PIC16C558T-04I/SS - 8-Bit 4MHz OTP MCU, 3.5KB | Microchip
MPN: PIC16C558T-04I/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.42 | $3.42 |
| 10 | $3.08 | $30.80 |
| 100 | $2.74 | $274.00 |
| 500 | $2.4 | $1,200.00 |
| 1,000 | $2.13 | $2,130.00 |
PIC16C558T-04I/SS Overview
An OTP (One-Time Programmable) microcontroller is a non-flash, non-EEPROM MCU variant where the program memory can be written exactly once via a dedicated programmer and then becomes read-only permanently. In the broader semiconductor taxonomy, the PIC16C558 sits within 8-bit microcontrollers -> microcontrollers -> microcontrollers and processors -> integrated circuits -> semiconductors. OTP MCUs occupy a specific niche: they are cheaper than flash equivalents, ideal for high-volume mature products, and well-suited for cost-sensitive industrial and automotive subsystems where firmware is finalized and production quantities justify masking the code once.
Key specifications of the PIC16C558T-04I/SS include 4MHz maximum oscillator frequency, 3.5KB OTP program memory (2K x 14-bit words), 128 bytes of data RAM, 13 digital I/O pins, two 8-bit timers (Timer0 and Timer2) and one 16-bit timer (Timer1), a watchdog timer with on-chip RC oscillator, and an operating temperature range of -40C to +85C (industrial grade, indicated by the 'I' suffix). The 20-pin SSOP package measures approximately 5.30mm body width with 0.65mm pitch.
The device is built on a low-power CMOS process supporting both 3.3V and 5V operation. The RISC architecture ensures deterministic instruction timing with most instructions completing in a single 200ns cycle at 4MHz, simplifying real-time control loops. The integrated watchdog timer with dedicated on-chip RC oscillator enhances system reliability in noisy industrial environments, while the programmable code protection prevents unauthorized firmware readout.
Typical applications include automotive subsystems (sensor interfaces, lighting controllers), industrial control (small appliance controllers, motor drivers), consumer electronics (remote controls, toys), and embedded control nodes requiring a minimal pin count. The 13 I/O pins make it suitable for human-machine interface (HMI) keypads and simple sensor front-ends.
When designing with the PIC16C558T-04I/SS, engineers should plan firmware development around OTP one-time programming: prototype using a windowed (JW) or UV-erasable sibling for code iteration, then commit to the OTP version only after firmware is finalized. Note that the PIC16C558 is now legacy - for new designs, evaluate flash-based PIC16F equivalents.
This page synthesizes distributor pricing, OTP-specific design notes, and a curated drop-in alternative list - practical information that supplements the manufacturer datasheet for legacy design support.
Drop-in alternatives for PIC16C558T-04I/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-04I/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, Timers, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558T-04/SS
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16C558-20I/SS
✅ Drop-In✓ In Stock
$2.15 / Unit
View Datasheet →PIC16C558-20E/SS
✅ Drop-In✓ In Stock
$2.53 / Unit
View Datasheet →PIC16C558-20/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C554T-04I/SS
✅ Drop-In✓ In Stock
$1.09 / Unit
View Datasheet →PIC16F558-I/SS
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C558T-04I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Series | PIC® 16C |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 3.5 KB (2K x 14) |
| RAM Size | 128 B |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns at 4 MHz |
| Instruction Set Size | 35 single-word instructions |
| I/O Pins | 13 |
| Timers | 1 x 8-bit, 1 x 8-bit, 1 x 16-bit (TMR0/TMR2/TMR1) |
| Watchdog Timer | Yes, with on-chip RC oscillator |
| Supply Voltage | 3.0 V to 5.5 V (3.3 V / 5 V operation) |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 20-SSOP (5.30 mm body width, 0.65 mm pitch) |
| Mounting Type | Surface Mount |
PIC16C558T-04I/SS Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (digital I/O) |
| Pin 2 | RA3 — Port A bit 3 (digital I/O) |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master Clear reset (active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt |
| Pin 7 | RB1 — Port B bit 1 (digital I/O) |
| Pin 8 | RB2 — Port B bit 2 (digital I/O) |
| Pin 9 | RB3 — Port B bit 3 (digital I/O) |
| Pin 10 | RB4 — Port B bit 4 (digital I/O) |
| Pin 11 | RB5 — Port B bit 5 (digital I/O) |
| Pin 12 | RB6 — Port B bit 6 (digital I/O) |
| Pin 13 | RB7 — Port B bit 7 (digital I/O) |
| Pin 14 | VDD — Positive supply (3.0V to 5.5V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock |
| Pin 17 | RA0 — Port A bit 0 (digital I/O) |
| Pin 18 | RA1 — Port A bit 1 (digital I/O) |
| Pin 19 | RA5 — Port A bit 5 (digital I/O) |
| Pin 20 | VSS — Ground reference (secondary) |
Typical Applications
PIC16C558T-04I/SS is suitable for 6 applications: Automotive Sensor Interface Modules, Small Appliance Control Boards, Remote Control and Toy Electronics, Industrial Lighting Controllers, Battery-Powered Sensor Nodes, Human-Machine Interface Keypads.
Automotive Sensor Interface Modules
The PIC16C558T-04I/SS fits automotive sensor interface modules where firmware is finalized at production ramp and the 4MHz RISC core can handle slow analog/digital signal conditioning at low cost. With 13 I/O pins it can multiplex multiple temperature, pressure, or position sensors, and the 3.5KB OTP memory is ample for filter coefficients, lookup tables, and linearization routines. The on-chip watchdog timer with dedicated RC oscillator enhances reliability in electrically noisy vehicle environments. Engineers should note that this part is industrial grade (-40C to +85C) and is not AEC-Q100 qualified; for under-hood or safety-critical nodes, choose the automotive-qualified PIC16F or PIC18 AEC-Q100 successors in the same SSOP-20 footprint.
Recommended
Small Appliance Control Boards
The PIC16C558T-04I/SS suits small appliance controllers (coffee makers, toasters, microwave ovens, blenders) where the BOM cost must be minimized and the firmware is locked at design freeze. The 35-instruction RISC core delivers deterministic 200ns cycle timing, ideal for triac/relay phase-angle control and PWM-driven heater regulation. The 128 bytes of RAM accommodates a small user-interface state machine plus keypad debounce logic, and the integrated watchdog prevents appliance lockup if firmware enters an illegal state. The OTP memory eliminates in-field firmware tampering concerns, which is desirable for safety-certified appliance designs. Pair with an optoisolated triac driver for mains-voltage switching.
Recommended
Remote Control and Toy Electronics
Consumer remote controls, electronic toys, and hobbyist products benefit from the PIC16C558T-04I/SS's low unit cost, small SSOP-20 footprint, and 4MHz operation that consumes minimal battery current. The 13 I/O pins drive IR LEDs, keypads, vibration motors, and a piezo buzzer simultaneously, while the 3.5KB OTP program memory holds IR protocol encoding routines (RC5, NEC, SIRC) and sound-generation lookup tables. The industrial temp range tolerates indoor thermal variation, and the OTP memory prevents firmware cloning by competitors - a commercial advantage in the toy market. Low-power sleep modes (below 1uA typical) extend battery life in remote-control use cases.
Recommended
Industrial Lighting Controllers
The PIC16C558T-04I/SS serves as the control core in industrial LED lighting fixtures and architectural dimmers, where 4MHz RISC performance handles DMX-512 or 0-10V dimming protocols without breaking a sweat. The 13 I/O pins accept dimmer pot inputs, push-button controls, and drive MOSFET gate drivers for LED strings or TRIAC firing circuits. OTP memory locks the dimming curve and safety limits at production, preventing field modification of certified lighting products. The watchdog timer ensures the controller recovers from brown-out events common in industrial power environments. Operating range -40C to +85C covers most indoor/outdoor lighting installations.
Recommended
Battery-Powered Sensor Nodes
Low-duty-cycle wireless sensor nodes benefit from the PIC16C558T-04I/SS's combination of low cost, low power consumption, and adequate I/O count. At 4MHz the device draws single-digit milliamps active and sub-microamp sleep current, enabling multi-year battery life when paired with an RF transmitter module that wakes the MCU only on measurement events. The 3.5KB OTP holds the sensor calibration table and RF protocol stack for proprietary sub-GHz or simple OOK modulation schemes. SSOP-20 package allows compact PCB integration alongside a CR2032 coin cell or 2xAA battery holder. For modern wireless sensor designs, the PIC16F1827 with integrated ADC and PWM is often preferred.
Recommended
Human-Machine Interface Keypads
The PIC16C558T-04I/SS handles 4x4 matrix keypads, rotary encoder inputs, and 7-segment display multiplexing in cost-sensitive HMI panels and instrument front-ends. With 13 I/O pins it can scan up to 16 keys via 4x4 matrix (8 pins) plus drive a 4-digit 7-segment display via BCD decoder or direct multiplexing. The 200ns instruction cycle allows software debounce of mechanical key bounce within a tight 10ms scan loop. OTP memory locks the keymap and command set, preventing reverse engineering. Watchdog timer and brown-out protection ensure the panel recovers from electrical transients in industrial cabinets.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-04I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558T-04/SS | PIC16C558-20I/SS | PIC16C558-20E/SS | PIC16C558-20/SS | PIC16C554T-04I/SS | PIC16F558-I/SS |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | 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 | 20-SSOP - same |
| Max Clock Frequency | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz | 4 MHz | 20 MHz |
| Program Memory Type | OTP | OTP | OTP | OTP | OTP | OTP | Flash |
| Program Memory Size | 3.5 KB | 3.5 KB | 3.5 KB | 3.5 KB | 3.5 KB | 0.5 KB | 3.5 KB |
| RAM Size | 128 B | 128 B | 128 B | 128 B | 128 B | 80 B | 128 B |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 | 13 |
| Operating Temperature | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +125C (extended) | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +85C (industrial) |
Key Differentiators
- Lowest-cost 4MHz OTP option in PIC16C558 family (vs PIC16C558-20I/SS)
- Industrial temperature grade -40C to +85C (vs PIC16C558T-04/SS)
- One-Time Programmable for code-locked designs (vs PIC16F558-I/SS)
Design Notes
OTP memory can be programmed only ONCE - there is no in-circuit reprogramming, no debugging via ICSP after programming, and no firmware update path. Therefore, develop and validate firmware on a windowed (JW) or flash-based sibling (PIC16F558 in same SSOP-20 footprint) and only commit to OTP programming after code is fully validated. A single mistake in OTP programming produces a bricked MCU; budgeting $0.50 to $2.00 for development-prototype JW/flash parts is highly recommended.
Decouple the VDD pin (pin 14) with a 100nF ceramic capacitor placed within 5mm of the MCU, plus a bulk 10uF tantalum or aluminum capacitor on the same rail. The PIC16C558T-04I/SS is sensitive to supply ripple during EEPROM/flash programming voltage transitions; inadequate decoupling causes programming failures and erratic behavior. Both VSS pins (5 and 20) must be connected to a low-impedance ground plane. MCLR (pin 4) requires a 10kohm pull-up to VDD and a 100nF capacitor to ground for reliable reset.
The 20-SSOP package has 0.65mm pin pitch, which is within the range of standard SMT assembly but requires careful stencil design - use a 4-mil (0.1mm) stencil and lead-free SAC305 solder paste for reliable reflow. Keep all 13 I/O traces short (under 50mm) to avoid EMI coupling; route OSC1/OSC2 traces symmetrically with ground guard traces if the crystal is more than 10mm away. Avoid routing high-frequency signals (PWM, switching converter nodes) parallel to the oscillator traces to prevent injection-locking.
Compliance Information
Compliance status not explicitly stated in verified distributor data; request certificates from Microchip. PIC16C558T-04I/SS is industrial grade but not AEC-Q100 qualified - for automotive designs choose PIC16F AEC-Q100 successor.
