PIC16C57T-XT/SO - 8-Bit 4MHz OTP MCU, 3KB | Microchip
MPN: PIC16C57T-XT/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.85 | $5.85 |
| 10 | $5.27 | $52.70 |
| 100 | $4.69 | $469.00 |
| 500 | $4.21 | $2,105.00 |
| 1,000 | $3.75 | $3,750.00 |
PIC16C57T-XT/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, data memory, and programmable I/O peripherals. The PIC16C5X family uses a 12-bit wide instruction word with Harvard architecture (separate program and data buses), achieving roughly 2:1 code compression over typical 8-bit microcontrollers in its class. Within the broader taxonomy, the PIC16C57 belongs to the OTP-microcontroller segment of the 8-bit MCU category, sitting between mask-ROM and Flash-based parts on the cost/flexibility curve.
Key differentiating features include the 4 MHz top operating frequency from an XT (crystal/ceramic resonator) oscillator, 20 I/O pins with individual direction control, a watchdog timer, a power-on reset circuit, and a programmable code-protection mechanism. The OTP program memory allows prototype-to-production migration without tooling charges that mask ROM parts require, while the 28-pin SOIC footprint is compatible with standard SMT assembly lines.
The PIC16C57T-XT/SO uses a RISC-like instruction set of 33 single-word/cycle instructions, an 8-bit ALU with internal accumulator, and a 2-level hardware stack. Peripherals include Timer0 (8-bit with prescaler), real-time clock/counter mode, and direct/indirect addressing modes for accessing the 72-byte data RAM.
Typical applications include appliance control, HVAC thermostat logic, simple sensor interfaces, automotive body controllers (non-safety), and legacy industrial automation. Designers choose this part when low unit cost, deterministic instruction timing, and a small footprint outweigh the need for in-system reprogrammability.
When designing with this device, ensure the XT-mode crystal or resonator value falls within the 4 MHz maximum and verify timing budget margins across the full -40 °C to +70 °C commercial operating range. OTP parts cannot be reprogrammed after encapsulation, so use a windowed/EPROM variant for prototyping.
This page synthesizes distributor pricing, drop-in same-package alternatives (including PIC16C57T family members from Microchip), and practical design considerations not consolidated in a single manufacturer datasheet view.
Drop-in alternatives for PIC16C57T-XT/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 PIC16C57T-XT/SO (same form factor and footprint) — differing in Package, Timers, Maximum Clock Frequency, Instruction Set, Oscillator Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C57T-10I/SO
✅ Drop-In✓ In Stock
$1.92 / Unit
View Datasheet →PIC16C57T-RCI/SS
✅ Drop-In✓ In Stock
$1.7 / Unit
View Datasheet →PIC16C57T-RCE/SS
✅ Drop-In✓ In Stock
$4.15 / Unit
View Datasheet →PIC16C57-RCI/SS
✅ Drop-In✓ In Stock
$3.5 / Unit
View Datasheet →PIC16F57-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C57T-XT/SO Maximum Ratings & Electrical Characteristics
| Core | 8-bit PIC |
| Series | PIC® 16C |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 3 KB (2K x 12) |
| RAM | 72 bytes |
| Data EEPROM | None |
| Maximum Clock Frequency | 4 MHz |
| Oscillator Type | XT (external crystal/resonator) |
| Supply Voltage | 5 V nominal |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (Timer0 with prescaler) |
| Instruction Set | 33 single-word/cycle instructions (12-bit wide) |
| Stack | 2-level hardware |
| Package | 28-SOIC (7.50 mm body width) |
| Mounting Type | Surface Mount |
PIC16C57T-XT/SO Pin Configuration
| Pin 1 | RA2 — PORTA bit 2 (bidirectional I/O) |
| Pin 2 | RA3 — PORTA bit 3 (bidirectional I/O) |
| Pin 3 | RA0 — PORTA bit 0 (bidirectional I/O) |
| Pin 4 | RA1 — PORTA bit 1 (bidirectional I/O) |
| Pin 5 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 6 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 7 | VSS — Ground reference |
| Pin 8 | RC0 — PORTC bit 0 (bidirectional I/O) |
| Pin 9 | RC1 — PORTC bit 1 (bidirectional I/O) |
| Pin 10 | RC2 — PORTC bit 2 (bidirectional I/O) |
| Pin 11 | RC3 — PORTC bit 3 (bidirectional I/O) |
| Pin 12 | RC4 — PORTC bit 4 (bidirectional I/O) |
| Pin 13 | RC5 — PORTC bit 5 (bidirectional I/O) |
| Pin 14 | RC6 — PORTC bit 6 (bidirectional I/O) |
| Pin 15 | RC7 — PORTC bit 7 (bidirectional I/O) |
| Pin 16 | VSS — Ground reference |
| Pin 17 | VDD — Positive supply (5 V nominal) |
| Pin 18 | RB0 — PORTB bit 0 (bidirectional I/O) |
| Pin 19 | RB1 — PORTB bit 1 (bidirectional I/O) |
| Pin 20 | RB2 — PORTB bit 2 (bidirectional I/O) |
| Pin 21 | RB3 — PORTB bit 3 (bidirectional I/O) |
| Pin 22 | RB4 — PORTB bit 4 (bidirectional I/O) |
| Pin 23 | RB5 — PORTB bit 5 (bidirectional I/O) |
| Pin 24 | RB6 — PORTB bit 6 (bidirectional I/O) |
| Pin 25 | RB7 — PORTB bit 7 (bidirectional I/O) |
| Pin 26 | T0CKI — Timer0 external clock input |
| Pin 27 | VDD — Positive supply (5 V nominal) |
| Pin 28 | MCLR/Vpp — Master clear reset / programming voltage input |
Typical Applications
PIC16C57T-XT/SO is suitable for 6 applications: Appliance Control (Washing Machine / Dishwasher), HVAC Thermostat Logic Controller, Automotive Body Controller (Non-Safety), Simple Sensor Interface Module, Vending Machine Coin Mechanism Controller, Industrial Timer / Counter Module.
Appliance Control (Washing Machine / Dishwasher)
The PIC16C57T-XT/SO fits appliance control boards thanks to its 20 I/O pins (enough to drive relays, status LEDs, push-buttons, and a 7-segment display), 4 MHz XT oscillator (sufficient for relay debouncing and timing sequences), and 3 KB OTP (enough for state-machine firmware). Its Harvard 12-bit core executes 1 µs per instruction at 4 MHz, giving deterministic timing for safety interlocks. The 28-SOIC package is compatible with high-volume SMT lines used in white goods. Compared to a Flash MCU, OTP prevents accidental firmware tampering after production.
Recommended
HVAC Thermostat Logic Controller
The PIC16C57T-XT/SO serves as a thermostat logic MCU thanks to its low unit cost, deterministic 4 MHz instruction timing for temperature sampling loops, and 20 I/O pins for keypad/display multiplexing. The 72-byte RAM supports a small setpoint buffer and hysteresis state, while the 8-bit Timer0 with prescaler generates the ADC-free temperature-to-time conversion (via thermistor RC charge timing). The 28-SOIC package tolerates the -10 °C to +60 °C range typical of indoor thermostats. Pairing with a 24LC02 serial EEPROM stores user schedules without expanding part count.
Recommended
Automotive Body Controller (Non-Safety)
The PIC16C57T-XT/SO is used in non-safety automotive body modules (window lifters, mirror adjusters, seat controllers) where its 5 V supply, 28-SOIC surface-mount footprint, and OTP memory protect against post-production firmware tampering. The 20 I/O pins drive H-bridge enable signals and read limit-switch inputs; the 4 MHz clock gives 250 ns per instruction cycle for fast PWM-free control loops. The automotive-grade variant PIC16C57T-10I/SO extends temperature to -40 °C to +85 °C for under-dash mounting. Cost per node is the primary selection driver versus Flash MCUs.
Recommended
Simple Sensor Interface Module
The PIC16C57T-XT/SO acts as a low-cost sensor hub (4-20 mA loop read, thermistor linearization, pulse counting) thanks to its 8-bit ALU, 20 I/O pins (configurable digital or analog comparator), and 4 MHz throughput for 100 Hz update rates. The 72-byte RAM buffers a few sensor readings before UART transmission. The 28-SOIC footprint fits standard 1-inch square sensor PCBAs. Engineers choose OTP over Flash to lock the calibration coefficients at production, preventing field-recalibration.
Recommended
Vending Machine Coin Mechanism Controller
The PIC16C57T-XT/SO controls coin acceptors and bill validators in vending machines, leveraging 3 KB OTP for the coin-discrimination state machine, 20 I/O for sensor inputs and dispenser relay control, and 4 MHz deterministic timing to debounce coin-pulse trains at 100 Hz. The 28-SOIC package survives the +5 °C to +50 °C indoor vending environment. OTP memory prevents field piracy of the coin-acceptance algorithm. The 2-level hardware stack is sufficient because the firmware is structured as a flat state machine.
Recommended
Industrial Timer / Counter Module
The PIC16C57T-XT/SO is well suited for DIN-rail-mountable industrial timers (cycle counters, delay-on-make relays, totalizers) due to its low cost, OTP code protection for OEM timing algorithms, and 8-bit Timer0 hardware counter that can be cascaded with external pulse sources. The 20 I/O pins handle start/stop inputs, mode selection switches, and relay coil drivers. The 4 MHz XT oscillator provides 1 µs resolution for sub-millisecond timing via prescaler. The 28-SOIC surface-mount package supports conformal-coated PCBAs for harsh industrial environments.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C57T-XT/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C57T-10I/SO | PIC16C57T-RCI/SS | PIC16C57T-RCE/SS | PIC16C57-RCI/SS | PIC16F57-I/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC | 28-SSOP | 28-SSOP | 28-SSOP | 28-SOIC |
| Program Memory | 3 KB OTP | 3 KB OTP | 3 KB OTP | 3 KB OTP | 3 KB OTP | 2 KB Flash |
| Max Clock Frequency | 4 MHz | 10 MHz | 4 MHz (RC) | 4 MHz (RC) | 4 MHz (RC) | 20 MHz |
| Oscillator Type | XT (crystal) | XT (crystal) | RC | RC | RC | XT (crystal) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Active |
| Pin Count | 28 | 28 | 28 | 28 | 28 | 28 |
Key Differentiators
- Same 28-SOIC footprint with higher 10 MHz grade for faster timing budgets (vs PIC16C57T-10I/SO)
- Flash memory for in-system reprogrammability vs OTP (vs PIC16F57-I/SO)
- Lower-cost RC oscillator option vs XT crystal requirement (vs PIC16C57T-RCI/SS)
Design Notes
The PIC16C57T-XT/SO requires a stable 5 V ±10 % supply (4.5 V to 5.5 V) on VDD pins 17 and 27, with decoupling 100 nF ceramic placed within 5 mm of each VDD pin. The MCLR/Vpp pin (pin 28) must be pulled to VDD through a 10 kΩ resistor for normal operation; during programming, Vpp rises to 13 V. Power-on reset (POR) is internal, so no external POR circuit is required, but ensure VDD rise time is under 50 ms per datasheet section on POR timing.
Use a 4 MHz fundamental-mode AT-cut crystal across OSC1 (pin 5) and OSC2 (pin 6), with two 22 pF load capacitors to ground. For higher-noise environments, add a 1 MΩ parallel resistor to bias the oscillator. Estimated: for a 4 MHz XT crystal at 20 pF load, total load capacitance is (C1 × C2)/(C1+C2) + Cstray ≈ 12 pF with 22 pF parts, which sits inside the 10-32 pF window the Microchip datasheet specifies for XT mode. Keep oscillator traces short and surrounded by ground pour.
Do not attempt to reprogram the OTP program memory after encapsulation: the PIC16C57T-XT/SO is one-time programmable and cannot be erased. Use a windowed UV-erasable PIC16C57 (e.g., PIC16C57-10/P with ceramic window) for prototyping, then move to OTP for production. Another common pitfall is overlooking the 2-level hardware stack: nested subroutine calls deeper than two will overwrite the return address and cause erratic resets; restructure as a flat state machine or inline the calls.
PORTB pins RB0-RB7 (pins 18-25) have internal weak pull-ups enabled by clearing the RBPU bit in the OPTION register; this simplifies switch input wiring but the pull-ups are ~50-100 kΩ nominal. For noisy environments, add 1 kΩ external pull-downs or debounce via 10 ms software delays rather than relying on the weak pull-ups alone. PORTA (pins 1-4) and PORTC (pins 8-15) have Schmitt trigger inputs and TTL-compatible outputs.
Compliance Information
Compliance status was not present in the verified web data. PIC16C5X OTP family predates widespread RoHS adoption; many -XT/SO variants are non-RoHS. Verify with the manufacturer's product compliance certificate before placing in RoHS-restricted designs. PIC16F57-I/SO is the active-lifecycle alternative with full RoHS compliance.
