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Microchip Technology AT43USB325E-AU
- Part No.:
- AT43USB325E-AU
- Manufacturer:
- Microchip Technology
- Category:
- Application Specific Microcontrollers
- Package:
- 64-LQFP
- Datasheet:
-
AT43USB325E-AU.pdf
- Description:
- IC USB KEYBOARD CTRLR 64LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:1,317
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Product details
Overview
AT43USB325E-AU from Microchip (formerly Atmel) is an 8-bit AVR RISC microcontroller with integrated USB 1.1 hub and keyboard controller, delivering 12 MIPS throughput at 12 MHz, featuring 16 KB on-chip SRAM program memory, 512-byte data SRAM, and 42 programmable I/O pins - designed for embedded USB keyboard systems supporting up to 20×8 matrix scanning and four LED drivers.
For engineers reviewing the AT43USB325E-AU datasheet, AT43USB325E-AU pinout, AT43USB325E-AU application, or AT43USB325E-AU equivalent, this device requires attention to its dual-role USB architecture (5-port hub + embedded function), SRAM-based firmware loading via SPI EEPROM, 64-lead LQFP package constraints, and absence of UART/SPI/EEPROM peripherals in runtime operation.
Technical Context
The AT43USB325E-AU implements a Harvard-architecture AVR core with 32 general-purpose registers directly connected to the ALU, enabling single-cycle execution of most instructions. Its USB subsystem comprises two independent logical devices: a 5-port USB 1.1 hub (with Port 1 permanently attached to the embedded keyboard function) and a compound USB device with one default endpoint plus three configurable 8-byte FIFO endpoints.
Program memory is loaded automatically at power-on reset from an external SPI serial EEPROM (e.g., AT25HP256) via dedicated PF[0:3] pins - which revert to GPIO after download. The microcontroller runs exclusively from a 12 MHz clock derived from the USB SIE's phase-locked loop, with no provision for external crystal oscillator use during normal operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core Architecture | AVR 8-bit RISC with 32 × 8-bit general-purpose registers and single-cycle ALU operations |
| Performance | 12 MIPS at 12 MHz; 83 ns instruction cycle time |
| Memory | 16 KB downloadable SRAM program memory; 512-byte internal SRAM data memory |
| USB Functionality | Integrated USB 1.1 hub (5 ports) + embedded keyboard function with 4 programmable endpoints |
| I/O Resources | 42 programmable I/O pins across Ports A–E; 4 LED driver outputs with built-in series resistors |
| Timing Peripherals | One 8-bit Timer/Counter with prescaler; one 16-bit Timer/Counter with dual 8-/9-/10-bit PWM |
| Power & Clock | 5 V operation with on-chip 3.3 V regulator; PLL-derived 12 MHz system clock; no external crystal support |
Pinout & Package
AT43USB325E-AU is housed in a 64-lead LQFP package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. Power supply pins include VCC1/VCC2 (5 V) and VSS1/VSS2 (ground); USB differential pairs DP0/DM0 (upstream) and DP2–DP5/DM2–DM5 (downstream ports) are assigned to dedicated bidirectional pins. Port A–E provide keyboard matrix strobes (COL[0:19]) and row inputs (ROW[0:7]), while PE4–PE7 serve as direct LED drivers.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DP0 / DM0 | Upstream USB differential pair | Connects to host controller or upstream hub; requires 1.5 kΩ pull-up on DP0 |
| DP2–DP5 / DM2–DM5 | Downstream USB differential pairs | Support up to four external USB devices; each pair requires 15 kΩ pull-down to VSS |
| PA0–PA7, PB0–PB7, PE0–PE3 | Keyboard column strobes (COL[0:19]) | Drive 20-column keyboard matrix; slew-rate controlled outputs |
| PC0–PC7 | Keyboard row inputs (ROW[0:7]) | Scan 8-row matrix; internal pull-ups enabled; used as interrupt sources |
| PE4–PE7 | LED driver outputs | Direct-drive capability with built-in current-limiting resistors; no external components needed |
| PF0–PF3 | SPI EEPROM interface (power-on only) | PF0 = SSN, PF1 = SCK, PF2 = SI, PF3 = SO; dedicated to firmware loading; not accessible in runtime |
Key Features
| Feature | Design Value |
|---|---|
| USB Hub + Keyboard Integration | Single-chip solution combining 5-port USB 1.1 hub and HID keyboard controller - eliminates need for separate hub IC and MCU |
| Matrix Scanning Support | Hardware-assisted 20×8 keyboard matrix scan with dedicated column strobes and row inputs - reduces firmware overhead and latency |
| LED Driver Outputs | Four integrated constant-current LED drivers (PE4–PE7) with on-die series resistors - enables direct connection of status LEDs without external components |
| SRAM-Based Firmware Loading | Automatic program memory initialization from external SPI EEPROM at power-on reset - supports field firmware updates without mask ROM commitment |
| Dedicated USB Register Map | USB control/status registers mapped to SRAM addresses $1F00–$1FFF - enables real-time hub and function management via standard memory access |
Applications
| USB Mechanical Keyboard Controller | Gaming Peripheral Hub |
|---|---|
Use Scenario: High-reliability mechanical keyboard with N-key rollover, macro programming, and RGB lighting control. IC Role / Device Role / Timing Role: Primary keyboard controller managing matrix scan, USB HID report generation, and LED driver timing synchronization. Use Value: Reduces BOM count by integrating hub and keyboard logic; supports consumer-page HID descriptors per USB Usage Tables. |
Use Scenario: Compact gaming dock connecting mouse, headset, and USB flash drive to laptop via single upstream port. IC Role / Device Role / Timing Role: USB 1.1 hub controller with embedded keyboard function for hotkey panel - operates as compound device with independent hub/function addresses. Use Value: Enables simultaneous downstream device enumeration and local key input without host-side driver modification. |
| Industrial Keypad Interface | Point-of-Sale (POS) Terminal Keyboard Module |
Use Scenario: Ruggedized industrial keypad for factory HMI with backlight control and ESD-hardened USB interface. IC Role / Device Role / Timing Role: Robust keyboard interface IC handling noisy environment scans, watchdog supervision, and 5 V tolerant I/O. Use Value: On-chip 3.3 V regulator and 5 V operation simplify power design; built-in pull-ups eliminate external bias components. |
Use Scenario: Integrated keyboard module for retail POS terminals requiring secure key reporting and tamper-evident LED indicators. IC Role / Device Role / Timing Role: Secure HID endpoint manager with four LED outputs for status indication (e.g., CAPS, NUM, SCROLL, READY). Use Value: Four dedicated LED drivers enable discrete visual feedback without GPIO bit-banging or external driver ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar USB keyboard controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ATMEGA32U4-AU | 32 KB flash program memory; native USB 2.0 device (no hub); includes UART, SPI, TWI, and ADC | Requires external USB hub IC for multi-device support; better suited for custom HID devices than integrated hub keyboards | Select when full USB 2.0 device functionality and peripheral flexibility outweigh need for on-chip hub integration |
| CH552G | 8051 core; 16 KB flash; USB 2.0 device-only; no integrated hub; supports HID, CDC, and MSC classes | Lacks USB hub capability; limited I/O (18 pins); no dedicated LED drivers or keyboard matrix hardware acceleration | Select for cost-sensitive HID devices where external hub and LED drivers are acceptable |
Compared with AT43USB325E-AU, ATMEGA32U4-AU offers greater peripheral richness but no native hub, while CH552G provides lower-cost USB device functionality at the expense of integrated keyboard infrastructure and LED drive capability.
Availability
AT43USB325E-AU is available at Aetrix Electronics and suitable for USB keyboard controllers, industrial keypads, gaming peripheral hubs, and point-of-sale terminal modules requiring stable component supply and long-term manufacturability.
Supply support for AT43USB325E-AU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microchip Technology acquired Atmel in 2016 and maintains full support for legacy AVR microcontrollers including the AT43USB325 series.
The AT43USB325 product line was specifically architected for USB-attached human interface devices requiring integrated hub functionality and keyboard matrix control - targeting cost-optimized, high-volume HID applications.
FAQ
What is the primary function of the AT43USB325E-AU?
The AT43USB325E-AU is an 8-bit AVR microcontroller with integrated USB 1.1 hub and keyboard controller. It functions as a compound USB device comprising a 5-port hub and an embedded HID keyboard function. Its design centers on reducing system complexity in USB keyboard and keypad applications by eliminating the need for separate hub and MCU components - all within a single 64-lead LQFP package.
How does firmware loading work on the AT43USB325E-AU?
Firmware is loaded automatically into the AT43USB325E-AU's 16 KB on-chip SRAM during power-on reset using an external SPI serial EEPROM (e.g., AT25HP256). Pins PF0–PF3 serve exclusively as the SPI interface (SSN, SCK, SI, SO) for this process and revert to GPIO after loading completes. No runtime firmware update capability exists - reprogramming requires power cycle and EEPROM content update.
Does the AT43USB325E-AU support USB 2.0?
No, the AT43USB325E-AU implements USB 1.1 Full-Speed (12 Mbps) only. Its USB hardware complies with the USB 1.1 specification and does not support high-speed (480 Mbps) signaling or USB 2.0 protocol extensions. All hub and function endpoints operate strictly at Full-Speed rates, with 8-byte FIFOs sized accordingly.
Can the AT43USB325E-AU be used without a keyboard matrix?
Yes - while optimized for keyboard applications, the AT43USB325E-AU's 42 general-purpose I/O pins, timers, interrupts, and USB endpoints can be repurposed. However, features like COL/ROW strobes, LED drivers, and USB keyboard descriptors are fixed in silicon. Non-keyboard use requires custom firmware and forfeits hardware acceleration benefits - making alternatives like ATMEGA32U4 more flexible for generic HID designs.
What are the critical power supply requirements for the AT43USB325E-AU?
The AT43USB325E-AU requires two 5 V supplies: VCC1 powers the USB transceivers and core logic; VCC2 powers the I/O ports. High-quality decoupling capacitors are mandatory: 2.2 µF on CEXT1 and 0.33 µF on CEXT2 for internal voltage regulation. The chip generates its own 3.3 V supply internally - no external LDO is needed. Ground planes must separate analog (VSS1) and digital (VSS2) returns.
AT43USB325E-AU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- AVR®
- Package/Case:
- 64-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Applications:
- Keyboard Controller
- Core Processor:
- AVR
- Program Memory Type:
- SRAM (16kB)
- Controller Series:
- AT43USB
- RAM Size:
- 512 x 8
- Interface:
- SPI, 3-Wire Serial
- Number of I/O:
- 42
- Voltage - Supply:
- 4.4V ~ 5.25V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-LQFP (10x10)
AT43USB325E-AU FAQ
1.How can I place an order for AT43USB325E-AU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT43USB325E-AU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT43USB325E-AU reliable?
The price and inventory of AT43USB325E-AU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT43USB325E-AU is usually 5 days.
3.What payment methods are accepted for AT43USB325E-AU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT43USB325E-AU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT43USB325E-AU?
AT43USB325E-AU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT43USB325E-AU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT43USB325E-AU?
For technical support, including AT43USB325E-AU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT43USB325E-AU requirements.
6.How does Aetrix verify that AT43USB325E-AU is sourced from the original manufacturer or authorized distributors?
All AT43USB325E-AU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT43USB325E-AU meets industry standards.
7.What is the process for return or replacement of AT43USB325E-AU?
All AT43USB325E-AU units undergo pre-shipment inspection (PSI). If there is an issue with AT43USB325E-AU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT43USB325E-AU part is unused and in its original packaging.
Return procedure for AT43USB325E-AU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT43USB325E-AU Tags
-
CYPD3175-24LQXQ
Infineon Technologies
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SLB9672VU20FW1523XTMA1
Infineon Technologies
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SLB9670VQ20FW785XTMA1
Infineon Technologies
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SLB9672XU20FW1523XTMA1
Infineon Technologies
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SLB9673XU20FW2613XTMA1
Infineon Technologies
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CYPD3125-40LQXIT
Infineon Technologies
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AT97SC3204-U2A1A-20
Microchip Technology
-
AT97SC3204-U2A1A-10
Microchip Technology
-
SLM9670AQ20FW1311XTMA1
Infineon Technologies
-
SLB9672XU20FW1613XTMA1
Infineon Technologies
-
SLB9672AU20FW1613XTMA1
Infineon Technologies
-
SLB9673AU20FW2613XTMA1
Infineon Technologies
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