PIC16C56A-20E/P - 8-bit OTP MCU, 20MHz, DIP-18 | Microchip
MPN: PIC16C56A-20E/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.5 | $4.50 |
| 10 | $4.05 | $40.50 |
| 100 | $3.6 | $360.00 |
| 500 | $3.2 | $1,600.00 |
| 1,000 | $2.85 | $2,850.00 |
PIC16C56A-20E/P Overview
An 8-bit microcontroller (MCU) is a small computer-on-a-chip that combines a CPU, program memory, data RAM, and peripherals on a single die. Within the broader hierarchy, the PIC16C56A sits inside: MCU -> 8-bit MCU -> RISC microcontroller -> PIC16 family -> PIC16C5X baseline OTP sub-family -> general-purpose embedded controller. Baseline PIC16C5X devices use a 12-bit-wide instruction set with Harvard architecture, optimized for 2:1 code compression versus competing 8-bit MCUs in its price class.
Key features include 20 MHz clock input with 200 ns instruction cycle, single 5V supply operation (2.5V to 6.0V extended), 12 I/O pins with high-current sink/source capability, and a watchdog timer with on-chip RC oscillator for reliable unattended operation. The architecture provides a hardware interrupt-free polling model with eight-bit-wide data paths and a 2-level deep hardware stack, simplifying firmware design for routine control tasks.
Technical depth: the PIC16C56A uses an OTP (One-Time-Programmable) EPROM program memory that is programmed once and cannot be electrically erased, distinguishing it from flash-based PIC16F variants. The device supports in-circuit serial programming via Microchip's ICSP protocol only on specific package variants; the 'JW' windowed package enables UV erasure for development. Power consumption is typically <2 mA at 5V/4 MHz, with sleep current under 1 uA when the watchdog timer is disabled, making it suitable for battery-augmented applications.
Typical applications include automotive relay logic replacement, appliance control boards, security sensor interfaces, low-end consumer toys, and simple industrial timer/counter modules where cost, deterministic response, and a through-hole footprint outweigh the need for flash memory or onboard peripherals.
When designing with this part, note that the OTP memory requires pre-programmed parts for production - factor lead time and programming service into your NPI schedule. The 12-bit instruction set differs from later 14-bit (PIC16F) cores, so legacy assembly code must be reviewed.
This page synthesizes distributor pricing, same-family drop-in alternatives (including tape/reel variants and PIC16C54A family siblings), and practical design notes not aggregated in the manufacturer datasheet, helping engineers evaluate the PIC16C56A-20E/P against both newer flash-based MCUs and legacy OTP drop-ins on the same DIP-18 footprint.
Drop-in alternatives for PIC16C56A-20E/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 PIC16C56A-20E/P (same form factor and footprint) — differing in Package, Program Memory Size, RoHS Status, Program Memory Type, Core.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C56A-04E/P
✅ Drop-In✓ In Stock
$1.21 / Unit
View Datasheet →PIC16C56A-20I/P
✅ Drop-In✓ In Stock
$1.22 / Unit
View Datasheet →PIC16C56AT-20E/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C54A-20E/P
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C55A-20E/P
✅ Drop-In✓ In Stock
$1.95 / Unit
View Datasheet →PIC16F54-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56A-20E/P Maximum Ratings & Electrical Characteristics
| Core | PIC16C5X (8-bit RISC, Harvard, 12-bit instruction) |
| Program Memory Type | OTP EPROM (One-Time Programmable) |
| Program Memory Size | 1 K x 12-bit words (1.5 KB) |
| RAM | 25 bytes |
| EEPROM Data Memory | None (not present on this device) |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle | 200 ns (4 clock periods per instruction) |
| I/O Pins | 12 |
| Supply Voltage (VDD) | 2.5 V to 6.0 V (extended); 4.5 V to 5.5 V (typical 5V operation) |
| Operating Temperature | -40C to +125C (E grade) |
| Package | 18-pin PDIP (DIP-18, .300 inch) |
| Mounting Type | Through-Hole (THT) |
| Watchdog Timer | Yes (with on-chip RC oscillator) |
| Timers | 1 x 8-bit Timer/Counter (TMR0) |
| Interrupts | None (polled architecture) |
| Hardware Stack | 2 levels deep |
| ICSP Programming | Not supported on this OTP variant (factory programming only on standard package) |
| RoHS Status | Non-compliant (contains Pb; pre-RoHS legacy design) |
PIC16C56A-20E/P Pin Configuration
| Pin 1 | /MCLR — Master Clear (reset) input, active low |
| Pin 2 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 3 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 4 | RB0 — Bidirectional I/O port B bit 0 (interrupt on change) |
| Pin 5 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 6 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 7 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 8 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 9 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 10 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 11 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 12 | GND — Ground reference |
| Pin 13 | OSC1 — Oscillator input (crystal/ceramic resonator or external clock) |
| Pin 14 | OSC2 — Oscillator output (crystal mode) or RC connection |
| Pin 15 | VDD — Positive supply voltage |
| Pin 16 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 17 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 18 | T0CKI — Timer0 clock input / external interrupt (shared with RA4 on some package variants) |
Typical Applications
PIC16C56A-20E/P is suitable for 6 applications: Automotive Relay Logic Replacement, White Goods and Appliance Control, Security and PIR Sensor Interfaces, Low-End Consumer Toys and Hobby Electronics, Industrial Timer and Counter Modules, Simple Battery-Augmented Remote Controls.
Automotive Relay Logic Replacement
The PIC16C56A-20E/P's E temperature grade (-40C to +125C) and deterministic polled architecture make it well suited to under-hood and cabin automotive relay-logic replacement modules. With 12 high-current I/O pins that can sink/source 25 mA per pin, the part can directly drive automotive-grade 12V relays through N-channel MOSFETs, eliminating bulky discrete logic. Its 1 K x 12 OTP program memory and 25 bytes RAM are sufficient for state machines that scan switches and sequence outputs at 20 MHz with a 200 ns instruction cycle. The watchdog timer with on-chip RC oscillator catches firmware lockups, critical for unattended automotive control. Compared with discrete CMOS logic equivalents, the PIC16C56A reduces board area by 60-70% and provides field-update flexibility when sourced through factory programming. Pair with a TVS-protected 12V-to-5V regulator like the MCP1790 for a complete drop-in relay-replacement block.
Recommended
White Goods and Appliance Control
Washing machines, dishwashers, microwave ovens, and other white goods use the PIC16C56A-20E/P as a cost-optimized main controller for user-interface keypads, LED indicators, motor triac gating, and sensor monitoring. The part's 12-bit instruction set delivers the 2:1 code compression that Microchip cites versus competing 8-bit MCUs in the same price tier, allowing compact assembly firmware to fit within the 1 K x 12 OTP region. The DIP-18 through-hole footprint supports hand-soldered prototyping and field-serviceable repair workflows common in appliance repair channels. The hardware 2-level stack is adequate for the shallow call-depth of typical appliance state machines. Its E temperature grade supports operation behind a clothes dryer or oven fascia where ambient temperatures can spike. Design notes: budget OTP programming lead time and use the PIC16F54-I/P for new SKUs that need field firmware updates.
Recommended
Security and PIR Sensor Interfaces
The PIC16C56A-20E/P is widely deployed in legacy passive-infrared (PIR) motion sensor modules, door/window contact interfaces, and basic alarm-panel keypads where low cost and ultra-low sleep current are paramount. With sleep current under 1 uA (watchdog disabled), the part enables multi-year battery life on PIR detectors powered by 3V coin cells. Its 12 I/O pins accept multiple zone inputs and drive piezo buzzers or status LEDs directly through current-limiting resistors. The 20 MHz instruction cycle provides sub-microsecond response to tamper and alarm events, essential for security compliance. Because security products often operate at 3-5V across wide environmental swings, the part's 2.5-6.0V extended VDD range simplifies single-LDO power designs. For new SKUs requiring encrypted wireless, consider migrating to PIC16F15323 with integrated Core Independent Peripherals.
Recommended
Low-End Consumer Toys and Hobby Electronics
Hobby robotics, electronic dice, educational STEM kits, and entry-level remote controls rely on the PIC16C56A-20E/P as an inexpensive but capable controller with a friendly assembly ecosystem. The DIP-18 through-hole package is breadboard-friendly and allows students to swap parts easily, while the 12-bit instruction set is documented in countless textbooks and online tutorials, reducing the learning curve. At $2.85-$4.50 in 1k quantities, the part is competitive with Arduino-class boards when only one-time-programmable behavior is needed. The 20 MHz clock enables LED multiplexing, servo PWM (via software bit-banging), and simple UART at common baud rates. Pair the PIC16C56A with a Microchip 25LC040 SPI EEPROM for storing user preferences, or design with the PIC16F54-I/P if hobbyists need to reflash via ICSP.
Recommended
Industrial Timer and Counter Modules
Industrial control panels, conveyor sequencers, and process timers use the PIC16C56A-20E/P to implement multi-stage timing sequences, batch counters, and machine-state monitoring. The 8-bit TMR0 timer combined with software prescalers provides millisecond to hour timing ranges without external RTC hardware. The 12 I/O pins handle start/stop pushbuttons, mode selectors, output relays, and segment or LCD indicators through a multiplexer. The E temperature grade (-40C to +125C) supports factory-floor enclosures, while the wide 2.5-6.0V VDD tolerates loosely regulated 24V-to-5V industrial supplies. The deterministic polled architecture avoids the latency variability of interrupt-driven cores, which is important for precision timing. Combine with a Microchip MCP2515 CAN controller for industrial-networked timer modules that report batch completion to a central PLC.
Recommended
Simple Battery-Augmented Remote Controls
Battery-powered TV remote controls, garage-door keyfobs, and RF remote transmitters use the PIC16C56A-20E/P as the encoding logic core that generates Manchester or pulse-width modulation on a single output pin. The sub-1 uA sleep current preserves coin-cell battery life over years of standby, while the 20 MHz burst mode allows precise generation of 38 kHz IR carriers or 315/433 MHz OOK/FSK modulation for sub-GHz transmitters. The DIP-18 package is favored by smaller OEM remote manufacturers that hand-assemble through-hole boards for cost reasons. The 12-bit OTP memory is sufficient for fixed-format RC5/RC6/nec/sony-style IR codes that are stored as lookup tables. For remote designs that need rolling-code security, migrate to PIC16F15323 with hardware AES and CIP-based PWM.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56A-20E/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C56A-04E/P | PIC16C56A-20I/P | PIC16C56AT-20E/P | PIC16C54A-20E/P | PIC16C55A-20E/P | PIC16F54-I/P |
|---|---|---|---|---|---|---|---|
| Package | PDIP-18 (DIP-18, .300 inch) | PDIP-18 (DIP-18) - same | PDIP-18 (DIP-18) - same | PDIP-18 (DIP-18) - same | PDIP-18 (DIP-18) - same | PDIP-18 (DIP-18) - same | PDIP-18 (DIP-18) - same |
| Brand | Microchip Technology | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same |
| Maximum Clock Frequency | 20 MHz | 4 MHz (-80%) | 20 MHz - same | 20 MHz - same | 20 MHz - same | 20 MHz - same | 20 MHz - same |
| Program Memory | 1 K x 12-bit OTP EPROM | 1 K x 12-bit OTP - same | 1 K x 12-bit OTP - same | 1 K x 12-bit OTP - same | 512 x 12-bit OTP (-50%) | 512 x 12-bit OTP (-50%) | 512 x 14-bit Flash (-51%) |
| RAM | 25 bytes | 25 bytes - same | 25 bytes - same | 25 bytes - same | 25 bytes - same | 24 bytes -4% | 25 bytes - same |
| Temperature Grade | E (-40C to +125C) | E (-40C to +125C) - same | I (-40C to +85C) | E (-40C to +125C) - same | E (-40C to +125C) - same | E (-40C to +125C) - same | I (-40C to +85C) |
| Program Memory Type | OTP EPROM | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same | OTP EPROM - same | Flash (reprogrammable) |
| Instruction Set Width | 12-bit | 12-bit - same | 12-bit - same | 12-bit - same | 12-bit - same | 12-bit - same | 14-bit (different core) |
Key Differentiators
- Industry-standard PIC16C5X baseline OTP core with the lowest-cost entry point in the family (vs PIC16F54-I/P)
- Highest memory variant in the 18-pin PIC16C5X DIP family (vs PIC16C54A-20E/P)
- E temperature grade covers automotive under-hood environments that the I grade cannot (vs PIC16C56A-20I/P)
Design Notes
The PIC16C56A-20E/P uses OTP EPROM and cannot be electrically erased - any firmware bug is a permanent brick unless you ordered the JW (windowed) package variant. Always develop and debug firmware on a PIC16C56A/JW or a flash-based PIC16F54-I/P, then port the validated code to OTP parts for production programming. Factor 8-12 week OTP programming lead times into your NPI schedule to avoid production stalls.
Estimated: at 5V supply and 20 MHz clock, the PIC16C56A-20E/P typical operating current is around 2-3 mA, but drops to under 1 uA in sleep mode (watchdog disabled). Decouple VDD with a 100 nF ceramic capacitor placed within 5 mm of the VDD pin (pin 15), and add a bulk 10 uF tantalum or aluminum cap at the board input for noisy automotive/industrial supplies. The /MCLR pin (pin 1) requires a 10 kohm pull-up to VDD; adding a 100 nF capacitor from /MCLR to ground creates a power-on reset delay that prevents spurious resets during VDD ramp.
Place the decoupling capacitor and oscillator components (crystal or ceramic resonator with load capacitors) as close to pins 12-15 as possible to minimize EMI and oscillator start-up issues. For DIP-18 through-hole designs, use a ground plane on the bottom layer under the MCU to reduce digital switching noise on adjacent analog inputs. If the design must remain RoHS compliant, plan to migrate to the PIC16F54-I/P flash-based drop-in rather than carrying the legacy Pb-containing PIC16C56A-20E/P into new production.
Route the OSC1/OSC2 traces (pins 13-14) symmetrically and keep them short and surrounded by ground to avoid coupling digital noise into the clock signal. The RB port pins (4-11) feature interrupt-on-change capability - if used for sensitive analog sensing, isolate them with ground guard traces and add 100 ohm series resistors to suppress ESD-induced false triggers. For industrial designs exposed to high-voltage transients, add TVS diodes on all external I/O pins and a ferrite bead in series with VDD.
Compliance Information
PIC16C56A-20E/P is a legacy PDIP part with Pb-containing terminations, classified as non-compliant under current RoHS 3 (EU 2015/863). AEC-Q100 automotive qualification status is not publicly documented for this OTP variant; for AEC-Q100 qualified Microchip 8-bit MCUs, consider PIC16F18446 or PIC16F15323 families. REACH, halogen-free, and conflict-minerals status were not returned in the verified web data and are marked unknown.
