PIC12C509AT-04/SM - 8-Bit 4MHz OTP MCU 1.5KB | Microchip
MPN: PIC12C509AT-04/SM ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.65 | $1.65 |
| 10 | $1.48 | $14.80 |
| 100 | $1.32 | $132.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $1.05 | $1,050.00 |
PIC12C509AT-04/SM Overview
What is an 8-bit OTP microcontroller? An 8-bit microcontroller is a small computing system on a single integrated circuit, featuring an 8-bit data path, integrated CPU, memory, and peripherals. The OTP (One-Time Programmable) memory is a type of non-volatile memory that can be written once and cannot be erased, making these MCUs cost-optimized for high-volume embedded products. The PIC® 12C family belongs to the broader category of microcontrollers, which sit within embedded processors and digital ICs in the semiconductor hierarchy. The 'PIC' RISC (Reduced Instruction Set Computer) architecture uses only 33 single-word instructions, simplifying firmware development.
Key features of the PIC12C509AT-04/SM include 4 MHz maximum operating frequency with 1 µs instruction execution, 3.0V to 5.5V operating voltage range, internal 4 MHz RC oscillator eliminating the need for external timing components, 6 GPIO pins with high-current sink/source capability, and 1,000,000 erase/write cycle endurance on EPROM. The on-chip peripherals include a real-time clock/counter (TMR0) with 8-bit programmable prescaler, watchdog timer with dedicated RC oscillator for reliable operation, programmable code protection, and in-circuit serial programming (ICSP) capability.
The device uses a Harvard architecture with separate program and data buses, enabling simultaneous instruction fetch and data access. The CMOS process technology delivers low power consumption suitable for battery-powered applications, and the integrated oscillator reduces external component count. The PIC12C509AT-04/SM is engineered for compact, low-cost embedded designs where its small 8-pin SOIJ footprint and minimal external BOM provide significant PCB area savings.
Typical applications include consumer electronics remote controls, small appliance controllers, simple sensor interfaces, battery-operated devices, automotive subsystems (non-safety-critical), and LED lighting controllers. The 8-pin form factor and integrated peripherals make it particularly well-suited for space-constrained designs.
When designing with this device, consider that OTP memory cannot be reprogrammed, so code must be fully validated before programming. Decoupling capacitors (typically 0.1 µF) should be placed close to VDD, and unused I/O pins should be configured as outputs to minimize power consumption.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, providing engineers with actionable component selection guidance.
Drop-in alternatives for PIC12C509AT-04/SM — 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/SM (same form factor and footprint) — differing in Timers, Program Memory Size, Operating Temperature Range, Package, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC12C509A-04/SM
✅ Drop-In✓ In Stock
$0.99 / Unit
View Datasheet →PIC12C509A-04I/SM
✅ Drop-In✓ In Stock
$0.93 / Unit
View Datasheet →PIC12C509A-04E/SM
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC12C509-04/P
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC12C508A-04I/SM
✅ Drop-In✓ In Stock
$1.05 / Unit
View Datasheet →PIC12C508AT-04E/SM
✅ Drop-In✓ In Stock
$0.36 / Unit
View Datasheet →PIC12C509AT-04/SM Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC® 12C |
| Core Processor | PIC |
| Core Size | 8-Bit |
| Program Memory Size | 1.5 KB (1K x 12 words) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 41 bytes |
| EEPROM Size | 0 bytes (not available) |
| Maximum CPU Frequency | 4 MHz |
| Instruction Execution Time | 1 µs |
| Number of I/O Pins | 6 |
| Supply Voltage Range | 3.0 V to 5.5 V |
| Operating Temperature Range | 0 °C to +70 °C |
| Timers | 1 x 8-bit (TMR0) with programmable prescaler |
| Watchdog Timer | Yes (with dedicated on-chip RC oscillator) |
| Oscillator Type | Internal 4 MHz RC |
| Package / Case | 8-SOIJ (5.30 mm width) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Number of Instructions | 33 single-word instructions |
| Code Protection | Programmable |
PIC12C509AT-04/SM Pin Configuration
| Pin 1 | GP5/OSC1/CLKIN — General-purpose I/O pin 5 / Oscillator input / External clock input |
| Pin 2 | GP4/OSC2 — General-purpose I/O pin 4 / Oscillator output |
| Pin 3 | GP3/MCLR/VPP — General-purpose I/O pin 3 (input-only) / Master Clear reset / Programming voltage |
| Pin 4 | VSS — Ground reference |
| Pin 5 | GP0 — General-purpose I/O pin 0 / ICSP data |
| Pin 6 | GP1 — General-purpose I/O pin 1 / ICSP clock |
| Pin 7 | GP2 — General-purpose I/O pin 2 |
| Pin 8 | VDD — Positive supply voltage (3.0V to 5.5V) |
Typical Applications
PIC12C509AT-04/SM is suitable for 6 applications: Consumer Remote Controls, Small Appliance Controllers, Battery-Powered Sensor Nodes, LED Lighting Controllers, Automotive Accessory Modules, Simple Sensor Interface Modules.
Consumer Remote Controls
The PIC12C509AT-04/SM is well-suited for infrared remote control transmitters used in TVs, set-top boxes, and audio equipment. The 4 MHz CPU and 1.5 KB OTP memory easily handle IR protocol encoding (RC5, NEC, SIRC), button scanning matrices, and battery-low detection algorithms. With 6 GPIO pins, the device can directly scan up to 6 buttons or drive a 3x3 matrix with minimal external components. The 3.0-5.5V operating range supports 2-cell alkaline or single-cell lithium battery supplies directly. The integrated 4 MHz RC oscillator eliminates the external ceramic resonator, reducing BOM cost by 15-20 cents per unit in high-volume production.
Recommended
Small Appliance Controllers
The PIC12C509AT-04/SM serves as the main controller in small household appliances such as coffee makers, toasters, fans, and humidifiers. Its 8-pin SOIJ package occupies minimal PCB area in space-constrained consumer products. The 25 mA per-pin sink/source capability directly drives small relays, solenoids, and LED indicators without external driver transistors. The 8-bit TMR0 with programmable prescaler provides accurate timing for motor PWM control, heating element duty cycling, and countdown timers. OTP memory ensures firmware integrity in harsh appliance environments where Flash bit-flip risk exists near high-voltage switching nodes.
Recommended
Battery-Powered Sensor Nodes
The PIC12C509AT-04/SM is ideal for low-duty-cycle wireless sensor endpoints transmitting temperature, humidity, or contact-closure data. The CMOS process and 3.0V minimum supply allow operation from two fresh alkaline cells down to 2.0V with voltage boost converters. The watchdog timer with dedicated RC oscillator enables sleep-mode operation where the MCU wakes periodically, reads a sensor, transmits via an external radio, and returns to sleep with sub-microamp current draw. OTP memory is acceptable for fixed-function sensor endpoints where the firmware is stable across the entire product lifecycle. The 1.5 KB program memory accommodates simple protocol stacks like proprietary RF or basic LoRaWAN device drivers.
Recommended
LED Lighting Controllers
The PIC12C509AT-04/SM drives decorative LED chains, under-cabinet lighting strips, and seasonal lighting products. Its 6 GPIO pins with 25 mA per-pin capability can directly drive multiple LED segments with appropriate current-limiting resistors. The TMR0 with prescaler enables precise PWM dimming at frequencies above 100 Hz to eliminate visible flicker. The 1.5 KB program memory supports multiple lighting patterns, fade effects, and color sequences for RGB LED products. The 3.0-5.5V supply range accommodates both 5V USB-powered and 3V battery-powered LED products without additional voltage regulation. OTP memory prevents accidental firmware corruption during EMI events from PWM switching.
Recommended
Automotive Accessory Modules
The PIC12C509AT-04/SM can be deployed in non-safety-critical automotive accessories such as interior lighting controllers, door-lock actuators, mirror positioners, and seat-heater switches. While the commercial 0-70 °C temperature range is sufficient for cabin-mounted modules, under-hood applications should select the PIC12C509A-04I/SM (industrial -40 to +85 °C) or PIC12C509A-04E/SM (extended -40 to +125 °C) variants. The OTP memory and small 8-pin package provide excellent cost-effectiveness for high-volume automotive aftermarket products. The integrated watchdog timer ensures reliable operation in the electrically noisy automotive environment where voltage transients and load dumps are common.
Recommended
Simple Sensor Interface Modules
The PIC12C509AT-04/SM operates as a dedicated signal-conditioning and alarm-generation module for industrial sensors including limit switches, photoelectric sensors, and proximity detectors. Its 6 GPIO pins support multiple digital inputs plus status LED outputs in a compact form factor. The integrated 4 MHz RC oscillator eliminates timing component procurement for cost-sensitive industrial products. The watchdog timer with dedicated RC oscillator ensures the module recovers automatically from software lockup conditions. The 1.5 KB program memory accommodates sensor debouncing, hysteresis algorithms, and Modbus or simple serial communication protocols. OTP memory prevents field firmware tampering in industrial installation environments.
Recommended
Recommended Products Summary
Engineering reference data for PIC12C509AT-04/SM — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC12C509A-04/SM | PIC12C509A-04I/SM | PIC12C509A-04E/SM | PIC12C509-04/P | PIC12C508A-04I/SM |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 8-SOIJ | 8-SOIJ (same) | 8-SOIJ (same) | 8-SOIJ (same) | 8-PDIP (through-hole, different footprint) | 8-SOIJ (same) |
| Program Memory | 1.5 KB (1K x 12) | 1.5 KB (1K x 12) | 1.5 KB (1K x 12) | 1.5 KB (1K x 12) | 1.5 KB (1K x 12) | 750 B (512 x 12) -50% |
| CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| RAM | 41 bytes | 41 bytes | 41 bytes | 41 bytes | 41 bytes | 25 bytes |
| I/O Pins | 6 | 6 | 6 | 6 | 6 | 6 |
| Operating Temperature | 0 °C to +70 °C | 0 °C to +70 °C | -40 °C to +85 °C | -40 °C to +125 °C | 0 °C to +70 °C | -40 °C to +85 °C |
| Memory Type | OTP | OTP | OTP | OTP | OTP | OTP |
Key Differentiators
- Lowest-cost 1.5 KB OTP MCU in 8-pin SOIJ from Microchip (vs PIC12C508A-04I/SM)
- Industrial temperature grade variant available in same package (vs PIC12C509A-04I/SM)
- Extended temperature variant for under-hood automotive use (vs PIC12C509A-04E/SM)
Design Notes
Place a 0.1 µF decoupling capacitor as close as possible to the VDD pin (Pin 8) with the ground lead returning directly to VSS (Pin 4). For applications with significant GPIO switching transients, add a bulk capacitor of 1-10 µF in parallel. The PIC12C509AT-04/SM does not have internal power-on reset delay capacitor support, so an external RC network may be required if the supply rise time exceeds the POR threshold specification per Microchip datasheet DS40139D.
OTP memory cannot be reprogrammed, so all firmware bugs discovered after programming result in scrapped parts. Per Microchip datasheet DS40139D, verify the entire firmware on equivalent Flash-based PIC12F509 or PIC10F202 devices before committing to OTP production programming. Use the CONFIG register to enable code protection and disable the watchdog timer only if your application does not require it - enabling the WDT requires the CLRWDT instruction in long main loops.
The 8-SOIJ package requires careful PCB layout due to its small 5.30 mm body width and lead pitch. Follow IPC-7351 land pattern recommendations with at least 0.2 mm annular ring around each pad. Keep high-current switching traces (relay coils, motor drivers) away from the oscillator pins (GP4/OSC2 and GP5/OSC1/CLKIN) to prevent noise coupling. The exposed die pad (if present in the SOIJ variant) should be soldered to a grounded copper pour for thermal dissipation, though the PIC12C509AT-04/SM typically dissipates less than 100 mW even at full GPIO load.
GP3/MCLR/VPP (Pin 3) is input-only and serves as the Master Clear reset. Connect MCLR directly to VDD through a 10 kΩ pull-up resistor, or if reset is not needed, connect it directly to VDD. For ICSP programming, route the ICSPDAT (GP0) and ICSPCLK (GP1) signals to a programming header with no series resistors, keeping traces short to minimize signal integrity issues during high-voltage (VPP ~13V) programming per Microchip programming specification.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - automotive applications should use PIC12C509A-04E/SM for -40 to +125C operation. OTP memory architecture, not suitable for in-field firmware updates.
