PIC16C57-XT/SP - 8-Bit OTP MCU, 4MHz, 28-SPDIP | Microchip
MPN: PIC16C57-XT/SP β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.5 | $6.50 |
| 10 | $5.85 | $58.50 |
| 100 | $5.1 | $510.00 |
| 500 | $4.4 | $2,200.00 |
| 1,000 | $3.75 | $3,750.00 |
PIC16C57-XT/SP Overview
Background: An OTP microcontroller is a class of MCU whose program memory is written once by a device programmer (or by the user with the appropriate programmer, e.g., Microchip MPLAB PM3) and cannot be erased thereafter. OTP parts sit in the broader hierarchy of one-time-programmable non-volatile memory -> EPROM-based program storage -> microcontroller -> embedded computing -> semiconductor. They are commonly used when code is finalized, unit cost must be minimized, and the production volume does not justify a windowed or flash-based variant. The PIC16C5X family is a classic baseline architecture - 12-bit wide instructions, 8-bit data path, a 2-level deep hardware call stack, and 33 single-word instructions - delivering efficient code density for control tasks.
Key features: 33 single-word instructions (12-bit wide), 4MHz maximum oscillator input, two-level deep hardware call stack, direct/indirect/relative addressing, an 8-bit real-time counter (TMR0), and a 4 MHz internal instruction cycle of 1us per instruction. Operating voltage is 3.0V-6.0V and the commercial temperature range is 0C to +70C. The 'XT' suffix denotes a standard crystal/resonator oscillator mode, and the /SP suffix indicates SPDIP packaging supplied in anti-static tube. Lifecycle status is NRND (Not Recommended for New Designs) - production continues for existing customers but new designs should target the flash-based PIC16F57 equivalent.
Technical depth: The PIC16C57 uses a Harvard-style RISC core with separate program and data buses, allowing instruction fetch and operand access in a single cycle. Program memory is 12 bits wide and is organized as 2K x 12 OTP, while data memory is 8 bits wide and organized into general-purpose and special-function registers. With a 4MHz oscillator the instruction cycle is 1 MHz (one instruction per microsecond). The 2-level hardware stack limits call depth - subroutines can only nest one level deep.
Typical applications: simple appliance controllers, keyboard and remote-control encoders, LED chaser and lighting effects, battery chargers, fan speed controllers, security keypads, and industrial sensor interfaces. Its 20 I/O pins and small code footprint make it ideal for cost-sensitive, high-volume embedded products where programming is done once at the factory.
Design consideration: Because the device is OTP, the firmware revision is permanent - any code bug discovered after programming requires scrapping the silicon. Use a flash-based sibling (PIC16F57) for prototype development, then convert the final binary to the OTP PIC16C57-XT/SP for production.
Drop-in alternatives for PIC16C57-XT/SP 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 PIC16C57-XT/SP (same form factor and footprint) β differing in Package, Mounting Type, Operating Temperature, Program Memory Type, Timers.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C57C-20/SP
β Drop-Inπ Reference alternative (not in catalog)
PIC16C57C-04/SP
β Drop-Inπ Reference alternative (not in catalog)
PIC16F57-I/SP
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55-XT/P
β Drop-Inβ In Stock
$4.05 / Unit
View Datasheet βPIC16C57-XT/P
β Drop-Inβ In Stock
$2.95 / Unit
View Datasheet βPIC16C57-XT/SP Maximum Ratings & Electrical Characteristics
| Core | PIC16 (8-bit RISC, 12-bit instruction word) |
| Program Memory | 3 KB (2K x 12 OTP) |
| Data RAM | 72 bytes |
| Maximum Clock Speed | 4 MHz (-XT speed grade) |
| Instruction Cycle | 1 us @ 4 MHz (4:1 clock-to-instruction ratio) |
| Instruction Set Size | 33 single-word instructions |
| Stack Depth | 2 levels (hardware) |
| Digital I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Program Memory Type | OTP EPROM (one-time programmable) |
| Operating Voltage | 3.0 V to 6.0 V |
| Operating Temperature | 0 C to +70 C (commercial) |
| Package | 28-SPDIP (Skinny Plastic DIP, 7.62 mm / 0.300 in row spacing) |
| Mounting Type | Through-Hole |
| Lead-Free / RoHS | Lead-free (per Microchip product page) |
PIC16C57-XT/SP Pin Configuration
| Pin 1 | RA2 β Port A bit 2 (bidirectional I/O) |
| Pin 2 | RA3 β Port A bit 3 (bidirectional I/O) |
| Pin 3 | T0CKI β Timer0 external clock input / RA4 |
| Pin 4 | /MCLR β Master Clear (reset, active low) |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0 β Port B bit 0 (bidirectional I/O) |
| Pin 7 | RB1 β Port B bit 1 (bidirectional I/O) |
| Pin 8 | RB2 β Port B bit 2 (bidirectional I/O) |
| Pin 9 | RB3 β Port B bit 3 (bidirectional I/O) |
| Pin 10 | RB4 β Port B bit 4 (bidirectional I/O) |
| Pin 11 | RB5 β Port B bit 5 (bidirectional I/O) |
| Pin 12 | RB6 β Port B bit 6 (bidirectional I/O) |
| Pin 13 | RB7 β Port B bit 7 (bidirectional I/O) |
| Pin 14 | VSS β Ground reference |
| Pin 15 | RC0 β Port C bit 0 (bidirectional I/O) |
| Pin 16 | RC1 β Port C bit 1 (bidirectional I/O) |
| Pin 17 | RC2 β Port C bit 2 (bidirectional I/O) |
| Pin 18 | RC3 β Port C bit 3 (bidirectional I/O) |
| Pin 19 | RC4 β Port C bit 4 (bidirectional I/O) |
| Pin 20 | RC5 β Port C bit 5 (bidirectional I/O) |
| Pin 21 | RC6 β Port C bit 6 (bidirectional I/O) |
| Pin 22 | RC7 β Port C bit 7 (bidirectional I/O) |
| Pin 23 | VSS β Ground reference |
| Pin 24 | RA0 β Port A bit 0 (bidirectional I/O) |
| Pin 25 | RA1 β Port A bit 1 (bidirectional I/O) |
| Pin 26 | OSC2 β Oscillator output (crystal/resonator) |
| Pin 27 | OSC1 β Oscillator input (crystal/resonator) |
| Pin 28 | VDD β Positive supply (3.0 V to 6.0 V) |
Typical Applications
PIC16C57-XT/SP is suitable for 6 applications: Appliance Control Boards, Remote Control and IR Encoder, LED Chaser and Decorative Lighting, Industrial Sensor Interface Module, Security Keypad and Access Controller, Battery Charger and Power Management Controller.
Appliance Control Boards
The PIC16C57-XT/SP is well matched to appliance control boards (washing machines, microwave ovens, dishwashers) because of its 3KB OTP program memory, 20 I/O pins for keypads, relays and seven-segment displays, and low unit cost. The -XT grade's 4 MHz oscillator is sufficient for time-based sequencing, sensor polling, and LED/multiplexed display driving at typical appliance response times. Unlike a flash MCU, the OTP memory is programmed once at the factory, eliminating field firmware corruption and reducing per-unit cost in high-volume production. The 1 us instruction cycle comfortably handles relay de-bounce loops, EEPROM emulation through external I/O, and user-interface button scanning. The 3.0-6.0 V supply range allows direct operation from a rectified 5 V transformer rail without additional regulation.
Recommended
Remote Control and IR Encoder
The PIC16C57-XT/SP is a classic choice for IR remote-control transmitters and simple RF key-fob encoders because its 3KB OTP is large enough to hold custom protocol tables while the 20 I/O lines easily accommodate a 4x4 keypad matrix, status LEDs, and the IR LED driver output. The 8-bit Timer0 generates the 38-56 kHz carrier frequency directly, and the 1 us instruction cycle produces the precise sub-millisecond pulse widths demanded by NEC, RC5, and Sony SIRC protocols. The 3.0-6.0 V supply matches a single CR2032 or two AAA cells via a simple boost. OTP memory prevents field tampering with the encoded IDs, a security advantage for fixed-code garage-door openers and consumer remote controls.
Recommended
LED Chaser and Decorative Lighting
The PIC16C57-XT/SP is a strong fit for LED chasers, Christmas light controllers, and decorative lighting drivers because its 20 I/O pins can directly drive up to 20 LED channels (with simple transistor or ULN2803 buffering for high-current LEDs) while the 3KB OTP holds complex chase patterns, fade tables, and timing sequences. The 4 MHz clock and 1 us instruction cycle enable smooth PWM-free sequenced on/off transitions, and the 8-bit Timer0 provides the heartbeat for multi-pattern switching. OTP memory makes the design immune to brown-out-induced firmware glitches, important for unattended decorative installations. The 0C-70C commercial range covers indoor and sheltered outdoor lighting, and the 28-SPDIP package is easy to hand-solder for small-batch custom lighting projects.
Recommended
Industrial Sensor Interface Module
The PIC16C57-XT/SP fits industrial sensor interface modules (limit-switch aggregators, simple PLC front-ends, encoder readers) because its 20 I/O lines accept many parallel contact inputs, the 3KB OTP holds debounce and event-counting logic, and the 1 us instruction cycle is fast enough for 10 kHz quadrature decoding through polled GPIO. The 3.0-6.0 V supply operates directly from a 5 V regulated rail, and the 0C-70C range covers most factory-floor cabinets. OTP memory prevents on-site firmware tampering, an important feature for safety-rated sensor conditioning modules. The 8-bit Timer0 also doubles as a watchdog-equivalent timebase for periodic sensor scans, and the 28-SPDIP package is easy to replace in the field on legacy equipment.
Recommended
Security Keypad and Access Controller
The PIC16C57-XT/SP is a strong fit for security keypads, access controllers, and simple alarm panels because its 20 I/O pins scan a 4x4 or larger matrix keypad, drive status LEDs, and trigger relays or buzzers, while the 3KB OTP stores PIN tables, access codes, and event-log summaries. The 4 MHz clock provides sub-millisecond keypad debounce and lockout timing; the 8-bit Timer0 schedules periodic arm/disarm checks. OTP memory prevents reverse-engineering of stored codes - a real security advantage compared with flash MCUs that can be probed and dumped. The 0C-70C range covers most indoor access-control environments, and the 28-SPDIP package is easy to integrate with legacy through-hole security hardware still in service.
Recommended
Battery Charger and Power Management Controller
The PIC16C57-XT/SP fits low-cost NiCd/NiMH/Li-ion charger controllers and simple DC-DC supervisor boards because its 20 I/O pins monitor battery voltage (via resistor divider to GPIO), temperature thermistor, charge current shunt, and drive MOSFET gate signals. The 3KB OTP holds CC/CV charge profiles, termination algorithms, and fault-recovery routines; the 1 us instruction cycle is fast enough for PWM-free bang-bang control at typical charger switching rates. The 3.0-6.0 V operating voltage is compatible with single-cell Li-ion and 6 V SLA battery stacks. OTP memory prevents accidental firmware loss in brown-out events, critical for unattended charger products. The 28-SPDIP package is convenient for hand-prototyped low-volume power designs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C57-XT/SP β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C57C-20/SP | PIC16C57C-04/SP | PIC16F57-I/SP | PIC16C55-XT/P | PIC16C57-XT/P |
|---|---|---|---|---|---|---|
| Package | 28-SPDIP | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same | 28-PDIP - different body width | 28-PDIP - different body width |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | PIC16 8-bit RISC, 12-bit instruction | PIC16 8-bit RISC, 12-bit instruction | PIC16 8-bit RISC, 12-bit instruction | PIC16 8-bit RISC, 12-bit instruction | PIC16 8-bit RISC, 12-bit instruction | PIC16 8-bit RISC, 12-bit instruction |
| Program Memory | 3 KB OTP (2K x 12) | 3 KB OTP | 3 KB OTP | 3 KB flash (reprogrammable) | 768 B OTP (smaller) | 3 KB OTP |
| Maximum Clock | 4 MHz | 20 MHz | 4 MHz | 20 MHz | 4 MHz | 4 MHz |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Program Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | Flash | OTP EPROM | OTP EPROM |
| Lifecycle Status | NRND | Production (active or NRND per Microchip) | Production (active or NRND per Microchip) | Active (recommended modern replacement) | Production (active or NRND per Microchip) | Production (active or NRND per Microchip) |
| Operating Voltage | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 2.0 V to 5.5 V | 3.0 V to 6.0 V | 3.0 V to 6.0 V |
Key Differentiators
- Genuine 4 MHz OTP silicon for the lowest-cost high-volume production (vs PIC16F57-I/SP)
- 5x faster clock headroom on same-package C-revision drop-in (vs PIC16C57C-20/SP)
- Skinny 28-SPDIP body enables high-density through-hole designs (vs PIC16C57-XT/P (28-PDIP))
Design Notes
The PIC16C57's OTP program memory cannot be erased - any firmware bug discovered after programming bricks the part permanently and requires scrapping the silicon. The Microchip-recommended workflow is to develop and debug on the flash-based PIC16F57 (same pinout, same instruction set, 20 MHz) and only commit to the OTP C57 once the firmware is fully frozen. Estimated: This typically costs 2-3 prototype spins of flash parts versus scrapping a full OTP production run.
The 28-SPDIP package has 0.300 in (7.62 mm) row spacing, narrower than the 0.600 in standard DIP used by the PIC16C57-XT/P (PDIP). Verify the PCB land pattern matches SPDIP (not PDIP) before ordering; mixing them will leave a 0.300 in mechanical offset. Place a 100 nF decoupling capacitor between VDD (pin 28) and the nearest VSS (pin 27) within 5 mm of the IC, and tie /MCLR (pin 4) high through a 10 kohm resistor to VDD for normal operation.
The PIC16C57's 2-level hardware call stack limits subroutine nesting to depth 1. Any routine that calls another routine that calls another will return to the wrong address. Engineers migrating from PIC16F1xx or PIC18 parts must refactor deeply nested code into iterative (state-machine) form. The instruction set is 12-bit, also different from the 14-bit PIC16F1xx instruction set; hex files are not portable between the PIC16C5X and PIC16F1xx families. Source: Microchip PIC16C5X family datasheet.
The PIC16C57's supply range is 3.0 V to 6.0 V, NOT 2.0 V to 5.5 V like the modern PIC16F57. Do not attempt to power the -XT/SP from a single 1.5 V cell or a 1.8 V regulator - the part will not start reliably below 3.0 V. The 4 MHz 'XT' oscillator mode requires a crystal or ceramic resonator with at least 200 ohm ESR; low-ESR crystals (below 20 ohm) will not oscillate. Add a 1 Mohm parallel resistor across OSC1/OSC2 if start-up is marginal with very high-frequency crystals.
Compliance Information
Lead-free and RoHS-compliant per Microchip product page. AEC-Q100 not applicable (this is a commercial-grade MCU). Halogen-free status not explicitly confirmed in the provided data.
