PIC16C558T-20/SS - 8-Bit 20MHz OTP MCU 20-SSOP | Microchip
MPN: PIC16C558T-20/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.2 | $3.20 |
| 10 | $2.85 | $28.50 |
| 100 | $2.42 | $242.00 |
| 500 | $2.1 | $1,050.00 |
| 1,000 | $1.85 | $1,850.00 |
PIC16C558T-20/SS Overview
What is an OTP microcontroller? An OTP (One-Time-Programmable) microcontroller contains EPROM-based program memory that can be written once during production programming and cannot be electrically erased. Compared to flash-based MCUs, OTP parts offer lower unit cost for high-volume production runs where firmware is finalized, and they provide higher density and radiation tolerance. The PIC16C558T belongs to the broader 8-bit microcontroller category -> CMOS RISC microcontroller -> embedded controller -> MCU -> semiconductor, occupying the entry-level / cost-optimized tier of the PIC16C5x family tree.
Key features include 13 I/O pins with individual direction control, two 8-bit timers (Timer0 and Timer2), a Watchdog Timer with on-chip RC oscillator, power-on reset, brown-out detection, and a 4-channel 8-bit ADC. The device operates from 2.5V to 5.5V and is rated for the commercial temperature range (0C to +70C). Its 20MHz clock rate yields a 200ns instruction cycle, sufficient for servo loops, sensor sampling, and simple protocol handling.
The architecture uses a RISC-style pipeline with only 33 single-cycle instructions, dramatically simplifying code generation in assembly or C. Internal peripheral integration (ADC, timers, WDT, POR/BOR) eliminates many external components, enabling compact PCB layouts and reducing BOM cost. The SSOP-20 footprint is compatible with the rest of the PIC16C5x family (PIC16C554, PIC16C55, PIC16C57, PIC16C58) where pin counts match, allowing PCB reuse across product variants.
Typical applications include appliance control, simple sensor interfaces, low-end consumer electronics, motor control front-ends, smart battery chargers, and remote controls. Engineers continue to design with PIC16C558 in legacy products where the OTP cost model fits the bill of materials and existing firmware has been qualified for years. The 'T' suffix indicates tape-and-reel packaging for high-volume SMT assembly.
When designing with this part, ensure programming is completed before final PCB assembly because OTP memory cannot be updated in the field. Use Microchip's PICSTART Plus or MPLAB PM3 programmer, and verify code protection bits are set if intellectual property protection is required. Decoupling: place a 0.1uF ceramic capacitor directly across VDD/VSS within 5mm of the pins.
This page synthesizes distributor stock data, drop-in alternatives from the PIC16C5x family, and design notes that go beyond the manufacturer datasheet to help engineers select, source, and integrate the PIC16C558T-20/SS.
Drop-in alternatives for PIC16C558T-20/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-20/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, Watchdog Timer, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-20/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C558-20I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558-20E/SS
✅ Drop-In✓ In Stock
$2.53 / Unit
View Datasheet →PIC16C558T-04/SS
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16C554T-20/SS
✅ Drop-In✓ In Stock
$1.74 / Unit
View Datasheet →PIC16C558T-20/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 16C5x (8-bit RISC) |
| Instruction Set | 33 single-cycle instructions, 12-bit instruction word |
| Program Memory Type | OTP (EPROM-based, One-Time-Programmable) |
| Program Memory Size | 3.5 KB (2K x 14) |
| RAM | 128 bytes |
| Data EEPROM | Not present (OTP MCU) |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns at 20 MHz |
| Supply Voltage (VDD) | 2.5 V to 5.5 V |
| I/O Pins | 13 |
| Timers | Timer0 (8-bit), Timer2 (8-bit) |
| ADC | 8-bit, 4 channels |
| Watchdog Timer | Yes (with on-chip RC oscillator) |
| Brown-Out Reset | Yes |
| Power-On Reset | Yes |
| Operating Temperature | 0 C to +70 C (commercial) |
| Package | 20-pin SSOP (5.30 mm body, 0.65 mm pitch) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life at <30C/85% RH) |
| RoHS Status | Non-compliant (legacy OTP process) |
| Code Protection | Yes (code-protect bit supported) |
PIC16C558T-20/SS Pin Configuration
| Pin 1 | RA2 — I/O port A bit 2 / analog channel 2 |
| Pin 2 | RA3 — I/O port A bit 3 / analog channel 3 |
| Pin 3 | RA4/T0CKI — I/O port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master Clear (reset, active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — I/O port B bit 0 / external interrupt |
| Pin 7 | RB1 — I/O port B bit 1 |
| Pin 8 | RB2 — I/O port B bit 2 |
| Pin 9 | RB3 — I/O port B bit 3 |
| Pin 10 | RB4 — I/O port B bit 4 |
| Pin 11 | RB5 — I/O port B bit 5 |
| Pin 12 | RB6 — I/O port B bit 6 |
| Pin 13 | RB7 — I/O port B bit 7 |
| Pin 14 | VSS — Ground reference (duplicate) |
| Pin 15 | OSC1/CLKIN — Oscillator input / external clock |
| Pin 16 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 17 | VDD — Positive supply voltage |
| Pin 18 | RA0/AN0 — I/O port A bit 0 / analog channel 0 |
| Pin 19 | RA1/AN1 — I/O port A bit 1 / analog channel 1 |
| Pin 20 | NC — Not connected (per datasheet) |
Typical Applications
PIC16C558T-20/SS is suitable for 6 applications: Appliance Control (Washing Machines, Microwaves), Sensor Interface Modules, Remote Control Transmitters, Smart Battery Chargers, Simple Motor Control (Fans, Pumps), LED Lighting Controllers.
Appliance Control (Washing Machines, Microwaves)
The PIC16C558T-20/SS is well-suited for household appliance control boards including washing machine timers, microwave oven user interfaces, and dishwasher cycle controllers. Its 20 MHz clock provides a 200 ns instruction cycle, enabling real-time response to keypad inputs and sensor feedback within 1 ms. The 13 I/O pins can directly drive LED indicators, relays via transistors, and 7-segment displays without external mux ICs. The integrated 4-channel 8-bit ADC reads water level, temperature, and motor current sensors. The 3.5 KB OTP program memory holds complete state-machine firmware for cycle sequencing. Compared to flash MCUs, the OTP memory locks the firmware permanently - preventing field tampering with safety-critical wash/dry profiles and ensuring regulatory compliance.
Recommended
Sensor Interface Modules
The PIC16C558T-20/SS handles sensor signal conditioning and digital conversion in industrial sensor interface modules, particularly for 4-20 mA loop-powered transmitters and RTD/thermocouple front-ends. The 8-bit ADC with 4 input channels can digitize up to four sensor signals sequentially at ~10 kSPS aggregate throughput. The 20 MHz CPU executes averaging, linearization, and HART-style protocol framing in real time. The wide 2.5-5.5V supply range tolerates the variable compliance voltage of loop-powered designs. OTP memory prevents accidental firmware updates in the field that could invalidate calibration certificates. Compared to a discrete op-amp + ADC approach, this single-chip solution reduces BOM count by 60% and PCB area by 50%.
Recommended
Remote Control Transmitters
The PIC16C558T-20/SS powers low-cost infrared and RF remote control transmitters for consumer electronics (TV, set-top box, garage door opener). Its low power consumption and 20 MHz clock support simple OOK/FSK modulation at 38 kHz carrier frequency without external timers. The 13 I/O pins connect to a keypad matrix (up to 4x4) and LED status indicators. The 3.5 KB OTP memory stores device codes and pairing sequences. OTP storage prevents firmware reverse-engineering - a security feature important for anti-cloning. The SSOP-20 package fits slim remote-control enclosures. Compared to ASIC encoder chips, this MCU is reprogrammable during development (using EPROM windowed versions like PIC16C558-20/P) and offers more flexible I/O assignments.
Recommended
Smart Battery Chargers
The PIC16C558T-20/SS serves as the control MCU in NiCd/NiMH smart battery chargers for power tools and consumer rechargeables. The 4-channel 8-bit ADC monitors battery voltage, charge current, temperature (via NTC), and timer elapsed - the four critical parameters for safe delta-V or delta-T charge termination. The two 8-bit timers generate PWM for switch-mode charger control and sample timing. OTP memory prevents firmware modifications that could create overcharge safety hazards. The 2.5-5.5V supply range matches single-cell Li-ion or multi-cell NiMH packs directly. Compared to discrete charger ASICs, the PIC16C558 enables custom charge profiles (satellite, trickle, refresh) in a single firmware revision.
Recommended
Simple Motor Control (Fans, Pumps)
The PIC16C558T-20/SS controls low-voltage brushed DC motors and small brushless fans in HVAC, computer cooling, and small pump applications. Timer0 generates PWM at up to 78 kHz (8-bit resolution) for variable-speed motor drive; Timer2 produces complementary PWM with dead-band insertion for half-bridge drivers. The 13 I/O pins handle H-bridge direction control, tachometer feedback, and fault input from current-sense comparators. The 20 MHz clock closes the speed-control loop in under 1 ms. OTP memory ensures firmware stability across the motor's lifetime. Compared to dedicated motor-controller ICs, the PIC16C558 adds programmability for custom ramp profiles, fault logging, and serial diagnostics on the same chip.
Recommended
LED Lighting Controllers
The PIC16C558T-20/SS drives decorative LED lighting chains, RGB color-mixing fixtures, and architectural LED dimmers. Timer0 PWM outputs (up to four channels via software multiplexing) generate 8-bit dimming at 1 kHz refresh, eliminating visible flicker. The 4-channel ADC reads ambient light sensors and user potentiometers for closed-loop brightness control. The 3.5 KB OTP memory stores multiple lighting scenes and fade profiles. OTP ensures firmware cannot be modified to bypass safety current limits, important for CE/UL compliance. Compared to dedicated LED driver ICs like WS2801, this MCU supports custom communication protocols (DMX, DALI, proprietary RF) without external bridge chips.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-20/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20/SS | PIC16C558-20I/SS | PIC16C558-20E/SS | PIC16C554T-20/SS |
|---|---|---|---|---|---|
| Brand | 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 |
| Program Memory | 3.5 KB (2K x 14) OTP | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB OTP | 1.75 KB OTP (-50%) |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Operating Temperature | 0C to +70C (commercial) | 0C to +70C | -40C to +85C (industrial) | -40C to +125C (extended) | 0C to +70C |
| I/O Pins | 13 | 13 | 13 | 13 | 13 |
| ADC | 8-bit, 4 channels | 8-bit, 4 channels | 8-bit, 4 channels | 8-bit, 4 channels | 8-bit, 4 channels |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Largest OTP memory in the PIC16C5x SSOP-20 family (vs PIC16C554T-20/SS)
- Drop-in commercial-temperature variant (vs PIC16C558-20I/SS)
- Industrial temperature drop-in available (vs PIC16C558-20/SS)
- Higher clock speed available as drop-in alternative (vs PIC16C558T-04/SS)
Design Notes
Decouple VDD (pin 17) and VSS (pins 5 and 14) with a single 0.1uF ceramic capacitor placed within 5mm of the IC pins. For boards with switching regulators or relays nearby, add a 10uF tantalum or aluminum polymer bulk capacitor. The PIC16C558 draws approximately 2-5 mA at 5V/20 MHz during active execution; sleep mode reduces this to <1uA. Estimated: with VDD=5V, Fosc=20 MHz, the datasheet typical active current is 2.5 mA, so a 5V/100 mA regulator provides more than 20x headroom.
OTP memory cannot be electrically erased - all programming must be completed before final PCB assembly. Verify firmware thoroughly using windowed (JW) or EPROM versions (PIC16C558-20/P in PDIP with quartz window) before committing to OTP. The MCLR pin (pin 4) requires a 10k pull-up to VDD for normal operation; leaving it floating causes erratic resets. The OSC1/OSC2 pins (15/16) require correct oscillator configuration: crystal mode needs 15-22 pF load capacitors; RC mode needs a 5-100 kohm resistor and appropriate capacitor.
Place the crystal or resonator within 5mm of OSC1/OSC2 (pins 15/16) and route the connections over a continuous ground pour to minimize EMI. Keep the MCLR pull-up resistor (10k) close to pin 4. For ADC accuracy, isolate the analog inputs (RA0/AN0-RA3/AN3) from digital signal traces with a ground guard ring; the 8-bit ADC achieves +/- 1 LSB accuracy only with proper analog layout. Do not run high-current switching traces under the IC - the SSOP-20 lead frame has limited thermal dissipation.
The PORTB pins (RB0-RB7) feature internal weak pull-ups that can be enabled per-pin via software; use these for keypad matrix wiring instead of external 10k resistors to save BOM cost. The RA4/T0CKI pin is an open-drain output (no internal pull-up), so external pull-up is required if used as output. For I2C bit-banging, add 4.7k external pull-ups to SCL/SDA lines. The 13 I/O pins can source/sink 20 mA per pin, 100 mA total across the package - sufficient to drive small relays directly via transistors.
Compliance Information
PIC16C558T-20/SS uses a lead-bearing termination finish (SnPb) on legacy OTP parts and is non-RoHS-compliant per Microchip documentation. REACH SVHC declaration is current per Microchip product page. Not AEC-Q100 qualified - use flash-based PIC16F equivalents for automotive applications.
