PIC12C509A-04I/SN - 8-bit OTP MCU, 1.5KB, 4MHz, SOIC-8 | Microchip
MPN: PIC12C509A-04I/SN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.34 | $134.00 |
| 500 | $1.1 | $550.00 |
| 1,000 | $0.92 | $920.00 |
PIC12C509A-04I/SN Overview
An OTP microcontroller is a class of embedded processor whose program memory can be written exactly once by the user (or the foundry) and thereafter behaves as read-only ROM. Microcontrollers sit at the heart of embedded systems as programmable compute engines that read sensors, drive actuators, and run deterministic control loops. The PIC12 family in particular belongs to Microchip's baseline 8-bit RISC architecture, sitting below PIC16/18 mid-range parts but above 6-pin PIC10 devices in the portfolio hierarchy.
Key features of the PIC12C509A-04I/SN include six general-purpose I/O pins, an 8-bit real-time clock/counter (TMR0) with an 8-bit programmable prescaler, a Power-On Reset (POR), a Device Reset Timer (DRT), a Watchdog Timer (WDT) with its own on-chip RC oscillator, and code-protection bit support. The Harvard RISC core executes instructions in a single cycle (1 microsecond at 4 MHz), and the part supports 33 single-word instructions for compact coding.
Typical applications include automotive body electronics, industrial appliance control, consumer products, and any low-pin-count embedded design where deterministic behavior, low power, and a small PCB footprint matter more than program-memory rewritability. The SOIC-8 footprint allows hand-soldering and reflow on standard 150-mil-pitch land patterns.
When designing with this part, verify that OTP write timing falls within the programmer specification, since OTP parts cannot be erased. For development, use the PIC12F509 (Flash-based, pin-compatible 8-pin drop-in) or the PIC12C509A-04/SN (commercial 0C to +70C grade) as engineering substitutes before committing to the -40C to +85C industrial "I" variant.
Drop-in alternatives for PIC12C509A-04I/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 PIC12C509A-04I/SN (same form factor and footprint) — differing in I/O Pins, Package, Core Architecture, Timers, Program Memory Size.
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/SM
✅ Drop-In✓ In Stock
$0.93 / Unit
View Datasheet →PIC12C509A-04I/MF
✅ Drop-In✓ In Stock
$0.99 / Unit
View Datasheet →PIC12C509AT-04I/SN
✅ Drop-In✓ In Stock
$1.05 / Unit
View Datasheet →PIC12C509A-04E/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12F509-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12LC509A-04E/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12C509A-04I/SN Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Instruction Set | 33 single-word instructions |
| Instruction Cycle Time | 1 us at 4 MHz |
| Maximum Clock Frequency | 4 MHz |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 1.5 KB (1K x 12) |
| Data RAM | 41 bytes |
| I/O Pins | 6 (5 Sublicensed per JLCPCB / 6 per Microchip) |
| Timers | TMR0 8-bit with 8-bit programmable prescaler |
| Watchdog Timer (WDT) | Yes, with dedicated on-chip RC oscillator |
| Power-On Reset (POR) | Yes |
| Device Reset Timer (DRT) | Yes |
| Code Protection | Programmable |
| Supply Voltage | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial, "I" suffix) |
| Package | 8-pin SOIC (SN) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Erase/Write Cycles | 1,000,000 (OTP rated for single-write production flow) |
PIC12C509A-04I/SN Pin Configuration
| Pin 1 | GP5/OSC1/CLKIN — Bidirectional I/O pin / crystal oscillator input / external clock input |
| Pin 2 | GP4/OSC2/CLKOUT — Bidirectional I/O pin / crystal oscillator output / clock output (1/4 of Fosc) |
| Pin 3 | GP3/MCLR/VPP — Input-only I/O pin / Master Clear reset (active low) / programming voltage input |
| Pin 4 | VSS — Ground reference |
| Pin 5 | GP0/T0CKI — Bidirectional I/O pin / Timer0 clock input |
| Pin 6 | GP1/AN0 — Bidirectional I/O pin / analog comparator input |
| Pin 7 | GP2/AN1/T0CKI/COUT — Bidirectional I/O pin / analog comparator input / alternate Timer0 clock / comparator output |
| Pin 8 | VDD — Positive supply voltage (3.0 V to 5.5 V) |
Typical Applications
PIC12C509A-04I/SN is suitable for 7 applications: Automotive Body Electronics, Industrial Appliance Control, Consumer Remote and Toy Electronics, Sensor Interface and Signal Conditioning, LED Lighting Drivers, Battery-Powered IoT Edge Nodes, Educational and Hobbyist Projects.
Automotive Body Electronics
The PIC12C509A-04I/SN is well suited to automotive body-electronics modules such as lighting controllers, key fob receivers, and simple sensor interfaces because its -40C to +85C industrial temperature rating covers under-dash and exterior-trim environments and its 6 GPIO pins can drive relays, LEDs, and discrete transistor stages directly. The on-chip Watchdog Timer with a dedicated RC oscillator ensures reliable recovery from electrical transients on the 12 V battery rail, while the 1.5 KB OTP memory holds a fixed lighting-sequence or polling algorithm without in-field firmware updates. Designers typically pair this MCU with a TVS-protected 5 V regulator and a CAN/LIN transceiver for chassis networking, where the PIC's deterministic 1 us instruction cycle keeps timing budgets predictable for ISO 7637-2 transient immunity tests.
Recommended
Industrial Appliance Control
In white-goods and small industrial appliances (coffee machines, fan controllers, washing-machine sub-modules), the PIC12C509A-04I/SN provides a deterministic 8-bit controller in a hand-solderable SOIC-8 footprint. Its 1 us instruction cycle at 4 MHz, combined with 33 single-word RISC instructions, allows tight timing loops for triac zero-crossing, PWM heating-element drive, and rotary-encoder debouncing without an RTOS. The 6 GPIO pins are sufficient to interface a keypad matrix, status LEDs, and a relay or SSR driver, while code protection secures the OEM firmware against copying. Typical designs add an optocoupler (MOC3021) for mains isolation and a TVS array for surge robustness, with the PIC handling all user-interface and safety-timer logic in 1.5 KB of OTP.
Recommended
Consumer Remote and Toy Electronics
The PIC12C509A-04I/SN's tiny 8-pin SOIC package, low cost, and OTP architecture make it an ideal controller for low-end consumer products such as IR remote controls, novelty toys, and battery-powered sensor tags. With 41 bytes of RAM and 1.5 KB of program memory, designers can implement button-scanning debouncing, IR carrier generation (typically 38 kHz), and simple state machines in a single chip. The 3.0 V to 5.5 V supply range accepts 2 x AA alkaline cells directly without a boost converter, extending battery life while the PIC's hardware Watchdog Timer guards against ESD-induced lockups. The OTP memory is acceptable here because production volumes are high and the unit cost saving over Flash parts is significant.
Recommended
Sensor Interface and Signal Conditioning
For simple sensor-interface boards (thermistor-to-PWM, photodiode frequency counters, reed-switch pulse loggers), the PIC12C509A-04I/SN provides a programmable front end with a precise 8-bit TMR0 counter that can capture events up to the 4 MHz instruction rate. Its 6 GPIO pins can directly read a digital sensor and drive an isolated UART or LED indicator, while code protection locks the calibration constants in OTP. The Harvard RISC architecture's deterministic timing supports accurate frequency-to-digital conversion over multiple decades without floating-point overhead, and the industrial -40C to +85C rating suits outdoor and factory-floor deployments. The 8-pin SOIC footprint also makes hand-rework simple during prototype bring-up.
Recommended
LED Lighting Drivers
Small LED lighting controllers - decorative strips, indicator rings, status bars - benefit from the PIC12C509A-04I/SN's compact SOIC-8 package and 6 GPIO pins, which can drive Charlieplexed LED arrays of up to 12 LEDs or multiplexed 7-segment displays directly through current-limit resistors. The hardware TMR0 with 8-bit prescaler enables accurate PWM dimming and color-mixing algorithms, while code protection prevents design piracy. Operating from 3.0 V to 5.5 V, the MCU pairs cleanly with constant-current LED drivers on the high side while remaining software-compatible with development on the Flash-based PIC12F509.
Recommended
Battery-Powered IoT Edge Nodes
Low-duty-cycle IoT edge nodes - door/window sensors, smart-meter pulse loggers, environmental beacons - can leverage the PIC12C509A-04I/SN's deterministic 4 MHz core, hardware Watchdog Timer, and OTP memory to keep bill-of-materials cost under USD 1 while delivering years of battery life. The PIC spends most of its time in SLEEP mode with the WDT waking it every few seconds to poll a sensor and transmit via a sub-GHz or BLE module; this pattern keeps average current in the low-microamp range when paired with a low-Iq LDO. Code protection in OTP prevents firmware cloning, while the SOIC-8 footprint supports reflow and hand-solder assembly on compact PCBs.
Recommended
Educational and Hobbyist Projects
The PIC12C509A-04I/SN's 33-instruction RISC architecture, predictable 1 us cycle time, and broad hobbyist tool-chain support (MPLAB X, XC8, PICKit programmers) make it a popular teaching platform for embedded systems courses and Maker projects. The 8-pin SOIC footprint is breadboard-friendly with an SOIC-to-DIP adapter, and the small 1.5 KB OTP memory challenges students to write tight assembly or C code, building real-world firmware-budget awareness. Because OTP cannot be re-flashed, learners are encouraged to prototype on the Flash-based PIC12F509-I/SN first and then commit production code to the cost-optimized PIC12C509A-04I/SN.
Recommended
Recommended Products Summary
Engineering reference data for PIC12C509A-04I/SN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC12C509A-04/SN | PIC12C509A-04I/SM | PIC12C509A-04I/MF | PIC12F509-I/SN |
|---|---|---|---|---|---|
| Package | 8-pin SOIC (SN) 150-mil | 8-pin SOIC (SN) 150-mil | 8-pin SOIJ (SM) 208-mil | 8-pin DFN (MF) | 8-pin SOIC (SN) 150-mil |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB OTP | 1.5 KB Flash |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Temperature Grade | Industrial -40C to +85C (I) | Commercial 0C to +70C | Industrial -40C to +85C (I) | Industrial -40C to +85C (I) | Industrial -40C to +85C (I) |
| RAM | 41 bytes | 41 bytes | 41 bytes | 41 bytes | 41 bytes |
| I/O Pins | 6 | 6 | 6 | 6 | 6 |
| Watchdog Timer | Yes (dedicated RC oscillator) | Yes (dedicated RC oscillator) | Yes (dedicated RC oscillator) | Yes (dedicated RC oscillator) | Yes (dedicated RC oscillator) |
| In-Circuit Reprogrammable | No (OTP) | No (OTP) | No (OTP) | No (OTP) | Yes (Flash) |
Key Differentiators
- Industrial -40C to +85C rating in standard 150-mil SOIC footprint (vs PIC12C509A-04/SN)
- Code protection in OTP locks firmware in place for cost-sensitive production (vs PIC12F509-I/SN)
- Dedicated on-chip RC Watchdog Timer independent of system clock (vs PIC12C509A-04E/SN)
- Compact 8-pin SOIC supports hand-soldering and 150-mil reflow (vs PIC12C509A-04I/MF)
Design Notes
OTP memory cannot be erased - any bit written incorrectly is permanent. Prototype and debug on the Flash-based PIC12F509-I/SN first (pin-compatible in SOIC-8), verify the hex image on a final test fixture, and only then commit to programming the PIC12C509A-04I/SN. Always read the device ID back after the OTP write cycle to confirm the silicon revision matches the programmer algorithm.
Place a 0.1 uF decoupling capacitor as close as possible to the VDD pin (pin 8) with a short, wide ground return to VSS (pin 4). For designs using an external crystal or resonator on GP5/OSC1/CLKIN and GP4/OSC2/CLKOUT, keep the traces short and surrounded by a grounded guard ring to minimize EMI pickup. The MCLR/VPP pin (pin 3) typically needs a 10 kohm pull-up to VDD and a 100 nF cap to ground for in-system ICSP.
The PIC12C509A-04I/SN operates from 3.0 V to 5.5 V; for 12 V automotive or 24 V industrial rails, use an MCP1700 (3.3 V or 5 V) or equivalent low-dropout regulator ahead of VDD. Add a TVS diode (e.g. SMAJ5.0CA) and series ferrite bead to survive load-dump and ESD transients per ISO 7637-2. The PIC's hardware Watchdog Timer should be enabled in any unattended application to recover from brown-out events.
When using GP3/MCLR/VPP as an input-only GPIO, ensure the MCLR function is disabled in the configuration word if you do not need an external reset, otherwise spurious resets may occur from noise on that pin. For analog comparator inputs (GP1/AN0, GP2/AN1), add a small RC filter (e.g. 1 kohm + 100 nF) to reject switching noise from adjacent digital lines, especially in motor-drive applications.
Compliance Information
RoHS and lead-free per Microchip product page and JLCPCB listing. The "I" suffix denotes industrial -40C to +85C temperature grade; AEC-Q100 qualification is not claimed by Microchip for this baseline 8-bit OTP part.
