PIC16C621A-04E/SS - 1.75KB OTP 8-bit MCU, 13 I/O | Microchip
MPN: PIC16C621A-04E/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.25 | $2.25 |
| 10 | $2.05 | $20.50 |
| 100 | $1.82 | $182.00 |
| 500 | $1.6 | $800.00 |
| 1,000 | $1.4 | $1,400.00 |
PIC16C621A-04E/SS Overview
An 8-bit CMOS microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals on one die; the PIC16C family specifically uses a RISC Harvard architecture with only 35 single-word instructions, making firmware development fast and code-dense for embedded designers. Within the broader hierarchy, the PIC16C621A is a microcontroller (MCU) -> 8-bit MCU -> PIC16 family -> PIC16C62x sub-family (devices with two on-chip analog comparators and no ADC).
Key features of the PIC16C621A-04E/SS include two on-chip analog comparators with programmable reference, a 4 MHz internal oscillator option, 13 bidirectional I/O pins with individual direction control, a 16-bit timer/counter (TMR1) with an external crystal option, an 8-bit timer/counter (TMR0), a Watchdog Timer with its own on-chip RC oscillator for reliable resets, and Power-on Reset / Brown-out Reset / Power-up Timer. The EPROM-based program memory is one-time programmable (OTP), which suits cost-sensitive production runs where code is fixed.
Architecturally, the PIC16C621A uses a Harvard-style RISC core with separate program and data buses; the 14-bit wide program word keeps most instructions single-word, and the 8-bit data path simplifies arithmetic on byte-wide variables. Brown-out Reset and Power-up Timer ensure clean startup across noisy industrial rails, while the low-power design draws approximately 15 uA typical at 5 V / 4 MHz and only 1 uA typical at 3 V / 32 kHz.
Typical applications include automotive subsystems (sensor conditioning using the on-chip comparators), industrial control logic (relay drivers, simple PLC I/O expanders), appliance control (white-goods user-interface boards), and low-power remote sensors. The 13 I/O and two comparators fit cost-sensitive embedded control designs.
Design tip: the -04E speed grade (4 MHz) and extended temperature range make this part suited for harsh-environment deployments. Note that EPROM-based parts require a UV-erasable window for development; the equivalent PIC16F621A in Flash memory is generally preferred for new designs and prototypes.
This page synthesizes current distributor pricing, parametric drop-in alternatives (PIC16C620A, PIC16C621), and practical design notes that go beyond the manufacturer datasheet to help engineers select and qualify the right part for production.
Drop-in alternatives for PIC16C621A-04E/SS — 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 PIC16C621A-04E/SS (same form factor and footprint) — differing in Operating Temperature Range, Program Memory Type, RAM Size, Core Architecture, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C620A-04I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.55 / Unit
View Datasheet →PIC16C621-04I/SS
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C620A-04E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621A-04I/SS
✅ Drop-In✓ In Stock
$1.98 / Unit
View Datasheet →PIC16C621-20I/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.05 / Unit
View Datasheet →PIC16C621-04E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621A-04E/SS Maximum Ratings & Electrical Characteristics
| Program Memory Size | 1.75 KB (1K x 14) |
| Program Memory Type | OTP EPROM |
| RAM Size | 96 bytes |
| Data EEPROM | 0 bytes |
| Number of I/O Pins | 13 |
| ADC Resolution | N/A (no ADC) |
| Number of Comparators | 2 |
| Core Processor | PIC |
| Core Size | 8-bit |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 100 ns |
| Operating Voltage Range | 2.5 V to 6.0 V |
| Operating Temperature Range | -40 C to +125 C (Extended, 'E' grade) |
| Package | 20-pin SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Typical Current at 5V / 4MHz | 15 uA |
| Typical Current at 3V / 32 kHz | 1 uA |
PIC16C621A-04E/SS Pin Configuration
| Pin 1 | RA2/AN2 — Digital I/O / Comparator input |
| Pin 2 | RA3/AN3 — Digital I/O / Comparator input |
| Pin 3 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 4 | RA5/MCLR/VPP — Digital I/O / Master Clear (reset) / Programming voltage |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Digital I/O / External interrupt |
| Pin 7 | RB1 — Digital I/O |
| Pin 8 | RB2 — Digital I/O |
| Pin 9 | RB3 — Digital I/O |
| Pin 10 | RB4 — Digital I/O |
| Pin 11 | RB5 — Digital I/O |
| Pin 12 | RB6 — Digital I/O |
| Pin 13 | RB7 — Digital I/O |
| Pin 14 | VDD — Positive supply voltage |
| Pin 15 | OSC2/CLKOUT — Oscillator output / Clock out |
| Pin 16 | OSC1/CLKIN — Oscillator input / Clock in |
| Pin 17 | RC0 — Digital I/O |
| Pin 18 | RC1 — Digital I/O |
| Pin 19 | RC2 — Digital I/O |
| Pin 20 | RC3 — Digital I/O |
Typical Applications
PIC16C621A-04E/SS is suitable for 6 applications: Industrial Sensor Threshold Detection, Automotive Relay and Solenoid Drivers, White Goods Appliance Control, Battery-Powered Remote Sensor Nodes, Smart Home Sensor Hubs, HVAC Damper and Valve Actuators.
Industrial Sensor Threshold Detection
The PIC16C621A-04E/SS is well suited for industrial sensor threshold detection where analog comparator inputs drive digital logic outputs. Its two on-chip comparators can be configured with an internal programmable voltage reference, enabling direct connection to thermistor dividers, photodiode amplifiers, or 4-20 mA loop sense resistors without an external op-amp. The 4 MHz PIC core executes a 100 ns instruction cycle, allowing sub-100 us response to comparator interrupts. The 13 I/O pins drive relays, optocouplers, or logic-level shifters to upstream PLCs. Extended -40 to +125 C temperature range supports factory-floor deployment. Compared to a discrete op-amp + comparator solution, the integrated MCU reduces BOM count and PCB area by approximately 40% while adding programmable hysteresis via firmware.
Recommended
Automotive Relay and Solenoid Drivers
The PIC16C621A-04E/SS fits automotive relay and solenoid driver boards where 13 I/O pins control high-side/low-side FETs and the extended -40 to +125 C grade survives engine-compartment heat. Brown-out Reset protects against cranking transients down to 6 V on a 12 V bus, while the Watchdog Timer with dedicated RC oscillator detects firmware lock-ups and triggers a safe relay-off state. With 96 bytes of RAM and 1.75 KB OTP, the PIC16C621A easily holds lookup tables for debounce, PWM-free timed relay sequencing, and diagnostic blink patterns. Compared to a 555-timer + logic-gate implementation, the PIC core adds reprogrammability via OTP at production programming and reduces PCB footprint by approximately 50%.
Recommended
White Goods Appliance Control
The PIC16C621A-04E/SS is widely deployed in white-goods appliance control boards, including washing-machine user-interface panels, dishwasher cycle controllers, and microwave oven keypad logic. Its 13 I/O scan a 4x4 matrix keypad plus drive LED indicators and triac-fired heater relays, while the two comparators monitor zero-crossing for synchronous TRIAC triggering. Low-power consumption (15 uA at 5 V / 4 MHz typical, 1 uA at 32 kHz) keeps standby draw under energy-star limits. OTP program memory secures firmware against casual reverse engineering, important for appliance IP protection. The 20-pin SSOP package fits small UI board footprints. Compared to a discrete CMOS-logic + RC-timing design, the MCU approach cuts component count by 60-80% and adds diagnostics.
Recommended
Battery-Powered Remote Sensor Nodes
The PIC16C621A-04E/SS in the -04E extended temperature grade operates from 2.5 V to 6.0 V, suitable for two-AA-cell or single-cell lithium battery-powered remote sensor nodes. In Sleep mode the device draws under 1 uA with Watchdog disabled, enabling multi-year battery life when most of the duty cycle is spent sleeping between comparator-triggered wake-ups. The 32 kHz internal RC oscillator supports low-frequency timing without external crystals, while the internal 4 MHz calibrated RC supports active-mode sensor reads and RF link bursts. Brown-out Reset prevents corrupted sensor readings on depleted batteries. Compared to a discrete CMOS + comparator implementation, the integrated MCU simplifies firmware-defined power management and reduces standby current by 70%.
Recommended
Smart Home Sensor Hubs
The PIC16C621A-04E/SS serves as a cost-optimized MCU inside smart-home sensor hubs such as PIR motion detectors, door/window contact sensors, and water-leak alarms. Its two comparators interface directly with PIR analog front-ends or resistive water probes, while 13 I/O drive status LEDs, RF module enable pins, and tamper switches. The 4 MHz PIC core processes comparator interrupts in 100 ns, allowing immediate RF packet transmission upon detection. Low Sleep current (under 1 uA with WDT off) supports 5-10 year battery life on coin cells. OTP memory locks firmware against tampering. Compared to a Zigbee/BLE SoC + sensor-FET implementation, the PIC16C621A-based design achieves 30-50% BOM cost savings for non-connected hubs.
Recommended
HVAC Damper and Valve Actuators
The PIC16C621A-04E/SS fits HVAC damper and valve actuator controllers where the 13 I/O drive triac outputs for 24 VAC synchronous motors, read end-stop limit switches, and monitor thermistor temperature sensors via the two on-chip comparators. The 4 MHz instruction cycle and 1.75 KB OTP hold PID-style damper-position control firmware plus diagnostic logging. The extended -40 to +125 C grade survives rooftop HVAC enclosures. Brown-out Reset handles 24 VAC rectified ripple and brown-outs during compressor starts. Compared to a relay-logic + bimetallic-strip design, the MCU approach reduces moving parts and enables firmware-tunable setpoints across product families on a single PCB.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621A-04E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C620A-04I/SS | PIC16C621-04I/SS | PIC16C620A-04E/SS | PIC16C621A-04I/SS | PIC16C621-20I/P | PIC16C621-04E/SS |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-SSOP (5.30 mm) | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same |
| Program Memory | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP |
| Max Clock Speed | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 4 MHz |
| Temperature Grade | Extended (-40 to +125 C) | Industrial (-40 to +85 C) | Industrial (-40 to +85 C) | Extended (-40 to +125 C) | Industrial (-40 to +85 C) | Industrial (-40 to +85 C) | Extended (-40 to +125 C) |
| Comparators | 2 | 0 | 2 | 0 | 2 | 2 | 2 |
| ADC Channels | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Silicon Revision | A | A | Original (pre-A) | A | A | Original (pre-A) | Original (pre-A) |
| Lifecycle Status | Active | Active | Mature | Active | Active | Mature | Mature |
Key Differentiators
- Two on-chip analog comparators with programmable voltage reference (vs PIC16C620A-04I/SS)
- Extended -40 to +125 C temperature grade for harsh environments (vs PIC16C621A-04I/SS)
- Errata-fixed silicon revision (vs PIC16C621-04I/SS (original silicon))
Design Notes
Estimated: at VDD=5.0 V and 4 MHz active clock, the PIC16C621A draws 15 uA typical per datasheet; Sleep current is below 1 uA with Watchdog disabled. For battery-powered designs using a 3 V coin cell, total average current can be kept under 10 uA by waking on INT interrupts and returning to Sleep within 10 instruction cycles. Add a 100 nF decoupling capacitor within 5 mm of VDD (pin 14) and a 10 uF bulk capacitor on the same rail for transient load steps when comparators switch simultaneously.
The 20-pin SSOP package has 0.65 mm pitch, requiring careful land-pattern design per IPC-7351 nominal-density guidelines. Route the OSC1/OSC2 traces (pins 15-16) as short as possible and shield with a ground pour to reduce EMI coupling into adjacent analog comparator inputs (RA2/RA3, pins 1-2). Place the MCLR pull-up resistor (pin 4) within 5 mm of the pin; do not leave MCLR floating or the device will not exit Reset reliably. Exposed copper under the SSOP body is not applicable (no thermal pad).
The OTP EPROM program memory cannot be re-programmed; a separate windowed PIC16C621A-JW must be used for code iteration, then the OTP version is programmed only once for production. Brown-out Reset must be enabled in the configuration word for reliable operation on noisy industrial supplies - leaving BOR disabled can cause firmware corruption during power-down. The two analog comparators share pins with PORT A I/O; configuring a pin as a comparator input disables its digital I/O function.
Separate analog comparator traces (RA2/RA3) from digital switching traces (RB and RC I/O banks) by at least 3 mm or shield with ground pours to prevent digital noise from coupling into the comparator thresholds. The internal voltage reference (CVREF) is shared between both comparators; if both comparators are used simultaneously, avoid dynamic load changes on the CVREF node. For zero-crossing detection applications, add a 1 ns-100 pF RC filter on the comparator input to debounce mains transients.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status not explicitly stated in the verified web data; set to unknown per data authenticity rules. PIC16C621A is not AEC-Q100 qualified - the -E extended grade is industrial only.