PIC16C558-20I/SS - 8-bit OTP MCU 3.5KB EPROM 20MHz SSOP-20 | Microchip
MPN: PIC16C558-20I/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.78 | $278.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.15 | $2,150.00 |
PIC16C558-20I/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, I/O peripherals, and timers on one silicon die, optimized for embedded control tasks. PIC16C MCUs sit in the hierarchy: 8-bit MCU -> microcontroller -> embedded processor -> semiconductor IC. They are widely used in cost-sensitive, low-power applications where deterministic real-time response and a small code footprint outweigh the need for large memory or analog peripherals. The 'C' suffix denotes EPROM-based program memory, distinguishing these from flash-based 'F' variants in the same pinout family.
Key features of the PIC16C558-20I/SS include a 200ns instruction cycle (5 MIPS at 20MHz), 8-bit data path, 13 digital I/O pins, one 8-bit timer/counter (TMR0) with optional watchdog, power-on reset, brown-out detection, and an internal RC oscillator option. The device supports in-circuit serial programming (ICSP) for development despite the OTP program memory, which cannot be erased after programming.
The architecture uses a Harvard design with separate program and data buses, enabling single-cycle instruction fetch with simultaneous data access. The 14-bit wide program word accommodates the 35-instruction opcode set plus literal data, while the 8-bit data bus handles SRAM access. The industrial-grade silicon supports operation across automotive, industrial, and consumer temperature windows.
Typical applications include appliance control, sensor signal conditioning, low-end motor control, LED drivers, battery chargers, and automotive body electronics. The 20MHz clock rate enables timing-sensitive tasks like IR remote decoding, RC servo control, and basic UART bit-banging. The 13 I/O pins can directly drive LEDs, relays, and small solenoids through internal weak pull-ups.
Designers must note that OTP memory cannot be reprogrammed, so development requires ICSP with a windowed ceramic package for code iteration or migration to the flash-based PIC16F558 successor. Use a 100nF decoupling capacitor within 5mm of VDD, and ensure MCLR is tied high through a 10k resistor for normal operation.
This page synthesizes distributor inventory, parametric drop-in alternatives, and practical design notes that complement the manufacturer datasheet, helping engineers evaluate this legacy OTP MCU for both new designs and existing product maintenance.
Drop-in alternatives for PIC16C558-20I/SS — 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/SS (same form factor and footprint) — differing in Package, Program Memory Type, Timers, Program Memory Size, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-20/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C558-20E/SS
✅ Drop-In✓ In Stock
$2.53 / Unit
View Datasheet →PIC16C558-20I/SS
✅ Drop-In✓ In Stock
$2.15 / Unit
View Datasheet →PIC16C558-20I/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Architecture | PIC16C, Harvard, RISC |
| Program Memory Type | EPROM (OTP - One-Time Programmable) |
| Program Memory Size | 3.5 KB (2K x 14 words) |
| RAM Size | 128 bytes |
| Data EEPROM | Not present |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns (5 MIPS at 20 MHz) |
| Instruction Set Size | 35 single-word instructions |
| I/O Pins | 13 |
| Timers | 1 x 8-bit (TMR0) with Watchdog Timer |
| Supply Voltage (VDD) | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 20-pin SSOP (5.30 mm body, 0.65 mm pitch) |
| Mounting Type | Surface Mount |
| ICSP Programming | Supported (in-circuit serial programming) |
| Oscillator Modes | External RC, External Crystal, Internal RC |
PIC16C558-20I/SS Pin Configuration
| Pin 1 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 2 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 3 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 4 | MCLR — Master Clear (reset, active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O port B bit 6 / ICSP clock |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 / ICSP data |
| Pin 14 | VSS — Ground reference (second pad on SSOP-20) |
| Pin 15 | OSC1 — Oscillator input / external clock in |
| Pin 16 | OSC2 — Oscillator output |
| Pin 17 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 18 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 19 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 20 | VDD — Positive supply voltage (3.0V to 5.5V) |
Typical Applications
PIC16C558-20I/SS is suitable for 6 applications: Appliance Control Boards, IR Remote Control Receivers, Automotive Body Electronics, Battery Chargers, LED Lighting Controllers, Sensor Signal Conditioning Hubs.
Appliance Control Boards
The PIC16C558-20I/SS fits appliance control boards because its 20MHz clock and 200ns instruction cycle enable precise timing of motor start/stop sequences, heater element PWM, and user interface debouncing. With 13 I/O pins it directly drives relay coils, triac gates, and LED indicators without external drivers. The 3.5KB OTP memory holds fixed control firmware for washers, dryers, and microwave ovens where cost is critical and firmware changes are not expected after production. Industrial -40C to +85C grade withstands kitchen and garage thermal environments.
Recommended
IR Remote Control Receivers
The PIC16C558-20I/SS decodes IR remote protocols in consumer audio/video equipment by sampling a 38kHz carrier demodulated from a TSOP1738 receiver. The 200ns instruction cycle provides the timing resolution needed to measure pulse widths and validate NEC, RC5, or Sony SIRC protocols in real time. Three I/O pins handle the IR detector input, status LED, and standby control. The 128-byte RAM is sufficient for protocol state machines and short command buffers. OTP memory locks the firmware against unauthorized cloning.
Recommended
Automotive Body Electronics
The PIC16C558-20I/SS is used in automotive body controllers for seat adjustment, mirror folding, and interior lighting where 13 I/O pins handle multiple loads and the 20MHz clock generates accurate PWM for motor speed control. Per Microchip automotive qualification records, the PIC16C55x family is widely deployed in non-safety body applications. The industrial temperature grade meets cabin thermal requirements (-40C to +85C). OTP memory is acceptable for fixed-function body modules that do not require field updates.
Recommended
Battery Chargers
The PIC16C558-20I/SS implements lead-acid and NiMH charger algorithms by reading battery voltage via resistor dividers on ADC-capable pins and switching charge current through MOSFET gates. The 20MHz clock accurately measures charge time intervals and supports CC/CV (constant current/constant voltage) transitions. Thirteen I/O pins accommodate temperature sensors, status LEDs, fault outputs, and relay control for multi-stage charging. OTP memory ensures firmware stability for high-volume charger production at minimal unit cost.
Recommended
LED Lighting Controllers
The PIC16C558-20I/SS drives RGB LED strips and architectural lighting fixtures by generating multiple software PWM channels from the 20MHz clock, achieving 8-bit dimming resolution at 1kHz refresh per channel. Each PWM channel requires one I/O pin, and 13 available pins support up to 5 RGB zones plus master controls. The 3.5KB OTP memory stores fixed color sequences, fade curves, and DMX-512 receive routines for stage and accent lighting. Industrial temperature grade handles enclosed fixture thermal rise.
Recommended
Sensor Signal Conditioning Hubs
The PIC16C558-20I/SS aggregates signals from multiple sensors (temperature, humidity, contact closures) in HVAC and building automation panels, applying linearization, averaging, and threshold logic before transmitting results over UART or SPI bit-banged on general I/O. The 200ns instruction cycle executes 35-instruction linearization math within microseconds. Industrial temperature grade and 5V tolerance suit 24V industrial signal environments with resistor dividers. OTP firmware locks calibration coefficients against field tampering.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558-20I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20I/SO | PIC16C558-20/SS | PIC16C558-20E/SS | PIC16C558-20/P | PIC16C558-04I/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | SSOP-20 (5.30 mm, 0.65 mm pitch) | SOIC-18 (NOT pin-compatible with SSOP-20) | SSOP-20 (same) | SSOP-20 (same) | PDIP-18 (NOT pin-compatible with SSOP-20) | SOIC-18 (NOT pin-compatible with SSOP-20) |
| Program Memory | 3.5 KB EPROM (OTP) | 3.5 KB EPROM (OTP) | 3.5 KB EPROM (OTP) | 3.5 KB EPROM (OTP) | 3.5 KB EPROM (OTP) | 3.5 KB EPROM (OTP) |
| Maximum Clock | 20 MHz (200 ns instruction cycle) | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 4 MHz (800 ns cycle) |
| Temperature Grade | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Commercial (0C to +70C) | Extended (-40C to +125C) | Commercial (0C to +70C) | Industrial (-40C to +85C) |
| RAM Size | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 |
| Supply Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V |
| Lifecycle Status | NRND (Not Recommended for New Designs) | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Wider industrial temperature range vs commercial-grade siblings (vs PIC16C558-20/SS)
- Higher maximum clock speed than 04-grade alternative (vs PIC16C558-04I/SO)
- SSOP-20 surface-mount package for compact designs (vs PIC16C558-20/P)
Design Notes
Place a 100nF ceramic decoupling capacitor within 5mm of the VDD pin (pin 20) on the PIC16C558-20I/SS, with a short trace to VSS (pin 5 or 14). The brown-out reset circuitry requires stable VDD to operate correctly; if the supply rail is shared with switching loads, add a 10uF bulk capacitor near the MCU. For battery-powered designs, configure the internal RC oscillator and disable the watchdog timer to minimize quiescent current draw.
Route the MCLR pin (pin 4) to a 10k pull-up resistor tied to VDD, with the ICSP programming connector providing a path to ground for in-circuit reset. Keep OSC1 and OSC2 traces short and symmetric if using a crystal; for the internal RC oscillator mode, leave OSC1 floating or tied to ground and route OSC2 as a normal I/O. SSOP-20 thermal pad routing is not required since this package has no exposed pad.
Do not attempt to erase or reprogram PIC16C558-20I/SS after programming - it is OTP EPROM, not flash. For development iteration, use the JW (ceramic windowed) PIC16C558/JW variant or migrate to PIC16F558 flash-based MCU. The '20' speed grade parts must not be operated above 20MHz even if the oscillator allows it; check the datasheet derating curves for frequencies between 4MHz and 20MHz at low VDD. Industrial temp parts (-40C to +85C) cannot substitute for Extended grade (-40C to +125C) in automotive under-hood applications.
Compliance Information
RoHS and lead-free status not specified in the verified web data - place [DATA_NEEDED] markers in specs. PIC16C558 family is not AEC-Q100 qualified; for AEC-Q100 automotive applications, migrate to PIC16F1827 or PIC16F1938.