PIC16C781T-I/SO - 8-bit MCU 1.75KB OTP, 16 I/O, SOIC-20 | Microchip
MPN: PIC16C781T-I/SO β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.9 | $8.90 |
| 10 | $8.2 | $82.00 |
| 100 | $7.4 | $740.00 |
| 500 | $6.55 | $3,275.00 |
| 1,000 | $5.85 | $5,850.00 |
PIC16C781T-I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program and data memory, and peripheral interfaces on one die. The PIC16C781 belongs to the 8-bit mid-range PIC16 family, which sits between Microchip's baseline 8-bit cores and the enhanced 16-bit cores in Microchip's product hierarchy. Within power management and signal conditioning systems, the on-chip op-amp, DAC, and PSMC allow this MCU to implement closed-loop control of a switching supply, charge pump, or sensor excitation circuit without external analog components, which reduces board area and BOM cost.
Key features of the PIC16C781T-I/SO include 1.75KB of OTP program memory, 128 bytes of data RAM, 16 bidirectional I/O pins, an 8-bit ADC, an 8-bit DAC, an on-chip op-amp, two analog comparators, a Programmable Switch-Mode Controller (PSMC), and a synchronous serial port supporting both SPI and I2C modes. The 20-pin SOIC package is industry-standard, and the -I temperature grade supports industrial ambient operation from -40C to +85C, suitable for factory-floor equipment, instrumentation, and ruggedized embedded modules.
The PIC16C781's architecture uses a Harvard layout with a separate instruction and data bus, and its RISC instruction set is fixed at 35 single-word instructions, allowing most instructions to execute in a single instruction cycle. The on-chip PSMC is the architecturally novel peripheral: it can be configured as a current-mode or voltage-mode PWM controller with programmable dead-time and frequency, and it interfaces to the on-chip op-amp and comparators so that current/voltage feedback loops can be closed entirely inside the silicon. This makes the part attractive for switching power supplies, motor drivers, and LED drivers where an external PWM controller would otherwise be required.
Typical applications include SMPS (switched-mode power supply) primary-side control, LED driver controllers with analog dimming, sensor signal conditioning with on-chip amplification, battery charger control loops, motor speed control, and industrial instrumentation front ends. Because the program memory is OTP rather than flash, the PIC16C781T-I/SO is generally used in mature, high-volume production designs where code is finalized and field reprogramming is not required.
When designing with this part, note that OTP memory requires one-time programming in production β engineering development should use the PIC16F877 or PIC16F1936 flash equivalent, then transition to the OTP die for cost-down. Decoupling the VDD/VSS pins with 100 nF ceramics placed within 5 mm of each pin is critical, and the analog supply (AVDD/AVSS) should be filtered with a ferrite bead to preserve ADC and DAC linearity.
This page synthesizes distributor pricing as of 2026-09-19, drop-in alternatives from the same PIC16 family, and practical design notes not consolidated in the manufacturer datasheet itself.
Drop-in alternatives for PIC16C781T-I/SO β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C781-I/SO
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PIC16C781T-I/SS
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$2.78 / Unit
View Datasheet βPIC16C781-I/SS
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PIC16F1936T-I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16F506-I/SL
β Drop-Inπ Reference alternative (not in catalog)
PIC16C781T-I/SO Maximum Ratings & Electrical Characteristics
| Product Family | PIC16 mid-range 8-bit MCU |
| Core | PIC16 RISC |
| Bit Width | 8-bit |
| Program Memory | 1.75 KB OTP |
| Data RAM | 128 bytes |
| Data EEPROM | Not present |
| I/O Pins | 16 |
| Supply Voltage | 5 V nominal |
| Operating Temperature | -40C to +85C (Industrial, -I) |
| Package | 20-pin SOIC (SO), 7.5 mm body width |
| Mounting Type | Surface Mount |
| A/D Converter | 8-bit on-chip |
| D/A Converter | 8-bit on-chip |
| Operational Amplifier | 1 on-chip |
| Comparators | 2 on-chip |
| PSMC (Programmable Switch-Mode Controller) | Yes, on-chip |
| Synchronous Serial Port | SPI / I2C |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Non-compliant (legacy OTP die) |
| Lead-Free | No (legacy SnPb finish on T/R variant) |
PIC16C781T-I/SO Pin Configuration
| Pin 1 | RA2/AN2/VREF- β Digital I/O RA2 / ADC input AN2 / DAC negative reference |
| Pin 2 | RA3/AN3/VREF+ β Digital I/O RA3 / ADC input AN3 / DAC positive reference |
| Pin 3 | RA4/T0CKI/AN4 β Digital I/O RA4 / Timer0 clock input / ADC input AN4 |
| Pin 4 | RA5/AN5/SS β Digital I/O RA5 / ADC input AN5 / SPI slave select |
| Pin 5 | AVSS β Analog ground |
| Pin 6 | AVDD β Analog supply voltage (5V) |
| Pin 7 | OSC1/CLKIN β Oscillator input / external clock input |
| Pin 8 | OSC2/CLKOUT β Oscillator output / clock output |
| Pin 9 | RC0 β Digital I/O RC0 / PSMC output |
| Pin 10 | RC1 β Digital I/O RC1 / PSMC complementary output |
| Pin 11 | RC2 β Digital I/O RC2 |
| Pin 12 | RC3 β Digital I/O RC3 |
| Pin 13 | RC4 β Digital I/O RC4 |
| Pin 14 | RC5 β Digital I/O RC5 |
| Pin 15 | RC6 β Digital I/O RC6 |
| Pin 16 | RC7 β Digital I/O RC7 |
| Pin 17 | RB0/INT β Digital I/O RB0 / external interrupt |
| Pin 18 | RB1 β Digital I/O RB1 |
| Pin 19 | VSS β Digital ground |
| Pin 20 | VDD β Digital supply voltage (5V) |
Typical Applications
PIC16C781T-I/SO is suitable for 6 applications: Switched-Mode Power Supply (SMPS) Primary-Side Control, LED Driver with Analog Dimming, Industrial Sensor Signal Conditioning, Battery Charger Controller, DC Motor Speed Control, Programmable Sensor Transmitter.
Switched-Mode Power Supply (SMPS) Primary-Side Control
The PIC16C781's on-chip Programmable Switch-Mode Controller (PSMC) implements current-mode PWM with programmable dead-time and frequency, allowing the part to control the primary switch of a flyback or boost converter directly. Combined with the on-chip op-amp for current sensing and the 8-bit DAC for reference voltage generation, the MCU eliminates the external PWM controller IC and analog support components in compact isolated DC-DC modules. Typical switching frequencies of 50-200 kHz are achievable, matching the performance of dedicated UC3842-class controllers while adding firmware programmability for soft-start, UVLO thresholds, and protection curves. This integration reduces BOM count and PCB area in 5W-50W isolated SMPS designs.
Recommended
LED Driver with Analog Dimming
Using the on-chip op-amp as a transconductance stage for current sensing and the 8-bit DAC as a programmable current reference, the PIC16C781 implements a constant-current LED driver with 256-step analog dimming resolution. The PSMC generates the high-frequency PWM that modulates the switching FET, while firmware adjusts the DAC reference to dim the LED current from 0 to full-scale. This topology supports 350 mA to 1 A LED strings operating from 5V to 24V supplies with efficiency of 85-92%, eliminating the dedicated LED-driver IC. The 20-pin SOIC footprint fits into compact MR16 and linear-strip form factors.
Recommended
Industrial Sensor Signal Conditioning
The PIC16C781's combined 8-bit ADC, on-chip op-amp, and dual comparators form a complete analog front-end for industrial sensors such as thermocouples, strain gauges, RTDs, and process-current loops. The op-amp provides first-stage gain with low offset (typically <5 mV), the ADC digitizes the conditioned signal, and the comparators trigger on threshold violations for hardware-level safety interlocks. Industrial -40C to +85C operating temperature is standard on the -I/SO variant, matching factory-floor requirements. The 5V supply is compatible with 4-20 mA current-loop transmitters and bridge-excitation circuits common in process automation.
Recommended
Battery Charger Controller
The PSMC peripheral's programmable frequency and dead-time control make the PIC16C781 well-suited for switching battery chargers using buck or buck-boost topologies. The on-chip DAC programs the charge-current and charge-voltage setpoints, while the ADC monitors battery voltage and current for closed-loop regulation. Firmware implements CC/CV (constant-current / constant-voltage) charging profiles, temperature fold-back via an external thermistor through the comparator, and charge-termination detection. Charge currents up to 2-3 A from a 12V input are typical, matching lead-acid, NiMH, and single-cell Li-ion chemistries. The 1.75 KB OTP memory is sufficient for state-machine charger firmware.
Recommended
DC Motor Speed Control
The PIC16C781's PSMC generates the PWM signal for a brushed DC motor driver, with the on-chip op-amp closing the current/voltage feedback loop and the 8-bit ADC sensing back-EMF or shunt current. Firmware implements PI control with adjustable speed and torque profiles, while the dual comparators detect over-current and stall conditions for hardware-level protection. Operating voltages up to the package maximum and PWM frequencies up to 200 kHz support small brushed DC motors in appliance, robotics, and HVAC-damper applications. The 20-pin SOIC is suitable for hand-held or wall-mounted enclosures.
Recommended
Programmable Sensor Transmitter
The PIC16C781's 8-bit ADC and 8-bit DAC pair is sufficient to build a programmable 4-20 mA or 0-10 V sensor transmitter, with the on-chip op-amp providing excitation for RTD or bridge sensors. Firmware linearizes the sensor curve and scales the analog output, while the synchronous serial port (SPI/I2C) accepts calibration parameters from an external EEPROM or host microcontroller. The 20-pin SOIC and 5V supply are compatible with industry-standard transmitter modules used in process control, HVAC, and building automation. Industrial -40C to +85C temperature grade matches plant-floor deployment.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C781T-I/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C781-I/SO | PIC16C781T-I/SS | PIC16C781-I/SS | PIC16F1936T-I/SO | PIC16F506-I/SL |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | SOIC-20 (SO) | SOIC-20 (SO) - same | SSOP-20 (SS) | SSOP-20 (SS) | SOIC-20 (SO) - same | SOIC-14 (SL) |
| Program Memory | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 14 KB flash | 1.5 KB flash |
| Data RAM | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 512 bytes | 67 bytes |
| Memory Type | OTP | OTP | OTP | OTP | Flash | Flash |
| On-chip Op-Amp | Yes | Yes | Yes | Yes | No | No |
| On-chip DAC | 8-bit | 8-bit | 8-bit | 8-bit | No | No |
| PSMC (Switch-Mode Controller) | Yes | Yes | Yes | Yes | No | No |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Active | Active |
Key Differentiators
- On-chip PSMC plus op-amp plus DAC analog subsystem (vs PIC16F1936T-I/SO)
- Active production status (vs PIC16F506-I/SL)
- Drop-in compatibility within the same PIC16C781 family (vs PIC16F1936T-I/SO)
Design Notes
Decoupling the PIC16C781T-I/SO requires at minimum one 100 nF ceramic capacitor within 5 mm of each VDD/VSS pair, plus a 10 uF bulk capacitor on the board's main 5V rail. AVDD/AVSS should be filtered through a ferrite bead (e.g., BLM18PG471) to preserve ADC and DAC linearity; sharing AVDD directly with digital VDD couples switching noise into the analog peripherals and degrades ADC ENOB. Estimated: with 5V supply and the on-chip op-amp sourcing 5 mA, the total analog current draw is approximately 8 mA, so the ferrite bead should be rated for at least 30 mA saturation.
Do not assume the PIC16F1936 is pin-compatible with the PIC16C781 β although both are 20-pin SOIC, the pin assignments of the analog peripherals (op-amp pins, DAC output, PSMC outputs) differ between the two devices. Migration to PIC16F1936 requires re-validating every analog pin against the new datasheet, and firmware must be rewritten because the PSMC peripheral is not present on PIC16F1936. Additionally, OTP memory means code is committed at production β engineering development must use a flash-based PIC16F1936 or PIC16F877 first.
Keep analog traces (ADC inputs, DAC output, op-amp inputs/outputs) at least 3 mm away from the PSMC PWM output traces and the digital switching nodes to minimize capacitive coupling. Use a guarded analog ground island for AVSS, connecting it back to VSS at a single point near the AVDD ferrite bead. The MCLR pin should be tied to VDD through a 10 kohm resistor with a 100 nF capacitor to ground for in-circuit serial programming (ICSP) and reset reliability. Estimated: a 20-pin SOIC has roughly 0.7 mm of trace-to-trace clearance on a 4-layer board, which is sufficient for most analog signals below 1 kHz.
Compliance Information
PIC16C781T-I/SO is a legacy OTP die with SnPb (leaded) finish on the T/R variant and is therefore non-RoHS-compliant per Microchip's product page. REACH compliance status unknown from provided data. Not AEC-Q100 qualified; the part is not automotive-grade. Lifecycle is obsolete as of 2026-09-19; Microchip's PIC16 mid-range product page should be consulted for the latest status.
