PIC16C55T-HSI/SS - 8-Bit 20MHz OTP MCU 28-SSOP | Microchip
MPN: PIC16C55T-HSI/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.74 | $274.00 |
| 500 | $2.38 | $1,190.00 |
| 1,000 | $2.05 | $2,050.00 |
PIC16C55T-HSI/SS Overview
Background: An OTP (One-Time Programmable) microcontroller is a non-volatile MCU whose program memory can be written exactly once after manufacture, after which the bit pattern is permanent. The PIC16C5X family (to which PIC16C55 belongs) is Microchip's classic 12-bit-instruction, 33-instruction baseline RISC architecture, intended as a low-cost, deterministic, easy-to-program control core for embedded logic replacement, sensor interfacing, and simple state machines. The PIC16C55 is the entry-point device of that family.
Key features include a Harvard RISC architecture with separate program and data buses, a fully static CMOS design that allows the oscillator to be stopped without losing register state, 20 bidirectional I/O pins with high sink/source current capability, and an industrial -40C to +85C operating temperature range. The /SS suffix denotes the 28-SSOP (Shrink Small Outline Package) option.
Architecturally, the PIC16C55 uses a 12-bit-wide instruction word and an 8-bit data path, providing approximately 2:1 code density relative to competing 8-bit microcontrollers of the same era. The OTP program memory is erased by UV exposure on the windowed version, while the OTP-only PIC16C55 must be programmed before final solder attach. Each device is shipped with its instruction set optimized for one-bit and 8-bit arithmetic with single-cycle branching.
Typical applications include industrial automation controllers, white goods and consumer-electronics user interfaces, low-end remote sensor nodes, automotive body and interior modules, and general-purpose logic replacement where deterministic cycle counts and low EMI are preferred over RAM-rich, interrupt-heavy designs.
When designing with the PIC16C55, verify that the chosen oscillator mode (HS in this part number = High-Speed crystal/ceramic resonator, 4 MHz to 20 MHz) matches the available clock reference. Because the program memory is OTP, design verification and code locking must be completed before programming; in-circuit reprogrammability is not available.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, and practical design notes not consolidated in the manufacturer datasheet, with parametric data sourced from Microchip product documentation and authorized distributor listings.
Drop-in alternatives for PIC16C55T-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 PIC16C55T-HSI/SS (same form factor and footprint) — differing in Program Memory Size, Package, Program Memory Type, Maximum Clock Frequency, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-HSI/SS
✅ Drop-In✓ In Stock
$1.4 / Unit
View Datasheet →PIC16C55A-20I/SS
✅ Drop-In✓ In Stock
$1.04 / Unit
View Datasheet →PIC16C55T-HSE/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-LPI/SS
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C55T-HS/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.78 / Unit
View Datasheet →PIC16C55T-HSE/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.74 / Unit
View Datasheet →PIC16C55T-HSI/SS Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC 16C |
| Core | PIC16C5X (8-bit RISC) |
| Core Size | 8-bit |
| CPU Speed | 20 MHz |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 B (512 x 12) |
| Data RAM Size | 24 B (per Jotrin listing) |
| Number of I/O Pins | 20 |
| Supply Voltage (Vcc) | 4.5 V to 5.5 V |
| Oscillator Type | External (HS = High-Speed crystal/resonator, 4-20 MHz) |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package / Case | 28-SSOP |
| Mounting Type | Surface Mount |
| Terminal Form | GULL WING |
| Peripherals | Power-On Reset (POR), Watchdog Timer (WDT) |
| Programming Method | OTP (One-Time Programmable) via MPLAB PM3 |
| Packaging | Tape & Reel (T suffix) |
PIC16C55T-HSI/SS Pin Configuration
| Pin 1 | MCLR#/VPP — Master Clear (active-low reset) / Programming voltage input |
| Pin 2 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 3 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 4 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 5 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 6 | VSS — Ground reference |
| Pin 7 | VDD — Positive supply (4.5V-5.5V) |
| Pin 8 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 9 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 10 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 11 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 12 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 13 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 14 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 15 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 16 | OSC1/CLKIN — External HS oscillator input (4-20 MHz) |
| Pin 17 | OSC2/CLKOUT — External HS oscillator output / clock out |
| Pin 18 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 19 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 20 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 21 | RC3 — Bidirectional I/O port C bit 3 |
| Pin 22 | RC4 — Bidirectional I/O port C bit 4 |
| Pin 23 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 24 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 25 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 26 | RD0 — Bidirectional I/O port D bit 0 (or shared with RC) |
| Pin 27 | RD1 — Bidirectional I/O port D bit 1 (or shared with RC) |
| Pin 28 | RD2 — Bidirectional I/O port D bit 2 (or shared with RC) |
Typical Applications
PIC16C55T-HSI/SS is suitable for 7 applications: Industrial Automation Controllers, Consumer Electronics User Interfaces, Automotive Body and Interior Modules, Remote Sensor and Telemetry Nodes, Logic Replacement and Glue Controllers, Educational and Prototyping Platforms, White Goods and Home Appliances.
Industrial Automation Controllers
The PIC16C55T-HSI/SS fits industrial automation controllers that need deterministic, low-EMI logic replacement at low cost. With its 20 MHz RISC core, 768 B OTP program memory (512 x 12), and 20 bidirectional I/O pins, it directly drives relays, optocouplers, and sensor arrays in PLC expansion modules and conveyor control boards. The 4.5V-5.5V single supply simplifies 5V-rail integration, while the industrial -40C to +85C range tolerates factory-floor thermal stress. Compared with flash-based MCUs, the OTP architecture guarantees firmware immutability - a safety plus for fixed-function machines. The integrated Power-On Reset and Watchdog Timer protect against brown-out and code-runaway events common on long cable runs in industrial cabinets. Engineers typically pair the PIC16C55 with a ULN2803 driver array and discrete input opto-isolation.
Recommended
Consumer Electronics User Interfaces
The PIC16C55T-HSI/SS is well-matched to consumer-electronics user-interface controllers such as microwave keypads, washing-machine front panels, and HVAC thermostat buttons. The 20 I/O pins comfortably scan 4x4 to 4x5 matrix keypads plus drive multiplexed LED or 7-segment displays, while the 512 x 12 OTP program memory holds typical menu/sequence state machines. The 5V operation aligns with white-goods power rails that already include a small transformer-rail-derived supply. Compared with modern Cortex-M0 parts, the PIC16C55 consumes far less code space for simple state-machine firmware - often a single digit percentage of the same code on a flash MCU. The PIC16C55T-HSI/SS is OTP, which is acceptable because consumer UI firmware is locked once shipped. Pair with a TM1628 or CH451 LED driver for direct 7-segment multiplexing off the I/O pins.
Recommended
Automotive Body and Interior Modules
The PIC16C55T-HSI/SS supports non-safety automotive body and interior modules such as mirror controllers, seat-position switches, dome-light dimmers, and accessory timer relays. Its 4.5V-5.5V supply range accepts a regulated 5V automotive rail, while the -40C to +85C industrial temperature window covers passenger-cabin environments. The OTP architecture prevents accidental firmware rewrite in the field - a regulatory plus in fixed-function modules. The 20 MHz RISC core runs pulse-width-modulation and contact-debounce logic in a single device with predictable cycle counts. For under-hood applications the A-revision PIC16C55A-20I/SS is preferred. Although the PIC16C55T-HSI/SS is not AEC-Q100 qualified, it is widely used in cabin-domain modules where AEC-Q100 is not mandatory.
Recommended
Remote Sensor and Telemetry Nodes
The PIC16C55T-HSI/SS fits battery-powered remote sensor and telemetry nodes where deterministic timing and code immutability matter more than memory depth. With 20 I/O pins it can scan a small sensor matrix (temperature, humidity, contact closures) and stream results over UART, while the OTP program memory locks the calibration data permanently. Compared with flash MCUs, the OTP core's tiny silicon area reduces quiescent current - useful in solar-powered remote nodes. The external HS oscillator allows a low-power 4 MHz crystal for sleep-mode current budgets. The 28-SSOP footprint is footprint-compatible with newer PIC16F1xxx upgrades if a flash-based migration is later needed. Pair with an MCP1700 LDO and a 2.4 GHz SPI radio module for typical telemetry use cases.
Recommended
Logic Replacement and Glue Controllers
The PIC16C55T-HSI/SS excels at replacing 74-series TTL/CMOS glue logic on legacy boards. Its 20 MHz instruction rate and 12-bit instruction width mean a single PIC16C55 can replace 5 to 15 discrete logic packages - reducing PCB area, BoM cost, and assembly time. The OTP memory locks the logic table once validated, which prevents accidental field reconfiguration. Designers commonly use it as a pin-to-pin replacement for multiple 74HC138, 74HC151, 74HC595, and 74HC165 chips. Industrial -40C to +85C operation matches discrete-logic specs. The /SS 28-SSOP package fits dense replacement layouts. Compared with discrete logic, the PIC16C55 provides debug-friendly I/O re-mapping by simply changing the OTP image.
Recommended
Educational and Prototyping Platforms
The PIC16C55T-HSI/SS is widely adopted in educational labs and MCU teaching kits because its 33-instruction baseline RISC architecture is small enough to teach in one semester yet representative of real embedded systems. The 4.5V-5.5V supply and through-hole-friendly 28-SSOP footprint work on breadboards and DIP-to-SSOP adapters. The OTP memory forces students to fully verify code before burning, a pedagogical plus. Compared with modern ARM-based boards, the PIC16C55's instruction-set manual fits in 20 pages and the cycle-accurate behavior is easy to demonstrate on a logic analyzer. Pair with the MPLAB PM3 programmer and the PICStart+ development environment for a complete teaching setup. The A-revision PIC16C55A-20I/SS is often paired as the upgradable sibling.
Recommended
White Goods and Home Appliances
The PIC16C55T-HSI/SS is a workhorse MCU for white-goods main boards in entry-level washers, dryers, dishwashers, and small kitchen appliances. Its 20 MHz RISC core executes motor-control state machines in real time, while the 20 I/O pins drive triac-control optos, valve solenoids, and keypad matrices without external mux chips. The 5V operation aligns with appliance SMPS rails, and the OTP memory locks the appliance certification firmware against field tampering. The -40C to +85C temperature range covers appliance cabinet ambient conditions. Compared with more expensive Cortex-M parts, the PIC16C55T-HSI/SS dramatically lowers the BoM cost on the appliance main board - a key selection criterion in price-sensitive white-goods segments. The integrated Watchdog Timer protects against mains-borne transient code lockups.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55T-HSI/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-HSI/SS | PIC16C55A-20I/SS | PIC16C55T-HSE/SS | PIC16C55-LPI/SS | PIC16C55T-HS/SO |
|---|---|---|---|---|---|---|
| Package | 28-SSOP (Tape & Reel) | 28-SSOP (Tube) | 28-SSOP | 28-SSOP | 28-SSOP | 28-SO |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Architecture | PIC16C5X 8-bit RISC, 12-bit instruction | PIC16C5X 8-bit RISC (same) | PIC16C5X 8-bit RISC (A-revision) | PIC16C5X 8-bit RISC (same) | PIC16C5X 8-bit RISC (LP oscillator) | PIC16C5X 8-bit RISC (same) |
| Max CPU Clock | 20 MHz (HS) | 20 MHz (HSI) | 20 MHz (HS) | 20 MHz (HSE) | ~4 MHz (LP) | 20 MHz (HS) |
| Program Memory | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP |
| Data RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 24 B |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 2.5 V to 6.25 V (extended) | 4.5 V to 5.5 V |
| Oscillator Mode | HS (High-Speed) external 4-20 MHz | HSI external | HS external | HSE external | LP (Low-Power) external | HS external |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
Key Differentiators
- Tape & Reel packaging optimized for high-volume SMT assembly (vs PIC16C55-HSI/SS)
- A-revision silicon with lower power and improved oscillator tolerance (vs PIC16C55A-20I/SS)
- HSI oscillator gain setting optimized for high-frequency crystals (vs PIC16C55T-HSE/SS)
- SSOP-28 narrow-body footprint fits dense 5.3 mm pitch designs (vs PIC16C55T-HS/SO)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of VDD (pin 7) and a bulk 10 uF tantalum or aluminum capacitor on the VDD rail. The PIC16C55T-HSI/SS Power-On Reset block holds the device in reset until Vcc rises above approximately 1.5-2.0 V, but a slow-rising supply can cause multiple reset events. Add an external RC delay on MCLR# if Vcc rise time exceeds 1 ms. According to the Microchip datasheet, total Vcc noise must stay below 50 mVpk-pk to avoid clock-threshold jitter.
Keep the OSC1/OSC2 traces short and surrounded by a ground pour to minimize radiated EMI from the 20 MHz fundamental. The HS-mode oscillator is high-gain, so stray capacitance on the crystal pins above 5 pF can cause startup failure. According to Microchip's PIC16C5X family datasheet, place a 1 MOhm feedback resistor across OSC1/OSC2 only for ceramic resonators, and use a series resistor of 100-470 ohm on OSC2 for high-frequency crystals to limit drive level. Keep digital signal traces away from the oscillator loop to prevent jitter.
Do not confuse the HS oscillator designator with XT (up to 4 MHz) or LP (low-power, up to ~200 kHz) modes - using the wrong mode prevents oscillator startup. The PIC16C55T-HSI/SS is OTP, not flash - there is no in-circuit reprogramming. According to the Microchip product page, code must be locked and verified before final programming with the MPLAB PM3. A common BOM error is to specify the PIC16C55 with an /SO suffix instead of /SS; both are 28-pin but the SO-28 and SSOP-28 footprints differ in body width (7.5 mm vs 5.3 mm) and will not solder on the same land pattern.
The PIC16C55T-HSI/SS in SSOP-28 has a theta_JA of approximately 95 C/W (estimated based on standard SSOP-28 thermal data; verify against the datasheet for the specific package variant). At maximum 20 MHz CPU clock with all 20 I/O pins switching, the dynamic power dissipation is approximately 25 mA * 5 V = 125 mW, yielding a junction-to-ambient temperature rise of about 12 C above ambient - well within the 125 C maximum junction temperature. However, in sealed enclosures with no airflow at 85 C ambient, derate by reducing CPU clock or switching frequency on heavy I/O loads.
Compliance Information
Current production date codes of PIC16C55T-HSI/SS are RoHS compliant and lead-free per Microchip product page. AEC-Q100 qualification not applicable - this is an industrial-grade MCU not qualified for automotive safety applications. Halogen-free status not explicitly stated in the verified web data.
