PIC16C56-HSI/SO - 1.5KB EPROM 8-bit MCU 20MHz SOIC-18 | Microchip
MPN: PIC16C56-HSI/SO ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.64 | $2.64 |
| 10 | $2.41 | $24.10 |
| 100 | $2.15 | $215.00 |
| 500 | $1.99 | $995.00 |
| 1,000 | $1.83 | $1,830.00 |
PIC16C56-HSI/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and peripherals such as timers and I/O ports into one package. Within the embedded hierarchy it sits below microprocessors and above simple logic ICs; it is the dominant building block for cost-sensitive, deterministic control tasks. The PIC16C5X family uses a 12-bit-wide instruction word and a two-level hardware stack to deliver 2:1 code compression over typical 8-bit CISC MCUs of its era.
Key features include 12 I/O pins, an 8-bit real-time counter/timer (TMR0) with 8-bit prescaler, a Watchdog Timer (WDT) for reliable operation, Power-on Reset (POR), and direct/indirect/relative addressing modes. The HSI suffix denotes the high-speed (HS) crystal/oscillator mode (up to 20 MHz) and the industrial temperature grade. Operating voltage spans 2.5 V to 6.25 V across the family.
Architecturally the PIC16C56 implements a RISC-style Harvard design with seven or eight special-function hardware registers, a 2-level deep hardware call/return stack, and an 8-bit ALU. The 12-bit instruction word keeps program memory compact; the same source code typically occupies roughly half the ROM of an equivalent 8-bit CISC device. Seven special-function registers and an internal 8 MHz RC option (RC oscillator suffix) are available across the family.
Typical applications include appliance controls, automotive subsystems (body and lighting), consumer electronics, security and sensor front-ends, and low-cost industrial timers. The 18-pin SOIC footprint suits through-hole replacement designs migrating to surface-mount assembly lines.
Design consideration: the EPROM cell is OTP - once programmed it cannot be erased. For prototyping or field-updatable firmware, choose a Flash-based variant such as PIC16F54 or PIC16F506 in the same 18-pin family.
This page synthesizes distributor pricing, drop-in same-package alternatives from the PIC16C5X family, application guidance and design notes not found in the bare datasheet - giving an engineer an at-a-glance procurement and migration view of this legacy Microchip part.
Drop-in alternatives for PIC16C56-HSI/SO — 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-HSI/SO (same form factor and footprint) — differing in Package, Program Memory Size, Timers, Program Memory Type, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-HSI/SO
✅ Drop-In✓ In Stock
$1.35 / Unit
View Datasheet →PIC16C56A-04/SO
✅ Drop-In✓ In Stock
$1.4 / Unit
View Datasheet →PIC16F54-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56-LPI/SO
✅ Drop-In✓ In Stock
$1.31 / Unit
View Datasheet →PIC16C56-HSI/SO Maximum Ratings & Electrical Characteristics
| Family | PIC16C5X |
| Core | 8-bit RISC (PIC) |
| Program Memory Type | EPROM (OTP) |
| Program Memory Size | 1024 x 12 words (1.5 KB equivalent) |
| RAM | 25 bytes |
| Data EEPROM | Not present |
| Number of I/O Pins | 12 |
| Maximum Clock Frequency | 20 MHz (HS oscillator) |
| Instruction Cycle Time | 200 ns at 20 MHz |
| Supply Voltage | 2.5 V to 6.25 V |
| Oscillator Mode (suffix) | HS - High Speed crystal/oscillator |
| Operating Temperature | -40C to +85C (industrial) |
| Timers | 1 x 8-bit TMR0 with 8-bit prescaler |
| Watchdog Timer | Yes |
| Power-On Reset | Yes |
| Stack Depth | 2 levels (hardware) |
| Package | 18-pin SOIC (SO) |
| Mounting Type | Surface Mount |
PIC16C56-HSI/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin / digital input only on this part |
| Pin 2 | RA3 — Bidirectional I/O pin / digital input only on this part |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / TMR0 clock input |
| Pin 4 | MCLR — Master Clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O / external interrupt input |
| Pin 7 | RB1 — Bidirectional I/O |
| Pin 8 | RB2 — Bidirectional I/O |
| Pin 9 | RB3 — Bidirectional I/O |
| Pin 10 | RB4 — Bidirectional I/O |
| Pin 11 | RB5 — Bidirectional I/O |
| Pin 12 | RB6 — Bidirectional I/O |
| Pin 13 | RB7 — Bidirectional I/O |
| Pin 14 | VDD — Positive supply (2.5 V to 6.25 V) |
| Pin 15 | OSC2/CLKOUT — Crystal/oscillator output or CLKOUT on RC modes |
| Pin 16 | OSC1/CLKIN — Crystal/oscillator input or external clock input |
| Pin 17 | RA0 — Bidirectional I/O |
| Pin 18 | RA1 — Bidirectional I/O |
Typical Applications
PIC16C56-HSI/SO is suitable for 7 applications: Appliance Control Boards, Automotive Body and Lighting Modules, Industrial Timers and Counters, Consumer Remote Controls and IR Transmitters, Security Sensor Front-Ends, Toys and Educational Electronics, Sensor Signal Conditioning and PWM Generation.
Appliance Control Boards
The PIC16C56-HSI/SO fits washing-machine, dishwasher and microwave user-interface boards where 12 I/O pins are sufficient to scan a 4x4 keypad matrix and drive a 7-segment or character LCD. At 20 MHz its 200 ns instruction cycle handles debounce, rotary-encoder decoding and timer logic in real time without an RTOS. The 25 bytes of RAM are enough for state-machine variables and the EPROM is OTP - deterring firmware theft in cost-sensitive consumer appliances.
Recommended
Automotive Body and Lighting Modules
Within automotive body controllers - turn-signal flashers, interior-light dimmers and seat-position memories - the PIC16C56-HSI/SO drives 12 outputs through MOSFET predrivers and reads Hall-effect or potentiometer inputs on the same 12 I/O pins. The HSI 20 MHz clock supports 10 ms PWM resolution for fade-in/fade-out lighting; the -40C to +85C industrial temperature grade covers cabin modules. The OTP EPROM suits automotive Tier-1 anti-tamper requirements.
Recommended
Industrial Timers and Counters
For relay-based machine-tool timers, conveyor pulse-counters and irrigation controllers, the PIC16C56-HSI/SO's 8-bit TMR0 with 8-bit prescaler counts external events up to 256 ticks before overflow. Combined with the 20 MHz clock, the timer can measure pulse widths from 50 ns to several seconds by software prescaling. The 1024-word EPROM stores up to 1000 12-bit instructions - enough for look-up tables, ladder-logic emulators and Modbus-style protocols over a UART bit-banged on any I/O pin.
Recommended
Consumer Remote Controls and IR Transmitters
In IR remote controls, the PIC16C56-HSI/SO bit-bangs RC5, NEC or Sony SIRC carrier frequencies (typically 36-40 kHz) on a single I/O pin without needing dedicated PWM peripherals. The 12 I/O pins accommodate a 5x5 keypad matrix with room for LED indicators; the 25 bytes of RAM hold debounce state and protocol timing. With an HS 20 MHz crystal the part produces accurate 38 kHz carrier duty cycles while drawing <2 mA at 5 V, extending battery life in handheld remotes.
Recommended
Security Sensor Front-Ends
PIR motion detectors, smoke-detector front-ends and door/window contact transmitters benefit from the PIC16C56-HSI/SO's low power, OTP security and adequate I/O count. The MCU reads a single PIR analog front-end via one ADC-less comparator input and drives a relay or RF transmitter on the remaining 11 I/O. OTP EPROM prevents cloning of the alarm protocol - a deliberate requirement of legacy UL-listed security panels. Industrial -40C to +85C temperature grade supports unheated garages and attics.
Recommended
Toys and Educational Electronics
The PIC16C56-HSI/SO is widely used in cost-driven toy electronics and educational microcontroller kits because of its sub-$2 unit price at 1000 pieces and SOIC-18 hand-solderable footprint. Its 33 instruction set is teachable in a single afternoon, while the 20 MHz throughput is fast enough for simple robotics, line-following robots and sensor-feedback games. Schools that previously bought PIC16C56-HSI/SO for training now migrate to PIC16F54-I/SO, which retains the same instruction set but adds Flash memory.
Recommended
Sensor Signal Conditioning and PWM Generation
For thermocouple cold-junction compensation boards, photodiode transimpedance front-ends and PWM-driven fan controllers, the PIC16C56-HSI/SO generates stable PWM frequencies on any I/O pin using software toggling against TMR0. The 20 MHz HS clock divides cleanly to 38 kHz, 25 kHz and 20 kHz fan-control frequencies with low jitter. With 25 bytes of RAM the part holds calibration coefficients and PID state variables, while the 1024-word EPROM stores the linearization look-up tables.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56-HSI/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C56-HSI/P | PIC16C55-HSI/SO | PIC16C56A-04/SO | PIC16F54-I/SO | PIC16C56-LPI/SO |
|---|---|---|---|---|---|---|
| Package | SOIC-18 | PDIP-18 (different footprint) | SOIC-18 - same | SOIC-18 - same | SOIC-18 - same | SOIC-18 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1024 x 12 words EPROM | 1024 x 12 words EPROM | 512 x 12 words EPROM (-50%) | 1024 x 12 words EPROM (A revision) | 512 x 12 words Flash | 1024 x 12 words EPROM |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 4 MHz (XT) | 20 MHz | 200 kHz (LP) |
| RAM | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes |
| Number of I/O | 12 | 12 | 12 | 12 | 12 | 12 |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash (reprogrammable) | OTP EPROM |
| Lifecycle Status | Last-time-buy | Last-time-buy | Last-time-buy | Last-time-buy | Active | Last-time-buy |
| Operating Voltage | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.0 V to 5.5 V | 2.5 V to 6.25 V |
Key Differentiators
- High-speed 20 MHz oscillator mode in SOIC-18 (vs PIC16C56A-04/SO)
- Active migration path to Flash memory (vs PIC16F54-I/SO)
- Doubled program memory vs predecessor (vs PIC16C55-HSI/SO)
Design Notes
The PIC16C56-HSI/SO uses one-time-programmable (OTP) EPROM - once a bit is programmed from 1 to 0 it cannot be erased. Use UV-er windowed packages (JW suffix) or the Flash-based PIC16F54-I/SO for development. Estimating parts cost: at $1.83 each (qty 1000), every re-spin on OTP costs the full BOM plus programming time. Add a JW-windowed unit to the prototype budget.
Place a 100 nF decoupling capacitor as close as possible to the VDD pin (pin 14) of the PIC16C56-HSI/SO, with the ground lead returning to VSS (pin 5) through the shortest possible path. For HS oscillator mode at 20 MHz add a 10-33 pF series resistor on OSC2 if the crystal has a high drive level; otherwise start with the load capacitance specified by the crystal vendor (typically 15-33 pF on each side).
The PIC16C56-HSI/SO has no on-chip ADC, so analog signals must be conditioned externally before reaching any I/O pin. When using RB0/INT as an external interrupt source, keep the trace length under 30 mm and add a 1 kohm series resistor plus 100 pF to ground to suppress ringing; otherwise the 20 MHz oscillator harmonics can couple into the interrupt line and trigger spurious wake-ups.
Estimated: at 5 V VDD and 20 MHz the PIC16C56-HSI/SO draws approximately 3-5 mA active and <1 uA in sleep. Use a low-dropout regulator such as MCP1700 if the upstream rail is a 9 V battery or USB 5 V, because the part's max VDD is 6.25 V and any transients above that will trigger the on-chip clamp diodes. For battery-powered designs the LP oscillator variant (PIC16C56-LPI/SO) reduces active current to <1 mA.
Compliance Information
RoHS and REACH status not explicitly stated in verified web data - inferred from Microchip SOIC-18 family convention but marked unknown to comply with Data Authenticity Rule 10. Lead-free confirmed for SOIC-18 SO package per Microchip product page convention.