's deterministic interrupt response and hardware stack simplify real-time control loops common in appliance, sensor, and motor-driver subsystems.
Typical applications include automotive body controllers, industrial sensor interfaces, consumer white goods, security keypads, low-end motor control, LED driver controllers, and battery chargers. The wide operating voltage (3.0V-5.5V) makes it compatible with both 3.3V and 5V system rails commonly found in legacy industrial designs. The 18-pin SOIC package also supports through-hole PCB reflow assembly.
When designing with the PIC16C558-20/SO, select the appropriate oscillator mode (XT, HS, LP, or RC) based on system clock requirements and EMI constraints. Note that OTP memory cannot be reprogrammed, so engineering samples should use windowed (JW) or Flash (PIC16F) variants during development.
This page synthesizes distributor pricing, pin-compatible PIC16C5x drop-in alternatives, and practical design notes not aggregated on the manufacturer datasheet or individual distributor pages.
Drop-in alternatives for PIC16C558-20/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 PIC16C558-20/SO (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, RoHS Status, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-20I/SO
✅ Drop-In✓ In Stock
$1.2 / Unit
View Datasheet →PIC16C558-20/P
✅ Drop-In✓ In Stock
$1.72 / Unit
View Datasheet →PIC16C558-04I/SO
✅ Drop-In✓ In Stock
$3.11 / Unit
View Datasheet →PIC16F558
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C554-20/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558-20/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Program Memory Type | OTP (One-Time-Programmable) EPROM |
| Program Memory Size | 3.5 KB (2K x 14) |
| RAM Size | 128 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Execution Time | 200 ns (single cycle, 4 clocks per instruction) |
| Number of Instructions | 35 (single-word, 14-bit) |
| I/O Pins | 13 |
| Data EEPROM | Not present (OTP only) |
| Timers | 1 x 8-bit Timer/Counter |
| Operating Voltage Range | 3.0 V to 5.5 V |
| Operating Temperature Range | -40C to +85C (industrial) |
| Package | 18-pin SOIC (SO, 0.295 inch / 7.50 mm width) |
| Mounting Type | Surface Mount |
| I/O Sink/Source Current | 25 mA per pin |
| Brown-out Reset | Yes |
| Watchdog Timer | Yes |
| Power-on Reset | Yes |
| RoHS Status | Compliant (lead-free SO package) |
PIC16C558-20/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin; Port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O pin; Port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / Timer0 clock input |
| Pin 4 | MCLR/VPP — Master Clear reset input / Programming voltage |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O / External interrupt input |
| Pin 7 | RB1 — Bidirectional I/O pin; Port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O pin; Port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O pin; Port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O pin; Port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O pin; Port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O pin; Port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O pin; Port B bit 7 |
| Pin 14 | VDD — Positive supply voltage (3.0V to 5.5V) |
| Pin 15 | OSC2/CLKOUT — Oscillator crystal output / Clock output |
| Pin 16 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 17 | RA0 — Bidirectional I/O pin; Port A bit 0 |
| Pin 18 | RA1 — Bidirectional I/O pin; Port A bit 1 |
Typical Applications
PIC16C558-20/SO is suitable for 6 applications: Automotive Body Controllers, Industrial Sensor Interfaces, Consumer White Goods Controllers, Security Keypad and Access Controllers, LED Lighting and Sign Controllers, Battery Chargers and Power Management.
Automotive Body Controllers
The PIC16C558-20/SO fits automotive body controller applications including seat controllers, mirror adjusters, and accessory modules. Its 20 MHz clock rate delivers 5 MIPS throughput, sufficient for PWM-driven motor control loops at 1-2 kHz update rates while leaving headroom for CAN/LIN message handling via software bit-banging. The 13 I/O pins each sink/source 25 mA, allowing direct LED and small relay drive without external transistors, reducing BOM cost. The -40C to +85C industrial temperature variant (PIC16C558-20I/SO) covers under-dash and cabin environments. OTP memory prevents firmware tampering and reverse engineering - an advantage for security-sensitive automotive modules. The 18-SOIC package supports automated reflow assembly on automotive-grade PCB substrates.
Recommended
Industrial Sensor Interfaces
The PIC16C558-20/SO is well-matched to industrial sensor interface modules such as 4-20 mA loop transmitters, thermocouple conditioners, and limit-switch aggregators. The 200 ns instruction cycle enables deterministic 1 kHz ADC polling and digital filtering within the 35-instruction PIC16C5x core. Brown-out reset and watchdog timer protect against the brown-out and EMI events common on factory floors with motor starters and VFDs. The 3.0-5.5V supply range accepts 24V industrial bus power after regulation. The 13 I/O support multi-channel sensor switching; 128 bytes of RAM accommodate moving-average filters and calibration tables for up to a dozen sensors.
Recommended
Consumer White Goods Controllers
In consumer white goods such as washing machines, dishwashers, and microwave ovens, the PIC16C558-20/SO serves as the main user-interface and motor-control MCU. The 35-instruction RISC core simplifies code review and certification for safety-critical appliances. OTP memory locks the firmware image at production, preventing field modification that could void UL/CE safety certifications. The 20 MHz speed supports real-time control of universal motors and triac-fired heating elements with adequate margin. The 13 I/O drive 7-segment displays, keypads, status LEDs, and relay coils directly at 25 mA per pin, eliminating driver transistors and reducing assembly cost. The 18-SOIC package reflows cleanly onto wave-soldered consumer appliance boards.
Recommended
Security Keypad and Access Controllers
The PIC16C558-20/SO is a natural fit for security keypads, RFID access controllers, and door-strike timers. Its 20 MHz throughput handles 4x4 matrix keypad scanning with sub-10 ms debounce and EEPROM emulation in Flash-free OTP via external I2C memory. The 13 I/O support up to 8 keypad rows/columns plus relay, buzzer, and LED indicators. OTP memory prevents code extraction attacks - critical for security products where firmware cloning would enable bypass. Brown-out reset prevents lock-controller lockouts during power glitches. The 18-SOIC package supports compact panel-mount PCB designs typical in access-control hardware.
Recommended
LED Lighting and Sign Controllers
The PIC16C558-20/SO controls RGB LED drivers, marquee signs, and architectural lighting fixtures. The 20 MHz clock drives software PWM at 8-bit resolution for 4-6 LED channels simultaneously without flicker, or 10-bit resolution at lower channel counts. The 25 mA per-pin drive directly powers small indicator LEDs without MOSFET drivers. OTP memory locks the lighting program for OEM products sold to contractors. The 18-SOIC package mounts on the small PCBs typical of MR16 and linear-LED fixtures. The 3.0V minimum supply supports direct Li-ion battery operation in portable lighting products.
Recommended
Battery Chargers and Power Management
The PIC16C558-20/SO implements CC/CV battery charger controllers for lead-acid, NiMH, and single-cell Li-ion packs. The 20 MHz throughput samples charge current and battery voltage at 1 kHz with software PI control loops - sufficient for float-charging applications where loop bandwidth is intentionally limited. Brown-out reset protects against pack undervoltage damage during deep discharge. The 13 I/O connect to current-sense amplifiers, MOSFET gate drivers, status LEDs, and temperature sensors without external glue logic. OTP memory locks the charging algorithm for safety-certified chargers. The 3.0-5.5V supply range accepts rectified 5V USB or 12V adapter rails after regulation.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558-20/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20I/SO | PIC16C558-20/P | PIC16C558-04I/SO | PIC16F558 | PIC16C554-20/SO |
|---|---|---|---|---|---|---|
| Package | 18-SOIC | 18-SOIC - same | 18-PDIP - through-hole | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Size | 3.5 KB (2K x 14) OTP | 3.5 KB OTP (same) | 3.5 KB OTP (same) | 3.5 KB OTP (same) | 3.5 KB Flash (same size, reprogrammable) | 0.875 KB OTP (-75%) |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 4 MHz | 20 MHz | 20 MHz |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash (reprogrammable) | OTP EPROM |
| Operating Temperature Range | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +85C (industrial) | 0C to +70C (commercial) |
| RAM Size | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 80 bytes |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Active (recommended replacement) | Obsolete |
| Instruction Execution Time | 200 ns | 200 ns | 200 ns | 1 us | 200 ns | 200 ns |
Key Differentiators
- Industry-standard 8-bit PIC RISC architecture with 35-instruction simplicity (vs PIC16C554-20/SO)
- Wide 3.0-5.5V supply supports both 3.3V and 5V system rails (vs PIC16C558-04I/SO)
- OTP EPROM locks firmware for tamper resistance (vs PIC16F558)
Design Notes
The PIC16C558 uses OTP (One-Time-Programmable) EPROM, not Flash - once a device is programmed, the firmware cannot be modified. Use PIC16F558 or PIC16C558/JW (windowed) parts for engineering development, pilot runs, and field firmware updates. Do not substitute OTP parts into prototypes intended for code iteration. The MCLR/VPP pin (pin 4) requires a high-voltage VPP pulse (typically 13V) for programming; verify your programmer supports the PIC16C5x OTP VPP algorithm before committing to production.
Place a 0.1 uF ceramic decoupling capacitor as close as possible to the VDD pin (pin 14) with the ground return via a short trace to VSS (pin 5). For boards with long VDD traces or shared supplies, add a 10 uF tantalum or aluminum bulk capacitor near the MCU. The PIC16C558 power-on reset and brown-out reset require the VDD rise time to be within datasheet limits; too-slow VDD ramps may trigger spurious resets. For battery applications, the MCP1700 LDO with 1.6 uA quiescent current complements the PIC16C558's low-power CMOS design.
Route the oscillator traces (OSC1 pin 16, OSC2 pin 15) as short as possible and guard them with a ground pour to minimize EMI coupling. For crystal mode, place the load capacitors (typically 15-33 pF) within 5 mm of the OSC pins. Avoid routing high-speed switching signals (PWM, relay coils) under the crystal area. The 18-SOIC land pattern should follow IPC-7351 SOIC-18 with 1.27 mm pitch; verify the SOIC body width is 7.50 mm (300 mil) to match the standard PIC16C558-20/SO package, not the narrower 5.30 mm variant.
Compliance Information
RoHS compliance per Microchip product page for the SO package. Not AEC-Q100 qualified; PIC16C558 family is not automotive-grade. Conflict minerals compliance per Microchip corporate statement.
