PIC16C55-HSI/SS - 8-Bit 20MHz 768B OTP MCU 28-SSOP
MPN: PIC16C55-HSI/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.06 | $2.06 |
| 10 | $1.9 | $19.00 |
| 100 | $1.75 | $175.00 |
| 500 | $1.55 | $775.00 |
| 1,000 | $1.4 | $1,400.00 |
PIC16C55-HSI/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, ROM/EPROM, and peripherals into one package. The PIC16C5x family belongs to the broader PIC architecture hierarchy: 8-bit MCU -> RISC microcontroller -> Harvard architecture -> embedded controller -> semiconductor. These MCUs use a 12-bit wide instruction word with 8-bit data path, delivering 2:1 code compression over competitors in the same price tier.
Key features include 20 MHz maximum clock, 768 bytes OTP program memory, 24 bytes of general-purpose RAM, 20 digital I/O pins, an 8-bit real-time clock/counter (TMR0), a hardware watchdog timer, and a two-level deep hardware stack. The device supports direct, indirect, and relative addressing modes. It runs from a single 4.5 V to 5.5 V supply and offers 12 I/O lines with high-current sink capability for direct LED driving.
Architecturally, the PIC16C5x employs a fully static CMOS Harvard RISC core with 33 single-cycle instructions, deterministic interrupt response, and a dedicated hardware multiply-by-constant mechanism via RETLW/PCLATH. The 20 MHz oscillator option provides 200 ns instruction cycle and supports DC to 20 MHz operation across the full industrial temperature range of -40C to +85C.
Typical applications include industrial control logic, automotive body electronics, appliance controllers, simple sensor interfaces, and battery-powered embedded subsystems. The 20 MHz speed and 20 I/O pins support mid-complexity sequencing tasks, while the 768-byte program memory suits compact state-machine and protocol-bridge firmware.
When designing with the PIC16C55-HSI/SS, note that OTP memory is one-time programmable and cannot be field-upgraded; choose PIC16C55A flash-based variants for prototype iteration. Always use the MPLAB PM3 programmer or equivalent EPROM programmer with the correct adapter socket, and verify oscillator start-up time at minimum VDD with the crystal or ceramic resonator specified by Microchip.
This page synthesizes distributor pricing, verified drop-in alternatives within the same PIC16C5x family, comparison parameters, and practical design notes that extend beyond the datasheet's pin description and electrical characteristics tables.
Drop-in alternatives for PIC16C55-HSI/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-HSI/SS (same form factor and footprint) — differing in Program Memory Size, Program Memory Type, Package, Operating Temperature, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-20I/SS
✅ Drop-In✓ In Stock
$1.04 / Unit
View Datasheet →PIC16C55A-04I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55AT-04/SS
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC16C55-10I/SS
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →PIC16C55AT-04E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558-20/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55-HSI/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC (Harvard) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 bytes (512 x 12) |
| RAM Size | 24 bytes |
| Maximum CPU Frequency | 20 MHz |
| Instruction Cycle | 200 ns |
| Operating Voltage (Vdd) | 4.5 V to 5.5 V |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Watchdog Timer | Yes (hardware) |
| Stack Depth | 2 levels (hardware) |
| Instruction Set | 33 single-cycle instructions |
| Addressing Modes | Direct, Indirect, Relative |
| Package | 28-pin SSOP |
| Operating Temperature | -40C to +85C (industrial) |
| Oscillator Type | External RC/HS, internal options |
| Mounting Type | Surface Mount |
| Lead-Free / RoHS | Compliant (per DigiKey listing) |
| Programming Method | MPLAB PM3 with 28-pin SSOP adapter |
PIC16C55-HSI/SS Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (bidirectional I/O) |
| Pin 2 | RA3 — Port A bit 3 (bidirectional I/O) |
| Pin 3 | RTCC — Timer/counter clock input (TMR0) |
| Pin 4 | MCLR — Master clear reset (active low) |
| Pin 5 | Vss — Ground reference |
| Pin 6 | RB0 — Port B bit 0 (bidirectional I/O) |
| Pin 7 | RB1 — Port B bit 1 (bidirectional I/O) |
| Pin 8 | RB2 — Port B bit 2 (bidirectional I/O) |
| Pin 9 | RB3 — Port B bit 3 (bidirectional I/O) |
| Pin 10 | RB4 — Port B bit 4 (bidirectional I/O) |
| Pin 11 | RB5 — Port B bit 5 (bidirectional I/O) |
| Pin 12 | RB6 — Port B bit 6 (bidirectional I/O) |
| Pin 13 | RB7 — Port B bit 7 (bidirectional I/O) |
| Pin 14 | Vss — Ground reference (secondary) |
| Pin 15 | OSC1 — Oscillator input |
| Pin 16 | OSC2 — Oscillator output |
| Pin 17 | RC0 — Port C bit 0 (bidirectional I/O) |
| Pin 18 | RC1 — Port C bit 1 (bidirectional I/O) |
| Pin 19 | RC2 — Port C bit 2 (bidirectional I/O) |
| Pin 20 | RC3 — Port C bit 3 (bidirectional I/O) |
| Pin 21 | RC4 — Port C bit 4 (bidirectional I/O) |
| Pin 22 | RC5 — Port C bit 5 (bidirectional I/O) |
| Pin 23 | RC6 — Port C bit 6 (bidirectional I/O) |
| Pin 24 | RC7 — Port C bit 7 (bidirectional I/O) |
| Pin 25 | RA0 — Port A bit 0 (bidirectional I/O) |
| Pin 26 | RA1 — Port A bit 1 (bidirectional I/O) |
| Pin 27 | Vdd — Positive supply voltage (4.5 V to 5.5 V) |
| Pin 28 | NC — Not connected (per datasheet package variant) |
Typical Applications
PIC16C55-HSI/SS is suitable for 6 applications: Industrial Control Logic Replacement, Appliance Control Boards, Automotive Body Electronics, Battery-Powered Sensor Nodes, LED Display and Lighting Controllers, Simple Protocol Bridge / Glue Logic.
Industrial Control Logic Replacement
The PIC16C55-HSI/SS suits industrial control logic replacement where a legacy 8-bit OTP MCU footprint must be honored. With 20 MHz CPU speed and 768 bytes of program memory, the device can manage state-machine-based conveyor sequencing, relay drivers, and sensor polling in 24V factory automation lines. The 4.5-5.5 V single supply matches 5 V regulated rails typical of PLC backplanes. Designers should pair the MCU with opto-isolated inputs and high-current sink drivers (ULN2803) since the PIC16C55-HSI/SS ports source/sink up to 25 mA per pin, sufficient for direct relay coil excitation at low duty cycles.
Recommended
Appliance Control Boards
The PIC16C55-HSI/SS fits white-goods appliance controllers such as washing-machine timers, microwave user interfaces, and dishwasher cycle managers. The 20 MHz execution rate handles debounced keypad scanning plus triac-fired heater control loops within a single instruction cycle budget. Its 20 I/O pins comfortably drive 7-segment LED displays, mode-selector switches, and triac optocouplers (MOC3041) without external I/O expanders. Industrial temperature grade (-40C to +85C) covers under-cabinet and garage-appliance thermal environments. Use watch-dog timer to recover from brown-out during motor inrush events.
Recommended
Automotive Body Electronics
The PIC16C55-HSI/SS addresses automotive body-electronics modules including seat controllers, mirror adjusters, and simple body-control nodes. With 768-byte OTP, the firmware fits compact tasks like BLDC wiper control, door-lock sequencing, or ambient lighting PWM. The 5V operation aligns with classic automotive 12V-bus regulated rails; for direct 12V-tolerant I/O add external TVS protection. The -HSI industrial temperature range meets cabin environments, though underhood modules require the AEC-Q100 qualified PIC16F equivalent. Always derate I/O current to 10 mA continuous for automotive reliability.
Recommended
Battery-Powered Sensor Nodes
The PIC16C55-HSI/SS with its low-power CMOS core and SLEEP instruction supports battery-powered sensor nodes for remote monitoring, HVAC thermostats, and simple IoT edge devices. The 20 MHz active mode is engaged only during measurement bursts; in SLEEP mode current drops to a few microamps, enabling multi-year battery life on 2x AA cells with a boost regulator. Its 20 I/O lines accommodate SPI sensor interfaces, 1-Wire temperature probes, and low-power RF module control lines. The 768-byte OTP suits firmware that performs periodic sampling, threshold detection, and infrequent RF transmission bursts.
Recommended
LED Display and Lighting Controllers
The PIC16C55-HSI/SS operates as an LED matrix display driver or decorative lighting controller, leveraging its 20 high-current I/O pins to multiplex 8x8 LED matrices or 7-segment numeric displays directly. At 20 MHz, software-driven PWM achieves visible-quality dimming at frequencies above 100 Hz, eliminating flicker in architectural and signage applications. The 768-byte program memory holds lookup tables for character fonts, animation patterns, or DMX-512 address decoding. Pair with TPIC6B595 high-current shift registers for expanded channel count beyond 20 outputs.
Recommended
Simple Protocol Bridge / Glue Logic
The PIC16C55-HSI/SS serves as a low-cost protocol-bridge MCU converting between UART, SPI, and I2C domains in legacy equipment upgrade scenarios. The PIC16C5x Harvard core with 33 single-cycle instructions executes bit-banged protocol translation in real time, replacing discrete glue logic that would otherwise require PAL/GAL devices. 768-byte OTP holds the translation state machine, and 24-byte RAM covers small receive buffers. Industrial temperature range suits factory-floor retrofit installations where protocol adapters must operate near motors and VFDs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-HSI/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-20I/SS | PIC16C55A-04I/SS | PIC16C55AT-04/SS | PIC16C55-10I/SS | PIC16C55AT-04E/SS | PIC16C558-20/SS |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 4 MHz | 4 MHz | 10 MHz | 4 MHz | 20 MHz |
| Program Memory Size | 768 bytes (512 x 12) OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 2048 bytes (1.5K x 12) OTP |
| RAM Size | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 68 bytes |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 | 20 |
| Operating Voltage | 4.5 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 4.5 V to 5.5 V | 3.0 V to 5.5 V | 2.5 V to 5.5 V |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (extended) | -40C to +85C |
Key Differentiators
- Highest 20 MHz CPU speed within the PIC16C5x 28-SSOP family (vs PIC16C55A-04I/SS)
- Industrial temperature range standard for legacy OEM designs (vs PIC16C55AT-04E/SS)
- Compact 768-byte OTP for cost-sensitive production runs (vs PIC16C558-20/SS)
Design Notes
The PIC16C55-HSI/SS operates from a single 4.5 V to 5.5 V supply. Place a 100 nF decoupling capacitor as close as possible between Vdd (pin 27) and Vss (pin 14), plus a bulk 10 uF tantalum or aluminum on the supply rail. For noisy industrial environments add a ferrite bead in series with Vdd and a TVS diode (5.1 V) for transient suppression. Estimated: at 20 MHz active current is approximately 10 mA and sleep current drops below 5 uA - verify with the PIC16C5x datasheet electrical characteristics table for your specific revision.
For -HSI 20 MHz operation use a parallel-resonant crystal with 33 pF load capacitors on OSC1/OSC2 (pins 15/16). Series resistors of 100 ohm in each oscillator line reduce drive level and EMI. For ceramic resonator applications use a three-terminal resonator with built-in capacitors. Avoid running the -HSI variant at supply voltages below 4.75 V as the oscillator start-up margin is reduced. Estimated: instruction cycle = 1/(Fosc/4) = 200 ns at 20 MHz.
Route the MCLR (pin 4) signal with a short trace and 10 kohm pull-up to Vdd, plus a 100 nF capacitor to ground for noise immunity - omit this capacitor only if in-circuit programming via high-voltage MCLR is required. Keep the oscillator traces short (under 10 mm), shield them with a ground pour, and avoid routing digital signals beneath the crystal/oscillator area. Place the ICSP programming connector (RB6/RB7/RA0/MCLR/Vss/Vdd) on the board edge for production programming access without disassembling the enclosure.
Do not assume PIC16C55A register-level compatibility with PIC16C55 - the OPTION register and TRIS port directions may differ between silicon revisions. Always consult the PIC16C55A errata and reference manual before substituting the A-suffix variant. PIC16C5x has a 2-level hardware stack only (no software stack pointer) - deep subroutine nesting will silently overflow. OTP EPROM cannot be erased - production units with firmware bugs must be physically replaced; for development use the JW windowed ceramic package or migrate to PIC16F flash-based pin-compatible parts (PIC16F57 or PIC16F72 with package change).
Compliance Information
RoHS and lead-free compliant per DigiKey product listing (319794). Not AEC-Q100 qualified - the PIC16C55-HSI/SS is positioned for industrial and consumer use; for AEC-Q100 automotive designs migrate to PIC16F57 or PIC16F72 with qualification. REACH compliance status inferred from Microchip product declaration; halogen-free status not explicitly stated in available data.
