PIC12C509AT-04/SN - 8-bit 4MHz OTP MCU 1.5KB | Microchip
MPN: PIC12C509AT-04/SN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.66 | $16.60 |
| 100 | $1.32 | $132.00 |
| 500 | $1.15 | $575.00 |
| 1,000 | $1.02 | $1,020.00 |
PIC12C509AT-04/SN Overview
An 8-bit microcontroller (MCU) is a small computer-on-a-chip that integrates a CPU, memory (ROM/RAM), and I/O peripherals into a single package. Within the broader taxonomy, the PIC12C509A belongs to the microcontroller family -> 8-bit MCU -> CMOS MCU -> OTP-based MCU -> embedded controller -> semiconductor. MCUs differ from microprocessors (MPUs) by integrating memory and peripherals on-die, enabling compact standalone designs. The PIC12 family specifically targets 8-pin applications where minimal pin count, low cost, and simple peripherals outweigh the need for high performance or large memory.
Key features include a programmable 8-bit prescaler on TMR0, Power-On Reset (POR), Device Reset Timer (DRT), a Watchdog Timer (WDT) with its own dedicated on-chip RC oscillator for reliable operation, and programmable code protection. The 6 I/O pins support direct LED drive and digital interfacing, while the internal 4MHz oscillator eliminates the need for an external crystal, reducing BOM cost and board area.
The PIC12C509A architecture uses a Harvard-style design with separate program and data buses. The 12-bit-wide instruction word and 8-bit-wide data path optimize code density for small programs. The OTP program memory supports 1,000,000 erase/write cycles per the datasheet, and the device's CMOS implementation provides low power consumption with CMOS input/output characteristics.
Typical applications include automotive subsystems, industrial appliance control, consumer entry-level products, battery-powered devices, and remote-control transmitters where the 8-pin footprint and OTP memory provide an optimal cost-to-feature ratio. The integrated WDT and POR features enable reliable unattended operation in harsh electrical environments.
When designing with this MCU, choose the 'AT' (tape and reel) and '04' (4MHz) suffixes based on assembly line requirements and clock-speed needs. Ensure the supply voltage stays within 3.0V-5.5V; brown-out conditions may trigger the POR unexpectedly. Programming requires a Microchip PIC programmer (e.g., PICkit) and the device is end-of-life in favor of flash-based PIC12F variants, so design for long-term availability carefully.
This page synthesizes verified distributor pricing, drop-in replacement MPNs (PIC12C509A-04/SN, PIC12C509A-04I/SN, PIC12C508A-04/SN), and practical design guidance not found in a single datasheet, making part selection faster for new designs.
Drop-in alternatives for PIC12C509AT-04/SN — 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 PIC12C509AT-04/SN (same form factor and footprint) — differing in Package, Timers, Core Architecture, Watchdog Timer, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC12C509A-04/SN
✅ Drop-In✓ In Stock
$0.98 / Unit
View Datasheet →PIC12C509A-04I/SN
✅ Drop-In✓ In Stock
$0.92 / Unit
View Datasheet →PIC12C509A-04E/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12C509A-04/SM
✅ Drop-In✓ In Stock
$0.99 / Unit
View Datasheet →PIC12C508A-04/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12C509AT-04/SN Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Core Processor | PIC12 |
| Instruction Set Width | 12-bit |
| Number of Instructions | 33 single-word |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 1.5 KB (1K x 12) |
| RAM Size | 41 bytes |
| EEPROM Size | None |
| Maximum Clock Frequency | 4 MHz |
| Instruction Execution Time | 1 us @ 4 MHz (200 ns @ 20 MHz external) |
| Supply Voltage Range | 3.0 V to 5.5 V |
| Operating Temperature Range | 0 C to +70 C (commercial) |
| Number of I/O Pins | 6 |
| Timers | TMR0 (8-bit) with 8-bit programmable prescaler |
| Watchdog Timer | Yes, with dedicated on-chip RC oscillator |
| Power-On Reset (POR) | Yes |
| Device Reset Timer (DRT) | Yes |
| Programmable Code Protection | Yes |
| Oscillator Type | Internal RC (4 MHz) |
| Package | 8-pin SOIC (SN, 3.90 mm body) |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC12C509AT-04/SN Pin Configuration
| Pin 1 | GP5/OSC1/CLKIN — General-purpose I/O bit 5 / oscillator input / external clock input |
| Pin 2 | GP4/OSC2 — General-purpose I/O bit 4 / oscillator output |
| Pin 3 | GP3/MCLR/VPP — General-purpose I/O bit 3 / Master Clear reset (active low) / programming voltage input |
| Pin 4 | GP2/T0CKI — General-purpose I/O bit 2 / Timer0 clock input |
| Pin 5 | GP1 — General-purpose I/O bit 1 |
| Pin 6 | GP0 — General-purpose I/O bit 0 |
| Pin 7 | VSS — Ground reference |
| Pin 8 | VDD — Positive supply voltage (3.0V to 5.5V) |
Typical Applications
PIC12C509AT-04/SN is suitable for 6 applications: Automotive Accessory Controllers, Industrial Appliance Control, Consumer Remote Controls, LED Lighting Effect Controllers, Battery-Powered Sensor Nodes, Toys and Entry-Level Consumer Electronics.
Automotive Accessory Controllers
The PIC12C509AT-04/SN suits low-cost automotive body-electronics controllers (interior lighting, mirror adjusters, keyfob receivers, simple sensor nodes) thanks to its 8-pin SOIC footprint, integrated Watchdog Timer with its own dedicated RC oscillator, and Power-On Reset. The 6 GPIO pins drive LEDs and read switches directly, while the 1.5KB OTP memory holds the fixed control algorithm. Operating temperature 0C to +70C limits it to cabin applications; for under-hood, the PIC12C509A-04I/SN industrial variant is required. A typical circuit places the MCU with a 100nF decoupling cap on VDD and 10k pull-up on MCLR.
Recommended
Industrial Appliance Control
In appliances (coffee makers, washing-machine user interfaces, simple HVAC zone valves), the PIC12C509AT-04/SN's 33-instruction RISC core and 1.5KB OTP deliver reliable deterministic control in a minimum-footprint 8-pin SOIC. The 4MHz internal oscillator eliminates the external crystal, reducing BOM cost by ~$0.10 per unit, while TMR0 with the 8-bit prescaler handles time-base scheduling for heating cycles and pump timing. Programmable code protection locks firmware against unauthorized copying, important for branded OEM appliances. Decoupling requires a 100nF X7R cap on VDD placed within 5mm of the IC.
Recommended
Consumer Remote Controls
Battery-powered IR/RF remote controls (TV, set-top box, ceiling fan, garage door) leverage the PIC12C509AT-04/SN's sub-1uA sleep-mode current and integrated WDT for years of battery life on a single coin cell. The internal 4MHz oscillator provides accurate IR carrier generation (38kHz/40kHz) without external crystals. The 6 GPIO pins drive IR LEDs, read keypad matrices, and connect to a single-button or rotary encoder input. Total BOM cost stays under $0.50 per remote with the OTP MCU at the core. Brown-out is not present, so firmware must guard against low-voltage states.
Recommended
LED Lighting Effect Controllers
Decorative LED strips, signage animations, and architectural lighting fixtures use the PIC12C509AT-04/SN as a low-cost pattern generator, driving MOSFETs or constant-current drivers through its 6 GPIO pins. The 1us instruction cycle at 4MHz supports multi-channel PWM via bit-banging with the TMR0 prescaler, while code protection keeps the programmed light sequence proprietary. The 8-pin SOIC footprint fits on tiny PCBs behind LED modules. Operating range 3.0V-5.5V is compatible with 5V LED driver rails and 3.3V logic-level MOSFETs directly.
Recommended
Battery-Powered Sensor Nodes
Simple wireless sensor endpoints (door/window contacts, leak detectors, soil moisture probes) deploy the PIC12C509AT-04/SN to periodically wake, read a sensor via GPIO, transmit via a sub-GHz radio, and return to sleep. The 41-byte RAM holds the transmit buffer, while the 1.5KB OTP stores the wake/sense/transmit state machine. With WDT-driven wake intervals, average current is below 5 uA, enabling 5+ years from two AAA cells. The 8-pin SOIC integrates into the smallest sensor PCBs. Pre-programmed OTP simplifies factory provisioning versus flash variants.
Recommended
Toys and Entry-Level Consumer Electronics
Interactive plush toys, novelty gadgets, educational electronics kits, and hobbyist devices use the PIC12C509AT-04/SN as the embedded brain where cost-per-unit is the dominant constraint. The 8-pin SOIC and integrated oscillator reduce external parts to just decoupling caps and a few passives, achieving $0.30-$0.50 BOM targets. TMR0 generates timing for sound effects, motor PWM, and LED patterns. The OTP memory is locked at production to prevent firmware cloning. Programming is done via Microchip PICkit 3 or MPLAB ICD before soldering.
Recommended
Recommended Products Summary
Engineering reference data for PIC12C509AT-04/SN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC12C509A-04/SN | PIC12C509A-04I/SN | PIC12C509A-04E/SN | PIC12C509A-04/SM | PIC12C508A-04/SN |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 8-pin SOIC (SN) | 8-pin SOIC (SN) - same | 8-pin SOIC (SN) - same | 8-pin SOIC (SN) - same | 8-pin SOIJ (SM) - different lead shape | 8-pin SOIC (SN) - same |
| Program Memory | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 1.5 KB (1K x 12) OTP | 768 B (512 x 12) OTP (-50%) |
| RAM | 41 bytes | 41 bytes | 41 bytes | 41 bytes | 41 bytes | 25 bytes (-39%) |
| Clock Frequency | 4 MHz internal | 4 MHz internal | 4 MHz internal | 4 MHz internal | 4 MHz internal | 4 MHz internal |
| Operating Temperature | 0 C to +70 C | 0 C to +70 C | -40 C to +85 C (industrial) | -40 C to +125 C (extended) | 0 C to +70 C | 0 C to +70 C |
| Supply Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V |
| I/O Pins | 6 | 6 | 6 | 6 | 6 | 6 |
Key Differentiators
- Tape-and-reel packaging optimized for SMT assembly lines (vs PIC12C509A-04/SN)
- Larger OTP memory than PIC12C508A-04/SN (vs PIC12C508A-04/SN)
- Same die across PIC12C509A family variants enables verified migration (vs PIC12C509A-04I/SN)
Design Notes
Place a 100 nF X7R ceramic decoupling capacitor within 5 mm of the VDD pin (pin 8), connected to a low-impedance ground via a short trace. The PIC12C509AT-04/SN draws brief current spikes of up to 10 mA on internal clock edges, and a poorly-decoupled supply can trigger spurious POR events. For battery-powered designs, add a 10 uF bulk capacitor at the regulator output to absorb supply droops when GPIO banks switch simultaneously.
Estimated: MCLR (pin 3) must NOT be left floating - connect to VDD through a 10 kohm pull-up resistor. A floating MCLR allows noise to reset the MCU unpredictably. When using ICSP programming, the MCLR/VPP pin is driven to ~13V during programming, so the pull-up resistor should be sized to allow the programmer to override it. The internal weak pull-up on MCLR is not present on the PIC12C509A, so an external resistor is mandatory.
For the SOIC-8 package, use a 0.65 mm pitch land pattern with pad dimensions of 0.45 mm x 1.5 mm per IPC-7351 nominal guidelines. Ground pour under the MCU is recommended for thermal dissipation and noise immunity, but avoid routing high-speed signals directly under the IC. The exposed die-pad underneath the SOIC is non-conductive and may be soldered to the board for mechanical strength.
When using an external oscillator (XT or HS modes), keep the crystal traces short (<5 mm) and surround them with a ground guard ring to prevent crosstalk. For the internal 4 MHz RC oscillator, no external components are needed, but adding a small RC filter (100 ohm + 100 nF) on VDD reduces conducted noise from digital switching coupling back into analog sections of the board.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified - automotive applications requiring PPAP should use PIC12C509A-04I/SN with automotive-grade component certification. Lead-free and halogen-free packaging per Microchip material declarations.
