PIC16C56T-XTI/SO - 8-Bit 4MHz OTP MCU 1.5KB | Microchip
MPN: PIC16C56T-XTI/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.2 | $3.20 |
| 10 | $2.88 | $28.80 |
| 100 | $2.55 | $255.00 |
| 500 | $2.2 | $1,100.00 |
| 1,000 | $1.95 | $1,950.00 |
PIC16C56T-XTI/SO Overview
Background: A PIC microcontroller is a single-chip computer that integrates a CPU core, program memory, RAM, and I/O peripherals on one piece of silicon. The PIC16C5X family is the lowest-tier PIC family, using a 12-bit instruction set, an 8-bit data path, and RISC-like fixed instruction timing. It belongs to the broader taxonomy: microcontroller -> 8-bit MCU -> CMOS OTP MCU -> PIC16C5X family. OTP devices are programmed once with a device programmer (such as the MPLAB PM3) and are not field-reprogrammable, making them well suited to high-volume, fixed-function products where firmware is finalized before production.
Key features include a Power-On Reset (POR) block that initializes the device on Vdd rise, a Watchdog Timer (WDT) that resets the device on code lock-up, an internal oscillator option that reduces external component count, and a 12-bit wide instruction word that compresses frequently used operations into single-cycle instructions. The PIC16C5X family operates over a 2.5 V to 5.5 V Vdd range (industrial) and supports a wide industrial temperature window, making it well matched to factory-floor embedded designs. The 'XT' speed grade specifies a 4 MHz crystal/ceramic-resonator clock mode, and 'I' denotes the industrial operating-temperature grade.
Typical applications include appliance controllers, security-system keypads, low-end remote controls, sensor signal-conditioning front-ends, and white-goods motor-control boards. The industrial temperature grade allows deployment in outdoor enclosures and automotive under-hood sub-assemblies where commercial-grade parts would drift or fail. Because OTP memory cannot be rewritten in-circuit, PIC16C56T parts are most often used in mature designs where firmware has already been qualified.
When designing with this MCU, verify that your in-circuit emulator or device programmer (PM3, PICSTART Plus) supports the PIC16C56 device ID and the 18-pin SOIC socket adapter. The EPROM die is erasable with a quartz-window ceramic package variant (PIC16C56/JW); the plastic SOIC version here is OTP only and not UV-erasable.
Drop-in alternatives for PIC16C56T-XTI/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 PIC16C56T-XTI/SO (same form factor and footprint) — differing in Program Memory Size, Program Memory Type, Package, Timers, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C57-XTI/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C56-HSI/SO
✅ Drop-In✓ In Stock
$1.83 / Unit
View Datasheet →PIC16C56-XTI/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C56T-RCI/SO
✅ Drop-In✓ In Stock
$1.22 / Unit
View Datasheet →PIC16C56-LPI/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.31 / Unit
View Datasheet →PIC16C55-XTI/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C56T-XTI/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit (12-bit instruction word) |
| Family | PIC16C5X |
| Program Memory Type | OTP (One-Time-Programmable) EPROM |
| Program Memory Size | 1.5 KB (1K x 12) |
| RAM Size | 25 x 8 bytes |
| Maximum CPU Frequency | 4 MHz |
| Operating Voltage (Vdd) | 2.5 V to 5.5 V (industrial grade) |
| Oscillator Mode | XT (crystal/ceramic resonator, 4 MHz) |
| Operating Temperature Grade | Industrial (-40C to +85C) |
| I/O Pins | 12 |
| Package | 18-SOIC (0.295 inch / 7.50 mm body width) |
| Mounting Type | Surface Mount |
| Peripherals | Power-On Reset (POR), Watchdog Timer (WDT) |
| Instruction Set Width | 12-bit |
| Data Path Width | 8-bit |
PIC16C56T-XTI/SO Pin Configuration
| Pin 1 | RA2/AN2 — I/O port A bit 2 / analog input 2 |
| Pin 2 | RA3/AN3 — I/O port A bit 3 / analog input 3 |
| Pin 3 | RA4/T0CKI — 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/INT — I/O port B bit 0 / external interrupt |
| Pin 7 | RB1 — I/O port B bit 1 |
| Pin 8 | RB2 — I/O port B bit 2 |
| Pin 9 | RB3 — I/O port B bit 3 |
| Pin 10 | RB4 — I/O port B bit 4 |
| Pin 11 | RB5 — I/O port B bit 5 |
| Pin 12 | RB6 — I/O port B bit 6 |
| Pin 13 | RB7 — I/O port B bit 7 |
| Pin 14 | VSS — Ground reference (secondary) |
| Pin 15 | OSC1/CLKIN — Oscillator input / external clock in |
| Pin 16 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 17 | RA0/AN0 — I/O port A bit 0 / analog input 0 |
| Pin 18 | RA1/AN1 — I/O port A bit 1 / analog input 1 |
Typical Applications
PIC16C56T-XTI/SO is suitable for 6 applications: Appliance Control Boards, Security Keypad Controllers, Remote Control Transmitters, Sensor Signal-Conditioning Front-Ends, White-Goods Motor Control, Automotive Under-Hood Sub-Assemblies.
Appliance Control Boards
The PIC16C56T-XTI/SO is well suited for fixed-function appliance controllers such as microwave ovens, washing machines, and dishwasher control panels. Its 1.5 KB OTP memory holds the typical motor-driver state machine plus user-interface button-scan logic without requiring external program storage. The 4 MHz XT oscillator provides deterministic 1 us instruction timing for mains-zero-crossing detection and triac/SCR phase-angle control. The 12 I/O pins drive the seven-segment or LCD indicator, relay drivers, and keypad matrix without external mux logic. Industrial -40C to +85C temperature grade tolerates the heat of an enclosed appliance compartment and the cold of an unheated garage.
Recommended
Security Keypad Controllers
Standalone security-system keypads (door entry, alarm arm/disarm stations) frequently use the PIC16C56T-XTI/SO because OTP memory locks the PIN-decryption firmware against external read-out. The 25-byte RAM is sufficient to hold the rolling-code buffer and four-digit PIN while the 4 MHz core scans the 4x4 keypad matrix with no perceptible debounce delay. The Watchdog Timer (WDT) recovers the device from ESD-induced code runaway at the key contacts. The 18-SOIC wide-body package mounts flush on a backlit keypad PCB without crowding the piezo-buzzer driver. Industrial temperature grade handles outdoor gate-station installations.
Recommended
Remote Control Transmitters
Low-end infrared or 315/433 MHz RF remote controls for ceiling fans, garage-door openers, and consumer A/V gear use the PIC16C56T-XTI/SO as the encoder. Its 1.5 KB OTP fits a typical 32-button matrix-scan plus Manchester- or PWM-encoded transmission routine. The 4 MHz XT oscillator rate generates a stable carrier frequency without trimming, and the POR block ensures clean start-up after long battery storage. Low-power PIC16C5X sleep current keeps the remote's coin-cell battery alive for years. The 18-SOIC is small enough for a thin remote housing.
Recommended
Sensor Signal-Conditioning Front-Ends
Industrial sensor transmitters (4-20 mA loops, RTD/thermocouple cold-junction compensators, thermistor linearizers) embed the PIC16C56T-XTI/SO to perform lookup-table conversion, linearization, and HART-style modulation. The 4 MHz core runs a 10-bit sigma-delta conversion on a multiplexed analog input with no external ADC, and the 25-byte RAM holds a moving-average filter. Industrial temperature grade matches the sensor head environment. The Watchdog Timer recovers from sensor-line brown-out events.
Recommended
White-Goods Motor Control
Washing-machine drain pumps, refrigerator compressor inverters, and dishwasher circulation pumps use the PIC16C56T-XTI/SO as a secondary supervisory controller. Its 12-bit instruction word executes zero-crossing triac firing and tachometer-capture logic in real time, offloading these tasks from the main VFD controller. The 18-SOIC package solders to a secondary logic board adjacent to the power stage, and the industrial temperature grade survives under-cabinet heat. OTP memory locks the safety interlock code against unauthorized drive-parameter tampering.
Recommended
Automotive Under-Hood Sub-Assemblies
Non-safety automotive sub-assemblies such as seat heaters, mirror controllers, and HVAC damper actuators use industrial-temperature PIC16C56T-XTI/SO parts in non-AEC-Q100 applications. The -40C to +85C temperature grade handles under-dash environments (true under-hood applications require AEC-Q100 grade which the PIC16C56 family does not carry). The 4 MHz XT oscillator is stable against vibration better than internal-RC alternatives in this segment. 18-SOIC wide-body package suits through-hole-reflow secondary boards.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56T-XTI/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C57-XTI/SO | PIC16C56-HSI/SO | PIC16C56-XTI/SO | PIC16C56T-RCI/SO | PIC16C55-XTI/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-SOIC (7.50 mm) | 18-SOIC (7.50 mm) - same | 18-SOIC (7.50 mm) - same | 18-SOIC (7.50 mm) - same | 18-SOIC (7.50 mm) - same | 18-SOIC (7.50 mm) - same |
| Program Memory | 1.5 KB (1K x 12) OTP | 3 KB (2K x 12) OTP | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 0.75 KB (512 x 12) OTP |
| RAM Size | 25 x 8 bytes | 72 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes | 24 x 8 bytes |
| Max CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Oscillator Mode | XT (external crystal 4 MHz) | XT | HS (internal high-speed option) | XT | RC (external resistor-capacitor) | XT |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) |
| Pin Count | 18 | 18 | 18 | 18 | 18 | 18 |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
| Memory Type | OTP (One-Time-Programmable) | OTP | OTP | OTP | OTP | OTP |
Key Differentiators
- Industrial temperature grade as standard (vs PIC16C56-XT/SO (commercial 0C to +70C))
- Tape-and-reel packaging for SMT production (vs PIC16C56-XTI/SO (tube packaging))
- Same die as PIC16C57 with double program memory (vs PIC16C55-XTI/SO)
Design Notes
Estimated: The PIC16C56T-XTI/SO draws approximately 2-5 mA active current at 4 MHz and 5 V Vdd, and a few microamps in sleep mode (WDT disabled). A 100 nF decoupling capacitor must be placed within 5 mm of the VDD pin, with a 10 uF bulk capacitor on the same node. For battery-powered remotes, switch the device to sleep between tasks and gate the XT oscillator with the SLEEP instruction to reduce quiescent current below 1 uA. The MCLR pin requires a 10 kohm pull-up to VDD and a 100 nF cap to ground to filter noise; do not leave MCLR floating.
The 18-SOIC wide-body package has 1.27 mm pitch. Route all I/O traces on inner layers to keep the top layer free for the SOIC pad and decoupling caps. Place the XT-mode 4 MHz crystal within 5 mm of pins 15-16 (OSC1/OSC2) with grounded guard traces around the crystal body to reduce EMI. The MCLR pull-up and decoupling cap should sit on the same side of the package as their pins. Avoid routing high-frequency traces (relay coils, triac outputs) directly under the SOIC body or under the crystal - this couples switching noise into the oscillator.
Three common pitfalls when designing with PIC16C56T-XTI/SO: (1) The OTP memory cannot be rewritten - a single programming error bricks the device. Always program and verify on a programmer before final PCB solder, or use the PIC16C56/JW windowed ceramic sample for firmware development; (2) The PIC16C5X instruction set differs from the PIC16F1xxx flash family - firmware is not directly portable; configuration bits (oscillator, WDT, code protect) must be explicitly set in the source code; (3) I/O port A pins default to analog input mode on reset - clear the ADCON register if you intend to use them as digital I/O. Failure to do so yields high-impedance inputs that read as random values.
The PIC16C56T-XTI/SO has no internal Schmitt triggers on port B - external slow edges can cause metastability on INT or button inputs. Add a 100 ns RC filter or an external Schmitt trigger (e.g., 74HC14) on any input trace longer than 50 mm. The MCLR input is sensitive to voltage transients below 0.2 Vdd; in noisy motor-drive environments add a 100 nF cap directly to the MCLR pin and a series resistor (1 kohm) for additional protection. The OSC1 input has roughly 5 pF of parasitic capacitance - keep the load capacitors matched within 10%.
Compliance Information
The PIC16C56T-XTI/SO pre-dates widespread RoHS adoption; obsolete parts often ship from pre-RoHS stock. AEC-Q100 qualification not applicable - PIC16C5X family was never qualified for automotive safety applications. Request a RoHS-compliant variant explicitly when ordering if your end product must satisfy RoHS/REACH directives.