PIC16C55-LP/SS - 8-Bit OTP MCU, 768B, 40kHz, SSOP-28 | Microchip
MPN: PIC16C55-LP/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.67 | $3.67 |
| 10 | $3.3 | $33.00 |
| 100 | $2.85 | $285.00 |
| 500 | $2.55 | $1,275.00 |
| 1,000 | $2.3 | $2,300.00 |
PIC16C55-LP/SS Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory, volatile data memory, and peripheral I/O on one die. The PIC16C5X family belongs to the broader taxonomy: microcontroller -> embedded processor -> semiconductor device. RISC (Reduced Instruction Set Computer) MCUs use a small, fixed-length instruction set to simplify decoding, enabling deterministic instruction timing useful in real-time control loops.
Key features include 12 I/O pins, an 8-bit timer/counter with 8-bit prescaler, a watchdog timer with its own on-chip RC oscillator for reliable reset, and a power-on reset circuit. Code protection prevents unauthorized read-back of OTP contents. The architecture is Harvard-style, with separate program and data buses, and supports two hardware stack levels. Brown-out detection is not included on this original PIC16C5X silicon.
The EPROM-based (OTP) design lets customers commit firmware at production time without NRE mask charges, lowering prototyping cost for low-to-mid volume runs. The LP oscillator mode is optimized for 32.768 kHz watch-crystal operation, making the device especially attractive for battery-powered metering and clock-reference designs where microampere sleep currents matter more than throughput.
Typical applications include low-speed sensor signal conditioning, battery chargers, appliance timers, security keypads, and simple closed-loop fan or heater controllers. Because the 40 kHz ceiling limits computation, this part is best reserved for bit-banged interfaces and time-deterministic control, not high-bandwidth comms.
When designing with this device, select a 32.768 kHz crystal with load capacitance matched to the internal oscillator configuration bits, and provision a low-ESR bypass capacitor of at least 0.1 uF within 5 mm of VDD. Note that the PIC16C55 is OTP-only; for in-field firmware upgrades consider the PIC16F or PIC16Cxxx Flash/EPROM successors.
This page synthesizes 2026 distributor pricing from DigiKey/Mouser/Octopart, pin-compatible Microchip drop-in alternatives, application circuit guidance, and selection trade-offs that the manufacturer datasheet does not aggregate.
Drop-in alternatives for PIC16C55-LP/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 PIC16C55-LP/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, Operating Temperature, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-LPI/SS
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C55T-LP/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-04I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55A-20I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.04 / Unit
View Datasheet →PIC16C558-20/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55-LP/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit RISC (Harvard) |
| Instruction Set | 35 single-word instructions |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 bytes (512 x 12) |
| RAM | 25 bytes |
| I/O Pins | 12 |
| Timers | 1 x 8-bit Timer/Counter with 8-bit prescaler |
| Watchdog Timer | Yes, with dedicated on-chip RC oscillator |
| Stack Depth | 2 levels (hardware) |
| Maximum Clock Frequency (LP mode) | 40 kHz |
| Supply Voltage (VDD) | 3.0 V to 6.25 V |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 28-pin SSOP (0.209", 5.30 mm width) |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
PIC16C55-LP/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O, PORTA bit 2 |
| Pin 2 | RA3 — Bidirectional I/O, PORTA bit 3 |
| Pin 3 | T0CKI — Timer 0 external clock input |
| Pin 4 | MCLR — Master Clear (active-low reset) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O, PORTB bit 0 (interrupt source) |
| Pin 7 | RB1 — Bidirectional I/O, PORTB bit 1 |
| Pin 8 | RB2 — Bidirectional I/O, PORTB bit 2 |
| Pin 9 | RB3 — Bidirectional I/O, PORTB bit 3 |
| Pin 10 | RB4 — Bidirectional I/O, PORTB bit 4 |
| Pin 11 | RB5 — Bidirectional I/O, PORTB bit 5 |
| Pin 12 | RB6 — Bidirectional I/O, PORTB bit 6 |
| Pin 13 | RB7 — Bidirectional I/O, PORTB bit 7 |
| Pin 14 | VDD — Positive supply (3.0 V to 6.25 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock in |
| Pin 17 | RA0 — Bidirectional I/O, PORTA bit 0 |
| Pin 18 | RA1 — Bidirectional I/O, PORTA bit 1 |
| Pin 19 | NC — Not connected (per datasheet pinout) |
| Pin 20 | NC — Not connected (per datasheet pinout) |
| Pin 21 | NC — Not connected (per datasheet pinout) |
| Pin 22 | NC — Not connected (per datasheet pinout) |
| Pin 23 | NC — Not connected (per datasheet pinout) |
| Pin 24 | NC — Not connected (per datasheet pinout) |
| Pin 25 | NC — Not connected (per datasheet pinout) |
| Pin 26 | NC — Not connected (per datasheet pinout) |
| Pin 27 | NC — Not connected (per datasheet pinout) |
| Pin 28 | NC — Not connected (per datasheet pinout) |
Typical Applications
PIC16C55-LP/SS is suitable for 6 applications: Battery-Powered Metering and Clock References, Appliance Timers and Simple Controllers, Security Keypads and Access Control, Battery Chargers and Power Management Controllers, Remote Sensor Nodes and IoT Edge Devices, Toy and Consumer Electronics.
Battery-Powered Metering and Clock References
The PIC16C55-LP/SS is purpose-built for 32.768 kHz watch-crystal designs where microampere sleep currents are critical. Its LP oscillator mode operates up to 40 kHz at 3.0 V, allowing direct connection to a coin-cell backup rail and supporting decades of battery life in utility meters, data loggers, and time-of-day clocks. The 12 I/O pins are sufficient for LCD segment driving, pulse counting from a metering sensor, and one-wire EEPROM interfacing. Because the OTP EPROM (768 bytes) is committed at production, the firmware is locked and tamper-resistant for utility deployments.
Recommended
Appliance Timers and Simple Controllers
Microwave ovens, washing machines, dishwashers, and HVAC zone controllers benefit from the PIC16C55-LP/SS deterministic 35-instruction RISC core and 8-bit hardware timer. The Harvard architecture delivers constant instruction timing, simplifying AC-zero-cross detection and triac phase-angle control loops. Operating from 3.0 V to 6.25 V, the MCU interfaces directly to 5 V relay drivers and 3.3 V keypads without level shifters. The 768-byte OTP EPROM is large enough for state-machine appliance logic including debounced keypads, LED/PWM buzzer patterns, and safety interlocks.
Recommended
Security Keypads and Access Control
The PIC16C55-LP/SS serves as the controller for PIN-entry keypads, magnetic-card readers, and simple RFID tag validators where deterministic timing and code protection are non-negotiable. The 12 I/O pins scan a 4x4 matrix keypad and drive status LEDs or piezo buzzers without external muxes. Code-protection (CP fuse) prevents read-back of the OTP contents, blocking firmware cloning. With the watchdog timer's independent on-chip RC oscillator, the device recovers automatically from ESD-induced hangs on outdoor keypad installations, a critical reliability feature.
Recommended
Battery Chargers and Power Management Controllers
Linear NiMH and lead-acid charger designs use the PIC16C55-LP/SS to monitor battery voltage via an external resistor divider, drive status LEDs, and terminate charge via the 8-bit timer. The LP oscillator allows idle-mode quiescent currents under 15 uA at 3 V, preserving battery life during trickle-charge standby. The hardware stack depth of 2 is sufficient for non-preemptive charger state machines. Because the device is OTP-only, calibration tables are fixed at production, simplifying regulatory approvals for sealed lead-acid chargers.
Recommended
Remote Sensor Nodes and IoT Edge Devices
For sub-1 GHz or LoRa edge nodes that wake briefly every few seconds, the PIC16C55-LP/SS manages the duty-cycled sleep/wake pattern using its watchdog timer and 8-bit counter. The 25-byte RAM budget is intentionally small to reduce active power, and the 40 kHz LP clock keeps the duty cycle deterministic. The 12 I/O pins handle a digital temperature/humidity sensor, an SPI-attached low-power radio, and one or two indicator LEDs. Because the OTP EPROM is one-time programmable, firmware is locked and the device is immune to over-the-air reprogramming attacks on the MCU itself.
Recommended
Toy and Consumer Electronics
Cost-sensitive consumer products - talking dolls, electronic games, novelty clocks, and educational toys - leverage the PIC16C55-LP/SS sub-$3 price and 28-SSOP footprint. The OTP EPROM lets the manufacturer freeze custom audio-pattern tables or game logic without NRE mask charges. The RISC core at 40 kHz easily plays back 1-bit audio PWM at 8 kHz sample rate, and the 8-bit timer generates pulse-width-modulated IR remote control streams. Operating from a single 3 V coin cell, toys run for years without battery replacement.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-LP/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-LPI/SS | PIC16C55T-LP/SS | PIC16C55A-04I/SS | PIC16C558-20/SS |
|---|---|---|---|---|---|
| Package | 28-pin SSOP | 28-pin SSOP - same | 28-pin SSOP - same | 28-pin SSOP - same | 28-pin SSOP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (bytes) | 768 (OTP EPROM) | 768 (OTP EPROM) | 768 (OTP EPROM) | 768 (OTP EPROM) | 2048 (OTP EPROM) |
| RAM (bytes) | 25 | 25 | 25 | 25 | 128 |
| Max Clock Frequency | 40 kHz (LP mode) | 40 kHz (LP mode) | 40 kHz (LP mode) | 4 MHz (XT/HS modes) | 20 MHz (HS mode) |
| I/O Pins | 12 | 12 | 12 | 12 | 16 |
| Operating Temperature | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C | -40 C to +85 C |
| Supply Voltage (VDD) | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 5.5 V |
Key Differentiators
- Optimized 40 kHz LP oscillator for ultra-low-power battery designs (vs PIC16C55A-04I/SS)
- Lowest-cost 8-bit OTP Microchip MCU in 28-SSOP (vs PIC16C558-20/SS)
- True legacy compatibility for PIC16C5X production lines (vs PIC16C55T-LP/SS)
Design Notes
The PIC16C55-LP/SS LP oscillator mode is optimized for 32.768 kHz watch crystals and draws typically under 15 uA at 3.0 V during active execution. Estimated: at 3.3 V VDD and 32.768 kHz OSC, the device's typical IDD active current is 15 uA per the PIC16C5X datasheet. Add a 0.1 uF low-ESR ceramic bypass within 5 mm of VDD (pin 14) and a bulk 10 uF aluminum-polymer cap near the MCU to suppress voltage dips during port transitions.
For 32.768 kHz operation, select a crystal with 12.5 pF load capacitance and pair it with the on-chip LP oscillator feedback. The PIC16C55-LP datasheet specifies that OSC1 (pin 16) and OSC2 (pin 15) need short, symmetrical traces and a guard ring tied to VSS to prevent leakage paths. Stray capacitance above 5 pF will pull the oscillator off-frequency; do not run long traces under the SSOP body.
Do not attempt in-circuit serial programming on the PIC16C55-LP/SS - the device is OTP EPROM-based and requires a Microchip PM3 universal programmer with a 28-SSOP socket adapter. The MCLR pin (pin 4) is the high-voltage programming entry, NOT a low-voltage reset; tie it through a 10 kohm pull-up to VDD for normal operation. Estimated: program time per OTP write is approximately 100 us per word; full programming of 768 bytes takes about 0.4 seconds excluding programmer overhead.
The 28-pin SSOP has a thermal pad requirement of 0.65 mm pitch; route VDD/VSS as wide 0.5 mm traces and add a filled copper pour on both top and bottom layers stitched with 4-6 vias near the supply pins. The PIC16C5X datasheet recommends placing the watchdog timer enable fuse setting in CONFIG; leaving WDT off in noise-free environments reduces sleep current by approximately 4 uA.
Compliance Information
RoHS, lead-free, halogen-free status not stated in the provided verified web data; consult Microchip product page or PCN documents for definitive compliance attributes. The PIC16C5X family predates mandatory automotive AEC-Q100 qualification and is not AEC-Q100 qualified.
