PIC12C509AT-04I/SN - 8-bit OTP MCU, 4MHz, 1.5KB | Microchip
MPN: PIC12C509AT-04I/SN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.38 | $138.00 |
| 500 | $1.21 | $605.00 |
| 1,000 | $1.05 | $1,050.00 |
PIC12C509AT-04I/SN Overview
An 8-bit microcontroller (MCU) is a small computer-on-a-chip that integrates a CPU, RAM, non-volatile program memory, and I/O peripherals on a single die. The PIC® 12C family belongs to the broader 8-bit MCU taxonomy (8-bit microcontroller -> microcontroller -> embedded processor -> semiconductor IC), and uses Microchip's RISC-style Harvard architecture. OTP program memory means the device is programmed once and cannot be electrically erased, making it well suited to high-volume, cost-sensitive end products where firmware is fixed.
Key features of the PIC12C509AT-04I/SN include a 4MHz internal oscillator, a 2.5V-5.5V wide supply-voltage range that supports both 3.3V and 5V rails, an 8-bit real-time clock/counter (TMR0) with programmable prescaler, Power-On Reset (POR), Device Reset Timer (DRT), a Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation, and programmable code protection. The industrial temperature rating (-40C to +85C) makes it suitable for harsh-environment deployments.
Architecturally, the part uses a 14-bit instruction word fetch but a 12-bit instruction set on the PIC12C509A, with a two-stage pipeline and 33 single-word instructions. The 6 I/O pins (GP0-GP5) share an interrupt-on-change capability, and the GP3 pin is input-only. With 41 bytes of data RAM, designs typically offload larger buffers to the EPROM program space or to external peripherals, and the 1000000 erase/write endurance figure applies to the EPROM-based (windowed) cousin rather than this OTP variant.
Typical applications include battery chargers, low-end remote controls, automotive courtesy lighting, simple sensor interfaces, fan controllers, and white-goods user-interface boards. Its tiny 8-pin footprint, wide voltage range, and integrated oscillator make it a popular choice for replacing discrete logic and 555-timer circuits in production-grade designs.
When designing with this part, pay close attention to the OTP-programming window in your production schedule - parts cannot be field-updated. The industrial-grade 'I' temperature suffix and the SOIC-8 'SN' package support standard 300mil reflow profiles, simplifying PCB assembly.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC12C509AT-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 PIC12C509AT-04I/SN (same form factor and footprint) — differing in Timers, Core Architecture, Package, Program Memory Size, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC12C509A-04I/SN
✅ Drop-In✓ In Stock
$0.92 / Unit
View Datasheet →PIC12C509AT-04/SN
✅ Drop-In✓ In Stock
$1.02 / Unit
View Datasheet →PIC12C509AT-04E/SN
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.25 / Unit
View Datasheet →PIC12C508A-04I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12C509AT-04I/SN Maximum Ratings & Electrical Characteristics
| Core | PIC 8-bit RISC |
| Core Size | 8-bit |
| Program Memory Type | OTP (One-Time-Programmable EPROM) |
| Program Memory Size | 1.5 KB (1K x 12) |
| RAM Size | 41 bytes |
| EEPROM Size | None |
| Clock Speed (Max) | 4 MHz |
| Instruction Cycle | 1 us (200 ns instruction execution, internal 4 MHz) |
| Supply Voltage Range | 2.5 V to 5.5 V |
| Number of I/O Pins | 6 (GP0-GP5, GP3 input-only) |
| Timers | 1 x 8-bit TMR0 with programmable prescaler |
| Watchdog Timer (WDT) | Yes, with dedicated on-chip RC oscillator |
| Oscillator Type | Internal 4 MHz RC |
| Package / Case | 8-SOIC (0.154 inch, 3.90 mm width) |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC12C509AT-04I/SN Pin Configuration
| Pin 1 | GP5/OSO/CLKOUT — Bidirectional I/O / OSC clock out |
| Pin 2 | GP4/OSC2 — Bidirectional I/O / oscillator output |
| Pin 3 | GP3/MCLR/Vpp — Input-only I/O / Master Clear (reset) / programming voltage |
| Pin 4 | GP2/T0CKI/INT — Bidirectional I/O / TMR0 clock input / external interrupt |
| Pin 5 | GP1 — Bidirectional I/O |
| Pin 6 | GP0 — Bidirectional I/O |
| Pin 7 | VSS — Ground reference |
| Pin 8 | VDD — Positive supply voltage (2.5V to 5.5V) |
Typical Applications
PIC12C509AT-04I/SN is suitable for 6 applications: Battery Charger Control, Remote Control / IR Transmitter, Automotive Courtesy Lighting, Sensor Interface / Smart Sensor Hub, Fan / Pump Speed Controller, White Goods User-Interface Board.
Battery Charger Control
The PIC12C509AT-04I/SN's 4MHz internal oscillator, 2.5V-5.5V wide supply range, and 6 GPIO pins make it well suited for low-cost NiMH or Li-ion charger controllers. Its 1.5KB OTP program memory comfortably holds a CC/CV charge state machine plus ADC-free voltage-divider thresholding, while the integrated 8-bit TMR0 handles charge-timer and -deltaV timebase functions. The Watchdog Timer with its own on-chip RC oscillator recovers the charger from firmware lockups caused by mains transients. At 8-SOIC the part drops onto a tiny footprint, and the 1us instruction cycle is fast enough for PWM drive of the pass element or relay control. Industrial temperature rating supports garage and outbuilding environments.
Recommended
Remote Control / IR Transmitter
With 1.5KB OTP and 6 GPIO, the PIC12C509AT-04I/SN can encode a multi-button IR protocol (RC-5, NEC, SIRC) using bit-banged TMR0 PWM on a single GPIO to drive an IR LED. The 4MHz internal oscillator and 1us instruction cycle give accurate 38kHz / 40kHz carrier generation without an external resonator, reducing BOM cost. The 2.5V-5.5V supply range supports both 3V coin-cell and 5V USB-powered remotes. Sleep current is low enough for battery-powered keyfob remotes, and the Watchdog Timer keeps the part recoverable if the carrier-generation ISR ever stalls.
Recommended
Automotive Courtesy Lighting
The PIC12C509AT-04I/SN's 6 GPIO are ideal for sequencing interior courtesy lamps, puddle lamps, and Puddle/Door-ajar indicator LEDs in entry-level automotive subsystems where AEC-Q100 is not mandated. Its 4MHz internal oscillator eliminates external clock components, the 8-SOIC footprint fits behind a door-switch housing, and TMR0 provides fade-in/fade-out PWM without software overhead. The 2.5V-5.5V supply range tolerates cranking transients when paired with a 5V regulator. Industrial temperature rating covers cabin environments.
Recommended
Sensor Interface / Smart Sensor Hub
For low-cost sensor-conditioning boards (temperature, humidity, contact closure), the PIC12C509AT-04I/SN offers 6 GPIO, 1.5KB OTP for linearization tables and threshold logic, and 4MHz throughput for polled sampling. A single GP pin can bit-bang a 1-Wire or I2C master to read a digital sensor, freeing firmware from external interface ICs. The wide 2.5V-5.5V supply range supports both 3.3V digital sensors and 5V analog front-ends, and the 8-SOIC pinout is friendly to hand-soldered prototypes as well as automated SMT lines.
Recommended
Fan / Pump Speed Controller
The PIC12C509AT-04I/SN drives a low-side N-FET or bipolar transistor for a brushed DC fan or small pump using TMR0-generated PWM on one GPIO, with a tach feedback input on another. Its 4MHz clock and 1us instruction cycle let it close a simple RPM-regulating loop without DSP overhead. 1.5KB of OTP holds the speed table and soft-start ramp, while the Watchdog Timer guards against stalled commutation events. The 2.5V-5.5V supply range and industrial temperature rating suit appliance and HVAC environments.
Recommended
White Goods User-Interface Board
Washing machines, dishwashers, and microwave ovens use the PIC12C509AT-04I/SN as a button-scan / LED-indicator MCU. The 6 GPIO scan a 3x3 keypad matrix or rotary encoder, drive status LEDs or a 7-segment via a serial LED driver, and TMR0 provides the debounce interval. The 4MHz internal oscillator removes the need for a crystal, and the 2.5V-5.5V supply range accepts rectified-and-regulated 5V or 3.3V rails from a small SMPS. Industrial temperature rating handles the inside of an appliance chassis.
Recommended
Recommended Products Summary
Engineering reference data for PIC12C509AT-04I/SN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC12C509A-04I/SN | PIC12C509AT-04/SN | PIC12C509AT-04E/SN | PIC12C508A-04I/SN |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 8-SOIC (SN) | 8-SOIC (SN) - same | 8-SOIC (SN) - same | 8-SOIC (SN) - same | 8-SOIC (SN) - same |
| Program Memory | 1.5 KB OTP | 1.5 KB OTP - same | 1.5 KB OTP - same | 1.5 KB OTP - same | 768 B OTP (-49%) |
| RAM | 41 bytes | 41 bytes - same | 41 bytes - same | 41 bytes - same | 25 bytes (-39%) |
| Clock Speed (Max) | 4 MHz | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same |
| Supply Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V - same | 2.5 V to 5.5 V - same | 2.5 V to 5.5 V - same | 2.5 V to 5.5 V - same |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +85 C - same | 0 C to +70 C (Commercial) | -40 C to +125 C (Extended) | -40 C to +85 C - same |
| Number of I/O | 6 | 6 - same | 6 - same | 6 - same | 6 - same |
Key Differentiators
- Industrial temperature rating in a same-package drop-in (vs PIC12C509AT-04/SN)
- 1.5KB of OTP vs 768B on the smaller cousin (vs PIC12C508A-04I/SN)
- Tape and Reel vs Tube packaging on the otherwise identical die (vs PIC12C509A-04I/SN)
Design Notes
The PIC12C509AT-04I/SN operates from 2.5V to 5.5V and includes a Power-On Reset (POR) and a Device Reset Timer (DRT). Place a 0.1 uF decoupling capacitor as close as possible to the VDD pin (pin 8), with a trace length below 5 mm to suppress VDD glitches. For battery applications, the supply current in SLEEP mode is typically in the microampere range, so a series resistor and bulk cap on VDD can support battery-isolation switching without losing the internal RAM contents.
GP3 (pin 3) is INPUT-ONLY on the PIC12C508/509 family and is also the MCLR/Vpp pin. Do not wire GP3 as an output - the datasheet pin description explicitly lists it as 'GP3/MCLR/Vpp' with no output driver. Pulling MCLR low resets the part; if the MCLR function is not needed, the pin can be used as a digital input only. Programming voltage Vpp is applied to this pin during OTP programming.
Keep the GP4/OSC2 trace short if using an external crystal/resonator; for the internal 4 MHz RC oscillator, GP4 can be used as a general-purpose bidirectional I/O. Route the ICSPDAT/ICSPCLK traces (typically on GP0/GP1) with adjacent ground to keep them noise-free during in-circuit serial programming. A 100 nF cap on VDD and a 10 kohm pull-up on MCLR (if used) are standard recommended values per the Microchip PIC12C509A datasheet family.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified; for AEC-Q100 automotive designs use a part from Microchip's automotive-qualified PIC families. Lead-free and halogen-free per Microchip material declaration.
