PIC16C558T-04E/SS - 4MHz 8-bit OTP MCU, 20-SSOP | Microchip
MPN: PIC16C558T-04E/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.55 | $3.55 |
| 10 | $3.2 | $32.00 |
| 100 | $2.75 | $275.00 |
| 500 | $2.4 | $1,200.00 |
| 1,000 | $2.1 | $2,100.00 |
PIC16C558T-04E/SS Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory, working RAM, and configurable peripherals. OTP microcontrollers store program code in one-time-programmable EPROM cells that retain data without power but cannot be rewritten, making them well-suited to cost-sensitive volume production where firmware is stable. The PIC16C558 belongs to the PICmicro mid-range family - a lineage of 8-bit MCUs known for deterministic interrupt latency, a Harvard memory architecture, and an instruction set optimized for compiled C and hand-written assembly.
Key features include a 4MHz internal oscillator-friendly design with external clock option, 128 x 8 bytes of general-purpose RAM, Power-On Reset (POR), Watchdog Timer (WDT) with on-chip RC oscillator, 13 bi-directional digital I/O pins, and code-protection support. The industrial-grade temperature range of -40C to +125C and 3.0V to 5.5V supply enable deployment in factory-floor and consumer applications.
The PIC16C558 uses a 14-bit instruction word with an 8-bit data path, separating program and data buses (Harvard architecture) so instruction fetch and data access occur in the same cycle. Peripherals are minimal by design: POR, WDT, and a programmable prescaler - this simplicity keeps quiescent current low and lets the MCU wake quickly from sleep.
Typical applications include industrial sensor interfaces, consumer appliance control, automotive body electronics (non-safety), HVAC thermostat controllers, and low-end motor control. The OTP memory is favored where unit cost dominates over firmware flexibility. The 20-SSOP package offers a small PCB footprint suitable for hand-held and space-constrained designs.
When designing with the PIC16C558, evaluate code protection settings and pre-program all units before final test because OTP cannot be erased. Account for the 13 I/O limitation versus larger PIC16C variants (e.g., PIC16C56/57 with fewer I/O) when allocating pin resources.
This page synthesizes distributor pricing, drop-in alternatives from the Microchip PIC16C family, and practical design notes not found in any single datasheet.
Drop-in alternatives for PIC16C558T-04E/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-04E/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, RoHS Status, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-04E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558T-04I/SS
✅ Drop-In✓ In Stock
$2.13 / Unit
View Datasheet →PIC16C558T-04/SS
✅ Drop-In✓ In Stock
$2.18 / 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-04E/SS
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C558T-04E/SS Maximum Ratings & Electrical Characteristics
| Core Processor | PIC |
| Core Size | 8-bit |
| CPU Speed | 4 MHz |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 3.5 KB (2K x 14) |
| RAM Size | 128 x 8 bytes |
| Number of I/O Pins | 13 |
| Supply Voltage Range | 3.0 V to 5.5 V |
| Operating Temperature Range | -40 C to +125 C |
| Package | 20-SSOP (5.30 mm) |
| Mounting Type | Surface Mount |
| Instruction Set | 35 single-word instructions |
| Instruction Execution Time | 200 ns |
| Peripherals | POR, WDT |
| RoHS Status | unknown |
PIC16C558T-04E/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin; Port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O pin; Port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O pin; Timer0 clock input (open-drain on PIC16C558) |
| Pin 4 | MCLR/VPP — Master Clear (reset) input / programming voltage input |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O pin; external interrupt input |
| Pin 7 | RB1 — Bidirectional I/O pin; Port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O pin; Port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O pin; Port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O pin; Port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O pin; Port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O pin; Port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O pin; Port B bit 7 |
| Pin 14 | VSS — Ground reference (second ground pin) |
| Pin 15 | RC0 — Bidirectional I/O pin; Port C bit 0 |
| Pin 16 | RC1 — Bidirectional I/O pin; Port C bit 1 |
| Pin 17 | RC2 — Bidirectional I/O pin; Port C bit 2 |
| Pin 18 | RC3 — Bidirectional I/O pin; Port C bit 3 |
| Pin 19 | RC4 — Bidirectional I/O pin; Port C bit 4 |
| Pin 20 | VDD — Positive supply voltage (3.0V to 5.5V) |
Typical Applications
PIC16C558T-04E/SS is suitable for 6 applications: Industrial Sensor Interface Controller, Consumer Appliance Control Board, Automotive Body Electronics (Non-Safety), HVAC Thermostat and Climate Controller, Low-End Motor Control (Brushed DC, Small BLDC), Smart Sensor Edge Nodes.
Industrial Sensor Interface Controller
The PIC16C558T-04E/SS fits industrial sensor-interface nodes because its 13 programmable I/O pins comfortably handle multiple digital sensors and actuators, and its 4 MHz CPU plus 200 ns instruction cycle provides responsive sampling for limit-switch or proximity-sensor debouncing. The industrial -40C to +125C temperature grade supports factory-floor enclosures and outdoor cabinets. The 3.0-5.5V supply range accepts unregulated 5V rails common in industrial cabinets. With 3.5 KB OTP program memory, the MCU can host sensor calibration tables, hysteresis logic, and serial-protocol frame handlers (Modbus RTU, custom binary). The integrated Watchdog Timer is critical for unattended sensor nodes that must recover from transient faults without operator intervention. Its 20-SSOP small footprint suits DIN-rail terminal blocks where PCB area is constrained.
Recommended
Consumer Appliance Control Board
In white-goods and small appliance control boards, the PIC16C558T-04E/SS offers the right balance of capability and unit cost. Its 35-instruction RISC core compiles efficiently in C, letting engineers squeeze user-interface handling, LED/keypad scanning, and motor-driver sequencing into 3.5 KB of OTP memory. The Watchdog Timer provides unsupervised recovery from line-voltage transients, important in appliances with inductive loads. The 13 I/O pins drive segment LCDs, keypads, relay coils, and triac interfaces. OTP memory is a deliberate cost-down choice for high-volume appliances where firmware is finalized before launch. The 20-SSOP package supports automated pick-and-place assembly. Operating from 3.0-5.5V makes the MCU compatible with both rectified-5V and 3.3V regulated rails inside appliances.
Recommended
Automotive Body Electronics (Non-Safety)
For non-safety automotive body modules such as interior lighting controllers, seat-position memory, mirror-adjust, and HVAC damper actuators, the PIC16C558T-04E/SS provides automotive-compatible 5V operation across -40C to +125C. The MCU's 13 I/O pins accommodate multiple H-bridge enable lines, position-sensor inputs, and LIN-bus style UART links. OTP memory locks firmware against field-tampering, an asset in warranty-management scenarios. The Harvard architecture with deterministic instruction timing simplifies CAN/LIN stack handling. Note that safety-critical applications require AEC-Q100-qualified MCUs; PIC16C558 is not AEC-Q100 qualified, so it is restricted to non-safety body functions. The 20-SSOP footprint fits compact body-control modules behind dashboards and in door panels.
Recommended
HVAC Thermostat and Climate Controller
The PIC16C558T-04E/SS is well-suited to HVAC thermostat mainboards, where it scans temperature sensors, drives the LCD display, controls relay outputs for the compressor contactor, and orchestrates fan-speed triac triggering. The 3.5 KB OTP program memory holds the scheduling state machine, hysteresis tables, and user-interface menus. The 4 MHz CPU provides ample bandwidth for 50/60 Hz zero-cross detection and PID control loops with sub-second update rates. The Watchdog Timer protects the thermostat against ESD-induced firmware upsets common in HVAC installations. Industrial -40C to +125C temperature rating handles equipment-room and rooftop unit environments. The 20-SSOP package allows compact wall-mount thermostat form factors.
Recommended
Low-End Motor Control (Brushed DC, Small BLDC)
For brushed DC or small sensorless brushless DC motor controllers in appliances and toys, the PIC16C558T-04E/SS provides enough computational bandwidth for trapezoidal commutation with back-EMF sensing at moderate RPM. The 13 I/O pins drive half-bridge enable signals, sense current with a comparator, and read Hall-effect sensors or back-EMF through the ADC-less analog comparator. The Watchdog Timer recovers the controller from stall conditions or commutation glitches. OTP memory protects proprietary motor-control algorithms against copying. The 3.0-5.5V supply range accepts battery packs (3x AA) or rectified-mower supplies. Operating-temperature rating supports outdoor power-tool and garden-equipment environments.
Recommended
Smart Sensor Edge Nodes
In distributed IoT-edge sensor nodes for building automation, the PIC16C558T-04E/SS serves as a low-power bridge between analog sensors and a host MCU or radio. It performs local ADC-free signal conditioning using its analog comparator, debounces digital inputs, and forwards formatted telegrams over UART/SPI. The 13 I/O pins multiplex several sensors on a shared bus. The Watchdog Timer and Power-On Reset ensure reliable recovery from brown-out conditions on long cable runs typical in building-automation retrofits. The 3.0-5.5V supply accepts Power-over-Ethernet derived rails or local 24V-to-5V converters. The 20-SSOP package minimizes node PCB size, allowing in-wall mounting inside standard electrical boxes.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-04E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-04E/SS | PIC16C558T-04I/SS | PIC16C558T-04/SS | PIC16C558-20E/SS | PIC16C558-20/SS | PIC16C554T-04E/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 |
| CPU Speed | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 4 MHz |
| Program Memory | 3.5 KB (2K x 14) OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 896 B (512 x 14) OTP |
| RAM | 128 x 8 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 80 bytes |
| I/O Pins | 13 | 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 | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +125 C (E grade) | -40 C to +125 C | -40 C to +85 C | 0 C to +70 C | -40 C to +125 C | 0 C to +70 C | -40 C to +125 C |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Industrial temperature grade -40C to +125C as standard (vs PIC16C558T-04/SS (commercial 0C-70C))
- Tape-and-reel packaging for high-volume SMT assembly (vs PIC16C558-04E/SS (tube packaging))
- 3.5 KB OTP program memory vs 896 B on PIC16C554 family (vs PIC16C554T-04E/SS)
Design Notes
PIC16C558 OTP memory cannot be erased. Once a unit is programmed, any firmware bug discovered post-production cannot be fixed without scrapping the device. Pre-programming strategy: design firmware in flash-based PIC16F equivalent first, validate thoroughly, then port to OTP only for the final production part. Use Microchip's device programmer with verified programming parameters and verify checksum after each write.
Estimated: at 4 MHz CPU clock with 5V supply, PIC16C558 core current is approximately 2-5 mA active and a few microamps in sleep. Add a 100 nF decoupling capacitor as close as practical to VDD (pin 20) and a bulk 10 uF tantalum or ceramic on the supply rail. Brown-Out Reset (BOR) configuration bits should be enabled to ensure clean reset under battery or rectified-rail droop conditions common in appliance and HVAC power environments.
Place the 20-SSOP decoupling capacitor within 3 mm of pin 20 (VDD) and pin 19/14 (VSS). Route MCLR/VPP (pin 4) with a 10 kohm pull-up to VDD for normal operation and provision a programming-header footprint for in-circuit serial programming (ICSP) access. The OSC1/OSC2 pins (17/18 on this variant - verify against datasheet pinout for your specific 20-SSOP variant) require short traces to the crystal or resonator; keep them away from switching traces to avoid injecting noise into the clock.
Compliance Information
PIC16C558 family predates widespread RoHS adoption in OTP PIC16C parts. PIC16C558T-04E/SS is not AEC-Q100 qualified - restrict to non-safety automotive body electronics. Compliance status not explicitly stated in the verified distributor data.
