PIC16C55-HSI/P - 8-Bit 20MHz OTP MCU 768B | Microchip | PDIP-28
MPN: PIC16C55-HSI/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.35 | $335.00 |
| 500 | $2.95 | $1,475.00 |
| 1,000 | $2.6 | $2,600.00 |
PIC16C55-HSI/P Overview
A baseline PIC microcontroller is a member of the simplest tier in Microchip's 8-bit PIC architecture family, optimized for cost-sensitive embedded control. Within the system hierarchy it sits below mid-range (PIC16) and enhanced mid-range (PIC16F1xxx) devices; baseline parts trade advanced peripherals for the lowest unit cost and the smallest instruction set (33 instructions, 12-bit wide). They are widely used in simple control loops, timers, and glue-logic replacement roles where computation demands are modest and pin-count is moderate.
Key specifications of the PIC16C55-HSI/P include 20 MHz maximum clock (200 ns instruction cycle), 768 bytes of OTP program memory organized as 512 x 12 words, 24 bytes of general-purpose RAM, 20 I/O pins, a single 8-bit timer/counter (TMR0) with an 8-bit prescaler, and an operating voltage range suitable for 5V systems. The device also includes a watchdog timer (WDT), power-on reset (POR), and an industrial-grade temperature rating. Its 12-bit instruction word yields a 2:1 code compression advantage over many competing 8-bit architectures in the same price class, reducing program-memory consumption for typical control firmware.
Architecturally, the PIC16C55-HSI/P uses a Harvard memory layout with separate program and data buses, enabling instruction fetch and operand access in a single cycle. The RISC-style instruction set comprises 33 fixed-width 12-bit opcodes, with all instructions executing in a single instruction cycle except branches (two cycles). This simplicity makes the part straightforward to program in assembly and provides deterministic real-time behavior, which is valuable in hard-real-time control applications.
Typical applications include appliance controls, simple sensor interfaces, LED driving and lighting controllers, low-cost consumer electronics, battery chargers, and hobbyist/educational embedded projects. The 28-pin PDIP package is also favored for through-hole prototype boards and educational development kits where socketed parts simplify repeated programming cycles.
When designing with this part, note that OTP memory can only be programmed once - prototype firmware must be validated on UV-erasable (JW) windowed variants or flash-based PIC16F5x equivalents before committing to OTP. A high-speed oscillator mode (HS) requires an external crystal or resonator in the 4 MHz to 20 MHz range, with proper PCB layout and load-capacitor selection to ensure stable startup.
This page synthesizes distributor availability, drop-in alternatives from the PIC16C5x family, and design considerations not aggregated in the manufacturer datasheet alone - giving engineers a single reference for sourcing, replacement, and integration of the PIC16C55-HSI/P.
Drop-in alternatives for PIC16C55-HSI/P — 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-HSI/P (same form factor and footprint) — differing in Package, Program Memory Size, Timers, Operating Temperature, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-HS/P
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →PIC16C55-10I/P
✅ Drop-In✓ In Stock
$2.58 / Unit
View Datasheet →PIC16C55A-20I/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.6 / Unit
View Datasheet →PIC16C55-04I/P
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C55-10/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.65 / Unit
View Datasheet →PIC16C55/JW
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$10.4 / Unit
View Datasheet →PIC16C55-HSI/P Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C5x (baseline 8-bit RISC) |
| Data Bus Width | 8 bit |
| Instruction Word Width | 12 bit |
| Maximum CPU Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns |
| Program Memory Type | OTP (One-Time-Programmable) |
| Program Memory Size | 768 B (512 x 12 words) |
| Data RAM | 24 B |
| Number of I/O Pins | 20 |
| Timers | TMR0 (8-bit with 8-bit prescaler) |
| Hardware Stack | 2 levels |
| Oscillator Mode (HS) | High-speed crystal/ceramic resonator, 4 MHz to 20 MHz |
| Operating Temperature | -40C to +85C (industrial grade) |
| Package | 28-PDIP (through-hole) |
| Watchdog Timer | Yes |
| Power-On Reset | Yes |
PIC16C55-HSI/P Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (digital I/O) |
| Pin 2 | RA3 — Port A bit 3 (digital I/O) |
| Pin 3 | RTCC — TMR0 real-time clock/counter input |
| Pin 4 | MCLR — Master clear reset (active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Port B bit 0 (digital I/O) |
| Pin 7 | RB1 — Port B bit 1 (digital I/O) |
| Pin 8 | RB2 — Port B bit 2 (digital I/O) |
| Pin 9 | RB3 — Port B bit 3 (digital I/O) |
| Pin 10 | RB4 — Port B bit 4 (digital I/O) |
| Pin 11 | RB5 — Port B bit 5 (digital I/O) |
| Pin 12 | RB6 — Port B bit 6 (digital I/O) |
| Pin 13 | RB7 — Port B bit 7 (digital I/O) |
| Pin 14 | VDD — Positive supply voltage |
| Pin 15 | OSC2 — Oscillator output (crystal/resonator) |
| Pin 16 | OSC1 — Oscillator input (crystal/resonator) |
| Pin 17 | RC0 — Port C bit 0 (digital I/O) |
| Pin 18 | RC1 — Port C bit 1 (digital I/O) |
| Pin 19 | RC2 — Port C bit 2 (digital I/O) |
| Pin 20 | RC3 — Port C bit 3 (digital I/O) |
| Pin 21 | RC4 — Port C bit 4 (digital I/O) |
| Pin 22 | RC5 — Port C bit 5 (digital I/O) |
| Pin 23 | RC6 — Port C bit 6 (digital I/O) |
| Pin 24 | RC7 — Port C bit 7 (digital I/O) |
| Pin 25 | RA0 — Port A bit 0 (digital I/O) |
| Pin 26 | RA1 — Port A bit 1 (digital I/O) |
| Pin 27 | RA3 — Port A bit 3 (per datasheet second RA3 location) |
| Pin 28 | NC — Not connected (per datasheet package variant) |
Typical Applications
PIC16C55-HSI/P is suitable for 6 applications: Appliance Control Boards, LED Lighting Controllers, Sensor Interface Hubs, Battery Chargers and Power Monitors, Hobbyist and Educational Embedded Projects, Industrial Timer and Relay Logic Replacement.
Appliance Control Boards
The PIC16C55-HSI/P's 20 I/O pins, 8-bit TMR0, and 200 ns instruction cycle make it a strong fit for low-cost appliance control boards such as washing-machine timers, microwave keypads, and fan-speed controllers. With 768 bytes of OTP program memory, the part comfortably stores fixed-function control firmware that rarely changes, keeping BOM cost down versus flash-based MCUs. The 20 MHz HS oscillator mode supports accurate time-base generation for motor PWM and display multiplexing. Industrial -40C to +85C temperature grade ensures reliability in the warm enclosures behind refrigerator compressors or above-range hoods. A 28-pin PDIP form factor suits through-hole assembly on consumer-grade PCBs and supports easy rework in service depots.
Recommended
LED Lighting Controllers
Driving LED strings and chasing-light displays requires precise PWM and modest code size, both strengths of the PIC16C55-HSI/P. The 20 I/O pins can directly source-sink 20 mA per pin (per datasheet) to multiplex small LED matrices, while the 8-bit TMR0 with 8-bit prescaler generates stable PWM channels for brightness control. The 200 ns instruction cycle keeps software bit-banged protocols like WS2811/NeoPixel within tight timing budgets at lower LED counts. Industrial temperature rating allows deployment in outdoor signage and architectural lighting fixtures. The HS oscillator accepts ceramic resonators that are less expensive than full crystals and tolerate mechanical vibration in portable fixtures.
Recommended
Sensor Interface Hubs
Simple sensor-hub applications that aggregate digital inputs (switches, contact closures, low-speed serial sensors) fit naturally on the PIC16C55-HSI/P. The 20 I/O pins map easily to four digital sensors plus indicator LEDs, and the watchdog timer recovers the hub automatically from any firmware lockup caused by electrical transients. The 2-level hardware stack constrains software architecture to flat functions, which is a feature rather than a limitation in this kind of fixed-logic application. OTP memory at this BOM level is cheaper than flash, and the HS oscillator accepts low-cost 4 MHz resonators when 20 MHz speed is not required. Industrial temperature grade is essential for factory-floor sensor boxes.
Recommended
Battery Chargers and Power Monitors
Low-to-mid-power battery chargers benefit from the PIC16C55-HSI/P's accurate TMR0-based timing and its ability to control discrete MOSFETs through 20 mA-rated GPIO. The 20 MHz CPU clock enables precise CC/CV charge-state transitions using software state machines, while 768 bytes of OTP memory holds multiple chemistry profiles for lead-acid, NiMH, or Li-ion variants in single SKU designs. Industrial temperature grade supports automotive and outdoor solar applications. The HS oscillator mode keeps the part stable across the input-voltage variations common in charger front-ends. OTP prevents accidental firmware tampering in field-deployed charging stations.
Recommended
Hobbyist and Educational Embedded Projects
The PIC16C55-HSI/P is a teaching staple in introductory microcontroller courses because its 33-instruction baseline RISC set can be learned in a single lab session. The 28-pin PDIP package fits standard 0.6-inch-wide breadboards and IC sockets, allowing students to swap the part repeatedly without soldering. The 20 MHz HS mode demonstrates crystal-based clocking fundamentals and prescaler-based timing. Industrial temperature grade lets the same part serve in student-built weather stations or robotics projects that operate outdoors. The 2-level hardware stack is pedagogically useful for illustrating call-depth limits before students migrate to mid-range PIC16F devices.
Recommended
Industrial Timer and Relay Logic Replacement
Replacing legacy electromechanical relay timers and cam timers with the PIC16C55-HSI/P delivers software-defined timing flexibility at lower long-term cost. The 8-bit TMR0 with prescaler supports timing intervals from tens of microseconds to multiple seconds, while 20 I/O pins drive multiple relay coils and read feedback switches. The industrial -40C to +85C range matches relay-panel environments in factories and HVAC systems. OTP memory ensures the timing program cannot be accidentally overwritten by EMI, while the HS oscillator tolerates the electrical noise common in industrial cabinets. The PIC16C55-HSI/P's 20 MHz throughput comfortably handles multi-channel sequencing.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-HSI/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-HS/P | PIC16C55-10I/P | PIC16C55A-20I/P | PIC16C55-04I/P | PIC16C55/JW |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | PDIP-28 (through-hole) | PDIP-28 (through-hole) - same | PDIP-28 (through-hole) - same | PDIP-28 (through-hole) - same | PDIP-28 (through-hole) - same | CERDIP-28 (windowed) - same pinout, different body |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 10 MHz | 20 MHz | 4 MHz | 20 MHz |
| Program Memory | 768 B OTP (512 x 12) | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B EPROM (UV-erasable) |
| Data RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 24 B |
| Operating Temperature | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) |
| Oscillator Mode | HS (high-speed, 4-20 MHz crystal/resonator) | HS (high-speed) | HS (high-speed, 10 MHz max) | HS (high-speed) | HS (high-speed, 4 MHz max) | HS (high-speed) |
| Number of I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Hardware Stack Levels | 2 | 2 | 2 | 2 | 2 | 2 |
| Approximate Unit Price (qty 1) | $4.20 | $3.90 | $3.50 | $4.40 | $3.20 | $24.00 (windowed premium) |
Key Differentiators
- Industrial temperature grade at HS 20 MHz speed (vs PIC16C55-HS/P)
- Flash-programmable alternative for modern designs (vs PIC16F54-I/P)
- Compatible with PIC16C5x family pinout (vs PIC16C558-20I/P)
Design Notes
Place the high-speed crystal or ceramic resonator within 5 mm of pins 15 (OSC2) and 16 (OSC1), with a ground guard ring around the oscillator traces to keep switching noise out of the clock signal. Use 15 pF to 33 pF load capacitors (per resonator datasheet) tied to a clean analog ground. Keep the MCLR pull-up (typically 10 kohm) close to the MCLR pin and add a 0.1 uF decoupling capacitor on VDD (pin 14) within 3 mm of the pin. Estimated: at 20 MHz CPU clock, stray capacitance above 5 pF on OSC1/OSC2 can shift the oscillator frequency by 1-2 percent, which is acceptable for serial-baud timing but not for precision timing.
The PIC16C55-HSI/P has a 2-level hardware stack, which limits CALL nesting to two subroutine levels deep. Writing a three-level call chain causes the deepest return address to be lost and the program to malfunction. Design firmware to be flat (no nested subroutines) or use computed GOTOs instead of CALL chains. Also note the 33-instruction baseline set is not binary-compatible with mid-range PIC16F parts; porting code requires rewriting the configuration-word and oscillator-setup sequences. The WDT is enabled by default on some configurations - explicitly clear it in the CONFIG fuse for time-critical loops.
Estimated: at 20 MHz CPU clock with all 20 I/O pins sourcing 5 mA simultaneously, the PIC16C55-HSI/P consumes approximately 15 mA to 25 mA active current from VDD. Add a 10 uF bulk capacitor near the VDD pin and a 0.1 uF ceramic bypass capacitor within 5 mm of the pin to handle GPIO switching transients. For battery-powered applications, drop to the PIC16C55-04I/P variant running at 4 MHz; the active current scales roughly linearly with clock frequency, yielding approximately 3 mA to 5 mA active current and proportionally lower sleep current if SLEEP mode is used.
When using the PIC16C55-HSI/P in electrically noisy environments (relay panels, motor controls), add series resistors (100 ohm) on each GPIO driving long cables or inductive loads, paired with Schottky diodes to VDD on lines exposed to back-EMF. The HS oscillator mode is more sensitive to EMI than LP (low-power) mode; if 4 MHz is sufficient, choose PIC16C55-LP variants for better noise immunity. Keep I/O traces short and avoid routing them parallel to the oscillator traces to minimize crosstalk.
Compliance Information
PDIP-28 package on PIC16C55-HSI/P typically uses lead-bearing solder finish (SnPb), making it non-RoHS compliant. Reach-compliant per Microchip documentation. Not AEC-Q100 qualified - select PIC16F54-I/P or PIC16C55A automotive-grade variants for vehicle applications.
