TUSB2046B Status: ACTIVE

Product Information

Features

• Fully Compliant With the USB Specification as a Full-Speed Hub: TID #30220231
• 32-Terminal LQFP⁽¹⁾ Package With a 0.8-mm Terminal Pitch or QFN Package with a 0.5-mm Terminal Pitch
• 3.3-V Low Power ASIC Logic
• Integrated USB Transceivers
• State Machine Implementation Requires No Firmware Programming
• One Upstream Port and Four Downstream Ports
• All Downstream Ports Support Full-Speed and Low-Speed Operations
• Two Power Source Modes
  • Self-Powered Mode
  • Bus-Powered Mode
• Power Switching and Overcurrent Reporting Is Provided Ganged or Per Port
• Supports Suspend and Resume Operations
• Supports Programmable Vendor ID and Product ID With External Serial EEPROM
• 3-State EEPROM Interface Allows EEPROM Sharing
• Push-Pull Outputs for PWRON Eliminate the Need for External Pullup Resistors
• Noise Filtering on OVRCUR Provides Immunity to Voltage Spikes
• Package Pinout Allows 2-Layer PCB
• Low EMI Emission Achieved by a 6-MHz Crystal Input
• Migrated From Proven TUSB2040 Hub
• Lower Cost Than the TUSB2040 Hub
• Enhanced System ESD Performance
• Supports 6-MHz Operation Through a Crystal Input or a 48-MHz Input Clock

⁽¹⁾ JEDEC descriptor S-PQFP-G for low profile quad flat pack (LQFP).

DESCRIPTION/ORDERING INFORMATION

The TUSB2046B is a 3.3-V CMOS hub device that provides one upstream port and four downstream ports in compliance with the Universal Serial Bus (USB) specification as a full-speed hub. Because this device is implemented with a digital state machine instead of a microcontroller, no firmware programming is required. Fully-compliant USB transceivers are integrated into the ASIC for all upstream and downstream ports. The downstream ports support both full-speed and low-speed devices by automatically setting the slew rate according to the speed of the device attached to the ports. The configuration of the BUSPWR terminal selects either the bus-powered or the self-powered mode.

Configuring the GANGED input determines the power switching and overcurrent detection modes for the downstream ports. External power-management devices, such as the TPS2044, are required to control the 5-V source to the downstream ports according to the corresponding values of the PWRON terminal. Upon detecting any overcurrent conditions, the power-management device sets the corresponding OVRCUR terminal of the TUSB2046B to a logic low. If GANGED is high, all PWRON outputs switch together and if any OVRCUR is activated, all ports transition to the power-off state. If GANGED is low, the PWRON outputs and OVRCUR inputs operate on a per-port basis.

The TUSB2046B provides the flexibility of using a 6-MHz or a 48-MHz clock. The logic level of the TSTMODE terminal controls the selection of the clock source. When TSTMODE is low, the output of the internal APLL circuitry is selected to drive the internal core of the device. When TSTMODE is high, the TSTPLL/48MCLK input is selected as the input clock source and the APLL circuitry is powered down and bypassed. The internal oscillator cell is also powered down while TSTMODE is high.

Low EMI emission is achieved because the TUSB2046B is able to utilize a 6-MHz crystal input. Connect the crystal as shown in Figure 6. An internal PLL then generates the 48-MHz clock used to sample data from the upstream port and to synchronize the 12 MHz used for the USB clock. If low-power suspend and resume are desired, a passive crystal or resonator must be used. However, a 6-MHz oscillator may be used by connecting the output to the XTAL1 terminal and leaving the XTAL2 terminal open. The oscillator TTL output must not exceed 3.6 V.

For 48-MHz operation, the clock cannot be generated with a crystal using the XTAL2 output because the internal oscillator cell supports only the fundamental frequency.

See Figure 7 and Figure 8 in the input clock configuration section for more detailed information regarding the input clock configuration.

The EXTMEM terminal enables or disables the optional EEPROM interface. When the EXTMEM terminal is high, the product ID (PID) displayed during enumeration is the general-purpose USB hub. For this default, terminal 5 is disabled and terminal 6 functions as the GANGED input terminal. If custom PID and vendor ID (VID) descriptors are desired, the EXTMEM terminal must be low (EXTMEM = 0). For this configuration, terminals 5 and 6 function as the EEPROM interface with terminals 5 and 6 functioning as EECLK and EEDATA, respectively. See for a description of the EEPROM memory map.

Other useful features of the TUSB2046B include a package with a 0.8-mm terminal pitch for easy PCB routing and assembly, push-pull outputs for the PWRON terminals eliminate the need for pullup resistors required by traditional open-collector I/Os, and OVRCUR terminals have noise filtering for increased immunity to voltage spikes.