PIC16C558T-04I/SO - 8-bit PIC MCU, 3.5KB OTP, 18-SOIC | Microchip
MPN: PIC16C558T-04I/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.34 | $4.34 |
| 10 | $3.91 | $39.10 |
| 100 | $3.25 | $325.00 |
| 500 | $2.78 | $1,390.00 |
| 1,000 | $2.41 | $2,410.00 |
PIC16C558T-04I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory, volatile data memory (RAM), and programmable peripherals into one package. The PIC16C558 belongs to Microchip's mid-range PIC16C family, which uses a RISC architecture with 35 single-word instructions. Within the broader component taxonomy, an MCU sits below the microprocessor/MCU hypernym and above the PIC16C mid-range sub-family; 8-bit MCUs like this one remain widely used in cost-sensitive, deterministic real-time applications.
Key features of the PIC16C558T-04I/SO include a 4 MHz maximum oscillator frequency (the -04 speed grade), 13 bidirectional I/O pins with individual direction control, an 8-bit timer/counter (TMR0) with an 8-bit prescaler, a Watchdog Timer with its own on-chip RC oscillator for reliable recovery, Power-on Reset, Brown-out Reset, and an in-circuit serial programming capability. Code protection and oscillator selection options are programmed into the device's configuration bits.
The architecture is built around a Harvard-separated program/data bus with a 14-bit instruction word, allowing most instructions to execute in a single 200 ns instruction cycle at 20 MHz. The '04 speed grade corresponds to a 4 MHz oscillator / 1 MHz instruction rate operation, simplifying EMI and power budgeting in industrial designs.
Typical applications include appliance control, automotive subsystems (body electronics, sensors, lighting), industrial automation (sensor interfaces, low-cost PLC I/O expanders), security and access control panels, and remote-control transmitters. The wide 2.5V-5.5V supply range and robust reset architecture make it a fit for harsh, electrically noisy environments.
When designing with the PIC16C558T-04I/SO, note that OTP memory cannot be re-programmed; for prototyping or field-upgradable firmware consider a Flash-based PIC16F equivalent. Place a 0.1 uF decoupling capacitor close to VDD, keep oscillator traces short, and respect the 4 MHz oscillator maximum for the -04 speed grade.
This page synthesizes distributor pricing as of 2026-09-16, drop-in alternatives drawn from the PIC16C558 same-family cross reference, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for PIC16C558T-04I/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 PIC16C558T-04I/SO (same form factor and footprint) — differing in Package, Program Memory Type, Program Memory Size, Core Architecture, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-04I/SO
✅ Drop-In✓ In Stock
$3.11 / Unit
View Datasheet →PIC16C558T-04/SO
✅ Drop-In✓ In Stock
$1.65 / Unit
View Datasheet →PIC16C558T-04I/SS
✅ Drop-In✓ In Stock
$2.13 / Unit
View Datasheet →PIC16C558-20I/SO
✅ Drop-In✓ In Stock
$1.2 / Unit
View Datasheet →PIC16C554T-04I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F630-I/SL
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558T-04I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 16C, 8-bit RISC |
| Instruction Set Width | 14-bit, 35 single-word instructions |
| Program Memory Type | OTP (One-Time-Programmable EPROM) |
| Program Memory Size | 3.5 KB (2K x 14 words) |
| Data RAM | 128 bytes |
| Maximum CPU Frequency | 4 MHz (oscillator) / 1 MHz instruction rate |
| Instruction Execution Time | 200 ns (typical, 4 MHz input) |
| Supply Voltage (VDD) | 2.5 V to 5.5 V |
| I/O Pins | 13 bidirectional digital I/O |
| Timers | 1 x 8-bit Timer (TMR0) with 8-bit prescaler, 1 x WDT |
| Reset Sources | Power-on Reset (POR), Brown-out Reset (BOR), WDT timeout, MCLR |
| Operating Temperature | -40 C to +85 C (industrial, I-suffix) |
| Package | 18-pin SOIC (SO), 7.50 mm body width, tape & reel |
| Mounting Type | Surface Mount |
| Programming | In-circuit serial programming (ICSP) |
| RoHS Status | Compliant |
PIC16C558T-04I/SO Pin Configuration
| Pin 1 | RA0 — Bidirectional digital I/O / ICSP data |
| Pin 2 | RA1 — Bidirectional digital I/O |
| Pin 3 | RA2 — Bidirectional digital I/O |
| Pin 4 | MCLR/VPP — Master Clear reset (active-low) / programming voltage input |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional digital I/O / external interrupt input |
| Pin 7 | RB1 — Bidirectional digital I/O |
| Pin 8 | RB2 — Bidirectional digital I/O |
| Pin 9 | RB3 — Bidirectional digital I/O |
| Pin 10 | RB4 — Bidirectional digital I/O |
| Pin 11 | RB5 — Bidirectional digital I/O |
| Pin 12 | RB6 — Bidirectional digital I/O / ICSP clock |
| Pin 13 | RB7 — Bidirectional digital I/O / ICSP data |
| Pin 14 | VDD — Positive supply (2.5 V to 5.5 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / CLKOUT for RC mode |
| Pin 16 | OSC1/CLKIN — Oscillator input / CLKIN for external clock |
| Pin 17 | RA3 — Bidirectional digital I/O |
| Pin 18 | RA4/T0CKI — Bidirectional digital I/O / TMR0 clock input |
Typical Applications
PIC16C558T-04I/SO is suitable for 7 applications: Automotive Body Electronics, Industrial Sensor Interface Module, Home Appliance Control Board, Security / Access Control Panel, Remote Control / RF Transmitter, Low-Cost PLC I/O Expander, HVAC Thermostat and Fan Controller.
Automotive Body Electronics
The PIC16C558T-04I/SO fits automotive body-electronics modules such as lighting controllers, seat controllers, and mirror actuators because its -40 C to +85 C industrial temperature range and robust Brown-out/Power-on Reset architecture tolerate under-hood electrical noise and cold-crank transients. The 3.5 KB OTP memory and 35-instruction PIC mid-range core are sufficient for state-machine-driven actuator logic. Pair the MCU with a CAN or LIN transceiver for body-network integration.
Recommended
Industrial Sensor Interface Module
For industrial 4-20 mA sensor transmitters, the PIC16C558T-04I/SO's 13 digital I/O pins and TMR0 with prescaler enable precise timing of sensor scans and PWM-driven 4-20 mA loops. The 2.5 V-5.5 V VDD range accommodates both 3.3 V and 5 V industrial rails, while the 4 MHz instruction rate (1 MIPS) is adequate for slow polling of temperature, pressure, or level sensors. The WDT provides field-reliable recovery if the sensor bus locks up.
Recommended
Home Appliance Control Board
The PIC16C558T-04I/SO is a strong fit for white-goods control boards (washing machines, dishwashers, microwave ovens) where its OTP memory and low BOM cost drive volume economics. The 13 I/O pins drive relay coils, triac gate controls, keypad matrix scans, and 7-segment LED multiplexing without external logic. Its Brown-out Reset survives brownouts caused by compressor inrush, and the 200 ns instruction cycle delivers deterministic real-time response to safety interlocks.
Recommended
Security / Access Control Panel
Keypad-based access control and intrusion alarm panels leverage the PIC16C558T-04I/SO's 13 I/O to scan a 4x4 matrix keypad, drive status LEDs, and interface to magnetic-reed or PIR sensors. OTP memory secures the firmware against copying, important for security products, and the 128-byte RAM is sufficient for event buffering. The WDT prevents firmware lock-ups that would otherwise leave a door insecure; 200 ns instruction cycle scans the keypad without perceptible lag.
Recommended
Remote Control / RF Transmitter
Battery-powered RF remote controls use the PIC16C558T-04I/SO because its low-cost OTP memory and 2.5 V-5.5 V range let the MCU run directly from a single 3 V coin-cell. TMR0 generates the carrier-frequency timing for ASK/OOK or FSK transmitters, while the 13 I/O accommodate matrix keypads and learning-mode buttons. The -40 C to +85 C industrial temperature range keeps the remote reliable in unheated garages and outdoor gate openers.
Recommended
Low-Cost PLC I/O Expander
In distributed I/O for small PLCs, the PIC16C558T-04I/SO acts as a digital edge expander that aggregates push-buttons, limit switches, and indicator lamps back to a host controller over UART or SPI. The OTP memory locks in the I/O mapping at production time and prevents costly field misconfiguration. Its 200 ns instruction cycle processes discrete I/O faster than typical 10 ms PLC scan times, providing deterministic refresh without burdening the main CPU.
Recommended
HVAC Thermostat and Fan Controller
Wall-mounted HVAC thermostats and standalone fan controllers use the PIC16C558T-04I/SO to read thermistor inputs, debounce user buttons, and PWM-drive triac-based fan speed stages. The 2.5 V-5.5 V supply range simplifies designs running from a small AC-DC wall adapter, while the -40 C to +85 C industrial rating is essential for equipment mounted near heating ducts. The Watchdog Timer protects the thermostat from firmware lock-ups that could leave a heater running indefinitely.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-04I/SO | PIC16C558-20I/SO | PIC16F630-I/SL | PIC16C554T-04I/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-SOIC (SO) | 18-SOIC (SO) - same | 18-SOIC (SO) - same | 18-SOIC (SL) - same family, slim body | 18-SOIC (SO) - same |
| Program Memory | 3.5 KB OTP (2K x 14) | 3.5 KB OTP | 3.5 KB OTP | 1.75 KB Flash | 896 B OTP |
| Data RAM | 128 B | 128 B | 128 B | 64 B | 80 B |
| Max Oscillator Frequency | 4 MHz (-04 speed grade) | 4 MHz | 20 MHz | 20 MHz | 4 MHz |
| Operating Temperature | -40 C to +85 C (industrial) | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Memory Type | OTP EPROM (one-time programmable) | OTP EPROM | OTP EPROM | Flash (re-programmable) | OTP EPROM |
| I/O Pins | 13 | 13 | 13 | 12 | 13 |
Key Differentiators
- Industrial -40 C to +85 C temperature range in production-grade SOIC (vs PIC16C558T-04/SO)
- Higher oscillator headroom for future-proof designs (vs PIC16C558-20I/SO)
- Flash-based modern alternative recommended by Microchip (vs PIC16F630-I/SL)
Design Notes
Place a 0.1 uF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 14), with the trace to VDD being wide and short. The PIC16C558T-04I/SO draws peak transient current during internal EPROM programming pulses; without local decoupling, VDD droops can cause programming failures or spurious resets. Add a bulk 10 uF tantalum or aluminium polymer cap at the board's regulator output if the design drives heavy relay coils or triacs.
Keep the oscillator traces (OSC1/OSC2, pins 16/15) shorter than 10 mm and routed over a continuous ground pour. Long oscillator traces act as antennas and couple noise into the MCU's internal clock, causing timing jitter and Brown-out Reset misfires. If using a crystal, place the loading capacitors (typically 15-33 pF for the PIC16C558) as close to the crystal pads as possible - never at the MCU side of the traces.
Because the PIC16C558T-04I/SO is OTP (one-time programmable), a single misconfiguration of the configuration bits (oscillator mode, WDT enable, code protect, Brown-out threshold) bricks the part for that application. Verify config words in a Flash-based PIC16F prototype first, then port the final bit pattern to OTP production parts. Also note the -04 speed grade limits the oscillator to 4 MHz - using a 20 MHz crystal will cause erratic execution, not a faster MCU.
When driving long cables (e.g., relay coils, 4-20 mA loops), add an external TVS diode and series resistor at each I/O pin, and use shielded cable for analog or high-speed signals. The PIC16C558T-04I/SO has no internal ESD clamps rated above HBM 2 kV per pin; for industrial environments, prefer the PIC16F or PIC18 variants with stronger ESD/EMC performance, or add external protection such as the PESD5V0L1BA from Nexperia.
Compliance Information
RoHS and REACH compliance per Microchip product page. Not AEC-Q100 qualified - PIC16C family targets industrial/commercial, not automotive safety-critical. Lead-free (Pb-free) and halogen-free per Microchip material declarations.
