PIC16C558-20I/SO - 8-Bit 20MHz OTP MCU 3.5KB | Microchip
MPN: PIC16C558-20I/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.74 | $1.74 |
| 10 | $1.62 | $16.20 |
| 100 | $1.48 | $148.00 |
| 500 | $1.34 | $670.00 |
| 1,000 | $1.2 | $1,200.00 |
PIC16C558-20I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non‑volatile program memory, working RAM, and peripheral interfaces such as timers, interrupts, and I/O. The PIC16C family is one of the foundational Microchip PIC architectures and sits within the broader taxonomy: microcontroller → embedded processor → semiconductor IC → electronic component. Within the power and signal hierarchy, an MCU orchestrates sensors, actuators, and communication interfaces while the system power supply, often an LDO or DC-DC converter, feeds it.
Key features of the PIC16C558-20I/SO include 35 single-word instructions, a RISC architecture with 14-bit instruction width, an 8-level deep hardware stack, a watchdog timer, power-on reset, power-saving SLEEP mode, and an internal oscillator option on certain family members. The device is OTP (One-Time Programmable), meaning the program memory can be written only once by the user, distinguishing it from flash-based PIC16F successors. The wide-body SOIC (SO) package measures 0.300 inch (7.50mm) and ships in anti-static tubes for prototyping and low-volume production.
Designed for cost-sensitive embedded control, the PIC16C558-20I/SO is widely deployed in white-goods controls, simple sensor interfaces, automotive body electronics, and industrial timers. Its 13 I/O pins comfortably drive LED indicators, keypads, relays, and serial links, while the 20MHz clock supports time-critical loops such as UART bit-banging or PWM motor control.
Typical applications include appliance control boards (washing machines, microwave ovens, coffee makers), HVAC thermostat logic, low-end battery chargers, and remote sensor nodes. The wide VCC range and industrial temperature rating (-40C to +85C for the -I grade) suit harsh environments.
When designing, note that OTP memory cannot be reprogrammed, so firmware must be fully validated before programming. The device has no built-in debug interface; development relies on the ICD header or production programmers, and emulator compatibility should be confirmed via the Microchip compatibility chart (DeviceDoc 00148J2).
This page synthesizes current distributor pricing, drop-in alternative candidates, and practical engineering notes beyond what the manufacturer datasheet alone provides.
Drop-in alternatives for PIC16C558-20I/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 PIC16C558-20I/SO (same form factor and footprint) — differing in Package, Program Memory Type, Program Memory Size, Core Architecture, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-20/SO
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C558-04I/SO
✅ Drop-In✓ In Stock
$3.11 / Unit
View Datasheet →PIC16C558T-20I/SO
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C558-20E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558-20I/P
✅ Drop-In✓ In Stock
$2.78 / Unit
View Datasheet →PIC16C554-20I/SO
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC16C558-20I/SO Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC 16C |
| Core Processor | PIC |
| Core Size | 8-bit |
| Program Memory Size | 3.5KB (2K x 14) |
| Program Memory Type | OTP |
| RAM Size | 128 bytes |
| Number of I/O Pins | 13 |
| Speed | 20 MHz |
| Instruction Cycle Time | 200 ns |
| Supply Voltage (Vcc) | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 18-SOIC (0.295 inch / 7.50 mm width) tube |
| Mounting Type | Surface Mount |
| Architecture | RISC |
| Number of Instructions | 35 single-word |
| Instruction Width | 14-bit |
| Oscillator Type | External |
| Peripherals | POR, WDT |
| Connectivity | UART |
| MSL Level | 1 |
| RoHS Status | Compliant |
PIC16C558-20I/SO Pin Configuration
| Pin 1 | RA2 — PORTA I/O bit 2 / analog input |
| Pin 2 | RA3 — PORTA I/O bit 3 / analog input |
| Pin 3 | RA4/RTCC — PORTA I/O bit 4 / RTCC timer input |
| Pin 4 | MCLR — Master clear (reset) input |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — PORTB I/O bit 0 / 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 |
| Pin 13 | RB7 — PORTB I/O bit 7 |
| Pin 14 | VDD — Positive supply voltage |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock in |
| Pin 17 | RA0 — PORTA I/O bit 0 |
| Pin 18 | RA1 — PORTA I/O bit 1 |
Typical Applications
PIC16C558-20I/SO is suitable for 7 applications: White Goods Appliance Control, HVAC Thermostat Logic, Automotive Body Electronics, Low-End Battery Chargers, Industrial Timers and Counters, Remote Sensor Nodes, Simple Sensor Interfaces.
White Goods Appliance Control
The PIC16C558-20I/SO fits white-goods appliance control boards because its 3.5KB OTP memory accommodates typical washing-machine, microwave-oven, and dishwasher control firmware, while the 13 I/O pins drive keypads, LED indicators, relay coils, and triac interfaces. The 20MHz clock and 200ns instruction cycle execute real-time control loops (water level sensing, motor RPM feedback, temperature PID) within sub-millisecond windows. Its -40C to +85C industrial temperature grade handles the thermal stress behind a washer fascia or oven control panel. OTP memory prevents end-user firmware tampering and provides a security guarantee that competitive flash MCUs cannot match without external lock bits.
Recommended
HVAC Thermostat Logic
The PIC16C558-20I/SO serves HVAC thermostat logic controllers where compact 18-SOIC packaging simplifies thermostat wall-plate PCB layout while delivering enough I/O for temperature sensors, button inputs, LCD segments, and HVAC relay switching. The 3.0V to 5.5V supply range aligns with typical 3.3V sensor and 5V relay-coil rails found in HVAC boards. Industrial -40C to +85C operation covers attic, basement, and outdoor-temperature installations. The RISC 35-instruction set is straightforward for legacy HVAC firmware engineers to maintain, and the OTP memory prevents accidental firmware corruption during field service.
Recommended
Automotive Body Electronics
The PIC16C558-20I/SO is well suited to automotive body modules such as interior lighting controllers, mirror-adjustment logic, and seat-position memory because the -40C to +85C industrial temperature grade covers cabin environments, while the wide VCC tolerance tolerates load-dump and cranking transients when paired with a TVS-protected 12V regulator. Its 13 I/O pins handle H-bridge enable signals, switch-scan matrices, and CAN/LIN transceiver handshake GPIO. OTP memory is valued in automotive for tamper-resistance. Engineers migrating new designs to AEC-Q100 qualified parts should evaluate the flash-based PIC16F family or dsPIC33 successors.
Recommended
Low-End Battery Chargers
The PIC16C558-20I/SO enables CC/CV battery charger controllers in cost-sensitive consumer applications such as cordless power tools, e-bike chargers, and small UPS units. The 3.0V to 5.5V supply is compatible with single-cell Li-ion chargers operating off USB or 12V adapters, and the 20MHz clock supports PWM control loops at 20kHz switching frequencies for synchronous buck converters. The 13 I/O pins drive MOSFET gate drivers, current-sense amplifiers, status LEDs, and charger-enable inputs. OTP memory ensures the charger profile cannot be corrupted in the field.
Recommended
Industrial Timers and Counters
The PIC16C558-20I/SO serves industrial timer and counter modules (machine-cycle timers, conveyor counters, process-event schedulers) where its 200ns instruction cycle executes precise timing loops and the 13 I/O pins interface with encoder inputs, opto-isolated event triggers, and relay outputs. The -40C to +85C industrial rating handles factory-floor temperature swings near motors and welding equipment. OTP memory provides security in factory IP-sensitive environments, and the 18-SOIC wide-body package allows wave-soldering on legacy through-hole-converted SMT lines.
Recommended
Remote Sensor Nodes
The PIC16C558-20I/SO is deployed in remote sensor nodes such as weather stations, agricultural probes, and remote metering where compact size, low cost, and OTP security outweigh the lack of flash. The 3.0V to 5.5V supply matches single-cell Li-ion or 4xAA battery packs, and the SLEEP mode combined with the watchdog timer enables multi-year battery life. The 13 I/O pins accommodate UART communication to a wireless module, sensor I/O, and interrupt wake-up sources. For new designs requiring over-the-air firmware updates, the flash-based PIC16F54 or PIC16F627A is recommended.
Recommended
Simple Sensor Interfaces
The PIC16C558-20I/SO acts as a sensor-interface front-end MCU for industrial sensors, parsing analog inputs from bridge sensors, thermistors, or simple 4-20mA loops and converting them to digital outputs over UART or SPI. The 13 I/O pins and external oscillator support enable flexible sensor-channel multiplexing, and the 20MHz clock comfortably executes oversampling averaging loops to improve effective ADC resolution. The wide-body 18-SOIC package is robust in vibration-prone installations. Engineers often pair this part with external ADCs when finer measurement resolution is required.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558-20I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20/SO | PIC16C558-04I/SO | PIC16C558T-20I/SO | PIC16C558-20E/SO | PIC16C554-20I/SO |
|---|---|---|---|---|---|---|
| Package | 18-SOIC (7.50 mm width) | 18-SOIC (7.50 mm width) | 18-SOIC (7.50 mm width) | 18-SOIC (7.50 mm width) | 18-SOIC (7.50 mm width) | 18-SOIC (7.50 mm width) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 1.75KB OTP |
| RAM | 128 B | 128 B | 128 B | 128 B | 128 B | 80 B |
| Clock Speed | 20 MHz | 20 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz |
| Instruction Cycle | 200 ns | 200 ns | 1000 ns | 200 ns | 200 ns | 200 ns |
| Operating Temperature | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | Extended (E) grade | -40C to +85C (Industrial) |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | NRND |
| RoHS Compliance | Compliant | Compliant | Compliant | Compliant | Compliant | Compliant |
Key Differentiators
- Larger program memory within PIC16C5x family in 18-SOIC (vs PIC16C554-20I/SO)
- Industrial temperature grade on a 20MHz 18-SOIC OTP PIC (vs PIC16C558-20/SO)
- Higher clock speed for time-critical control loops (vs PIC16C558-04I/SO)
Design Notes
The PIC16C558-20I/SO uses OTP memory that cannot be erased or rewritten; firmware must be fully validated on a development part (such as the PIC16F54 equivalent windowed/flash sibling) before committing to OTP programming. Always program at least 2-3 spare parts during NPI to handle rework, because OTP defects are unrecoverable. Keep an ICD-compatible header footprint on the production PCB so engineers can program pre-production units; production OTP programming must use a verified programmer profile per Microchip's device programming specification.
The PIC16C558-20I/SO requires a stable VDD between 3.0V and 5.5V with a decoupling capacitor (100nF ceramic) placed within 5mm of the VDD pin, plus a 10uF bulk capacitor on the supply rail. Brown-out detection is not present in this part, so an external voltage supervisor such as MCP130 or TPS3823 is recommended for industrial applications where VDD may dip below the minimum operating threshold during load transients or cold-crank events. The POR (power-on reset) circuitry requires VDD rise time below the datasheet-specified limit to guarantee a clean reset.
For 18-SOIC wide-body (7.50mm) package, allocate a PCB land pattern per IPC-7351 nominal density with 1.27mm pitch and 0.45mm pad width; this matches Microchip's recommended SOIC-18 footprint. Place the MCLR pull-up resistor (typically 10kohm) and any decoupling capacitors on the same PCB side as the MCU, routed with short traces to minimize EMI pickup on the reset line. The crystal or resonator (if used instead of internal oscillator) should be placed within 10mm of OSC1/OSC2 with a ground guard ring.
Estimated: the PIC16C558-20I/SO at 20MHz with all peripherals active draws approximately 5-10mA from VDD, dissipating 25-50mW at 5V. The 18-SOIC package has theta_JA around 75-100 C/W in still air, resulting in a junction temperature rise of 2-5 C above ambient - well within the -40C to +85C industrial rating. For high-temperature installations (above 70 C ambient) verify thermal margins by measuring VDD current and applying P = V x I, then compare to the package derating curve.
Compliance Information
RoHS and REACH compliant per Microchip product page and distributor datasheet portals. The part is not AEC-Q100 qualified - for automotive designs requiring AEC-Q100 grade, evaluate the PIC16F or dsPIC33 families instead. Lead-free and halogen-free per Microchip environmental compliance documentation.
