PIC16C558T-20I/SO - 8-Bit 20MHz 3.5KB OTP MCU | Microchip
MPN: PIC16C558T-20I/SO β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.66 | $16.60 |
| 100 | $1.48 | $148.00 |
| 500 | $1.33 | $665.00 |
| 1,000 | $1.18 | $1,180.00 |
PIC16C558T-20I/SO Overview
A microcontroller (MCU) is a single-chip computer containing a CPU, memory, and programmable I/O peripherals. The PIC16C5x family uses a Harvard-architecture RISC core with 33 single-word instructions, delivering deterministic throughput for embedded control. Within the broader hierarchy, the PIC16C558 sits between the smaller PIC12/14 families (typically 6-14 pins) and the larger PIC16F and PIC18 families; it is designed for cost-sensitive 18-pin applications that need more code space than PIC16C54/55/56 but fewer peripherals than modern PIC16F1xxx devices.
Key features of the PIC16C558T-20I/SO include 13 digital I/O pins, a Power-On Reset (POR), Watchdog Timer (WDT), and a Timer0 8-bit counter/timer. The '20' speed suffix indicates the 20MHz maximum oscillator frequency, while the 'T' indicates tape-and-reel packaging, 'I' specifies the industrial -40C to +85C operating temperature range, and '/SO' denotes the 18-pin SOIC outline. The OTP memory is programmed once via standard Microchip device programmers, making the part ideal for high-volume, low-cost field-deployed products where firmware is stable and flash reprogrammability is not required.
Typical applications include appliance controllers, sensor signal conditioning front-ends, simple motor control drivers, automotive body electronics, lighting controllers, low-end remote keyless entry transmitters, security alarm panels, and battery-powered instrumentation. Because OTP memory cannot be erased and rewritten, designers typically prototype with the PIC16F558 (Flash) equivalent and migrate to the PIC16C558 once firmware is finalized.
A key design consideration is migration from the Flash PIC16F558: the two parts share pinout and core peripherals, allowing a single PCB to support both. Use a 4.7kohm pull-up on MCLR/VPP and 100nF decoupling on VDD, with a 22pF or 33pF load capacitor pair on OSC1/OSC2 for a crystal oscillator reference design.
Drop-in alternatives for PIC16C558T-20I/SO β 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-20I/SO (same form factor and footprint) β differing in Package, Program Memory Size, Instruction Cycle Time, Program Memory Type, Core Architecture.
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PIC16C558-20I/SO
β Drop-Inβ In Stock
$1.2 / Unit
View Datasheet βPIC16F558-I/SO
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PIC16C558T-20E/SO
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PIC16C554T-20I/SO
β Drop-Inβ In Stock
$1.82 / Unit
View Datasheet βPIC16C558T-20I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Family | PIC16C5x |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 3.5 KB (2K x 14) |
| RAM Size | 128 x 8 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns |
| Instruction Set Size | 33 single-word instructions |
| I/O Pins | 13 |
| Timers | 1 x 8-bit (Timer0) |
| Watchdog Timer | Yes |
| Power-On Reset | Yes |
| Supply Voltage | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 18-pin SOIC (SO, 0.300") |
| Mounting Type | Surface Mount |
| Lead-Free / RoHS | Lead-Free finish available (check variant suffix) |
PIC16C558T-20I/SO Pin Configuration
| Pin 1 | MCLR/VPP β Master Clear (Reset) input / Programming voltage |
| Pin 2 | RA0 β Port A bit 0 (digital I/O) |
| Pin 3 | RA1 β Port A bit 1 (digital I/O) |
| Pin 4 | RA2 β Port A bit 2 (digital I/O) |
| Pin 5 | RA3 β Port A bit 3 (digital I/O) |
| Pin 6 | RB0/INT β Port B bit 0 / External interrupt |
| Pin 7 | RB1 β Port B bit 1 |
| Pin 8 | RB2 β Port B bit 2 |
| Pin 9 | RB3 β Port B bit 3 |
| Pin 10 | RB4 β Port B bit 4 |
| Pin 11 | RB5 β Port B bit 5 |
| Pin 12 | RB6 β Port B bit 6 |
| Pin 13 | RB7 β Port B bit 7 |
| Pin 14 | VSS β Ground reference |
| Pin 15 | OSC2/CLKOUT β Oscillator output / Clock output (Fosc/4) |
| Pin 16 | OSC1/CLKIN β Oscillator input / External clock input |
| Pin 17 | VDD β Positive supply (3.0V to 5.5V) |
| Pin 18 | RA4/T0CKI β Port A bit 4 / Timer0 clock input |
Typical Applications
PIC16C558T-20I/SO is suitable for 7 applications: Appliance Control (White Goods), Sensor Signal Conditioning Front-End, Low-End Automotive Body Electronics, Remote Keyless Entry (RKE) Transmitter, Lighting Controllers and LED Chasers, Security Alarm Panels and Access Control, Battery-Powered Instrumentation.
Appliance Control (White Goods)
The PIC16C558T-20I/SO fits appliance controllers because it offers 13 digital I/O pins sufficient to drive relays, switches, and indicator LEDs in washing machines, microwave ovens, and dishwashers. Its 3.5KB OTP memory and 200ns instruction cycle handle state-machine control loops and timing functions for cycle sequencing. The industrial -40C to +85C temperature range withstands the thermal stress of enclosed motor compartments. Designers select this part for high-volume programs where firmware is finalized and the low unit cost of OTP outweighs the loss of in-field reprogrammability. Typical interfaces: 7-segment LED drivers via PORTB, push-button inputs on PORTA.
Recommended
Sensor Signal Conditioning Front-End
The PIC16C558T-20I/SO is well suited to sensor signal conditioning where a microcontroller scans multiple digital sensors and drives a display or communication interface. The 13 I/O lines accommodate 4-bit PORT A and 8-bit PORT B, allowing connection to several switch or threshold sensors simultaneously. The 20MHz core supports polling at high rates, and Timer0 enables precise interval timing for sensor sampling. Its OTP memory keeps unit cost low when firmware is locked, while the Watchdog Timer and Power-On Reset improve field reliability in remote installations.
Recommended
Low-End Automotive Body Electronics
The PIC16C558T-20I/SO is appropriate for automotive body controllers - simple functions like seat-position memory, mirror-fold logic, or interior lighting sequencers where 3.5KB of code is sufficient. The device operates from 3.0V-5.5V with low quiescent current, ideal for ignition-off battery-drain minimization. For under-hood or extreme-temperature applications, designers step up to the PIC16C558T-20E/SO (-40C to +125C). The 18-SOIC footprint is compatible with hand-soldered prototypes and high-volume pick-and-place assembly.
Recommended
Remote Keyless Entry (RKE) Transmitter
The PIC16C558T-20I/SO fits low-cost RKE keyfob transmitters that transmit encrypted rolling codes via SAW or PLL-based RF. The 3.5KB OTP holds the encryption routine and the button-debounce logic, while Timer0 generates the bit-timing for the RF protocol (typically 100us-1ms per bit). The industrial temperature range is adequate for keyfob environments (-40C to +85C). Battery life is maximized by the MCU's sleep-mode behavior between button presses. OTP memory prevents firmware extraction from a stolen device, adding a security layer.
Recommended
Lighting Controllers and LED Chasers
The PIC16C558T-20I/SO drives LED chasers, decorative lighting sequencers, and architectural light controllers where many GPIO pins are needed to multiplex LEDs. PORTB (8 pins) handles a direct LED bank while PORTA handles control inputs from buttons or rotary encoders. At 20MHz, the MCU easily generates PWM-style chase patterns in software without dedicated peripherals. OTP memory suits high-volume decorative products where firmware changes are infrequent. The low BOM cost supports consumer price points.
Recommended
Security Alarm Panels and Access Control
The PIC16C558T-20I/SO is well suited to security alarm panels for small commercial or residential installations where it monitors up to 8 zones via PORTB and reports status via relays or serial interface from PORTA. The Watchdog Timer ensures panel recovery from software lockups, and Power-On Reset guarantees clean startup after power failures. OTP memory prevents code extraction by tampering. Industrial temperature range accommodates unheated enclosures. For panel designs requiring keypad scanning, an I2C-expander MCP23008 can extend I/O without losing the cost advantage.
Recommended
Battery-Powered Instrumentation
The PIC16C558T-20I/SO fits battery-powered instruments like handheld multimeters, environmental loggers, or portable test tools where low active current and minimal sleep-mode current are essential. The 3.0V minimum supply voltage enables direct operation from 2x AA alkaline cells or a single Li-ion cell with simple regulation. The 20MHz clock can be throttled or halted to extend battery life. With Watchdog Timer-based wakeup, the MCU sleeps for seconds between measurements. The 128B RAM buffers recent readings before the device writes to an external EEPROM.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-20I/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20I/SO | PIC16F558-I/SO | PIC16C558T-20E/SO | PIC16C554T-20I/SO |
|---|---|---|---|---|---|
| Package | 18-SOIC (SO) | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 3.5 KB OTP | 3.5 KB OTP | 3.5 KB Flash | 3.5 KB OTP | 0.875 KB OTP (-75%) |
| RAM | 128 B | 128 B | 128 B | 128 B | 80 B (-37%) |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Memory Type | OTP (one-time) | OTP | Flash (10k erase cycles) | OTP | OTP |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +85C | -40C to +125C (Extended) | -40C to +85C |
| I/O Pins | 13 | 13 | 13 | 13 | 13 |
| Packaging | Tape & Reel | Tube | Tube | Tape & Reel | Tape & Reel |
Key Differentiators
- Larger program memory than PIC16C554 at same price tier (vs PIC16C554T-20I/SO)
- OTP memory provides cost advantage over Flash in high volume (vs PIC16F558-I/SO)
- Industrial temperature range vs extended variants available (vs PIC16C558T-20E/SO)
Design Notes
The PIC16C558T-20I/SO requires a clean VDD supply: place a 100nF ceramic decoupling capacitor within 5mm of the VDD pin (pin 17) with a direct ground connection to pin 14. Add a bulk 10uF tantalum or aluminum electrolytic capacitor on the same rail if the supply is shared with motors or relays. For battery-powered designs, add a 10kohm pull-down on MCLR/VPP (pin 1) to ensure defined reset state during power-up; an external 4.7kohm pull-up to VDD is also acceptable per datasheet Figure 7-1.
OTP memory can be programmed only once. A programming error or late-stage code change requires discarding the silicon. To mitigate, prototype with the Flash-based PIC16F558-I/SO (same 18-SOIC pinout, same peripherals) and migrate to the PIC16C558 OTP version only after firmware is fully validated. For volume production, always order OTP parts with a 5-10% overage to cover programming losses and avoid reorders that may collide with NRND supply constraints.
Route the crystal traces (OSC1 pin 16 and OSC2 pin 15) as short and symmetric as possible, with the crystal placed within 10mm of the MCU. Surround the crystal with a ground guard ring to reduce EMI radiation. When using an external clock source instead of a crystal, drive OSC1 only and leave OSC2 floating. For RC oscillator mode (lowest cost), connect a resistor from OSC1 to VDD and a capacitor from OSC1 to VSS; expect wider frequency tolerance (typically +/- 5-10%) than crystal mode.
Compliance Information
Lead-free finish available with standard Microchip ordering suffix. RoHS compliance per Microchip product page. AEC-Q100 not applicable for the I-suffix industrial grade; use Q-suffix variants for automotive qualification.
