ATMEGA8535-16AU - 8-Bit AVR MCU 8KB Flash 16MHz | Microchip
MPN: ATMEGA8535-16AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.42 | $5.42 |
| 10 | $4.88 | $48.80 |
| 100 | $4.35 | $435.00 |
| 500 | $3.92 | $1,960.00 |
| 1,000 | $3.48 | $3,480.00 |
ATMEGA8535-16AU Overview
An AVR microcontroller is a Harvard-architecture 8-bit RISC device that executes most instructions in a single clock cycle, sitting within the hierarchy of microcontroller -> embedded processor -> integrated circuit -> semiconductor. The ATmega family is the classic general-purpose AVR line, and the ATmega8535 is the Flash-based successor to the mask-ROM AT90S8535, retaining pin compatibility for legacy board reuse.
Key features include 8 KB ISP Flash with Read-While-Write, 512 B EEPROM for non-volatile parameter storage, 512 B SRAM, 32 general-purpose I/O lines, 32 general-purpose working registers, three flexible Timer/Counters with compare modes, internal and external interrupts, a programmable USART, a byte-oriented Two-wire Serial Interface (TWI/I2C), and an 8-channel 10-bit successive-approximation ADC. The 130-instruction RISC core achieves 16 MIPS at 16 MHz, and the on-chip ISP interface allows in-system reprogramming without removing the device.
The device uses a low-power CMOS process with multiple sleep modes (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby), making it suitable for battery-backed and always-on control applications. The 44-pin TQFP (10x10 mm, 0.80 mm pitch) surface-mount package provides 32 I/O pins plus dedicated power, ground, reset, crystal, and analog reference pins.
Typical applications include industrial control panels, motor and relay control, sensor data acquisition, legacy AT90S8535 board migration, and educational embedded systems. The combination of 8 KB Flash, 512 B EEPROM, and a 10-bit ADC in one package reduces external component count for mixed-signal control designs.
When designing with this device, decouple AVCC and VCC separately and place the 100 nF bypass capacitors within a few millimeters of the pins; the ADC reference and analog supply pins are noise-sensitive. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA8535-16AU β 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 ATMEGA8535-16AU (same form factor and footprint) β differing in Package, SRAM, Operating Temperature, Instruction Set, Debug Interface.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA8535-16AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA16-16AU
β Drop-Inβ In Stock
$4.41 / Unit
View Datasheet βATMEGA16L-8AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA32-16AUR
β Drop-Inβ In Stock
$3.41 / Unit
View Datasheet βATMEGA8515-16AUR
β Drop-Inβ In Stock
$2.35 / Unit
View Datasheet βATMEGA32L-8AU
β Drop-Inβ In Stock
$3.72 / Unit
View Datasheet βATMEGA8535-16AU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory | 8 KB In-System Programmable Flash (4K x 16) |
| EEPROM | 512 B |
| SRAM | 512 B |
| Maximum Clock Frequency | 16 MHz |
| Throughput | 16 MIPS at 16 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V |
| General Purpose I/O Lines | 32 |
| General Purpose Working Registers | 32 |
| ADC | 8-channel, 10-bit successive approximation |
| Timer/Counters | 3 (two 8-bit, one 16-bit) with compare modes |
| Serial Interfaces | USART, TWI (I2C), SPI |
| Instruction Set | 130 powerful instructions, most single-clock cycle |
| Package | 44-pin TQFP (10x10 mm, 0.80 mm pitch) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C |
| RoHS Status | Compliant |
| Life Cycle Stage | Active |
ATMEGA8535-16AU Pin Configuration
| Pin 1 | PB0 β Port B bit 0 / T0 / XCK |
| Pin 2 | PB1 β Port B bit 1 / T1 / AIN0 |
| Pin 3 | PB2 β Port B bit 2 / INT2 / AIN1 |
| Pin 4 | PB3 β Port B bit 3 / MOSI / OC0 |
| Pin 5 | PB4 β Port B bit 4 / MISO |
| Pin 6 | PB5 β Port B bit 5 / SCK |
| Pin 7 | PB6 β Port B bit 6 / XTAL1 |
| Pin 8 | PB7 β Port B bit 7 / XTAL2 |
| Pin 9 | RESET β Reset input (active low) |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Crystal oscillator output |
| Pin 13 | XTAL1 β Crystal oscillator input / external clock |
| Pin 14 | PD0 β Port D bit 0 / RXD |
| Pin 15 | PD1 β Port D bit 1 / TXD |
| Pin 16 | PD2 β Port D bit 2 / INT0 |
| Pin 17 | PD3 β Port D bit 3 / INT1 |
| Pin 18 | PD4 β Port D bit 4 / OC1B |
| Pin 19 | PD5 β Port D bit 5 / OC1A |
| Pin 20 | PD6 β Port D bit 6 / ICP1 |
| Pin 21 | PD7 β Port D bit 7 / OC2 |
| Pin 22 | PC0 β Port C bit 0 / SCL |
| Pin 23 | PC1 β Port C bit 1 / SDA |
| Pin 24 | PC2 β Port C bit 2 |
| Pin 25 | PC3 β Port C bit 3 |
| Pin 26 | PC4 β Port C bit 4 |
| Pin 27 | PC5 β Port C bit 5 |
| Pin 28 | PC6 β Port C bit 6 |
| Pin 29 | PC7 β Port C bit 7 |
| Pin 30 | AVCC β Analog supply voltage for ADC |
| Pin 31 | GND β Ground |
| Pin 32 | AREF β Analog reference voltage for ADC |
| Pin 33 | PA7 β Port A bit 7 / ADC7 |
| Pin 34 | PA6 β Port A bit 6 / ADC6 |
| Pin 35 | PA5 β Port A bit 5 / ADC5 |
| Pin 36 | PA4 β Port A bit 4 / ADC4 |
| Pin 37 | PA3 β Port A bit 3 / ADC3 |
| Pin 38 | PA2 β Port A bit 2 / ADC2 |
| Pin 39 | PA1 β Port A bit 1 / ADC1 |
| Pin 40 | PA0 β Port A bit 0 / ADC0 |
| Pin 41 | VCC β Digital supply voltage |
| Pin 42 | GND β Ground |
| Pin 43 | GND β Ground |
| Pin 44 | GND β Ground |
Typical Applications
ATMEGA8535-16AU is suitable for 6 applications: Industrial Control Panels, Legacy AT90S8535 Board Migration, Sensor Data Acquisition, Motor and Relay Control, Embedded Education and Prototyping, Battery-Backed Data Logging.
Industrial Control Panels
The ATMEGA8535-16AU fits industrial control panels because its 32 general-purpose I/O lines and -40 C to +85 C operating range directly interface 5 V relays, opto-isolators, and panel indicators without level shifting. Three timer/counters generate PWM and timed event outputs, while the 8-channel 10-bit ADC reads potentiometers and 4-20 mA loop sensors through sense resistors. The device is typically clocked from an external 16 MHz crystal on XTAL1/XTAL2, with the USART providing RS-232 or RS-485 panel communications. A practical trade-off is that the 8 KB Flash limits very large ladder-logic firmware, so complex panels may need the pin-compatible ATMEGA16-16AU with 16 KB Flash. Decouple AVCC and VCC separately with 100 nF capacitors to keep ADC readings stable in electrically noisy cabinets.
Recommended
Legacy AT90S8535 Board Migration
The ATMEGA8535-16AU is the Flash-based successor to the mask-ROM AT90S8535 and is pin compatible with it, allowing existing AT90S8535 PCBs to be upgraded without layout changes. Programming the S8535C compatibility fuse makes the ATmega8535 behave like the AT90S8535 for legacy firmware, while the 8 KB in-system programmable Flash replaces one-time-programmable ROM and enables field updates. The 512 B EEPROM preserves calibration constants that were previously stored externally. Designers must note that fuse-bit locations and some electrical characteristics differ between the two devices, so the fuse configuration and brown-out settings must be re-validated. This migration path extends the service life of industrial equipment originally designed around the AT90S8535 without a board respin.
Recommended
Sensor Data Acquisition
The ATMEGA8535-16AU suits sensor data acquisition because its 8-channel 10-bit successive-approximation ADC converts analog sensor outputs directly, eliminating an external ADC and its digital interface. With 512 B SRAM and 512 B EEPROM, the device buffers samples in RAM and stores calibration coefficients in EEPROM across power cycles. The TWI (I2C) interface connects digital sensors such as temperature and pressure devices, while the USART streams acquired data to a host. A practical consideration is that ADC accuracy depends on a clean AREF and AVCC supply, so a dedicated 100 nF bypass and a low-impedance reference are required; the 10-bit resolution limits effective dynamic range to about 60 dB, which is adequate for control loops but not precision instrumentation. Sampling at up to 15 kSPS supports moderate-speed monitoring.
Recommended
Motor and Relay Control
The ATMEGA8535-16AU is well suited to motor and relay control because its three timer/counters generate hardware PWM for H-bridge and driver stages while the CPU handles commutation logic, and its 32 I/O lines drive multiple relay coils through transistor or opto-isolator stages. At 16 MHz and 16 MIPS, the core executes control loops fast enough for brushed DC and stepper motor positioning. The 4.5 V to 5.5 V supply matches standard 5 V gate-driver and relay logic levels directly. A key trade-off is that inductive loads inject transients, so flyback diodes on relay coils and snubbers on motor terminals are mandatory, and the ADC should be kept away from switching nodes. The 8 KB Flash accommodates moderate motion-control firmware; larger multi-axis code may require the pin-compatible ATMEGA32-16AU.
Recommended
Embedded Education and Prototyping
The ATMEGA8535-16AU is a strong platform for embedded education and prototyping because its 8-bit AVR RISC core with 130 instructions and 32 working registers is simple to teach, and the MightyCore Arduino hardware package supports the ATmega8535 with the Urboot bootloader, so students can use the Arduino IDE. The 44-pin TQFP package exposes 32 I/O lines, making breadboard and breakout prototyping straightforward, and the ISP interface allows rapid reprogramming. The 8 KB Flash and 512 B SRAM are sufficient for teaching exercises in GPIO, timers, interrupts, USART, TWI, and ADC. A practical limitation is that the TQFP package requires an adapter for breadboard use, and the 4.5 V to 5.5 V supply means 3.3 V-only systems need level shifting.
Recommended
Battery-Backed Data Logging
The ATMEGA8535-16AU supports battery-backed data logging because its low-power CMOS process offers multiple sleep modes including Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby, letting the MCU draw minimal current between measurements. The 512 B EEPROM stores logged samples and configuration without an external memory device, and the 8-channel 10-bit ADC digitizes sensor inputs directly. The USART or TWI exports stored data to a host or radio module. A practical trade-off is that the 4.5 V to 5.5 V supply requires a 5 V rail, so battery systems need a boost converter or a 4-cell alkaline pack; the 512 B EEPROM also limits total log depth, so periodic upload or external memory is needed for long deployments. Sleep-mode current and brown-out detection should be tuned for the target battery life.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA8535-16AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA8535-16AUR | ATMEGA16-16AU | ATMEGA8515-16AU | ATMEGA32-16AU |
|---|---|---|---|---|---|
| Package | 44-pin TQFP (10x10 mm) | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Program Memory | 8 KB (4K x 16) | 8 KB (4K x 16) | 16 KB (8K x 16) | 8 KB (4K x 16) | 32 KB (16K x 16) |
| SRAM | 512 B | 512 B | 1 KB | 512 B | 2 KB |
| EEPROM | 512 B | 512 B | 512 B | 512 B | 1 KB |
| Maximum Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| 10-bit ADC Channels | 8 channels | 8 channels | 8 channels | None (0 channels) | 8 channels |
| General Purpose I/O Lines | 32 | 32 | 32 | 32 | 32 |
| Packaging | Tray | Tape & Reel | Tray | Tray | Tray |
Key Differentiators
- On-chip 8-channel 10-bit ADC (vs ATMEGA8515-16AU)
- Pin compatibility with legacy AT90S8535 (vs ATMEGA16-16AU)
- Lower cost per unit than larger-memory siblings (vs ATMEGA32-16AU)
- Tape-and-reel option with identical silicon (vs ATMEGA8535-16AUR)
Design Notes
Decouple every VCC pin (pins 10 and 41) with a 100 nF ceramic capacitor placed within a few millimeters of the pin, and add a 10 uF bulk capacitor on the board rail. The AVCC pin (pin 30) must be decoupled separately with its own 100 nF capacitor and connected to VCC through a low-pass filter (10 uH inductor or 10 ohm resistor) to isolate ADC noise. AREF (pin 32) should be bypassed with 100 nF to ground. Estimated: at 16 MHz and 5 V, core current is on the order of 10-15 mA, so a 100 nF per-pin bypass keeps supply ripple below the ADC noise floor.
Keep the 16 MHz crystal and its two load capacitors as close as possible to XTAL1 (pin 13) and XTAL2 (pin 12), with short, symmetric traces and a solid ground plane beneath. Route the crystal traces away from the ADC input pins (Port A) and from switching outputs such as PWM pins PD4/PD5. Place the ISP header (MOSI, MISO, SCK, RESET) near the MCU to keep programming stub lengths short. For the 44-pin TQFP, use a thermal-relief-free ground connection on all four GND pins (11, 31, 42, 43, 44) to minimize ground bounce.
Do not leave the RESET pin (pin 9) floating; add an external 10 kohm pull-up to VCC and a 100 nF capacitor to ground to prevent spurious resets, especially in noisy industrial environments. When migrating from the AT90S8535, remember that fuse-bit locations and electrical characteristics differ, so the S8535C compatibility fuse and brown-out level must be re-validated. Also verify that the 8 KB Flash and 512 B SRAM fit the application; if code size approaches the limit, migrate to the pin-compatible ATMEGA16-16AU rather than optimizing prematurely.
Compliance Information
RoHS compliance is indicated by distributor listings for the ATMEGA8535-16AU. REACH, halogen-free, and conflict-minerals status were not stated in the provided verified web data and are marked unknown. The device is not AEC-Q100 qualified; the -40 C to +85 C industrial temperature range applies.
