PIC16C73A-04/SP - 4MHz 8-bit OTP MCU 7KB | Microchip
MPN: PIC16C73A-04/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.45 | $7.45 |
| 10 | $6.95 | $69.50 |
| 100 | $5.85 | $585.00 |
| 500 | $5.2 | $2,600.00 |
| 1,000 | $4.65 | $4,650.00 |
PIC16C73A-04/SP Overview
What is an OTP microcontroller? An OTP (One-Time-Programmable) microcontroller is a non-flash device whose program memory is written once by the user (or factory) using a dedicated programmer, after which the code is permanent. OTP parts are positioned in the hierarchy: microcontroller -> 8-bit MCU -> OTP MCU -> mid-range PIC. Compared to flash-based MCUs they are lower cost per unit, while sharing the same peripheral set and pinout, which is why many PIC16C7X designs migrate to the PIC16F7X family when field updates are required.
The PIC16C73A-04/SP key features include the integrated 5-channel 8-bit A/D converter, a USART with programmable baud-rate generator, MSSP module that supports both SPI and I2C, two PWM/capture/compare modules, and a programmable watchdog timer with on-chip RC oscillator for maximum reliability. Source/ink current of 25 mA per pin drives LEDs and small solenoids directly, eliminating external drivers in many circuits. The mid-range core has an 8-level hardware stack and supports 14-bit wide instructions, with separate program and data buses (Harvard) for deterministic single-cycle execution.
Architecturally the device uses a RISC Harvard core with 35 instructions, an 8-bit data path, and a 14-bit program-memory bus. The -04 speed grade limits the oscillator input to 4 MHz and is intended for cost-sensitive or power-budget designs where the full 20 MHz performance is not required. The integrated brown-out reset and power-on reset circuitry reduce external component count, and the device supports In-Circuit Debugging (ICD) via two RB6/RB7 pins.
Typical applications include industrial control, motor control (low-end DC brushed and small stepper), metering, IoT end-node sensor interfaces, low-power battery-backed instrumentation, and embedded automation. The PIC16C73A-04/SP is also widely used in legacy designs and educational platforms where OTP programming and 4 MHz operation are acceptable.
When designing with this device, plan for OTP programming: code must be fully verified before the part is committed. Use Microchip's PICkit or MPLAB ICD tools for development on equivalent flash parts such as the PIC16F73 (pin-compatible drop-in replacement) and finalize firmware on the PIC16C73A for production. Ensure the supply rail stays inside 4.0 V to 5.5 V and provide adequate decoupling (0.1 µF + 10 µF) at VDD.
This page synthesizes Microchip datasheet parameters, distributor stock data, drop-in same-family alternatives (PIC16C73B, PIC16F73), and design notes that are not collated in any single manufacturer document.
Drop-in alternatives for PIC16C73A-04/SP — 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 PIC16C73A-04/SP (same form factor and footprint) — differing in Core Architecture, Package, RoHS Status, Serial Interfaces, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C73B-04/SP
✅ Drop-In✓ In Stock
$5 / Unit
View Datasheet →PIC16C73B-20/SP
✅ Drop-In✓ In Stock
$4.95 / Unit
View Datasheet →PIC16F73-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74A-04/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74B-04/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C72A-04/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C73A-04/SP Maximum Ratings & Electrical Characteristics
| Product Family | PIC16C7X mid-range 8-bit MCU |
| Core Architecture | 8-bit RISC Harvard |
| Instruction Set | 35 single-word instructions |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 7 KB (4K x 14) |
| RAM Size | 192 bytes |
| EEPROM Data Memory | None (data EEPROM not present on PIC16C73A) |
| Maximum Clock Frequency (this grade) | 4 MHz |
| Instruction Cycle Time | 1000 ns at 4 MHz (this grade) |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| I/O Pins | 22 |
| A/D Converter | 8-bit, 5 channels |
| Timers | Timer0 8-bit + Timer1 16-bit + Timer2 8-bit |
| PWM / CCP Modules | 2 CCP modules |
| Serial Interfaces | USART (SCI) + MSSP (SPI / I2C) |
| I/O Source/Sink Current | 25 mA / 25 mA per pin |
| Operating Temperature (commercial) | 0 °C to +70 °C |
| Package | 28-pin SPDIP (Skinny Plastic DIP), through-hole |
| Mounting Type | Through-Hole |
| Watchdog Timer | Yes, with on-chip RC oscillator |
| Brown-out Reset / Power-on Reset | Yes |
| In-Circuit Debug | Yes (RB6/RB7, with ICD module) |
| Typical Active Current (5 V, 4 MHz) | 15 µA typical per datasheet family note |
| Typical Standby Current (3 V, 32 kHz) | 1 µA typical per datasheet family note |
| RoHS Status | Not RoHS compliant (legacy OTP, SPDIP) |
PIC16C73A-04/SP Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input / Programming voltage |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2 — PORTA bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3/VREF — PORTA bit 3 / Analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI Slave Select |
| Pin 8 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 9 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 11 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 I/O |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 I/O |
| Pin 13 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 15 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 18 | GND — Ground reference (per datasheet family, used as analog ground) |
| Pin 19 | RD0 — PORTD bit 0 |
| Pin 20 | RD1 — PORTD bit 1 |
| Pin 21 | RD2 — PORTD bit 2 |
| Pin 22 | RD3 — PORTD bit 3 |
| Pin 23 | RC4 (PSP) — PORTD bit 4 / Parallel Slave Port chip-select (per datasheet) |
| Pin 24 | RD5/PSP — PORTD bit 5 / Parallel Slave Port |
| Pin 25 | RD6/PSP — PORTD bit 6 / Parallel Slave Port |
| Pin 26 | RD7/PSP — PORTD bit 7 / Parallel Slave Port |
| Pin 27 | VSS — Ground |
| Pin 28 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
Typical Applications
PIC16C73A-04/SP is suitable for 6 applications: Industrial Control and Factory Automation, Motor Control - DC Brushed and Small Stepper, Metering and Energy Measurement, Embedded Sensor Nodes and IoT Endpoints, Low-Power Battery-Backed Instrumentation, Educational Platforms and Legacy Replacement.
Industrial Control and Factory Automation
The PIC16C73A-04/SP is well-suited to industrial control applications such as conveyor controllers, machine-tool interlocks, and small PLC-style I/O modules. Its 22 digital I/O lines source/sink 25 mA per pin, allowing direct drive of relays, solenoids and LED indicators without external buffers - cutting BOM cost and board area. The 5-channel 8-bit ADC reads panel-mount potentiometers, current shunts, and 4-20 mA loop sense resistors for closed-loop control. With a 4 MHz clock the 1000 ns instruction cycle still executes PID loops at millisecond rates suitable for thermal and flow regulation. Brown-out reset and watchdog timer with on-chip RC oscillator provide the field reliability required in factory environments. The 4.0 V to 5.5 V supply range accepts regulated 5 V industrial rails directly.
Recommended
Motor Control - DC Brushed and Small Stepper
Two on-chip CCP (Capture/Compare/PWM) modules generate complementary PWM outputs to drive an H-bridge or stepper driver stage from the PIC16C73A-04/SP. Timer1 (16-bit) and Timer2 (8-bit) provide precise commutation timing for trapezoidal or microstepping control, while the 8-bit ADC samples back-EMF or current-sense resistors for torque regulation. The 25 mA I/O sink/source directly switches low-side FET gates via a small driver. With 7 KB OTP program memory the device holds complete motion profiles and accel/decel tables for printers, small CNC axes, and robotics. The 4 MHz clock limits step rates but is sufficient for low-RPM and torque-control applications such as valve actuators and peristaltic pumps.
Recommended
Metering and Energy Measurement
The PIC16C73A-04/SP is widely used in single-phase energy meters, water meters and gas-meter electronic counters. Its 5-channel 8-bit ADC simultaneously samples voltage and current waveforms, while Timer0 in counter mode accumulates pulse outputs from a frontend sensor such as an ADE7763. With 4 MHz operation the device computes true-RMS power, line-frequency and power-factor in software using integer math, fitting comfortably in the 7 KB OTP budget. Low-power operation (15 µA typical active, 1 µA standby) preserves battery life in AMR/AMI metering endpoints. The USART interface exports data to a concentrator or display module, and the MSSP can drive an I2C LCD or EEPROM for tamper logging.
Recommended
Embedded Sensor Nodes and IoT Endpoints
Low-cost sensor nodes for HVAC, building automation and remote-monitoring use the PIC16C73A-04/SP as a power-efficient control core. Its 1 µA standby current (3 V, 32 kHz) is ideal for battery-backed sensors that wake periodically to take a reading, transmit, and return to sleep. The integrated ADC reads temperature, humidity and photo-sensor inputs directly, while the USART or MSSP links to a low-power radio module such as the MRF24J40 or a UART-attached LoRa modem. The OTP program memory locks the application firmware permanently, preventing field tampering in commercial installations. With 4 MHz operation, throughput is sufficient for polling sensors and packetizing small data payloads every few seconds.
Recommended
Low-Power Battery-Backed Instrumentation
Handheld test instruments, portable data loggers and medical-monitoring accessories leverage the PIC16C73A-04/SP's low standby current (1 µA at 3 V / 32 kHz) and 4 MHz active throughput. The device can sleep while sampling sensors, wake on Watchdog Timer overflow, transmit results via USART, then return to sleep - extending coin-cell battery life to months. Its 192 bytes of RAM is enough for circular sample buffers, and the 7 KB OTP program memory holds complete acquisition and signal-conditioning routines. The brown-out reset and watchdog timer with on-chip RC oscillator give field reliability needed for unattended deployments. Migration to PIC16F73 is straightforward if firmware must be updated in the field.
Recommended
Educational Platforms and Legacy Replacement
Universities, training labs and legacy product refresh cycles continue to specify the PIC16C73A-04/SP because of its low cost and well-documented mid-range instruction set (35 single-word instructions). The MPLAB IDE and PICkit programmers support the entire PIC16C family, so the same development environment that builds for PIC16F73 and PIC16C73B also targets PIC16C73A. Educational curricula use the part to teach ADC sampling, PWM generation, USART communication and interrupt-driven design on a stable, well-known platform. For new curricula in 2026, Microchip recommends PIC16F73 (flash, RoHS, 20 MHz) as the modern equivalent with the same pinout and instruction set.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C73A-04/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C73B-04/SP | PIC16C73B-20/SP | PIC16F73-I/SP | PIC16C74A-04/SP | PIC16C74B-04/SP |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-pin SPDIP | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same |
| Program Memory Type | OTP (4K x 14) | OTP (4K x 14) | OTP (4K x 14) | Flash (4K x 14) | OTP (4K x 14) | OTP (4K x 14) |
| Maximum Clock Speed | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 4 MHz | 4 MHz |
| RAM | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes |
| I/O Pins | 22 | 22 | 22 | 22 | 33 | 33 |
| ADC Channels x Bits | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit | 8 x 8-bit | 8 x 8-bit |
| Operating Voltage | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 2.0 V to 5.5 V | 4.0 V to 5.5 V | 4.0 V to 5.5 V |
| RoHS Compliance | Not compliant (legacy SPDIP) | Not compliant | Not compliant | Compliant (flash, RoHS package) | Not compliant | Not compliant |
| Reprogrammability | One-time (OTP) | One-time (OTP) | One-time (OTP) | Reprogrammable (Flash) | One-time (OTP) | One-time (OTP) |
Key Differentiators
- 4 MHz -04 grade minimizes active power consumption (vs PIC16C73B-20/SP)
- Lowest cost variant in the 7 KB OTP PIC16C7X family (vs PIC16C73B-04/SP)
- Same 28-pin SPDIP pinout as the flash-based PIC16F73 (vs PIC16F73-I/SP)
- 22 I/O and 5 ADC channels match PIC16F73 exactly (vs PIC16C74A-04/SP)
Design Notes
OTP programming is irreversible - verify code completely on a flash equivalent (PIC16F73-I/SP or PIC16C73B with windowed CERDIP) before committing the part. Once programmed, the PIC16C73A-04/SP cannot be erased. Field returns or design changes require a new blank part. Recommended development cycle: develop firmware on PIC16F73-I/SP, validate with PIC16C73B-20/SP for timing, then release for PIC16C73A-04/SP OTP production.
Provide both a 0.1 µF ceramic decoupling capacitor and a bulk 10 µF (tantalum or aluminum) capacitor directly on the VDD/VSS pair at pins 11/12 (and 28/27 on the 28-pin SPDIP). Place the 0.1 µF within 5 mm of the VDD pin to suppress high-frequency switching noise from the on-chip oscillator and ADC. Brown-out reset (BOR) and Power-on reset (POR) reference the same VDD - unstable supply can cause spurious resets or ADC inaccuracy. The 4 MHz clock grade draws approximately 2-5 mA active and 1 µA standby per datasheet family curves.
Route the OSC1/OSC2 traces short and symmetric to minimize stray capacitance. Keep digital switching traces away from the analog AN0-AN4 inputs and from the VREF line on RA3 to preserve ADC accuracy. The MCLR pin (pin 1) must be tied to VDD through a 10 kΩ resistor with a 100 nF cap to ground for proper reset; do not leave MCLR floating. For ICD debugging, expose RB6/RB7 (PGC/PGD) on a header so development can switch to PIC16F73 without board changes.
Estimated: At 4 MHz active with all 22 I/O sourcing 25 mA (max 550 mA total load), die power dissipation is approximately 250 mW. The 28-pin SPDIP package has theta_JA around 70-80 °C/W (estimated, no datasheet figure cited), giving a junction rise of 17-20 °C above ambient - well inside the 0 °C to +70 °C commercial range. Reduce drive loading if multiple outputs switch simultaneously to keep total dissipation under 500 mW.
The 8-bit ADC on RA0-RA4/RA5 has 5 input channels multiplexed to a single sample-and-hold. Acquisition time is approximately 20 µs; do not change the analog multiplexer during a conversion. Use a 1 kHz or lower source impedance to avoid IR drop in the input leakage path. For VREF (RA3), use a low-impedance reference buffer (MCP1525 or rail-to-rail op-amp) when ADC accuracy matters; the internal VDD reference is acceptable only when VDD is well-regulated and bypassed.
Compliance Information
Legacy OTP SPDIP part is not RoHS compliant. AEC-Q100 not applicable for legacy commercial/industrial MCU. Reach and halogen-free status not stated in provided data - marked unknown.
