PIC16C56AT-20E/SS - 8-Bit 20MHz 1.5KB OTP MCU 20-SSOP | Microchip
MPN: PIC16C56AT-20E/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.32 | $4.32 |
| 10 | $3.78 | $37.80 |
| 100 | $3.12 | $312.00 |
| 500 | $2.65 | $1,325.00 |
| 1,000 | $2.21 | $2,210.00 |
PIC16C56AT-20E/SS Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory, working RAM, and peripheral interfaces on one die. The PIC16C5X family belongs to the broader category of 8-bit microcontrollers -> RISC microcontrollers -> embedded controllers -> semiconductor ICs, and represents one of the earliest commercially successful Harvard-architecture MCU lines from Microchip. Its 12-bit wide instructions provide roughly 2:1 code compression over typical 8-bit CISC contemporaries, which was a key selling point in the 1990s and remains attractive for tight assembly routines.
Key features of the PIC16C56AT-20E/SS include a fully static CMOS design that allows the clock to be stopped without losing register state, a wide 3.0V to 6.0V operating range, a low-power sleep mode that drops supply current to the microampere range, and a 20MHz maximum clock frequency at 5V that yields a 200ns instruction cycle. The 12 I/O pins are bidirectional with individually programmable direction registers, and the 8-bit timer/counter (TMR0) with an 8-bit programmable prescaler is sufficient for basic event counting and PWM generation. The OTP program memory and 25-byte RAM make the device suitable for high-volume, fixed-function appliances where firmware is finalized at production time.
Architecture-wise, the PIC16C56A uses a 14-bit instruction word with a two-stage pipeline (fetch/execute overlap), enabling most instructions to complete in one instruction cycle. The device has no interrupt controller, only a single hardware interrupt source from the TMR0 overflow and the external GP2/INT pin, which keeps the silicon small and the firmware deterministic. Peripherals are kept to a minimum to reduce cost: POR, WDT, TMR0, and the I/O ports. The 'E' suffix denotes the Enhanced (-40C to +125C) operating temperature range, and the 'T' in the part number indicates Tape & Reel packaging. The '20' speed suffix specifies the 20MHz maximum clock.
Typical applications include small appliance controllers (rice cookers, microwave oven keypads, washing-machine front panels), battery chargers, toys and educational electronics, remote control transmitters, low-cost sensor interface boards, and replacement logic for legacy designs in industrial control panels. The wide supply range and small SSOP footprint also suit handheld instrumentation and consumer white goods.
When designing with this part, note that OTP memory cannot be re-programmed; prototypes should use a windowed ceramic or flash-based PIC16F5X equivalent for firmware development. The 25-byte RAM constraint forces tight stack and variable management, and the absence of a hardware multiplier means multiply operations must be performed in software.
This page synthesizes distributor pricing, drop-in compatible PIC16C5X family alternatives, and design considerations not typically compiled in the manufacturer datasheet, helping engineers compare the PIC16C56AT-20E/SS against modern flash-based and OTP replacements in the same SSOP-20 footprint.
Drop-in alternatives for PIC16C56AT-20E/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-20E/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, I/O Pins, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F57-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F59-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56A-20I/SS
✅ Drop-In✓ In Stock
$0.67 / Unit
View Datasheet →PIC16C56AT-20/SS
✅ Drop-In✓ In Stock
$0.85 / Unit
View Datasheet →PIC16C55AT-20E/SS
✅ Drop-In✓ In Stock
$2.31 / Unit
View Datasheet →PIC16C56AT-20E/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Series | PIC16C5X (PIC16C56A) |
| Program Memory Size | 1.5 KB (1K x 12) OTP |
| RAM Size | 25 bytes |
| I/O Pins | 12 |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle | 200 ns at 20 MHz |
| Supply Voltage Range | 3.0 V to 6.0 V |
| Operating Temperature Range | -40 C to +125 C (Enhanced, 'E' suffix) |
| Package | 20-pin SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Timers | 1 x 8-bit (TMR0 with prescaler) |
| Watchdog Timer (WDT) | Yes |
| Power-On Reset (POR) | Yes |
| Interrupts | 1 source (TMR0 overflow / external INT) |
| Program Memory Type | OTP (One-Time Programmable) |
| Data EEPROM | None |
| ADC | None |
| Packaging | Tape & Reel ('T' suffix) |
| RoHS Status | Compliant (per distributor listing) |
PIC16C56AT-20E/SS Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset) input / programming voltage input |
| Pin 2 | GP0/RB0 — Bidirectional I/O port B bit 0 |
| Pin 3 | GP1/RB1 — Bidirectional I/O port B bit 1 |
| Pin 4 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 5 | OSC2/CLKOUT — Oscillator crystal output / clock output (Fosc/4) |
| Pin 6 | VDD — Positive supply voltage |
| Pin 7 | VSS — Ground reference |
| Pin 8 | GP2/RB2/INT/T0CKI — Bidirectional I/O / external interrupt / Timer0 clock input |
| Pin 9 | GP3/RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | GP4/RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | GP5/RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RA0/GP0 — Bidirectional I/O port A bit 0 |
| Pin 13 | RA1/GP1 — Bidirectional I/O port A bit 1 |
| Pin 14 | RA2/GP2 — Bidirectional I/O port A bit 2 |
| Pin 15 | RA3/GP3 — Bidirectional I/O port A bit 3 |
| Pin 16 | RB0 — Bidirectional I/O port B bit 0 (alternate) |
| Pin 17 | RB1 — Bidirectional I/O port B bit 1 (alternate) |
| Pin 18 | RB2 — Bidirectional I/O port B bit 2 (alternate) |
| Pin 19 | RB3 — Bidirectional I/O port B bit 3 (alternate) |
| Pin 20 | VSS — Ground reference (secondary) |
Typical Applications
PIC16C56AT-20E/SS is suitable for 6 applications: Small Appliance Control Boards, Battery Charger Controllers, Remote Control Transmitters, Toy and Educational Electronics, Low-Cost Sensor Interface Boards, Legacy Logic Replacement in Industrial Panels.
Small Appliance Control Boards
The PIC16C56AT-20E/SS fits small appliance control boards (rice cookers, microwave keypads, washing-machine panels) because its 12 I/O pins can directly scan 4x4 matrix keypads and drive 7-segment LED displays without external logic. The 1.5 KB OTP memory holds the fixed control sequence (timing profiles, sensor thresholds) with no field-update requirement, reducing BOM cost. The Enhanced -40C to +125C temperature range handles the thermal environment inside consumer white goods, while the 20 MHz clock rate provides 200 ns instruction cycles for sub-millisecond keypad debounce and PWM motor control.
Recommended
Battery Charger Controllers
The PIC16C56AT-20E/SS serves well as the control core in low-to-medium-power battery charger designs for NiCd, NiMH, and small Li-ion packs. Its 12-bit instruction width is compact enough to fit charge-state algorithms (CC-CV profiles, -delta-V detection, timer-based termination) within the 1.5 KB OTP budget. The 25-byte RAM is adequate for storing voltage/current sample averages. The wide 3.0V to 6.0V supply lets the MCU run directly from a rectified 5V adapter rail, and the Watchdog Timer protects against firmware lockup during long charge cycles.
Recommended
Remote Control Transmitters
The PIC16C56AT-20E/SS is ideal for IR/RF remote control transmitters in consumer electronics (TV, set-top box, fan, lighting) due to its low cost, small SSOP-20 footprint, and 12 I/O pins to drive up to 32 keys on a matrix keypad. The 20 MHz instruction rate generates accurate 38 kHz / 40 kHz / 56 kHz carrier frequencies for IR protocols (NEC, RC5, Sony SIRC) without external oscillators. Low-power sleep mode at microampere currents extends battery life when the remote is idle, and the OTP memory prevents firmware theft/reverse engineering of proprietary protocols.
Recommended
Toy and Educational Electronics
Toy and educational electronics use the PIC16C56AT-20E/SS as the brain of electronic toys, learning kits, and hobbyist microcontroller boards because its deterministic 200 ns instruction cycle is easy to teach in assembly language courses. The 1.5 KB OTP memory holds simple reaction games, LED chasers, and motor sequencers while keeping the per-unit cost under USD 5 in volume. The 12 I/O pins drive LEDs, buzzers, and small DC motors via discrete drivers. The Enhanced temperature grade supports indoor and outdoor toy applications, and the SSOP-20 footprint reflows cleanly on through-hole-to-SMD adapter boards for breadboard prototyping.
Recommended
Low-Cost Sensor Interface Boards
The PIC16C56AT-20E/SS works as a low-cost sensor interface and signal-conditioning MCU in industrial sensor transmitters (temperature, humidity, simple 4-20 mA loops). Its TMR0 timer with prescaler can measure pulse-train outputs from flow meters or optical encoders with microsecond resolution. The wide supply range accepts 24V industrial bus power after a simple linear regulator drop. OTP memory secures calibration constants. The 12 I/O pins multiplex sensor inputs, status LEDs, and serial data output. The Enhanced -40C to +125C grade supports outdoor and factory-floor deployment.
Recommended
Legacy Logic Replacement in Industrial Panels
The PIC16C56AT-20E/SS replaces legacy 74-series glue logic and small PAL/GAL devices in industrial control panels where discrete logic has become obsolete or unreliable. Its 12 I/O pins implement state machines, sequence interlocks, and timing relays in firmware rather than hardware, simplifying PCB layout and reducing component count. The 1.5 KB OTP holds ladder-logic-equivalent programs, and the Enhanced temperature grade ensures operation in factory environments. Engineers retrofitting legacy equipment can drop the PIC16C56AT-20E/SS into existing 20-SSOP footprints without re-spinning the PCB.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56AT-20E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F57-I/SS | PIC16F59-I/SS | PIC16C56A-20I/SS | PIC16C56AT-20/SS | PIC16C55AT-20E/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-SSOP | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same |
| Program Memory | 1.5 KB OTP | 2 KB Flash | 3 KB Flash | 1.5 KB OTP - same | 1.5 KB OTP - same | 512 B OTP |
| RAM | 25 bytes | 72 bytes | 134 bytes | 25 bytes - same | 25 bytes - same | 25 bytes - same |
| Max Clock Frequency | 20 MHz | 20 MHz - same | 20 MHz - same | 20 MHz - same | 20 MHz - same | 20 MHz - same |
| I/O Pins | 12 | 12 - same | 32 | 12 - same | 12 - same | 20 |
| Operating Temperature | -40C to +125C (Enhanced) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +125C (Enhanced) |
| Memory Type | OTP | Flash (re-programmable) | Flash (re-programmable) | OTP - same | OTP - same | OTP - same |
| Lifecycle Status | NRND | Active | Active | NRND | NRND | NRND |
Key Differentiators
- Lowest-cost OTP PIC16C5X family member with 12 I/O in 20-SSOP (vs PIC16F57-I/SS)
- Enhanced -40C to +125C operating temperature range (vs PIC16C56A-20I/SS)
- Same 20-SSOP footprint as modern flash PIC16F5X family (vs PIC16C55AT-20E/SS)
Design Notes
The PIC16C56AT-20E/SS uses One-Time Programmable (OTP) memory, which can be written exactly once. Engineers prototyping firmware MUST use a windowed ceramic package (PIC16C56A-20E/JW) or a flash-based equivalent (PIC16F57-I/SS) instead, because mistakes in OTP code cannot be corrected. Programming voltage VPP (typically 13.5V) must be applied to the MCLR pin during programming; ensure your programmer supports the PIC16C5X family.
The PIC16C56AT-20E/SS has a wide supply range of 3.0V to 6.0V, but the 20 MHz clock rating is only guaranteed at 4.5V to 5.5V. At VDD below 4.5V the maximum instruction rate drops (e.g. 4 MHz at 3.0V per the speed grade). Add a 100 nF decoupling capacitor as close as possible to the VDD pin, and a bulk 10 uF capacitor on the supply rail for switching noise immunity.
When laying out the 20-SSOP footprint, keep the crystal or resonator within 5 mm of the OSC1/OSC2 pins to minimize parasitic capacitance that can detune the oscillator. The SSOP-20 thermal pad is not present, so ground plane stitching beneath the device helps EMI. Leave pin 1 (MCLR) accessible for in-system programming via a header or test pad.
Estimated: at VDD=5V, 20 MHz clock, all 12 I/O pins toggling, the PIC16C56AT-20E/SS draws approximately 10-15 mA active and less than 5 uA in sleep mode per Microchip datasheet DC characteristics. Power dissipation is well under 100 mW, so no heatsinking is required even in enclosed appliances. However, junction-to-ambient thermal resistance of ~100 C/W means self-heating is negligible.
Compliance Information
RoHS and REACH compliant per Microchip product documentation. Lead-free matte-tin plating. NOT AEC-Q100 qualified - for automotive designs use PIC16F57-E/SS or PIC16F59-E/SS. Halogen-free status not explicitly stated in available data.