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ASIX Electronics Corporation Notice USB to LAN products 
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If you got some problems on ASIX USB to LAN products, please download the How to identify authentic ASIX USB to LAN Products document to double check if your USB to LAN device includes an Non-authentic ASIX USB to LAN solution inside or not? If yes, please contact the manufacturer of your USB to LAN device to get proper drivers instead. ASIX DOES NOT GUARANTEE AND PROVIDE ANY SUPPORT FOR THOSE NON-AUTHENTIC ASIX PRODUCTS.

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Home >> Products >> I/O Connectivity ICs >> USB Bridge >> AX78120

 AX78120 -- USB 2.0 to Multi I/O (1S or 2S) Controller

With the rapid proliferation of USB interface in the embedded world, developers are looking for easiest ways to add USB to microcontroller-based applications in their design. ASIX’s new AX781x0 family features four USB connectivity bridge solutions including USB 2.0 to Single Serial (AX78120), USB 2.0 to Dual Serial (AX78120), USB 2.0 to Quad Serial (AX78140) and USB 2.0 to Dual Serial and Single Parallel (AX78140) controllers. Enabling smooth migration from legacy system using ASIX’s MCS78x0 series, AX78120/AX78140 provide pin-to-pin compatible and driver backward compatible with MCS7810/MCS7820/MCS7840.

AX78120 is a USB 2.0 to Multi I/O (1S or 2S) Controller. It has been developed to connect a wide range of standard serial devices to a USB host.

The AX78120’s support for the following serial communication program are included: HyperTerminal, PComm, Windows direct connection, Windows dial-up connection through modem, Networking over IrDA and Windows direct connection over IrDA, Minicom.

The AX78120, in 48-pin LQFP, are available with RoHS compliant package and supports commercial grade operating temperature range from 0 to 70°C and industrial grade from -40 to 85°C.


  • Single chip USB 2.0 to Multi I/O (1S or 2S) Controller
  • USB Device Controller
    • Integrates on-chip USB 2.0 PHY and controller compliant to USB Spec 2.0 and 1.1
    • Supports all USB 2.0 power saving modes (L1, L2)
    • Supports USB High/Full Speed modes with Bus-power or Self-power device auto-detect capability
    • Supports USB LPM (Link Power Management)
  • Dual Serial Port Controller
    • Two 16c450/16c550 compatible UARTs
    • Supports SIR IrDA mode on any/all ports
    • Supports RS-232, RS-422 and RS-485 serial ports
    • Supports multi-protocol serial transceivers
    • Supports 5, 6, 7 & 8 bit serial data
    • Supports automatic data direction control
    • Supports multi-drop mode with auto address detection
    • Supports hardware and software flow control
    • Supports baud rates from 50bps to 6Mbps
    • Supports custom baud rates from external clock
    • On-Chip 1024-Byte FIFO for upstream and 512-Byte for downstream data transfer for each Serial Port
    • I2C interface for EEPROM
    • Supports read/write EEPROM through USB interface
    • On-Chip buffers for serial port signals to operate without external transceivers over short cable
    • Pin-to-Pin compatible with MCS7810/MCS7820/MCS7840
    • Driver backward compatible with MCS7810/MCS7820/MCS7840
  • Support Remote Wake Up Function
    • Supports Suspend Mode and Remote Wakeup via RXD, RI, DSR, DCD and CTS pin
  • Advanced Power Management Features
    • Supports USB LPM (Link Power Management)
    • Supports remote wake up re-trigger
  • Integrates on-chip 1.8V and 3.3V voltage regulator and only requires a single 5V power supply
  • Single 12MHz clock input from either crystal or oscillator source
  • Integrates on-chip power-on reset circuit
  • Small form factor with 48-pin LQFP RoHS compliant package
  • Operating over 0°C to 70°C or -40°C to +85°C temperature range
Target Applications:
  • Serial Attached Devices
  • Serial Networking / Monitoring Equipment
  • Data Acquisition System
  • POS Terminal & Industrial PC

 Block Diagram


 Selection Guide


 Development Board

AX78120 USB 2.0 to 2S Demo Board  Available
 This is an AX78120 USB 2.0 to 2S adapter for users to evaluate AX78120 USB 2.0 to 2S functionalities.

Technical Documentation

 Product Brief, Product Introduction and Datasheet

AX78120 Brief316.6 KB2017-12-08
AX78120 Product Introduction 1.1 MB2017-03-14
AX78120 Datasheet 1.1 MB2017-08-18

 Reference Manuals and User Guides

AX78120 EEPROM User Guide   
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AX78120 Reliability Report 233.5 KB2016-10-14
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AX78120 RoHS Report   
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Hardware Design Documentation

 Reference Schematics

AX78120 USB 2.0 to 2S Demo Board Reference Schematic 253.7 KBV1.002016-05-25
AX78120 USB 2.0 to 1S Reference Schematic 254.6 KBV1.012017-11-09

 Bill of Materials, Application Notes and Layout Guides

AX78120 USB 2.0 to 2S Demo Board BOM File 190.3 KB2016-06-22
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AX78120 USB 2.0 to 1S Schematic BOM File 189.3 KB2016-07-18
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AX78120 Application Design Note 1020.4 KBV1.002016-06-24
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 PCB Layout, Gerber and IBIS Model

AX78120 USB 2.0 to 2S Demo Board PCB Layout Files 217.3 KB2016-02-25
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AX78120 USB 2.0 to 2S Demo Board Gerber Files 837.3 KB2016-02-25
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AX78120 IBIS Model 391.1 KB2016-09-14
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Windows EEPROM Utility   
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Windows MP Tool   
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Driver TypeRevision Release DateDescriptionFile Size
Linux kernel 4.x/3.x/2.6.x Driver V3.4.02018-09-28 For all Android systems, Linux kernel 2.6.15 and later32.2 KB
Windows 10 32-bit Driver V3.20.6.02019-05-13 For x86 CPU platform, HLK/WHCK certified851.5 KB
Windows 10 64-bit Driver V3.20.6.02019-05-13 For x64 CPU platform, HLK/WHCK certified952.3 KB
Windows 8.x 32-bit Driver V3.18.6.02018-11-14 For 32-bit x86 CPU platform, HLK/WHCK certified898.2 KB
Windows 8.x 64-bit Driver V3.18.6.02018-11-14 For 64-bit x86 CPU platform, HLK/WHCK certified1 MB
Windows 7/Vista/XP 32-bit Driver V3.12.6.02018-11-14 For 32-bit x86 CPU platform, WHCK certified1.1 MB
Windows 7/Vista/XP 64-bit Driver V3.12.6.02018-11-14 For 64-bit x86 CPU platform, WHCK certified1.2 MB


click here for more AX78120 FAQs....
Q0001: Is AX78120 IC pin-to-pin compatible to MCS7820 IC?
A0001: Yes, AX78120 IC is pin-to-pin compatible to MCS7820 IC.

Q0002: Where can I obtain the latest AX78120 datasheet, reference schematic and other hardware design archives?
A0002: Please register MyASIX membership ( and then download the latest AX78120 datasheet, reference schematic, PCB layout guide, etc. from AX78120 Product web page (;74;109&PLine=74) directly.

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