PIC16C65AT-04I/PQ - 8-Bit 4MHz 7KB OTP MCU, 44-MQFP | Microchip
MPN: PIC16C65AT-04I/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.45 | $12.45 |
| 10 | $11.2 | $112.00 |
| 100 | $9.85 | $985.00 |
| 500 | $8.6 | $4,300.00 |
| 1,000 | $7.95 | $7,950.00 |
PIC16C65AT-04I/PQ Overview
What is a PIC16C OTP microcontroller? An OTP (One-Time-Programmable) microcontroller is a class of MCU whose program memory can be written exactly once after manufacture, sitting in the hierarchy of embedded controllers between mask-ROM parts (cheapest, programmed only at the fab) and flash-based MCUs (reprogrammable, higher cost per bit). The PIC16C family uses a Harvard RISC core with 35 instructions and a deterministic single-cycle execution model, making PIC16C65A variants popular in cost-sensitive industrial and appliance control where firmware is final at production.
Key features include the high-performance PIC16C6X RISC CPU, a wide operating voltage range typical of the family (2.5V to 6.0V), 33 I/O pins with individual direction control, an integrated USART for serial communication, multiple timer modules, and an industrial operating temperature grade of -40C to +85C as denoted by the I suffix. The 4 MHz top speed is the standard variant; faster 20 MHz versions exist in the same family. The A-suffix silicon revision provides silicon-level fixes documented in the datasheet errata (DS30234D).
Architecturally, the PIC16C65AT-04I/PQ separates program and data buses (Harvard architecture) to allow simultaneous instruction fetch and data access, and uses a 14-bit instruction word aligned to an 8-bit data path. Its interrupt structure supports both peripheral interrupts and a single hardware save/restore context mechanism, and the core delivers up to 5 MIPS at 20 MHz and 1 MIPS at 4 MHz. The A silicon revision is functionally identical to earlier revisions in normal operation and only diverges under specific peripheral edge cases.
Typical applications include industrial control systems, motor control front-ends, HVAC controllers, appliance subsystems, automotive body electronics (pre-CAN), and embedded data-acquisition nodes where the OTP one-time-programmable model and 33 I/O simplify BOM and PCB layout. The 44-MQFP package offers generous I/O count in a low-profile surface-mount footprint suitable for hand-soldered prototypes and high-volume reflow assembly alike.
When designing with this part, confirm oscillator choice (crystal/resonator vs. RC) against the PIC16C65A datasheet (DS30234D) and reserve the MCLR pin for a proper reset circuit. Because OTP memory cannot be field-updated, build a robust in-system programming path or use the JW windowed version for prototype development before locking firmware.
This page combines verified distributor pricing, drop-in same-package alternatives, and practical engineering design notes that complement the manufacturer's datasheet for engineers selecting or sourcing the PIC16C65AT-04I/PQ.
Drop-in alternatives for PIC16C65AT-04I/PQ — 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 PIC16C65AT-04I/PQ (same form factor and footprint) — differing in Program Memory Size, Core Architecture, Package, Program Memory Type, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C65A-04I/PQ
✅ Drop-In✓ In Stock
$9.95 / Unit
View Datasheet →PIC16C65A-20I/PQ
✅ Drop-In✓ In Stock
$8.62 / Unit
View Datasheet →PIC16C65A-04E/PQ
✅ Drop-In✓ In Stock
$5.25 / Unit
View Datasheet →PIC16C65A-10/PQ
✅ Drop-In✓ In Stock
$6.1 / Unit
View Datasheet →PIC16C65A-20E/PQ
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC16LC65BT-04I/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C65AT-04I/PQ Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C RISC, 8-bit 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 |
| Maximum Clock Speed | 4 MHz |
| Number of I/O Pins | 33 |
| Package / Case | 44-MQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Oscillator Type | External |
| Operating Temperature Range | -40C to +85C (industrial, I suffix) |
| Silicon Revision | A (per DS30234D) |
| Packaging | Tape & Reel (TR) |
PIC16C65AT-04I/PQ Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, active low |
| 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/SS/AN4 — PORTA bit 5 / SSP slave select / analog input 4 |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / external clock in |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / clock out |
| Pin 11 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator out / clock in |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator in / CCP2 |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / Capture-Compare-PWM 1 |
| Pin 14 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — PORTC bit 6 / USART TX / clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART RX / data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply |
| Pin 21 | RB0/INT — PORTB bit 0 / external interrupt |
| Pin 22 | RB1 — PORTB bit 1 |
| Pin 23 | RB2 — PORTB bit 2 |
| Pin 24 | RB3 — PORTB bit 3 |
| Pin 25 | RB4 — PORTB bit 4 |
| Pin 26 | RB5 — PORTB bit 5 |
| Pin 27 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 28 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 29 | VSS — Ground reference |
| Pin 30 | VDD — Positive supply |
| Pin 31 | RD0/PSP0 — PORTD bit 0 / Parallel Slave Port bit 0 |
| Pin 32 | RD1/PSP1 — PORTD bit 1 / Parallel Slave Port bit 1 |
| Pin 33 | RD2/PSP2 — PORTD bit 2 / Parallel Slave Port bit 2 |
| Pin 34 | RD3/PSP3 — PORTD bit 3 / Parallel Slave Port bit 3 |
| Pin 35 | RD4/PSP4 — PORTD bit 4 / Parallel Slave Port bit 4 |
| Pin 36 | RD5/PSP5 — PORTD bit 5 / Parallel Slave Port bit 5 |
| Pin 37 | RD6/PSP6 — PORTD bit 6 / Parallel Slave Port bit 6 |
| Pin 38 | RD7/PSP7 — PORTD bit 7 / Parallel Slave Port bit 7 |
| Pin 39 | VSS — Ground reference |
| Pin 40 | VDD — Positive supply |
| Pin 41 | RE0/RD/AN5 — PORTE bit 0 / read control / analog input 5 |
| Pin 42 | RE1/WR/AN6 — PORTE bit 1 / write control / analog input 6 |
| Pin 43 | RE2/CS/AN7 — PORTE bit 2 / chip select / analog input 7 |
| Pin 44 | VDD — Positive supply |
Typical Applications
PIC16C65AT-04I/PQ is suitable for 7 applications: Industrial Control & PLC I/O Modules, Appliance Control (Washing Machines, Dishwashers, Ovens), HVAC Thermostat & Zone Controllers, Automotive Body Electronics (Pre-CAN Era), Point-of-Sale Terminals & Vending Machines, Industrial Data Acquisition Front-Ends, Educational & Legacy Maintenance Designs.
Industrial Control & PLC I/O Modules
The PIC16C65AT-04I/PQ fits industrial control and PLC-style I/O modules because its 33 GPIO pins can sink/source the typical 24V opto-isolated inputs and relay outputs after buffering, while its industrial -40C to +85C temperature rating survives factory-floor enclosures. The PIC16C6X Harvard core executes a deterministic 35-instruction RISC set, simplifying IEC 61131-3-style ladder logic emulation. The 4 MHz clock rate is sufficient for 1 ms scan-time loops in most discrete I/O applications. Compared with switching to a flash MCU, the OTP variant locks firmware at production, eliminating accidental field reprogramming.
Recommended
Appliance Control (Washing Machines, Dishwashers, Ovens)
The PIC16C65AT-04I/PQ is widely deployed in appliance controllers because the OTP memory locks motor-control and safety-interlock firmware at production, while 192 bytes of RAM are ample for state-machine cycles of pumps, valves, and triac-driven heaters. Its 33 I/O can directly drive LED status arrays, keypad matrices, and zero-cross triac triggers through current-limiting resistors. The -40C to +85C industrial temperature range tolerates under-counter kitchen heat and laundry-room humidity. Drop-in compatibility with the -20I variants supports migration to higher-speed models without PCB rework.
Recommended
HVAC Thermostat & Zone Controllers
The PIC16C65AT-04I/PQ serves HVAC thermostat and zone-controller boards by integrating a 10-bit ADC-class comparator chain, multiple timers for PWM damper control, and the USART for talking to remote wall sensors, all on a single 44-MQFP die. The OTP memory prevents firmware tampering after safety certification, which is critical for UL-listed HVAC products. The 33 I/O handle thermostat buttons, LCD segment drivers, relay coils, and triac phase-angle controls. Industrial temperature rating ensures reliability in attic and basement installations.
Recommended
Automotive Body Electronics (Pre-CAN Era)
The PIC16C65AT-04I/PQ was a workhorse in pre-CAN automotive body modules such as seat controllers, mirror adjusters, and lighting timers because its 33 I/O can drive MOSFET gates and monitor switch matrixes, while OTP memory secures the calibration against unauthorized reflashing. The industrial temperature grade accommodates cabin environments although it is not AEC-Q100 qualified for under-hood use. The integrated USART supports LIN-bus slave implementations via bit-banging or external transceiver. Designers requiring AEC-Q100 should migrate to PIC18F or dsPIC33 Q-qualified parts.
Recommended
Point-of-Sale Terminals & Vending Machines
The PIC16C65AT-04I/PQ drives vending machine coin acceptors, bill validators, and small point-of-sale terminals thanks to its USART for talking to cellular modems, CCP modules for motor control of product dispensing augers, and 33 GPIO for keypad scanning and seven-segment displays. The 7 KB OTP program memory accommodates vending state-machine firmware without external ROM. Industrial temperature rating supports outdoor vending kiosks. The 4 MHz clock is sufficient because most I/O is event-driven rather than compute-bound.
Recommended
Industrial Data Acquisition Front-Ends
The PIC16C65AT-04I/PQ is used in industrial data-acquisition front-ends where its integrated ADC, multiple timers for sampling-rate generation, and USART for transmitting readings to a host controller provide a one-chip analog frontend. The 33 GPIO accept multiplexer outputs from thermocouples, RTDs, and 4-20 mA loops. OTP memory secures calibration constants and unit-specific serial numbers. The 4 MHz clock is adequate for low-speed multi-channel scanning at 100 Hz rates. Pin-compatibility with PIC16C65A-20I/PQ enables easy migration if higher sampling rates are needed.
Recommended
Educational & Legacy Maintenance Designs
The PIC16C65AT-04I/PQ continues to appear in educational labs and legacy maintenance inventories because the PIC16C instruction set is the canonical teaching vehicle for RISC embedded programming and the 44-MQFP is large enough to hand-solder on through-hole adapter boards. The OTP variant teaches students that firmware must be final before production, contrasting with flash MCUs that allow iteration. 33 GPIO cover most textbook peripherals (LEDs, switches, UART, PWM). Drop-in variants in the Site MPN list (PIC16C65A-04I/PQ, PIC16C65A-20I/PQ) preserve the lab footprint while allowing speed upgrades.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C65AT-04I/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C65A-04I/PQ | PIC16C65A-20I/PQ | PIC16C65A-04E/PQ | PIC16C65A-10/PQ | PIC16C65A-20E/PQ | PIC16LC65BT-04I/PQ |
|---|---|---|---|---|---|---|---|
| Package | 44-MQFP (10x10 mm) | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Speed | 4 MHz | 4 MHz | 20 MHz | 4 MHz | 10 MHz | 20 MHz | 4 MHz |
| Program Memory | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP |
| RAM | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes |
| I/O Pins | 33 | 33 | 33 | 33 | 33 | 33 | 33 |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | 0C to +70C (commercial) | 0C to +70C (commercial) | 0C to +70C (commercial) | -40C to +85C (industrial) |
| Silicon Revision | A | A | A | A | A | A | B |
| Packaging | Tape & Reel | Tube / Tray | Tube / Tray | Tube / Tray | Tube / Tray | Tube / Tray | Tube / Tray |
Key Differentiators
- Same-package drop-in alternatives across the PIC16C65A family simplify inventory management (vs PIC16C65A-04I/PQ)
- Lower-voltage LC variant enables portable battery-powered designs on the same footprint (vs PIC16LC65BT-04I/PQ)
- Industrial temperature rating versus commercial alternatives broadens deployment options (vs PIC16C65A-04E/PQ)
Design Notes
The PIC16C65AT-04I/PQ requires a single 5V nominal supply and decoupling on each VDD/VSS pair as documented in the datasheet DC characteristics. Place a 0.1 uF ceramic bypass within 5 mm of every VDD pin (pins 20, 30, 40, 44) with a shared 10 uF bulk capacitor at the regulator output. Add bulk capacitance near analog AVdd if used; brown-out behaviour is handled internally via the POR circuit, but an external reset supervisor is recommended for motor-control applications where supply droop could corrupt EEPROM-mirrored state.
OTP memory is one-time-programmable, so any bug in shipped firmware bricks the device. Use the PIC16C65A-04/PQ (windowed EPROM version) or PIC16F877A-I/PQ (flash) for firmware development and only lock OTP for production runs. Verify with the DS30234D revision-A silicon errata list - several peripheral edge cases differ from revision 0 and can corrupt USART reception under specific baud-rate combinations. Use Microchip's MPASM or XC8 toolchain with the -O1 optimisation level to keep cycle-counted delays deterministic.
The 44-MQFP package has a 0.8 mm lead pitch and 10x10 mm body, requiring reflow soldering with a fine-paste stencil (0.15 mm thickness recommended). Reserve at least 1.5 mm of keep-out around the package perimeter for the rework iron tip and 3 mm clearance for the MQFP gull-wing leads during visual inspection. Place the oscillator crystal within 10 mm of OSC1/OSC2 and guard the traces with a ground pour to minimise EMI radiation that can corrupt ADC readings on PORTA analog inputs.
Long parallel-port traces (PORTD) can act as antennas if routed beyond 50 mm; series-terminate each PSP line with 33 ohm resistors when interfacing to external bus controllers. The USART TX line should be kept short (<25 mm) and routed away from the oscillator to prevent capacitive coupling that shifts the baud rate. MCLR requires a 10 kohm pull-up to VDD and a 100 nF cap to ground for clean reset behaviour during power-up; do not omit the cap as it filters out EFT bursts on long cables.
Compliance Information
Compliance data not provided in Verified Web Data; PIC16C family predates widespread RoHS/AEC-Q100 reporting, so engineers should request the latest Material Declaration from Microchip for current production. The I-suffix industrial temperature range does not imply AEC-Q100 automotive qualification.
