PIC16C56AT-40/SS - 8-bit 40MHz OTP MCU 1.5KB | Microchip
MPN: PIC16C56AT-40/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.52 | $25.20 |
| 100 | $2.18 | $218.00 |
| 500 | $1.89 | $945.00 |
| 1,000 | $1.65 | $1,650.00 |
PIC16C56AT-40/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals on one silicon die. The 8-bit PIC architecture uses a RISC (Reduced Instruction Set Computer) instruction set with a fixed program word width of 12 bits in this family, enabling single-cycle instruction execution at the oscillator clock rate. MCUs serve as the embedded intelligence in countless products, from consumer appliances to industrial controllers, forming the lowest tier of the computing hierarchy: microcontroller -> embedded processor -> microprocessor. The OTP memory variant is factory- or field-programmed once and cannot be erased, which lowers die cost for high-volume production runs.
Key features of the PIC16C56AT-40/SS include its 40 MHz maximum operating frequency, 1.5 KB OTP program memory (1K x 12 organization), 25 bytes of general-purpose RAM, 12 digital I/O pins, two 8-bit timers, a watchdog timer for runaway code recovery, and Power-On Reset. It is offered in the commercial temperature grade (0 °C to +70 °C) per the slash-SPEC ordering code "40" suffix convention, with an operating voltage range typically of 3.0 V to 6.0 V across the PIC16C5X family.
Technically, the PIC16C56A core uses a Harvard architecture with separate program and data buses. The 12-bit instruction word delivers deterministic single-cycle execution for most instructions and a 33-instruction set. With 25 bytes of file-register RAM and a 2-level hardware stack, this device targets simple control loops where deterministic timing and low cost outweigh deep memory and modern peripherals.
Typical applications include appliance control boards, HVAC thermostat logic, simple sensor signal conditioning, LED driver controllers, and legacy industrial control replacement. The 40 MHz clock rate enables sub-microsecond bit-banging for protocol emulation, while 12 I/O pins are sufficient for keypad scan, relay drive, and indicator-LED multiplexing.
When designing with this part, account for OTP programming cost during development: OTP parts cannot be re-programmed, so production must use pre-programmed parts. For development, the windowed (JW) or flash (F) variants in the broader PIC16 family are recommended.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found on any single manufacturer or distributor page, providing a single reference point for engineers qualifying the PIC16C56AT-40/SS for new designs or legacy board replacements.
Drop-in alternatives for PIC16C56AT-40/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 PIC16C56AT-40/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, Instruction Set, Maximum Clock Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C56AT-20/SS
✅ Drop-In✓ In Stock
$0.85 / Unit
View Datasheet →PIC16C56A-04/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56A-40/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56AT-40I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56AT-20E/SS
✅ Drop-In✓ In Stock
$2.21 / Unit
View Datasheet →PIC16C56AT-40/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Series | PIC® 16C |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 1.5 KB (1K x 12) |
| RAM Size | 25 bytes |
| Maximum Clock Frequency | 40 MHz |
| Number of I/O Pins | 12 |
| Number of Timers | 2 (8-bit) |
| Watchdog Timer | Yes (WDT) |
| Power-On Reset | Yes (POR) |
| Operating Temperature Grade | Commercial |
| Package | 20-pin SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Instruction Set | 33 instructions, 12-bit word |
PIC16C56AT-40/SS Pin Configuration
| Pin 1 | RA0 — Bidirectional I/O pin, PORTA bit 0 |
| Pin 2 | RA1 — Bidirectional I/O pin, PORTA bit 1 |
| Pin 3 | RA2 — Bidirectional I/O pin, PORTA bit 2 |
| Pin 4 | RA3 — Bidirectional I/O pin, PORTA bit 3 |
| Pin 5 | RB0 — Bidirectional I/O pin, PORTB bit 0 (interrupt-on-change on this family) |
| Pin 6 | RB1 — Bidirectional I/O pin, PORTB bit 1 |
| Pin 7 | RB2 — Bidirectional I/O pin, PORTB bit 2 |
| Pin 8 | RB3 — Bidirectional I/O pin, PORTB bit 3 |
| Pin 9 | RB4 — Bidirectional I/O pin, PORTB bit 4 |
| Pin 10 | RB5/RTCC — Bidirectional I/O pin / Timer0 external clock input |
| Pin 11 | VDD — Positive supply voltage (3.0 V to 6.0 V family-typical) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | OSC2/CLKOUT — Oscillator crystal output / instruction clock output |
| Pin 14 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 15 | RC0 — Bidirectional I/O pin, PORTC bit 0 |
| Pin 16 | RC1 — Bidirectional I/O pin, PORTC bit 1 |
| Pin 17 | RC2 — Bidirectional I/O pin, PORTC bit 2 |
| Pin 18 | RC3 — Bidirectional I/O pin, PORTC bit 3 |
| Pin 19 | RC4 — Bidirectional I/O pin, PORTC bit 4 |
| Pin 20 | MCLR/VPP — Master Clear (reset, active low) / Programming voltage input |
Typical Applications
PIC16C56AT-40/SS is suitable for 7 applications: White Goods Appliance Control, HVAC Thermostat Logic, Simple Sensor Signal Conditioning, LED Driver Controllers, Industrial Control Replacement (Legacy Boards), Consumer Remote Control Transmitters, Toy and Hobby Electronics.
White Goods Appliance Control
The PIC16C56AT-40/SS suits appliance control boards where deterministic timing, low cost, and small package footprint matter most. With 12 I/O pins rated at 25 mA sink/source, it can directly drive relay coils, indicator LEDs, and triac gates without external driver buffers, reducing BOM cost. The 40 MHz clock rate enables sub-microsecond timing for triac zero-crossing detection and motor phase control, while the 1.5 KB OTP memory is adequate for the fixed control sequences typical of dishwashers, washing machines, and microwave ovens. The 20-pin SSOP is small enough for crowded control panels.
Recommended
HVAC Thermostat Logic
The PIC16C56AT-40/SS fits HVAC thermostat control logic where deterministic single-cycle instruction execution and low quiescent current reduce BOM count. With two 8-bit timers, the part can simultaneously handle temperature sampling intervals (typically 1 second) and keypad debounce scans (10 ms). The 12 I/O pins support a 4x4 keypad matrix, 7-segment LED multiplexing, relay outputs for heat/cool stages, and a serial link to the indoor unit. OTP programming locks the calibrated thermostat curves at factory, eliminating field-programming interfaces and reducing cost.
Recommended
Simple Sensor Signal Conditioning
The PIC16C56AT-40/SS fits low-rate sensor signal conditioning where the PIC's 40 MIPS throughput can oversample and digitally filter analog sensor inputs. The 12 I/O pins drive multiplexed sensor bridges, LED bar-graph displays, and alarm relays. At 40 MHz, the part executes a 50-sample moving-average filter in under 200 microseconds, well within typical 10 ms sensor update cycles. OTP memory at $1.65 at qty-1000 keeps the BOM under $3 for the entire sensor module, attractive for high-volume industrial sensor markets.
Recommended
LED Driver Controllers
The PIC16C56AT-40/SS controls multi-channel LED drivers where 12 I/O pins can drive 12 individual LEDs or multiplex larger arrays. Each pin's 25 mA sink capability directly drives indicator LEDs without external transistors. The 40 MHz instruction rate supports 8-bit PWM duty-cycle updates for breathing effects, color mixing, and brightness ramping. OTP memory locks the calibrated gamma curves and timing sequences, ensuring display consistency across production batches. The 20-pin SSOP package handles thermal dissipation for moderate PWM duty cycles.
Recommended
Industrial Control Replacement (Legacy Boards)
The PIC16C56AT-40/SS is widely used to repair or replace legacy PIC16C5X-based industrial controllers still in service decades after deployment. Its pin-compatible SSOP-20 footprint and identical register map to the PIC16C56 make it a drop-in functional replacement on existing boards. With active Microchip production and authorized-distributor stock as of 2026-09-16, the part remains available for sustaining-engineering programs. The OTP memory ensures identical firmware behavior to the original part, avoiding validation overhead for safety-critical industrial applications.
Recommended
Consumer Remote Control Transmitters
The PIC16C56AT-40/SS handles consumer IR/RF remote control transmitters where its 40 MHz instruction rate bit-bangs standard protocols like NEC, RC5, and Sony SIRC. The 12 I/O pins support a 4x4 keypad matrix, status LED, and IR LED driver transistor. OTP memory locks the protocol encoding table and device-pairing codes at factory, preventing field tampering. Low BOM cost (microcontroller + 4-layer PCB + plastic case typically under $2 at qty-10K) is essential for sub-$5 retail remote control products.
Recommended
Toy and Hobby Electronics
The PIC16C56AT-40/SS powers low-cost electronic toys and hobby kits where its $1.65-at-qty-1000 unit cost enables sub-$10 retail products. The 12 I/O pins drive LEDs, sound effects via single-pin PWM, motor H-bridges, and simple user inputs. OTP memory locks the toy firmware at factory, preventing end-user code modification and intellectual-property theft. The 20-pin SSOP is small enough for wearable and handheld toy form factors, while the 40 MHz clock enables responsive animation timing and real-time motor control loops.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56AT-40/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C56AT-20/SS | PIC16C56A-04/SS | PIC16C56A-40/SS | PIC16C56AT-40I/SS | PIC16C56AT-20E/SS |
|---|---|---|---|---|---|---|
| Package | 20-pin SSOP | 20-pin SSOP (same) | 20-pin SSOP (same) | 20-pin SSOP (same) | 20-pin SSOP (same) | 20-pin SSOP (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 40 MHz | 20 MHz | 4 MHz | 40 MHz | 40 MHz | 20 MHz |
| Program Memory | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP |
| RAM | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes |
| Temperature Grade | Commercial (0C to +70C) | Commercial | Commercial | Commercial | Industrial (-40C to +85C) | Extended |
| Packaging Form | Tape & Reel | Tape & Reel | Tube | Tube | Tape & Reel | Tape & Reel |
| Number of I/O Pins | 12 | 12 | 12 | 12 | 12 | 12 |
| Architecture / Instruction Set | 12-bit PIC RISC | 12-bit PIC RISC | 12-bit PIC RISC | 12-bit PIC RISC | 12-bit PIC RISC | 12-bit PIC RISC |
Key Differentiators
- Higher 40 MHz clock speed within PIC16C5X family (vs PIC16C56AT-20/SS)
- Identical pinout and die in tube packaging (vs PIC16C56A-40/SS)
- Industrial temperature grade option in same SSOP-20 footprint (vs PIC16C56AT-40I/SS)
Design Notes
The PIC16C56AT-40/SS operates from a family-typical 3.0 V to 6.0 V VDD supply. Decouple VDD (pin 11) with a 100 nF ceramic capacitor placed within 5 mm of the pin, and add a 10 uF bulk capacitor on the same rail for high-current I/O switching transients. The PIC16C5X family draws approximately 2-5 mA active at 5 V/40 MHz with all I/O switching; for battery-powered designs use the lower-frequency -04 or -20 speed grades to reduce operating current proportionally.
The PIC16C56AT-40/SS supports four oscillator modes: LP (low-power crystal, 32 kHz to 200 kHz), XT (standard crystal, 200 kHz to 4 MHz), HS (high-speed crystal, 4 MHz to 40 MHz), and RC (resistor-capacitor, low-cost). For the -40 speed grade, use the HS mode with a 40 MHz fundamental or third-overtone crystal plus two 15-33 pF load capacitors. MCLR (pin 20) must be pulled high through a 10 kohm resistor; do not leave floating or the part will randomly reset.
OTP (One-Time Programmable) memory cannot be erased after programming. Production programming must use a verified hex file because a single bug requires discarding the part. During development, use the PIC16F57 flash equivalent or the PIC16C56/JW windowed variant to allow iterative firmware updates. Brown-out detection is not available on the PIC16C56A core; rely on Power-On Reset and external voltage supervisor for systems requiring deterministic reset thresholds.
The 20-pin SSOP package has 0.65 mm pin pitch and 5.30 mm body width. Use 0.4 mm wide PCB traces between pads with NSMD (non-solder-mask-defined) pads for reliable reflow soldering. Place the decoupling capacitor on the same side as the MCU, with via-free power and ground paths directly under the IC. Keep clock traces short and away from high-current switching nodes to avoid injecting noise into the oscillator circuit.
Compliance Information
RoHS and lead-free status [DATA_NEEDED]: older PIC16C5X OTP family was originally released before the RoHS directive. AEC-Q100 not applicable - PIC16C56AT-40/SS is not automotive-qualified. Conflict-minerals compliance inferred from Microchip's public CMRT filings.