PIC17C756AT-33I/L - 33MHz 8-Bit OTP MCU, 32KB, 50 I/O | Microchip
MPN: PIC17C756AT-33I/L ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.85 | $168.50 |
| 100 | $15.2 | $1,520.00 |
| 500 | $13.75 | $6,875.00 |
| 1,000 | $12.4 | $12,400.00 |
PIC17C756AT-33I/L Overview
A microcontroller (MCU) is an integrated circuit that combines a CPU core, non-volatile program memory, working RAM, and a set of on-chip peripherals behind a unified instruction set, allowing a single chip to replace dozens of discrete logic devices. The PIC17C family sits between Microchip's baseline PIC16C5X/PIC16CXX devices and the later PIC18F parts, adding a 16-bit-wide instruction word (which yields 32KB of code space from a single OTP array) while keeping an 8-bit data path and only 58 single-word instructions to learn. This positioning explains why PIC17C756A-series parts are still specified in long-lifecycle industrial designs even after the family was officially replaced by the PIC18F6520.
Key features of the PIC17C756AT-33I/L include 50 programmable digital I/O lines, 12 channels of 10-bit Analog-to-Digital conversion, a single-cycle 8-bit hardware multiplier, dual hardware PWM/Capture/Compare modules, an asynchronous serial port (USART), a synchronous serial port (SSP) for SPI/I2C, and a wide 4.5V to 5.5V supply range suited to industrial 5V rails. The /L suffix denotes the 68-pin PLCC (Plastic Leaded Chip Carrier, J-leaded, 24.23 x 24.23 mm) surface-mount package, and the /I industrial temperature grade spans -40C to +85C.
Architecturally, the PIC17C756A uses a RISC-style Harvard bus with separate program and data paths, an internal instruction pipeline, and an 8-level deep hardware stack, which together enable deterministic 121 ns instruction cycles except for two-cycle program branches and table reads/writes. The on-chip peripherals are mapped into the SFR space, and the 10-bit ADC includes dedicated sample-and-hold and programmable acquisition timing.
Typical applications include industrial automation controllers, motor control front-ends, instrumentation front panels, automotive body electronics (where the part was historically qualified in non-AEC-Q100 designs), HVAC control boards, and legacy embedded products that were designed around the PIC17C family before migrating to PIC18F. The combination of 50 I/O, 12 ADC channels, and a 5V-tolerant architecture makes it a frequent choice for sensor aggregation nodes.
When designing with this part, allow at least a 2-layer board with a solid ground pour under the PLCC footprint and place a 0.1 uF decoupling capacitor on every VDD/VSS pair. Because the device is OTP rather than flash, the firmware must be fully validated before programming - in-circuit reprogramming is not possible.
This page synthesizes current distributor stock, parametric cross-references, and application guidance for engineers who still need to source or design around the PIC17C756A family.
Drop-in alternatives for PIC17C756AT-33I/L — 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 PIC17C756AT-33I/L (same form factor and footprint) — differing in Core Architecture, Package, Data Bus Width, Program Memory Type, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C756A-33I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C756AT-33I/L024
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C756AT-33I/CL
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C756AT-33E/L
✅ Drop-In✓ In Stock
$10.4 / Unit
View Datasheet →PIC17C756AT-33I/L
✅ Drop-In✓ In Stock
$12.4 / Unit
View Datasheet →PIC17C756AT-33I/L Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC17C, 8-bit RISC (Harvard) |
| Instruction Word Width | 16-bit |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 32 KB (16K x 16) |
| Data RAM | 902 bytes |
| Maximum Clock Frequency | 33 MHz |
| Instruction Cycle Time | 121 ns (single-cycle, except branches/table reads) |
| Throughput | 8.25 MIPS |
| Supply Voltage (VDD) | 4.5 V to 5.5 V |
| I/O Pins | 50 programmable digital I/O |
| ADC | 12 channels x 10-bit |
| Hardware Multiplier | 8 x 8 single-cycle |
| PWM / CCP Modules | Dual Capture/Compare/PWM |
| Serial Interfaces | USART (async) + SSP (SPI / I2C) |
| Package | 68-pin PLCC (LCC-68), J-lead, 24.23 x 24.23 mm |
| Operating Temperature Range | -40 C to +85 C (Industrial / 'I' grade) |
| Mounting Type | Surface Mount (PLCC socket compatible) |
| RoHS Status | Not RoHS compliant (PLCC with matte-tin/lead finish historically) |
| Instruction Set | 58 single-word instructions |
PIC17C756AT-33I/L Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) input, active low |
| Pin 2 | OSC1 — Crystal oscillator / clock input |
| Pin 3 | OSC2 — Crystal oscillator output |
| Pin 4 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 5 | RA1/AN1 — Port A bit 1 / Analog input 1 |
| Pin 6 | RA2/AN2 — Port A bit 2 / Analog input 2 |
| Pin 7 | RA3/AN3 — Port A bit 3 / Analog input 3 |
| Pin 8 | RA4/AN4 — Port A bit 4 / Analog input 4 |
| Pin 9 | RA5/AN5 — Port A bit 5 / Analog input 5 |
| Pin 10 | AVDD — Analog VDD supply |
| Pin 11 | AVSS — Analog VSS ground |
| Pin 12 | VSS — Digital ground |
| Pin 13 | VDD — Digital supply |
| Pin 14 | RB0/INT — Port B bit 0 / External interrupt |
| Pin 15 | RB1 — Port B bit 1 |
| Pin 16 | RB2 — Port B bit 2 |
| Pin 17 | RB3 — Port B bit 3 |
| Pin 18 | RB4 — Port B bit 4 |
| Pin 19 | RB5 — Port B bit 5 |
| Pin 20 | RB6 — Port B bit 6 |
| Pin 21 | RB7 — Port B bit 7 |
| Pin 22 | VSS — Digital ground |
| Pin 23 | VDD — Digital supply |
| Pin 24 | RC0 — Port C bit 0 / CCP1 |
| Pin 25 | RC1 — Port C bit 1 / CCP2 |
| Pin 26 | RC2 — Port C bit 2 |
| Pin 27 | RC3 — Port C bit 3 / SCL (SSP) |
| Pin 28 | RC4 — Port C bit 4 / SDA (SSP) |
| Pin 29 | RC5 — Port C bit 5 / SDO (SSP) |
| Pin 30 | RC6 — Port C bit 6 / TX (USART) |
| Pin 31 | RC7 — Port C bit 7 / RX (USART) |
| Pin 32 | VSS — Digital ground |
| Pin 33 | VDD — Digital supply |
| Pin 34 | RD0 — Port D bit 0 |
| Pin 35 | RD1 — Port D bit 1 |
| Pin 36 | RD2 — Port D bit 2 |
| Pin 37 | RD3 — Port D bit 3 |
| Pin 38 | RD4 — Port D bit 4 |
| Pin 39 | RD5 — Port D bit 5 |
| Pin 40 | RD6 — Port D bit 6 |
| Pin 41 | RD7 — Port D bit 7 |
| Pin 42 | VSS — Digital ground |
| Pin 43 | VDD — Digital supply |
| Pin 44 | RE0/AN6 — Port E bit 0 / Analog input 6 |
| Pin 45 | RE1/AN7 — Port E bit 1 / Analog input 7 |
| Pin 46 | RE2/AN8 — Port E bit 2 / Analog input 8 |
| Pin 47 | RE3/AN9 — Port E bit 3 / Analog input 9 |
| Pin 48 | RE4/AN10 — Port E bit 4 / Analog input 10 |
| Pin 49 | RE5/AN11 — Port E bit 5 / Analog input 11 |
| Pin 50 | VSS — Digital ground |
| Pin 51 | VDD — Digital supply |
| Pin 52 | RF0 — Port F bit 0 |
| Pin 53 | RF1 — Port F bit 1 |
| Pin 54 | RF2 — Port F bit 2 |
| Pin 55 | RF3 — Port F bit 3 |
| Pin 56 | RF4 — Port F bit 4 |
| Pin 57 | RF5 — Port F bit 5 |
| Pin 58 | RF6 — Port F bit 6 |
| Pin 59 | RF7 — Port F bit 7 |
| Pin 60 | VSS — Digital ground |
| Pin 61 | VDD — Digital supply |
| Pin 62 | RG0 — Port G bit 0 |
| Pin 63 | RG1 — Port G bit 1 |
| Pin 64 | RG2 — Port G bit 2 |
| Pin 65 | RG3 — Port G bit 3 |
| Pin 66 | RG4 — Port G bit 4 |
| Pin 67 | T0CKI — Timer 0 clock input |
| Pin 68 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C756AT-33I/L is suitable for 7 applications: Industrial Automation Controllers, Motor Control Front-End, Instrumentation Front Panels, HVAC Control Boards, Sensor Aggregation Nodes, Legacy Embedded Maintenance, Automotive Body Electronics (Legacy).
Industrial Automation Controllers
The PIC17C756AT-33I/L's 50 programmable I/O lines, 12-channel 10-bit ADC, and dual Capture/Compare/PWM peripherals make it well-suited to industrial automation controllers that aggregate sensors and drive actuators from a single 5V rail. Its 8.25 MIPS throughput and 121 ns instruction cycle are sufficient for PID loops sampled at sub-millisecond rates, while the 32 KB OTP code space accommodates ladder-logic-equivalent C state machines. The 4.5V to 5.5V supply range aligns with legacy 24V industrial backplanes that regulate down to 5V.
Recommended
Motor Control Front-End
With dual PWM/CCP modules, an 8-bit hardware multiplier (single-cycle), and the 10-bit ADC's 12 analog inputs, the PIC17C756AT-33I/L can implement sensored or sensorless motor control for low- to mid-power BLDC, brushed DC, and stepper drives. The 33 MHz / 8.25 MIPS throughput supports trapezoidal commutation loops up to tens of kHz. Engineers should note that for higher-performance vector control, migration to a dsPIC33 part (e.g., DSPIC33EP64MC504) is recommended.
Recommended
Instrumentation Front Panels
The PIC17C756AT-33I/L integrates the CPU, code memory, RAM, ADC, and serial interfaces required to drive instrumentation front panels that combine a 7-segment or character-LCD display with pushbuttons and analog sensor inputs. Its USART (async) and SSP (SPI/I2C) peripherals simplify interfacing to backplane MCUs, display controllers, and digital sensors. The wide 5V tolerance and industrial -40C to +85C range suit benchtop and rack-mounted test equipment.
Recommended
HVAC Control Boards
HVAC control boards typically require multiple analog inputs (temperature, pressure, humidity transducers), digital outputs for relays and triac drivers, and serial communications for building-automation backbones - exactly the role profile of the PIC17C756AT-33I/L. Its 12 ADC channels cover multiple thermistor/sensor inputs, while 50 I/O drive fans, dampers, and triacs. The 5V operation and -40C to +85C industrial range match typical equipment-room environments.
Recommended
Sensor Aggregation Nodes
As a sensor aggregation node in legacy distributed I/O systems, the PIC17C756AT-33I/L reads multiple analog and digital sensors, performs local averaging/threshold processing in its 902-byte RAM, and reports results via USART or SSP. The 32 KB OTP code space supports simple MODBUS-RTU or vendor-proprietary protocols. The part's deterministic 121 ns instruction cycle makes it well-suited to time-stamped data acquisition where jitter must be minimized.
Recommended
Legacy Embedded Maintenance
The PIC17C756AT-33I/L remains in use for service and spare-part replacement of fielded industrial and medical equipment that was designed around the PIC17C family in the late 1990s. With Microchip now in last-time-buy for this part, EOL planning requires identifying pin-compatible variants (PIC17C756AT-33E/L for higher temp, PIC17C756A-33I/L for non-T&R) and modern replacements (PIC18F6520) for board redesigns. Functional testing must verify ADC linearity and I/O timing against the original design's qualification data.
Recommended
Automotive Body Electronics (Legacy)
Some legacy automotive body-electronics modules were designed around the PIC17C756A in the late 1990s and early 2000s. While the part is not AEC-Q100 qualified, it was deployed in cabin-mounted modules with relaxed thermal and qualification requirements. The 50 I/O and 12 ADC channels support multi-zone lighting control, seat/mirror positioning, and HVAC blend-door control. New automotive designs must use AEC-Q100-qualified parts such as PIC18F46K22 or dsPIC33EV parts.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C756AT-33I/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C756A-33I/L | PIC17C756AT-33I/L024 | PIC17C756AT-33I/CL | PIC17C756AT-33E/L |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 68-pin PLCC (LCC-68) | 68-pin PLCC (LCC-68) - same | 68-pin PLCC (LCC-68) - same | 68-pin PLCC (LCC-68), ceramic windowed - same | 68-pin PLCC (LCC-68) - same |
| Program Memory | 32 KB (16K x 16) OTP | 32 KB OTP - same | 32 KB OTP - same | 32 KB EPROM (windowed) | 32 KB OTP - same |
| RAM | 902 bytes | 902 bytes - same | 902 bytes - same | 902 bytes - same | 902 bytes - same |
| Maximum Clock | 33 MHz | 33 MHz - same | 33 MHz - same | 33 MHz - same | 33 MHz - same |
| I/O Pins | 50 | 50 - same | 50 - same | 50 - same | 50 - same |
| ADC Channels | 12 x 10-bit | 12 x 10-bit - same | 12 x 10-bit - same | 12 x 10-bit - same | 12 x 10-bit - same |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C - same | -40C to +85C - same | -40C to +85C - same | -40C to +125C (Extended) |
| Memory Type | OTP (one-time programmable) | OTP - same | OTP - same | Windowed EPROM (UV-erasable, prototype/debug) | OTP - same |
Key Differentiators
- Industrial temperature range with same silicon as E/L variant (vs PIC17C756AT-33E/L)
- OTP rather than windowed EPROM (vs PIC17C756AT-33I/CL)
- Pin-compatible with the broader PIC17C family migration path (vs PIC18F6520)
Design Notes
Decouple every VDD/VSS pair on the 68-pin PLCC with a 100 nF X7R ceramic placed as close to the package pin as possible; add a single 10 uF bulk tantalum or aluminum-polymer capacitor at the board's 5V entry. The PIC17C756AT-33I/L has multiple VDD/VSS pins distributed around the package to reduce internal ground bounce, and each one must be individually bypassed - relying on a single bulk cap will cause ADC noise and I/O glitches at high switching rates.
Place the 33 MHz crystal or resonator within 10 mm of the OSC1/OSC2 pins with short, symmetric traces and a guard ground ring. Keep digital switching traces (especially PWM and USART lines) away from the analog AN0-AN11 inputs and the AVDD/AVSS pair. If the design mixes analog and digital ports, route analog signals with a ground-shielded microstrip and place a small RC filter (10 ohm + 100 pF) on each ADC input to suppress transient injection from nearby digital edges.
Because the PIC17C756AT-33I/L is OTP, firmware bugs cannot be fixed in-circuit; every code revision requires a new device. Mitigate this by developing and qualifying firmware on the PIC17C756AT-33I/CL ceramic-windowed part (same silicon, UV-erasable), then transferring the verified image to OTP for production. Always order a small prototype batch of OTP parts and run full functional tests before committing to volume.
Estimated: at VDD = 5V and 33 MHz with all 50 I/O switching, supply current is approximately 50 mA (per datasheet ICC typical); power dissipation is therefore approximately 0.25 W, well within the 68-PLCC's thermal envelope (theta_JA around 50 C/W). At elevated ambient (>70C), verify junction temperature rise with a thermal probe in the application's worst-case I/O profile; the -40C to +85C industrial range provides adequate margin for cabinet-mounted designs.
Compliance Information
68-pin PLCC package historically uses SnPb (tin-lead) finish and is not RoHS compliant; PIC17C756A family is not AEC-Q100 qualified. For new RoHS or automotive designs, migrate to PIC18F6520 (RoHS, flash) or PIC18F46K22 (AEC-Q100).
