PIC16C55A-20/SP - 8-Bit 20MHz OTP MCU, 20 I/O, SPDIP-28 | Microchip
MPN: PIC16C55A-20/SP β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.42 | $6.42 |
| 10 | $5.78 | $57.80 |
| 100 | $4.95 | $495.00 |
| 500 | $4.21 | $2,105.00 |
| 1,000 | $3.69 | $3,690.00 |
PIC16C55A-20/SP Overview
A baseline PIC microcontroller is an 8-bit CMOS MCU that executes a compact 12-bit-wide instruction set optimized for low-cost embedded control. It belongs to the hierarchy: PIC16C5X -> PIC16 family -> 8-bit microcontroller -> microcontroller -> embedded processor -> semiconductor. Baseline PICs use a separate program and data bus (Harvard architecture variant), enabling single-cycle instruction fetch and deterministic timing - they are favored where predictable execution, OTP cost, and small footprint outweigh the need for large memory or advanced peripherals. The 16C5X family uses seven or eight Special Function Registers and provides direct, indirect, and relative addressing modes for both data and instructions.
Key features include an 8-bit real-time clock/counter (TMR0) with programmable prescaler, a Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable recovery, on-chip power-on reset (POR), and brown-out detection. Power-saving features include a SLEEP mode with wake-up on pin change, and the device operates from a 2.5 V to 5.5 V supply. CMOS process technology delivers low power consumption with typical active current in the low-mA range and standby currents in the microamp region.
The PIC16C55A architecture uses a 12-bit instruction word and an 8-bit data path, providing roughly 2:1 code compression over competitive 8-bit MCUs in the same price class. The OTP program memory suits low-to-medium volume production where in-system re-programmability is not required, keeping unit cost low for high-volume appliance, sensor, and consumer-electronics designs.
Typical applications include washing-machine controllers, microwave-oven user interfaces, remote-control transmitters, smoke and gas detectors, battery chargers, and small motor-control boards. Its wide operating temperature range (commercial 0 C to +70 C; industrial -40 C to +85 C via the -I variant) also makes it viable for HVAC, lighting ballasts, and industrial sensor front-ends.
When designing with this part, evaluate OTP lock-in versus the flash-based PIC16F5X equivalents if in-field firmware updates may be required. For new designs, prefer flash-based PIC16F counterparts unless OTP cost is the dominant constraint.
This page synthesizes parametric data, drop-in alternatives, and practical design notes not consolidated on a single manufacturer or distributor page.
Drop-in alternatives for PIC16C55A-20/SP 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 PIC16C55A-20/SP (same form factor and footprint) β differing in Operating Temperature, Package, Core, Family, Maximum Clock Frequency.
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No drop-in alternatives available for this product.
Request AlternativesPIC16C55A-20/SP Maximum Ratings & Electrical Characteristics
| Family | PIC16C5X (PIC16 baseline) |
| Core | 8-bit RISC (PIC16) |
| Clock Speed (Max) | 20 MHz |
| Instruction Cycle | 200 ns (at 20 MHz) |
| Program Memory | 768 B (512 x 12 OTP) |
| RAM | 24 B |
| I/O Pins | 20 |
| Timers | TMR0 (8-bit), WDT (with on-chip RC) |
| Stack Depth | 2 hardware levels |
| Supply Voltage | 2.5 V to 5.5 V |
| Operating Temperature | 0 C to +70 C (commercial) |
| Package | 28-SPDIP (SP) |
| Mounting Type | Through-Hole |
| Instruction Width | 12-bit |
| Data Path Width | 8-bit |
PIC16C55A-20/SP Pin Configuration
| Pin 1 | RA2 β I/O port A bit 2 |
| Pin 2 | RA3 β I/O port A bit 3 |
| Pin 3 | RA4/T0CKI β I/O port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR β Master Clear (Reset) input, active low |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0/INT β I/O port B bit 0 / External interrupt input |
| Pin 7 | RB1 β I/O port B bit 1 |
| Pin 8 | RB2 β I/O port B bit 2 |
| Pin 9 | RB3 β I/O port B bit 3 |
| Pin 10 | RB4 β I/O port B bit 4 |
| Pin 11 | RB5 β I/O port B bit 5 |
| Pin 12 | RB6 β I/O port B bit 6 |
| Pin 13 | RB7 β I/O port B bit 7 |
| Pin 14 | VSS β Ground reference (or NC on some PIC16C5X variants) |
| Pin 15 | OSC1/CLKIN β Oscillator crystal input / external clock input |
| Pin 16 | OSC2/CLKOUT β Oscillator crystal output / clock output |
| Pin 17 | VDD β Positive supply voltage (2.5 V to 5.5 V) |
| Pin 18 | NC β Not connected |
| Pin 19 | NC β Not connected |
| Pin 20 | NC β Not connected |
| Pin 21 | RC0 β I/O port C bit 0 |
| Pin 22 | RC1 β I/O port C bit 1 |
| Pin 23 | RC2 β I/O port C bit 2 |
| Pin 24 | RC3 β I/O port C bit 3 |
| Pin 25 | RC4 β I/O port C bit 4 |
| Pin 26 | RC5 β I/O port C bit 5 |
| Pin 27 | RC6 β I/O port C bit 6 |
| Pin 28 | RC7 β I/O port C bit 7 |
Typical Applications
PIC16C55A-20/SP is suitable for 6 applications: Washing Machine Controller, Microwave Oven User Interface, Remote Control Transmitter, Smoke and Gas Detector, Battery Charger Controller, Small Motor Control Board.
Washing Machine Controller
The PIC16C55A-20/SP fits washing machine controllers because 768 bytes of OTP program memory is enough for the wash-cycle state machine, 20 I/O pins drive the motor relays, valve solenoids, and the user-interface LED/segment display, and the 20 MHz clock executes scan loops fast enough for membrane-key debouncing. The Watchdog Timer (WDT) with on-chip RC oscillator provides reliable recovery from electrical noise on the motor line. The 2-level hardware stack handles the limited subroutine nesting typical of appliance firmware, and OTP memory locks the wash program against accidental erasure in the field. Compared with a flash MCU, the OTP variant reduces per-unit cost at high-volume SKUs.
Recommended
Microwave Oven User Interface
Microwave oven keypads and 7-segment displays are driven well by the PIC16C55A-20/SP's 20 I/O pins and 24 bytes of RAM for keypad state buffering. The 20 MHz clock provides responsive key-debounce and display-multiplex loops, while the PIC16C5X instruction set compiles compact code - the 768-byte OTP is sufficient for menu handling, beep patterns, and timer logic. The PIC's CMOS low-power design keeps standby consumption negligible, and SLEEP mode with pin-change wake-up supports door-open detection. OTP programming locks the firmware at production, preventing tampering with safety timing constants such as maximum cook duration.
Recommended
Remote Control Transmitter
Battery-powered remote controls benefit from the PIC16C55A-20/SP's CMOS low-power design, 2.5 V to 5.5 V supply (single-cell Li or two AAs), and SLEEP mode with wake-up on pin change for ultra-low standby current. The 20 MHz clock handles IR or RF encoder bit-banging within tight timing tolerances, and 20 I/O pins support matrix keypads plus indicator LEDs. The PIC16C5X 12-bit instruction set compiles the encoder firmware into a small footprint that fits the 768-byte OTP, and OTP locks the remote's fixed transmission code at production. Brown-out protection prevents undefined behavior as the battery discharges below the safe VDD threshold.
Recommended
Smoke and Gas Detector
Smoke and gas detectors use the PIC16C55A-20/SP for low-power detection-loop scanning, alarm-tone generation, and self-test sequencing. The Watchdog Timer is critical - it forces a clean restart if firmware execution locks up, ensuring the detector never goes blind. The 24-byte RAM buffers ADC samples from the sensor front-end, while 20 I/O pins drive the piezo buzzer, status LED, and interconnect to the alarm panel. OTP programming locks the firmware so safety logic cannot be modified in the field, and the commercial 0 C to +70 C range covers indoor residential use; the -I variant covers industrial sites down to -40 C.
Recommended
Battery Charger Controller
Smart battery chargers use the PIC16C55A-20/SP to execute CC/CV charge profiles, monitor temperature via NTC, and time the charge cycle. The 20 MHz clock runs the PWM firmware and ADC sampling at rates tight enough for accurate voltage and current regulation. 20 I/O pins handle the charge FET gate drive, status LEDs, and the optional 1-wire or SMBus interface to smart battery packs. SLEEP mode extends standby life when no battery is connected, and the brown-out reset prevents erroneous charging on a weak input supply. OTP programming locks the safe charge-voltage ceiling for the target battery chemistry, which is a safety-critical parameter.
Recommended
Small Motor Control Board
Small brushed-DC and stepper motor controllers use the PIC16C55A-20/SP's TMR0 for commutation timing and its 20 MHz clock for fast current-loop sampling in the firmware. The 20 I/O pins drive the H-bridge FET gates, encoder inputs, and limit-switch sensing. The Watchdog Timer recovers from electrical noise generated by the motor's commutator, and the PIC16C5X's deterministic instruction timing produces a stable PWM frequency. The 2-level hardware stack suffices for the small control firmware typical of these boards. For low-volume or hobby motor controllers, the PIC16C55A-20/SP's low unit cost and simple development toolchain (PICSTART, MPLAB) accelerate time-to-market.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-20/SP β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-20I/SP | PIC16C55A-20/P | PIC16C55-10/SP | PIC16C55A-04E/SP | PIC16F570-I/SP |
|---|---|---|---|---|---|---|
| Package | 28-SPDIP (SP) | 28-SPDIP (SP) - same | 28-PDIP (P) - same pin count | 28-SPDIP (SP) - same | 28-SPDIP (SP) - same | 28-SPDIP (SP) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Clock Speed (Max) | 20 MHz | 20 MHz | 20 MHz | 10 MHz | 4 MHz | 20 MHz |
| Program Memory | 768 B (512 x 12 OTP) | 768 B OTP | 768 B OTP | 384 B OTP | 768 B OTP | 2 KB Flash |
| RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 128 B |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Operating Temperature | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C | 0 C to +70 C | -40 C to +125 C | -40 C to +85 C |
| Program Memory Type | OTP | OTP | OTP | OTP | OTP | Flash (ICSP) |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | Active |
Key Differentiators
- Highest-density PIC16C5X OTP at commercial temp (vs PIC16C55-10/SP)
- Commercial temp grade - same price as -I variant in many channels (vs PIC16C55A-20I/SP)
- OTP locks firmware at production (vs PIC16F570-I/SP)
Design Notes
Place a 0.1 uF ceramic decoupling capacitor within 5 mm of the PIC16C55A-20/SP VDD pin (Pin 17). Add a bulk electrolytic (10-47 uF) on the VDD rail if the supply is shared with a motor-driver or relay board. VDD must rise monotonically above the brown-out threshold (typically ~2.0 V) for the internal POR to release reset cleanly; an RC delay on MCLR is unnecessary because POR is on-chip. Use a low-ESR regulator to keep digital VDD ripple below 50 mVpk-pk to avoid spurious resets.
Estimated: at fOSC = 20 MHz the PIC16C55A-20/SP draws roughly 5-10 mA active and < 10 uA in SLEEP from a 5 V supply (exact figures vary by I/O load). For through-hole SPDIP-28 designs, keep crystal traces short (< 10 mm) and route them over a continuous ground pour to minimize EMI pickup. If using an external crystal (XT mode), add 15-33 pF load caps on OSC1/OSC2; for cost-sensitive designs the internal RC oscillator eliminates these components but reduces timing accuracy.
Do not assume flash-style programming procedures on this OTP part - PIC16C55A-20/SP code must be programmed before solder or in a programming socket; it cannot be reprogrammed in-circuit. Brown-out detection must be enabled in the configuration word for safety-critical applications, otherwise a slow-rising VDD can leave the MCU in undefined states. Watchdog Timer (WDT) must be cleared via the CLRWDT instruction inside any loop longer than ~18 ms (typical WDT period at 5 V), or the MCU will reset unexpectedly.
Compliance Information
MSL Level, RoHS, lead-free, and halogen-free status not present in the verified web data - see [DATA_NEEDED] markers in specs. AEC-Q100 not applicable to baseline PIC microcontrollers; Microchip's automotive PIC16 equivalents are qualified separately. Conflict-minerals compliance assumed per Microchip corporate policy.
