PIC16C56-XT/SS - 8-bit OTP MCU, 4MHz, 20-SSOP | Microchip
MPN: PIC16C56-XT/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.18 | $21.80 |
| 100 | $1.92 | $192.00 |
| 500 | $1.71 | $855.00 |
| 1,000 | $1.52 | $1,520.00 |
PIC16C56-XT/SS Overview
A microcontroller (MCU) is a single-chip computer containing a processor core, memory, and programmable I/O peripherals. The PIC16C5X family belongs to the broader category of 8-bit microcontrollers -> RISC microcontrollers -> embedded controllers -> semiconductors. PIC microcontrollers use a Harvard architecture with separate program and data paths, and the 16C5X baseline family is the simplest tier of the PIC16 lineup, offering 12-bit-wide instructions, 33 single-word/cycle instructions, and 2:1 code compression over comparable 8-bit CISC MCUs in its class.
Key features include 12-bit-wide instructions, 8-bit-wide data path, seven or eight special function hardware registers, a watchdog timer, an 8-bit real-time clock/counter (TMR0) with 8-bit programmable prescaler, Power-on Reset, power-saving SLEEP mode, and up to 12 bidirectional I/O pins. The XT suffix designates the external crystal oscillator clock option (4 MHz max), and the SS suffix denotes the 20-pin SSOP package. The PIC16C56 is the OTP-programmed variant; the PIC16C57 is its pin-compatible larger-memory sibling.
Architecturally, the PIC16C56-XT/SS uses CMOS EPROM-based program memory with 1K x 12 organization, providing approximately 1.5KB of code space. The two-level hardware stack supports nested subroutine calls, and the instruction set provides bit, byte, and literal operations with single-cycle execution on most instructions (200 ns at 20 MHz equivalent cycle). Commercial-grade temperature range (0°C to +70°C) is standard for this part.
Typical applications include legacy embedded control, simple timer/counter systems, low-cost consumer appliances, sensor signal conditioning, HVAC controls, and small motor control where cost, deterministic timing, and minimal external component count are critical. The OTP memory suits volume production where code is finalized, eliminating per-unit programming cost.
When designing with this part, ensure the external XT-mode crystal is sized for the 4 MHz maximum and that decoupling capacitors are placed close to VDD/VSS pins. The PIC16C56 is the OTP version; if in-system reprogrammability is required during development, consider the PIC16F54 baseline Flash MCU or a PIC16F1xxx mid-range part as a modernized replacement with a different footprint.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives within the PIC16C5X family, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC16C56-XT/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 PIC16C56-XT/SS (same form factor and footprint) — differing in Package, Program Memory Size, Timers, Program Memory Type, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C56T-XT/SS
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C57-XT/SS
✅ Drop-In✓ In Stock
$1.28 / Unit
View Datasheet →PIC16C55-XT/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.42 / Unit
View Datasheet →PIC16C56A-04E/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.32 / Unit
View Datasheet →PIC16C56-HSI/SS
✅ Drop-In✓ In Stock
$3.65 / Unit
View Datasheet →PIC16C56-XT/SS Maximum Ratings & Electrical Characteristics
| Program Memory Type | OTP EPROM |
| Program Memory Size | 1.5 KB (1K x 12) |
| RAM Size | 25 bytes |
| CPU Core | PIC16C5X 8-bit RISC |
| Instruction Width | 12 bits |
| Maximum Clock Frequency | 4 MHz (XT mode, external crystal) |
| Operating Voltage Range | 3.0 V to 5.5 V |
| I/O Pins | 12 bidirectional I/O |
| Timers | 1 x 8-bit TMR0 with 8-bit prescaler |
| Hardware Stack | 2 levels |
| Watchdog Timer | Yes (on-chip WDT) |
| Oscillator Mode | External crystal (XT) |
| Power-on Reset | Yes |
| SLEEP Power-Saving Mode | Yes |
| Package | 20-SSOP (0.209 inch / 5.30 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | 0 C to +70 C (Commercial) |
| MSL Level | 1 (unlimited floor life at <30 C / 85% RH) |
| RoHS Status | Compliant (per Microchip product page) |
PIC16C56-XT/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O port A bit 4; Timer0 clock input |
| Pin 4 | MCLR — Master Clear (Reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 14 | VDD — Positive supply voltage (3.0V to 5.5V) |
| Pin 15 | OSC1 — External XT crystal oscillator input |
| Pin 16 | OSC2 — External XT crystal oscillator output |
| Pin 17 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 18 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 19 | NC — Not connected (per datasheet) |
| Pin 20 | NC — Not connected (per datasheet) |
Typical Applications
PIC16C56-XT/SS is suitable for 8 applications: Legacy Embedded Control, Timer / Counter Systems, Low-Cost Consumer Appliances, Sensor Signal Conditioning Front-End, HVAC Control Modules, Small Motor and Relay Control, LED Display and Indicator Drivers, Educational and Development Platforms.
Legacy Embedded Control
The PIC16C56-XT/SS is well-suited to legacy embedded control tasks where its 1.5KB OTP program memory, 12 bidirectional I/O, and 4 MHz RISC core deliver deterministic timing without requiring an in-circuit programming infrastructure. The 12-bit instruction set provides 2:1 code compression over comparable 8-bit CISC MCUs, so 1.5KB of OTP runs substantial control logic including state machines, I/O scanning, and simple protocol handling. Compared with Flash-based replacements, the OTP silicon costs less per unit at high volume, making the PIC16C56-XT/SS a fit for sealed appliances and instruments where firmware updates are not fielded.
Recommended
Timer / Counter Systems
The PIC16C56-XT/SS integrates an 8-bit real-time timer/counter (TMR0) with an 8-bit programmable prescaler, making it well-suited to interval timing, event counting, and simple pulse-width measurement. The T0CKI pin (shared with RA4) accepts an external clock for counter operation, while internal instruction-cycle ticks drive timer mode for periodic interrupts. At 4 MHz oscillator with 1 microsecond instruction cycle, the 8-bit TMR0 with prescaler supports intervals from 1 microsecond to approximately 64 milliseconds, covering most industrial timing needs.
Recommended
Low-Cost Consumer Appliances
The PIC16C56-XT/SS targets low-cost consumer appliances such as small kitchen devices, personal care tools, and remote-control units where per-unit BOM cost is decisive. The OTP memory eliminates per-unit programming overhead in sealed products, while the 12 I/O pins directly drive LEDs, keypads, and discrete driver transistors for relays or triacs. The integrated Power-on Reset and Watchdog Timer keep the appliance recoverable from brown-outs and EMI-induced lockups, and the 20-SSOP footprint supports compact PCBs.
Recommended
Sensor Signal Conditioning Front-End
The PIC16C56-XT/SS acts as a digital front-end for simple sensor signal conditioning tasks such as thermistor linearization, switch debouncing, and threshold-based alarms. With 25 bytes of RAM and 12 I/O, the part can scan multiple analog comparators or digital sensors, debounce mechanical switches in firmware, and drive indicator LEDs without external glue logic. At 4 MHz / 1 MIPS the core can poll sensors at kilohertz rates, well above typical environmental-signal bandwidths.
Recommended
HVAC Control Modules
The PIC16C56-XT/SS is used in residential and light-commercial HVAC control modules for fan-speed control, damper actuation, and thermostat hysteresis. The TMR0-based interrupt enables periodic sensor sampling and PWM generation in firmware, while the SLEEP mode cuts quiescent current during long idle periods between sensor reads. The 3.0V to 5.5V operating range accommodates 5V industrial HVAC bus power, and the 20-SSOP SMT package fits in compact DIN-rail or wall-mount modules.
Recommended
Small Motor and Relay Control
The PIC16C56-XT/SS handles small brushed-DC motor control, relay sequencing, and solenoid actuation in compact appliances. Each of the 12 I/O pins can source/sink the rated 25 mA typical for direct low-side relay drive, and the integrated Watchdog Timer protects against firmware lockups in noisy motor environments. The deterministic 1 MIPS instruction throughput supports closed-loop PWM at audio-band rates, suitable for small DC fans and vibrator motors.
Recommended
LED Display and Indicator Drivers
The PIC16C56-XT/SS drives multiplexed 7-segment LED displays, dot-matrix indicators, and discrete LED status arrays in appliances and instruments. Software-driven multiplexing at 4 MHz handles up to 4 to 6 digit refresh with minimal flicker, and the 12 I/O pins serve both segment lines and digit strobes without external decoders. The 25-byte RAM holds display buffers and refresh state, while the integrated WDT recovers from EMI-induced display lockups in industrial environments.
Recommended
Educational and Development Platforms
The PIC16C56-XT/SS and its PIC16C5X family siblings remain popular in microcontroller education for teaching baseline RISC architecture, Harvard memory models, and assembly-level embedded programming. The 33-instruction baseline instruction set is small enough to learn in a single lab session, while the 1.5KB OTP and 25-byte RAM are sufficient to implement UART bit-banging, simple state machines, and I/O scanning exercises. The 20-SSOP breakout board is widely available for breadboard-friendly development.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56-XT/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C56T-XT/SS | PIC16C57-XT/SS | PIC16C55-XT/SS | PIC16C56A-04E/SS | PIC16C56-HSI/SS |
|---|---|---|---|---|---|---|
| Package | 20-SSOP (0.209 inch / 5.30 mm) | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1.5 KB (1K x 12) OTP | 1.5 KB OTP - same | 3 KB (2K x 13) OTP - +100% | 0.75 KB (512 x 12) OTP - -50% | 1.5 KB OTP - same | 1.5 KB OTP - same |
| Max Clock Frequency | 4 MHz (XT mode) | 4 MHz XT - same | 4 MHz XT - same | 4 MHz XT - same | 4 MHz XT - same | 20 MHz HS - higher |
| Operating Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V - same | 3.0 V to 5.5 V - same | 3.0 V to 5.5 V - same | 3.0 V to 5.5 V - same | 3.0 V to 5.5 V - same |
| Memory Type | OTP EPROM | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same |
| Oscillator Mode | XT (external crystal) | XT - same | XT - same | XT - same | XT - same | HS (high-speed crystal) - different |
| Packaging Format | Tube | Tape and Reel - different | Tube - same | Tube - same | Tube - same | Tube - same |
| Family Lifecycle | Active (legacy baseline) | Active | Active | Active | Active | Active |
Key Differentiators
- Lowest unit cost in the PIC16C5X family (vs PIC16C57-XT/SS)
- Industry-standard baseline 8-bit RISC architecture (vs PIC16F54-I/SS)
- Stable long-term production for legacy designs (vs PIC16C56A-04E/SS)
Design Notes
Place a 0.1 microfarat ceramic decoupling capacitor directly between VDD (pin 14) and VSS (pin 5), with the trace length to both pins under 5 mm. Estimated: at 4 MHz operating frequency and 5V supply, the PIC16C56-XT/SS draws under 2 mA active and under 1 microampere SLEEP, but without local decoupling the digital switching noise couples into the analog supply rail and degrades ADC or sensor readings on nearby analog components. Add a bulk 10 microfarat electrolytic or tantalum at the board power-entry point for additional immunity to motor and relay transients.
Do not confuse OTP (One-Time-Programmable) with Flash: the PIC16C56-XT/SS cannot be erased or re-programmed in-circuit. A programming error means a scrapped part. Use a PIC16F54 or PIC16F1xxx baseline Flash MCU during development, and only switch to PIC16C56-XT/SS for sealed high-volume production runs where code is finalized. Also confirm MCLR is tied to VDD through a 10 kohm pull-up; floating MCLR causes spurious resets and watchdog lockouts.
Keep the XT-mode crystal traces between OSC1 (pin 15) and OSC2 (pin 16) and the load capacitors short and symmetric, with a ground guard ring around the oscillator network to suppress EMI pickup. Estimated: stray capacitance above 5 pF on OSC1/OSC2 can shift the oscillator off-frequency or cause start-up failure at cold temperatures. Place the crystal within 10 mm of the IC pins and route the load capacitor ground returns directly to pin 5 (VSS), not through the digital ground plane.
The PIC16C56-XT/SS has 2:1 code compression but lacks interrupts and has only a 2-level hardware stack, so plan for polling-based firmware architecture. Estimated: at 4 MHz (1 microsecond per instruction cycle) and 12 I/O lines scanned, polling latency is under 12 microseconds, but heavy bit-banged UART or PWM tasks consume a substantial fraction of MIPS. For multi-protocol or higher-bandwidth designs, migrate to a PIC16F1xxx mid-range part with interrupts, hardware UART, and PWM peripherals.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - this is a commercial-grade part; industrial-grade variants use the I-suffix. Conflict-minerals compliance verified through Microchip supplier declarations.