PIC16C621A-20E/SS - 8-Bit 20MHz 1.75KB OTP MCU | Microchip
MPN: PIC16C621A-20E/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.45 | $6.45 |
| 10 | $5.78 | $57.80 |
| 100 | $5.05 | $505.00 |
| 500 | $4.5 | $2,250.00 |
| 1,000 | $4.12 | $4,120.00 |
PIC16C621A-20E/SS Overview
An 8-bit microcontroller is a single-chip computer that integrates a CPU, memory, and peripherals on one die; in the broader hierarchy it sits within microcontrollers, which in turn belong to integrated circuits and the semiconductor category. The PIC16C621A family targets cost-sensitive embedded applications where deterministic instruction execution and small code size outweigh the need for large memory. Built on Microchip's original PIC RISC architecture with only 35 single-word instructions, this MCU is also exceptionally easy to program.
Key features include 100 ns instruction execution time, 13 I/O pins with individual direction control, two on-chip analog comparators with configurable reference, an internal watchdog timer, power-on reset, and brown-out detection. The device supports in-circuit serial programming (ICSP) via RB6/RB7, allowing firmware updates without removing the part from the board.
The PIC16C621A architecture uses a Harvard-style design with separate program and data buses, enabling simultaneous instruction fetch and operand access. The 14-bit wide instruction word improves code density compared to 12-bit PIC cores, while the OTP EPROM memory allows fast prototype-to-production transitions on the same die. The comparator module can wake the part from Sleep, enabling ultra-low standby power in battery-fed designs.
Typical applications include appliance control panels, automotive sensor interfaces, HVAC fan controllers, battery chargers, and simple human-machine interface boards. The wide operating temperature range makes it suitable for both commercial and industrial environments.
When designing with the PIC16C621A-20E/SS, ensure VDD decoupling uses a 0.1 uF ceramic capacitor placed within 5 mm of the supply pin, and keep the MCLR pin pulled high through a 10 kohm resistor to avoid spurious resets. The Extended (E) temperature grade supports -40 C to +125 C operation, so the part is appropriate for automotive and industrial deployments.
This page synthesizes current distributor pricing, drop-in alternatives from Microchip's 20-pin SSOP PIC family, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for PIC16C621A-20E/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-20E/SS (same form factor and footprint) — differing in Instruction Set, Package, Program Memory Type, Core Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C621-20E/SS
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16C620A-20E/SS
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →PIC16C621A-20/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C620T-20E/SS
✅ Drop-In✓ In Stock
$3.89 / Unit
View Datasheet →PIC16F628A-20E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F88-20E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621A-20E/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit CMOS Microcontroller (MCU) |
| Core Architecture | PIC (Harvard RISC) |
| Series | PIC16C |
| Program Memory | 1.75 KB (1K x 14) OTP EPROM |
| RAM | 96 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns |
| Supply Voltage (VDD) | 2.5 V to 5.5 V |
| I/O Pins | 13 |
| Analog Comparators | 2 |
| Package | 20-pin SSOP (5.30 mm body) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +125 C (Extended, "E" grade) |
| Instruction Set | 35 single-word instructions |
| In-Circuit Programming | ICSP (RB6/RB7) |
| MSL Level | 1 |
| RoHS Status | Compliant (per available distributor listings) |
PIC16C621A-20E/SS Pin Configuration
| Pin 1 | RA2/AN2 — PORTA bit 2 / analog comparator input |
| Pin 2 | RA3/AN3 — PORTA bit 3 / analog comparator input |
| Pin 3 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master Clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — PORTB bit 0 / external interrupt |
| Pin 7 | RB1 — PORTB bit 1 |
| Pin 8 | RB2 — PORTB bit 2 |
| Pin 9 | RB3 — PORTB bit 3 |
| Pin 10 | RB4 — PORTB bit 4 |
| Pin 11 | RB5 — PORTB bit 5 |
| Pin 12 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 13 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 14 | RA0/AN0 — PORTA bit 0 / analog comparator input |
| Pin 15 | RA1/AN1 — PORTA bit 1 / analog comparator input |
| Pin 16 | OSC1/CLKIN — Crystal oscillator input / external clock |
| Pin 17 | OSC2/CLKOUT — Crystal oscillator output / clock out |
| Pin 18 | VDD — Positive supply voltage (2.5 V to 5.5 V) |
| Pin 19 | VSS — Ground reference |
| Pin 20 | NC — Not connected on PIC16C621A 20-SSOP |
Typical Applications
PIC16C621A-20E/SS is suitable for 6 applications: Appliance Control Panels, Automotive Sensor Interfaces, HVAC Fan and Blower Controllers, Battery Chargers and Power Management, Human-Machine Interface (HMI) Boards, Industrial Sensor Conditioning Modules.
Appliance Control Panels
The PIC16C621A-20E/SS fits appliance control panels because its 13 I/O pins can directly drive LED indicators, 7-segment displays, and matrix keypads without external logic, while the 1.75 KB OTP program memory holds typical wash-cycle, cook-profile, or thermostat state machines. Its 20 MHz clock gives responsive button debouncing and PWM-style soft-start of relays. Two on-chip analog comparators handle zero-crossing detection for triac-driven loads. The wide 2.5 V to 5.5 V VDD range supports both 3.3 V logic interfaces and legacy 5 V relay drivers, simplifying BOM consolidation in white-goods designs.
Recommended
Automotive Sensor Interfaces
In automotive body and chassis modules the PIC16C621A-20E/SS serves as a low-cost sensor-front-end MCU because its Extended -40 C to +125 C temperature grade handles underhood environments, and the two analog comparators can directly condition NTC thermistor or Hall-effect sensors without external op-amps. The 13 I/O pins communicate via LIN, PWM, or simple GPIO to a body controller. 96 bytes of RAM are sufficient for filtering and decision logic in tire-pressure, ambient-light, or seat-occupancy modules. The 20-pin SSOP footprint is small enough for distributed ECUs placed close to the sensor.
Recommended
HVAC Fan and Blower Controllers
The PIC16C621A-20E/SS is well suited to HVAC blower control because its 20 MHz instruction rate lets the firmware execute closed-loop RPM control on a brushed or BLDC fan, while the two comparators sense back-EMF zero crossings or thermistor input for overtemperature shutdown. Its 2.5 V to 5.5 V operating range accommodates 24 VAC-derived DC rails after rectification. The Extended temperature grade survives attic and plenum mounting. The PIC RISC instruction set keeps the state machine compact enough to fit in 1.75 KB OTP, leaving headroom for soft-start curves and fault logging.
Recommended
Battery Chargers and Power Management
For sealed lead-acid or NiMH charger designs, the PIC16C621A-20E/SS hosts the charge algorithm in its 1.75 KB OTP memory, monitors battery voltage and current via the on-chip comparators, and drives a MOSFET or relay through its 13 I/O pins. Sleep current below 1 uA preserves shelf life when the charger is idle, and the watchdog timer plus brown-out reset protect against low-battery brown-outs. The 5 V operation matches most power-conversion auxiliary rails. Designers can implement CC/CV profiles, temperature-compensated float voltages, and LED status indication without external logic.
Recommended
Human-Machine Interface (HMI) Boards
In HMI boards for vending machines, access control, or industrial keypads, the PIC16C621A-20E/SS scans up to a 4x4 matrix keypad and drives multiplexed 7-segment or character LCDs using its 13 I/O pins and a simple Charlieplexing scheme, eliminating external display drivers. The 200 ns instruction cycle makes debounce and key-repeat logic trivial. The two analog comparators can monitor supply voltage or external sensor lines. ICSP via RB6/RB7 lets the same PCB be re-flashed during factory test, reducing time-to-market on keypad layout revisions.
Recommended
Industrial Sensor Conditioning Modules
Industrial 4-20 mA loop-powered sensor modules use the PIC16C621A-20E/SS to linearize thermocouple, RTD, or strain-gauge inputs, drive a 4-20 mA current loop, and implement HART or simple digital trim. The two comparators support window-discriminator inputs for fault detection, while the 13 I/O pins handle loop direction control and digital calibration inputs. Its wide 2.5 V to 5.5 V supply range tolerates the loose regulation of loop-derived rails. Extended temperature operation ensures long-term stability in factory-floor cabinets without active cooling.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621A-20E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C621-20E/SS | PIC16C620A-20E/SS | PIC16C621A-20/SS | PIC16F628A-20E/SS | PIC16F88-20E/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-SSOP | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same |
| Program Memory | 1.75 KB OTP (1K x 14) | 1.75 KB OTP | 0.875 KB OTP | 1.75 KB OTP | 2 KB Flash | 4 KB Flash |
| RAM | 96 bytes | 80 bytes | 96 bytes | 96 bytes | 224 bytes | 368 bytes |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| I/O Pins | 13 | 13 | 13 | 13 | 16 | 16 |
| Operating Temperature | -40 C to +125 C (Extended) | -40 C to +125 C (Extended) | -40 C to +125 C (Extended) | 0 C to +70 C (Commercial) | -40 C to +125 C (Extended) | -40 C to +125 C (Extended) |
| Supply Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| Memory Technology | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash | Flash |
Key Differentiators
- Highest-density OTP memory in 20-SSOP PIC16C family (vs PIC16C620A-20E/SS)
- Flash reprogrammability without changing the PCB (vs PIC16C621A-20/SS (commercial temperature variant))
- Two on-chip analog comparators reduce BOM cost (vs PIC16F88-20E/SS)
- Extended temperature grade for automotive and industrial (vs PIC16C621A-20/SS)
Design Notes
Place a single 0.1 uF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 20 on the 20-SSOP package). For noisy industrial or HVAC environments add a bulk 10 uF tantalum or aluminum polymer capacitor on the same rail. Keep the MCLR pull-up resistor at 10 kohm to VDD and place a 100 nF cap on MCLR to ground to filter short glitches; together these guarantee a clean Power-on Reset per the datasheet BOR specification.
Do not assume the two analog comparators behave like the PIC16F628 comparator module: register names differ, and the comparator output routing into Timer1 is configured through the CMCON register on PIC16C621A. When migrating firmware from a PIC16C621A prototype to a PIC16F628A production board, double-check the CMCON bits and TRIS settings. Also remember the PIC16C621A 20-SSOP pin 20 is typically NC on this package variant rather than VDD; verify against the package marking on your reel before routing.
Use a four-layer PCB with a continuous ground plane for any design switching above 1 MHz or driving AC loads. Keep the oscillator traces short (under 5 mm) and surround them with a ground guard ring to avoid injecting noise into the analog comparators. Route the ICSP pins RB6/PGC and RB7/PGD to a 2x3 0.1 inch header so production programming is straightforward, and place the MCLR test point on the same side. For automotive layouts add a TVS diode on VDD and MCLR to absorb inductive transients from the harness.
The PIC16C621A-20E/SS SSOP-20 package has a theta_JA around 100 C/W on a standard 2-layer JEDEC test board. Estimated: at 5 V VDD, 20 MHz active, and 2 mA ICC, the die dissipates roughly 10 mW, so self-heating is negligible. However, when the device is co-located with power MOSFETs on a small PCB, measure junction temperature under worst-case ambient; for industrial -40 C to +125 C operation the thermal margin is comfortable as long as ambient stays below +115 C with no airflow.
Compliance Information
RoHS and lead-free status inferred from Microchip product family statements and Hotenda listing for the 20-SSOP package. AEC-Q100 qualification not stated in available data; the PIC16C family is industrial/consumer grade only.