PIC16LC558T-04/SS - 8-bit 4MHz OTP MCU 3.5KB 128B RAM 20-SSOP
MPN: PIC16LC558T-04/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.68 | $46.80 |
| 100 | $4.15 | $415.00 |
| 500 | $3.72 | $1,860.00 |
| 1,000 | $3.3 | $3,300.00 |
PIC16LC558T-04/SS Overview
What is an OTP microcontroller? An OTP (One-Time Programmable) microcontroller is a type of MCU whose program memory can be written exactly once at production time using a device programmer, after which the code is permanent. OTPs are the predecessor to flash-based MCUs and remain popular in cost-sensitive high-volume products where firmware updates are unnecessary. The PIC16LC558 belongs to the broader category of 8-bit microcontrollers, which sits within embedded microcontrollers (a sub-class of microprocessors). The PIC architecture uses a RISC instruction set with only 33 single-word/single-cycle instructions, simplifying firmware development and accelerating execution compared to CISC alternatives.
Key features include 4MHz maximum clock speed, 13 digital I/O lines, 128 bytes of general-purpose RAM, on-chip Power-On Reset (POR) and Watchdog Timer (WDT) peripherals, and a wide 2.5V-5.5V operating voltage range. The low-voltage "LC" designation enables direct battery operation (e.g., 3.3V Li-ion) without additional regulation. Compared to flash-based PIC16F5x successors, the OTP PIC16C5x/LC55x family offers lower unit cost at high volumes, making it attractive for cost-driven consumer and industrial appliances.
The PIC16LC558T-04/SS uses a Harvard architecture with separate program and data buses, allowing instruction fetch and operand access to occur in the same cycle. Its 14-bit instruction word (2K x 14 = 3.5KB) enables compact opcode encoding with most instructions executing in a single instruction cycle (4 clock periods). This yields effective throughput of approximately 1 MIPS at 4MHz, adequate for simple control loops, sensor interfacing, and user-interface tasks.
Typical applications include low-cost consumer appliances (toys, remote controls, small kitchen devices), battery-powered sensors and timers, automotive accessory controllers (non-safety-critical), LED drivers and lighting controllers, and simple industrial control tasks such as relay or solenoid drivers. The 13 I/O pins are sufficient for keypad scanning, 7-segment displays, and basic peripheral interfaces. The 20-pin SSOP package is compact yet hand-solderable for prototypes.
When designing with this device, note that OTP memory cannot be reprogrammed in-circuit. Use a flash-based PIC16F5x or PIC16F15x with equivalent pinout for development and prototype phases, then migrate to the PIC16LC558 for production. The Watchdog Timer must be cleared periodically in firmware to prevent unintended resets, and unused I/O pins should be configured as outputs to minimize current draw.
This page synthesizes distributor pricing, lifecycle status, drop-in pin-compatible alternatives, and engineering design notes not found in the manufacturer datasheet alone, providing actionable information for both procurement and design engineering teams.
Drop-in alternatives for PIC16LC558T-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 PIC16LC558T-04/SS (same form factor and footprint) — differing in RAM Size, Program Memory Size, Program Memory Type, Core Architecture, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC558T-04I/SS
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →PIC16LC558T-04E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558T-04/SS
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16C558-04/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F15344T-I/SS
✅ Drop-In✓ In Stock
$0.72 / Unit
View Datasheet →PIC16LC558T-04/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Series | PIC® 16C |
| Program Memory Size | 3.5 KB (2K x 14) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 128 x 8 bytes (128 B) |
| EEPROM Size | None |
| Maximum CPU Speed | 4 MHz |
| Operating Voltage Range | 2.5 V to 5.5 V (3.3V/5V) |
| Number of I/O Pins | 13 |
| Peripherals | POR, WDT (Power-On Reset, Watchdog Timer) |
| Connectivity | None (no UART, SPI, I2C on this variant) |
| Package Type | 20-pin SSOP (209 mil) |
| Mounting Type | Surface Mount |
| Instruction Set | 33 instructions, 14-bit wide |
| MSL Level | 1 |
| RoHS Status | Compliant |
PIC16LC558T-04/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / Timer0 clock input |
| Pin 4 | MCLR — Master Clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O port B bit 0 / external interrupt |
| 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 |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 14 | VDD — Positive supply voltage (2.5V-5.5V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 17 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 18 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 19 | VDD — Positive supply voltage (tied to pin 14) |
| Pin 20 | VSS — Ground reference (tied to pin 5) |
Typical Applications
PIC16LC558T-04/SS is suitable for 6 applications: Low-Cost Consumer Appliance Controller, Battery-Powered Sensor and Timer Module, LED Lighting Controller and Driver, Automotive Accessory Controller (Non-Safety), Simple Industrial Control and Relay Driver, User Interface and Keypad Scanner.
Low-Cost Consumer Appliance Controller
The PIC16LC558T-04/SS is well-suited for high-volume cost-sensitive consumer appliances such as remote controls, small kitchen devices, toys, and personal care products. Its 3.5KB OTP memory is sufficient for fixed-function control firmware, while the 13 I/O pins directly drive LEDs, keypads, simple relays, or segment displays. The 3.3V native operation enables direct Li-ion battery use without external regulation, reducing BOM cost. For applications needing 2-5 buttons, a few LEDs, and PWM motor control, this MCU delivers the lowest unit cost in the Microchip 8-bit portfolio, especially above 100k-unit volumes where OTP pricing advantage peaks.
Recommended
Battery-Powered Sensor and Timer Module
The PIC16LC558T-04/SS fits battery-powered sensors, irrigation timers, and standalone timing modules where firmware is fixed at production and battery life is critical. Its low-voltage CMOS "LC" process minimizes active current consumption at 3.3V, and the 4MHz max clock allows firmware to idle the CPU in sleep mode most of the time. The on-chip Watchdog Timer automatically recovers from firmware lock-ups in unattended field installations. With 13 I/O pins, the device can interface to a single analog sensor (via external ADC), drive a small LCD, and handle a few pushbuttons - typical requirements for an irrigation controller or thermostat.
Recommended
LED Lighting Controller and Driver
For decorative LED lighting, signage controllers, and small RGB drivers, the PIC16LC558T-04/SS provides adequate processing for simple color-mixing algorithms and chase patterns. The 13 I/O pins can drive multiple MOSFETs or LED driver channels directly via PWM, although the device has no hardware PWM peripheral - PWM is generated via firmware bit-banging at 4MHz. The 128B RAM stores pattern state for up to ~50 LED channels with 8-bit color depth. The 3.3V or 5V operating range accepts power from USB supplies or AC-DC adapters. Use software PWM since the PIC16LC558 lacks a hardware CCP/PWM module.
Recommended
Automotive Accessory Controller (Non-Safety)
In non-safety automotive accessories such as interior lighting controllers, simple seat controllers, or auxiliary switch panels, the PIC16LC558T-04/SS can serve as a low-cost logic controller. However, note that the part is NOT AEC-Q100 qualified and should only be used in non-safety applications where automotive-grade qualification is not required. The 20-pin SSOP package withstands automotive vibration environments when properly soldered. Operating temperature must be considered; the standard "04" variant supports 0C to +70C only - use the "I" (industrial -40C to +85C) or "E" (extended -40C to +125C) variant for under-dash installations.
Recommended
Simple Industrial Control and Relay Driver
The PIC16LC558T-04/SS is suitable for simple industrial control tasks such as relay switching, solenoid drivers, conveyor counters, or basic machine interlocks. The 13 I/O pins can directly drive opto-isolators or low-side MOSFETs to control 24V industrial loads, with the MCU operating from a 5V regulated rail. The Watchdog Timer prevents lock-up in factory environments with electrical noise. For new industrial designs, the flash-based PIC16F15344-I/SS is preferred since it allows in-circuit firmware updates for field bug fixes - critical for installed industrial equipment.
Recommended
User Interface and Keypad Scanner
For matrix keypads, 7-segment display drivers, or simple LCD interfaces, the PIC16LC558T-04/SS offers the right balance of I/O count, code size, and cost. The 13 I/O pins support a 4x4 matrix keypad (8 pins) plus 4 indicator LEDs, or a 3-digit 7-segment multiplexed display (11 pins) plus 2 user buttons. The 4MHz CPU executes keypad-debounce and display-multiplex firmware efficiently. The 3.5KB OTP is sufficient for full state-machine UI code with EEPROM emulation in flash-free OTP devices (using spare program memory for non-volatile storage).
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC558T-04/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC558T-04I/SS | PIC16LC558T-04E/SS | PIC16C558T-04/SS | PIC16C558-04/SS | PIC16F15344T-I/SS |
|---|---|---|---|---|---|---|
| Package | 20-pin SSOP | 20-pin SSOP - same | 20-pin SSOP - same | 20-pin SSOP - same | 20-pin SSOP - same | 20-pin SSOP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 3.5KB OTP | 28KB Flash (reprogrammable) |
| RAM Size | 128 B | 128 B | 128 B | 128 B | 128 B | 2 KB (+1500%) |
| Maximum CPU Speed | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 32 MHz (+700%) |
| Operating Voltage | 2.5V to 5.5V (LC) | 2.5V to 5.5V (LC) | 2.5V to 5.5V (LC) | 3.0V to 6.0V (non-LC) | 3.0V to 6.0V (non-LC) | 2.3V to 5.5V |
| Temperature Range | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +125C (extended) | 0C to +70C (commercial) | 0C to +70C (commercial) | -40C to +85C (industrial) |
| Number of I/O Pins | 13 | 13 | 13 | 13 | 13 | 18 (+5 pins) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Active (recommended new design) |
| Approx. Unit Price (qty 1) | $5.20 | $5.50 (estimated) | $5.80 (estimated) | $4.95 (estimated) | $4.80 (estimated) | $1.85 (estimated) |
Key Differentiators
- Low-voltage CMOS process enables direct 3.3V battery operation (vs PIC16C558T-04/SS)
- Industrial temperature range (-40C to +85C) available with same die (vs PIC16LC558T-04I/SS (same product family))
- Significantly lower cost at high volumes (vs PIC16F15344T-I/SS)
Design Notes
The OTP (One-Time Programmable) memory cannot be erased or rewritten. Once programmed, the firmware is permanent. Design-in must use a flash-based equivalent (e.g., PIC16F15344T-I/SS) for development and prototyping, then migrate the verified firmware to the PIC16LC558T-04/SS for high-volume production. Any firmware bug found after OTP programming results in a scrapped MCU, so plan for code review and extensive testing before final programming.
Estimated: At 4MHz CPU and 3.3V VDD, the PIC16LC558T-04/SS active current is approximately 1-2 mA depending on I/O loading. For battery-powered designs, use sleep mode aggressively - in sleep the part draws microampere-level currents. Decouple VDD with a 100 nF ceramic capacitor placed within 5 mm of the VDD pin, and add a bulk 10 uF tantalum or ceramic capacitor on the supply rail for transient suppression.
The 20-pin SSOP package has a 0.65mm pin pitch, requiring careful PCB layout. Use ENIG or immersion-tin surface finish for reliable soldering. The exposed SSOP leads benefit from solder paste stencil apertures slightly reduced (e.g., 90% of pad size) to prevent solder bridging. Place the MCLR pull-up resistor (typically 10 kohm) close to the MCLR pin to minimize noise susceptibility, and add a 100 nF capacitor on MCLR if the application has noisy reset requirements.
The PIC16LC558T-04/SS has no internal oscillator - the OSC1/OSC2 pins require an external crystal, ceramic resonator, or clock source. For cost-sensitive designs, a 4MHz ceramic resonator with built-in capacitors (e.g., Murata CSTCR4M00G55Z-R0) simplifies layout vs. discrete crystal + capacitors. Keep the oscillator traces short (under 10mm) and surrounded by ground pour to minimize EMI susceptibility, since the PIC16LC558 lacks modern oscillator-fail detection features.
Compliance Information
RoHS compliant per distributor listings (DigiKey P/N 321302-ND). Not AEC-Q100 qualified - do not use in safety-critical automotive applications. REACH and halogen-free status not explicitly stated in verified data; consult Microchip directly for SVHC declarations.
