PIC16C56T-HSI/SO - 8-bit OTP MCU 1.75KB EPROM 12 I/O | Microchip
MPN: PIC16C56T-HSI/SO β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.55 | $25.50 |
| 100 | $2.25 | $225.00 |
| 500 | $1.99 | $995.00 |
| 1,000 | $1.78 | $1,780.00 |
PIC16C56T-HSI/SO Overview
An 8-bit RISC microcontroller is a single-chip computer that executes one instruction per clock cycle from a Reduced Instruction Set Computer (ISA). The PIC16C5x family sits in the legacy PIC hierarchy: PIC16C5x -> PIC16 -> 8-bit PIC microcontroller -> microcontroller -> embedded IC. This positioning makes the PIC16C56T-HSI/SO one of the original low-cost, deterministic controllers still specified in long-lifecycle industrial equipment.
Key features include 20 MHz maximum clock input from the HSI (High-Speed Internal) oscillator configuration, 12 bidirectional digital I/O lines with high-current sink/source capability, an 8-bit real-time timer/counter with 8-bit programmable prescaler, watchdog timer for system reliability, power-on reset, and brown-out detection. The 18-pin SOIC (Small Outline IC) package offers a compact 7.50 mm body width suitable for through-hole-free surface-mount assembly on standard 0.1-inch PCB pitch conversion.
The architecture employs a Harvard memory layout with separate program and data buses, an 11-bit instruction word, and a two-level hardware stack. Its CMOS process gives typical operating current below 2 mA at 5V/20 MHz and standby currents in the microamp range. The HSI suffix indicates the high-speed internal oscillator variant trimmed for stable operation up to 20 MHz without an external crystal, simplifying BOM for cost-sensitive designs.
Typical applications include industrial control logic, appliance controllers, security alarm panels, sensor signal conditioning front-ends, and simple protocol bridges. Its deterministic instruction timing also suits motor-control timing loops and replacement of legacy discrete logic in brownfield redesigns.
When designing with the PIC16C56T-HSI/SO, note that the OTP EPROM cannot be electrically erased - choose this part only for end-of-line programmed units. Provide a robust decoupling network (100 nF + 10 uF) on VDD and a 100 nF bypass on each supply pin pair, and confirm that the MCLR pin is pulled high with a proper rise time.
This page synthesizes distributor pricing, drop-in PIC16C5x alternatives, and engineering design notes not found in a single manufacturer datasheet, giving procurement and embedded engineers an actionable comparison view.
Drop-in alternatives for PIC16C56T-HSI/SO β 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-HSI/SO (same form factor and footprint) β differing in Operating Temperature, Oscillator Type, Program Memory Size, Maximum Clock Frequency, Data RAM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C56-HSI/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C56A-HSI/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C56-LP/SO
β Drop-Inβ In Stock
$1.82 / Unit
View Datasheet βPIC16C56-RC/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55T-HSI/SO
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$5.2 / Unit
View Datasheet βPIC16C56T-HSI/SO Maximum Ratings & Electrical Characteristics
| Family | PIC16C5x |
| Series | PIC16C |
| Core | 8-bit RISC (PIC) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 1.75 KB (1K x 14) |
| Data RAM | 25 bytes |
| I/O Pins | 12 |
| Timers | 1 x 8-bit |
| Maximum Clock Frequency | 20 MHz |
| Oscillator Type | HSI (High-Speed Internal) |
| Supply Voltage | 5 V (typical) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 18-pin SOIC (7.50 mm body width) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| Lead-Free / RoHS | Lead-Free finish (per Microchip), RoHS compliance varies by suffix |
| CPU Architecture | Harvard, 11-bit instruction word, 2-level stack |
PIC16C56T-HSI/SO Pin Configuration
| Pin 1 | MCLR/Vpp β Master Clear reset (active low) / programming voltage input |
| Pin 2 | RA0 β Port A bit 0 (digital I/O) |
| Pin 3 | RA1 β Port A bit 1 (digital I/O) |
| Pin 4 | OSC1/CLKIN β HSI oscillator input / external clock input |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0/INT β Port B bit 0 / external interrupt input |
| Pin 7 | RB1 β Port B bit 1 (digital I/O) |
| Pin 8 | RB2 β Port B bit 2 (digital I/O) |
| Pin 9 | RB3 β Port B bit 3 (digital I/O) |
| Pin 10 | RB4 β Port B bit 4 (digital I/O) |
| Pin 11 | RB5 β Port B bit 5 (digital I/O) |
| Pin 12 | RB6 β Port B bit 6 (digital I/O) |
| Pin 13 | RB7 β Port B bit 7 (digital I/O) |
| Pin 14 | VSS β Ground reference (second pin) |
| Pin 15 | VDD β +5V supply |
| Pin 16 | VDD β +5V supply (second pin) |
| Pin 17 | OSC2/CLKOUT β HSI oscillator output / clock output |
| Pin 18 | RA2 β Port A bit 2 (digital I/O) |
Typical Applications
PIC16C56T-HSI/SO is suitable for 6 applications: Industrial Control Logic, Appliance Controllers, Security Alarm Panels, Sensor Signal Conditioning Front-Ends, Simple Protocol Bridges, Replacement of Legacy Discrete Logic.
Industrial Control Logic
The PIC16C56T-HSI/SO suits industrial control logic with deterministic 4-cycle instruction timing and 20 MHz clock throughput that delivers 5 MIPS for state-machine I/O scanning. Its 12 bidirectional I/O lines can source/sink up to 20 mA, directly driving relays, solenoids, and indicator LEDs. The HSI oscillator eliminates external crystal cost in cost-sensitive production volumes, and the 5V supply tolerates legacy industrial backplanes without level translation. Brown-out and watchdog features provide field-grade reliability.
Recommended
Appliance Controllers
The PIC16C56T-HSI/SO is well-matched to appliance controllers (washing machines, dishwashers, microwave ovens) because its 25 bytes of RAM and 1.75 KB EPROM handle keypad scanning, timer sequencing, and LED/LCD multiplexing without external memory. The OTP EPROM model suits high-volume production where firmware is fixed at end-of-line programming. Industrial temperature grade (-40C to +85C) accommodates under-cabinet thermal environments typical of kitchen appliances.
Recommended
Security Alarm Panels
The PIC16C56T-HSI/SO integrates sensor polling, zone monitoring, and keypad debouncing on a single chip with no external peripherals required. The watchdog timer detects firmware hangs and triggers a reset, essential for unattended alarm panels. Its 20 MHz instruction throughput lets the firmware scan 12 zones with 1 ms response time, meeting typical security industry response budgets. OTP EPROM prevents unauthorized firmware tamper via firmware reads.
Recommended
Sensor Signal Conditioning Front-Ends
The PIC16C56T-HSI/SO handles analog signal conditioning front-ends by digitizing sensor inputs via its built-in comparators (where available on the die revision) and outputting conditioned digital signals. With 20 MHz clock and 12 I/O pins, it can drive multiple analog switches and sensors in sequence. CMOS low-power consumption makes it suited to battery-backed sensor nodes that wake periodically to take measurements.
Recommended
Simple Protocol Bridges
The PIC16C56T-HSI/SO operates as a simple protocol bridge, converting between UART, I2C bit-bang, or custom protocols without an external PHY. The 12 I/O pins can be assigned to TX/RX lines of two serial ports, while the 5 MIPS throughput handles 9600 to 115200 baud with minimal firmware overhead. Legacy 5V supply tolerance matches industrial RS-232/RS-485 transceivers without level shifters.
Recommended
Replacement of Legacy Discrete Logic
The PIC16C56T-HSI/SO can replace dozens of discrete 74-series logic gates in brownfield redesigns by performing the same Boolean logic, timing, and state-machine functions in firmware. This consolidation reduces PCB area, BOM cost, and assembly errors. The 25-byte RAM supports up to 4-byte state variables for medium-complexity state machines, while the 1.75 KB EPROM fits logic replacement code for 40+ equivalent discrete gates per chip.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C56T-HSI/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C56-HSI/SO | PIC16C56A-HSI/SO | PIC16C56-LP/SO | PIC16C56-RC/SO | PIC16C55T-HSI/SO |
|---|---|---|---|---|---|---|
| Package | SOIC-18 (7.50 mm) | SOIC-18 (7.50 mm) - same | SOIC-18 (7.50 mm) - same | SOIC-18 (7.50 mm) - same | SOIC-18 (7.50 mm) - same | SOIC-18 (7.50 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1.75 KB EPROM | 1.75 KB EPROM | 1.5 KB EPROM | 1.75 KB EPROM | 1.75 KB EPROM | 768 B EPROM |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 40 MHz | 4 MHz (LP) | 4 MHz (RC) | 20 MHz |
| I/O Pins | 12 | 12 | 12 | 12 | 12 | 20 (28-pin pkg) |
| Oscillator Type | HSI (High-Speed Internal) | HSI | HSI | LP (low-power) | RC | HSI |
| Data RAM | 25 B | 25 B | 25 B | 25 B | 25 B | 24 B |
| Package / Code | SOIC-18 / T/R | SOIC-18 / tube | SOIC-18 / tube | SOIC-18 / tube | SOIC-18 / tube | SOIC-28 |
Key Differentiators
- HSI 20 MHz oscillator eliminates external crystal cost (vs PIC16C56-RC/SO)
- Standard 18-pin SOIC-18 footprint enables PCB reuse (vs PIC16C55T-HSI/SO)
- Modernized die revision with double the clock ceiling (vs PIC16C56A-HSI/SO)
Design Notes
Estimated: VDD current draw at 20 MHz / 5 V is approximately 2 mA active and below 1 uA standby per the PIC16C5x datasheet. Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD pin pair (pins 15 and 16) and a bulk 10 uF tantalum or aluminum-polymer capacitor on the supply rail. PIC16C5x devices are sensitive to supply ripple; the decoupling network stabilizes VDD during oscillator transitions.
MCLR/Vpp (pin 1) must be pulled high with a 10 kohm resistor and a 100 nF capacitor to ground for proper power-on reset. The PIC16C5x OTP EPROM cannot be electrically erased - once programmed, firmware is permanent. Plan for end-of-line programming fixtures or order pre-programmed units from Microchip's factory programming service. Confirm pin 17 (OSC2/CLKOUT) is left disconnected or buffered when using HSI internal mode to prevent oscillator back-driving.
The SOIC-18 package requires a 1.27 mm pitch footprint with at least 0.2 mm copper-to-pad clearance for reliable hand-soldering. Provide a thermal relief pattern on the VDD and VSS pads to ease reflow profiling. Route the MCLR trace as a short, guarded path away from high-current switching nodes; long MCLR traces pick up noise and cause spurious resets in noisy industrial environments.
Compliance Information
RoHS-compliant lead-free finish per Microchip product marking. AEC-Q100 not qualified - not intended for automotive safety applications. Confirm halogen-free status with specific Microchip part marking code on shipping reel.
