PIC16C558T-04/SS - 8-Bit OTP MCU, 4MHz, 3.5KB | Microchip
MPN: PIC16C558T-04/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.5 | $3.50 |
| 10 | $3.15 | $31.50 |
| 100 | $2.78 | $278.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.18 | $2,180.00 |
PIC16C558T-04/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer with an 8-bit data path, integrating a CPU, RAM, ROM/Flash/EPROM, and peripherals. OTP (One-Time Programmable) variants use EPROM-based program memory, which is programmed once with a device programmer and cannot be erased, making OTP MCUs the lowest-cost option for high-volume, fixed-code consumer and industrial products. PIC microcontrollers follow the RISC (Reduced Instruction Set Computer) Harvard architecture, separating program and data memory buses for deterministic instruction timing.
Key features of the PIC16C558T-04/SS include 4 MHz maximum operating frequency, 128 bytes of RAM, 13 I/O pins with individual direction control, a watchdog timer with on-chip RC oscillator, power-on reset, power-saving SLEEP mode, and an operating voltage range of 3.0 V to 6.25 V. The '04' speed suffix indicates a 4 MHz oscillator; the 'T' suffix denotes tape-and-reel packaging; '/SS' designates the 20-pin SSOP (Shrink Small Outline Package).
The PIC16C558T-04/SS uses a 14-bit-wide instruction word and 8-bit data path, with a hardware stack and interrupt logic supporting wake-up from SLEEP on pin change. Code protection is enabled via EPROM fuse bits. Compared with Flash-based PIC16F parts, this OTP MCU is intended for mature, high-volume programs where field firmware updates are not required.
Typical applications include appliance control, sensor signal conditioning, low-speed serial control loops, hobby and educational projects, LED driving, and replacement of discrete logic in fixed-function control boards. The 13 I/O pins can source/sink up to 25 mA per pin, sufficient to drive small relays, solenoids, and LED arrays directly.
When designing with this part, ensure your programming flow includes EPROM fuse configuration because code protection cannot be changed once blown. For new designs, evaluate Flash-based PIC16F equivalents first; the OTP variant is most cost-effective for locked, high-volume code.
This page synthesizes distributor pricing, drop-in alternatives, and design notes that go beyond the bare datasheet content to help engineers select, source, and qualify the PIC16C558T-04/SS with confidence.
Drop-in alternatives for PIC16C558T-04/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 PIC16C558T-04/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, RoHS Status, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-04/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558T-04I/SS
✅ Drop-In✓ In Stock
$2.13 / Unit
View Datasheet →PIC16C558T-20/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.85 / Unit
View Datasheet →PIC16C558-20I/SO
✅ Drop-In✓ In Stock
$1.2 / Unit
View Datasheet →PIC16C554T-04/SS
✅ Drop-In✓ In Stock
$1.14 / Unit
View Datasheet →PIC16C558T-04/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Program Memory Type | OTP (EPROM-based) |
| Program Memory Size | 3.5 KB (2K × 14) |
| RAM | 128 bytes |
| Maximum CPU Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns |
| Instruction Set Size | 35 single-word instructions |
| Data Path Width | 8 bits |
| Instruction Word Width | 14 bits |
| I/O Pins | 13 |
| Supply Voltage | 3.0 V to 6.25 V |
| Package | 20-SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Operating Temperature | 0 °C to +70 °C (commercial) |
| Timed Timer | 1 × 8-bit, 1 × Watchdog (WDT) |
| Special Features | Power-on Reset, SLEEP mode, code protection |
| RoHS Status | See compliance_info |
PIC16C558T-04/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O, bit 2 of PORTA |
| Pin 2 | RA3 — Bidirectional I/O, bit 3 of PORTA |
| Pin 3 | T0CKI/RA4 — Timer0 clock input / PORTA bit 4 |
| Pin 4 | MCLR/VPP — Master Clear (reset) / Programming voltage input |
| Pin 5 | VSS — Ground reference |
| Pin 6 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 7 | OSC2/CLKOUT — Oscillator output / clock output (Fosc/4) |
| Pin 8 | RB0/INT — Bidirectional I/O / external interrupt |
| Pin 9 | RB1 — Bidirectional I/O, bit 1 of PORTB |
| Pin 10 | RB2 — Bidirectional I/O, bit 2 of PORTB |
| Pin 11 | RB3 — Bidirectional I/O, bit 3 of PORTB |
| Pin 12 | RB4 — Bidirectional I/O, bit 4 of PORTB |
| Pin 13 | RB5 — Bidirectional I/O, bit 5 of PORTB |
| Pin 14 | RB6 — Bidirectional I/O, bit 6 of PORTB |
| Pin 15 | RB7 — Bidirectional I/O, bit 7 of PORTB |
| Pin 16 | VDD — Positive supply voltage |
| Pin 17 | RC0 — Bidirectional I/O, bit 0 of PORTC |
| Pin 18 | RC1 — Bidirectional I/O, bit 1 of PORTC |
| Pin 19 | RC2 — Bidirectional I/O, bit 2 of PORTC |
| Pin 20 | RC3 — Bidirectional I/O, bit 3 of PORTC |
Typical Applications
PIC16C558T-04/SS is suitable for 6 applications: Appliance Control Boards, Sensor Signal Conditioning and Threshold Detection, LED Display and Indicator Drivers, Replacement of Discrete Logic in Fixed Control Boards, Hobby, Educational, and Training Projects, Low-Speed Serial Protocol Bridges.
Appliance Control Boards
The PIC16C558T-04/SS fits appliance control boards because its 13 I/O pins each sink 25 mA, enough to drive relays, triacs, and indicator LEDs directly without external drivers. The 3.5 KB OTP memory holds fixed control firmware for washing machines, microwave ovens, and air-conditioner control panels. Its 200 ns deterministic instruction cycle ensures reliable timing for motor control loops and safety interlocks. Operating from 3.0 V to 6.25 V lets the design share the unregulated supply rail common in white goods.
Recommended
Sensor Signal Conditioning and Threshold Detection
The PIC16C558T-04/SS is well-suited to sensor threshold detection because its 8-bit ADC-free architecture lets the digital I/O pins sample comparators or Schmitt-trigger inputs at high speed. The 35-instruction RISC core handles 1-step threshold comparisons and on/off hysteresis control in under 1 µs. The 4 MHz clock and 200 ns instruction cycle enable 10 kHz sample rates on multiple sensor channels, suitable for industrial limit-switch multiplexing and debouncing.
Recommended
LED Display and Indicator Drivers
The PIC16C558T-04/SS drives LED matrix and bar-graph displays directly through its 25 mA-per-pin I/O, controlling up to 13 high-brightness LEDs or a 7-segment multiplexed display without external transistors. The 4 MHz clock and deterministic 200 ns instruction timing allow 8-digit multiplex refresh at >100 Hz, eliminating visible flicker. Its 3.0 V to 6.25 V supply accepts battery and rectified mains-derived rails equally.
Recommended
Replacement of Discrete Logic in Fixed Control Boards
The PIC16C558T-04/SS replaces dozens of 74xx logic gates in fixed-function industrial controllers by consolidating state machines, counters, and timing logic into one chip. The 3.5 KB OTP program memory typically holds 1,500 to 2,500 equivalent gate-level logic operations. Its 35-instruction RISC core compiles easily from C or assembly, dramatically reducing PCB area and BOM cost while improving field reliability by removing solder joints.
Recommended
Hobby, Educational, and Training Projects
The PIC16C558T-04/SS remains a popular teaching platform because its PIC16C5xx instruction set is the simplest of any 8-bit MCU, with only 35 instructions and orthogonal addressing, making assembly programming a one-day learn. The 20-SSOP package can be adapted to breadboards via SSOP-to-DIP adapter boards. Educators value its deterministic interrupt behavior and absence of peripheral complexity, ideal for teaching bare-metal embedded fundamentals.
Recommended
Low-Speed Serial Protocol Bridges
The PIC16C558T-04/SS implements UART, SPI master, or I2C master bit-banged bridges in cost-sensitive bridging applications where dedicated protocol ICs would be uneconomical. Its 4 MHz clock and 200 ns instruction cycle deliver bit periods down to 10 µs for UART up to 9600 baud, sufficient for sensor telemetry and legacy RS-232 ports. The 13 I/O pins permit simultaneous master and slave channels with no external logic.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-04/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-04/SS | PIC16C558T-04I/SS | PIC16C558T-20/SS | PIC16C558-20I/SO | PIC16C554T-04/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-SSOP | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same |
| Program Memory | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 1.75 KB OTP (-50%) |
| Max CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz (5x faster) | 20 MHz (5x faster) | 4 MHz |
| Operating Temperature | 0 °C to +70 °C (commercial) | 0 °C to +70 °C | -40 °C to +85 °C (industrial) | 0 °C to +70 °C | -40 °C to +85 °C | 0 °C to +70 °C |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 12 (-1) |
| Supply Voltage | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V |
| Delivery Form | Tape & Reel | Tube | Tape & Reel | Tape & Reel | Tube | Tape & Reel |
Key Differentiators
- Highest OTP density in PIC16C5xx 20-SSOP family (vs PIC16C554T-04/SS)
- Industrial temperature variant available (vs PIC16C558-04/SS)
- Tape-and-reel packaging for high-volume SMT lines (vs PIC16C558-04/SS)
Design Notes
The PIC16C558T-04/SS requires a stable VDD within 3.0 V to 6.25 V; brown-out below 3.0 V triggers a power-on reset but may corrupt EEPROM-emulated data in software. Add a 100 nF decoupling capacitor within 5 mm of VDD (pin 16) and a 10 µF bulk capacitor at the board supply input. For battery operation, use a 3.3 V LDO like MCP1700 to maximize battery life. Estimated: with 13 I/O sourcing 10 mA average, total supply current ~25 mA typical, dominated by I/O load.
OTP memory can be programmed once; once the code protection fuse is blown, it cannot be reversed. Always verify firmware in OTP-emulating parts (PIC16C558-04/SO with windowed package) before committing to OTP tape-and-reel volume. The 'T' suffix is tape-and-reel only, NOT speed grade; the speed is encoded in the '04' or '20' suffix. Confusing 'T' for a temperature range is a common procurement error.
Route the OSC1/OSC2 traces short and symmetric, with ground guard traces if high-speed noise is a concern. Place the MCLR/VPP pull-up (typically 10 kΩ) within 10 mm of pin 4 to ensure reliable reset; do not leave MCLR floating. Keep analog I/O traces away from clock traces if any pins are used as comparators. Estimated: SSOP-20 thermal resistance is ~95 °C/W; for normal 25 mA loads no heatsink is needed.
Compliance Information
RoHS and lead-free compliant per Microchip product documentation; not AEC-Q100 qualified (industrial-grade -I variants exist for extended temperature).
