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Hardware Overview

2

Hardware Overview

The TUSB4041PAPEVM board hardware can be divided into six functional areas:

2.1

TUSB4041PAP

The TUSB4041PAPEVM (U2 on the schematic) operates as a functional interconnect between an

upstream connection to a USB host or hub and up to two directly-connected downstream devices or hubs.

More devices and hubs can be supported if arranged in tiers. The TUSB4041 is capable of supporting

operation at High-Speed (HS), Full Speed (FS), or Low Speed (LS). In general, the speed of the upstream

connection of the TUSB4041PAPEVM limits the downstream connections to that speed (HS and FS) or

lower.

The TUSB4041 requires a 24-MHz low-ESR crystal, Y1 with a 1-M

Ω feedback resistor. The crystal should

be fundamental mode with a load capacitance of 12 pF – 24 pF and a frequency stability rating of ±100

PPM or better. To ensure a proper startup oscillation condition, a maximum crystal equivalent series

resistance (ESR) of 50

Ω is recommended.

The TUSB4041 can also use an oscillator or other clock source. When using an external clock source

such as an oscillator, the reference clock should have ±100 PPM (or better) frequency stability and have

less than 50-ps absolute peak-to-peak jitter (or less) than 25-ps peak-to-peak jitter after applying the USB

3.0 jitter transfer function.

2.2

USB Port Connectors

The TUSB4041PAPEVM is equipped with five standard USB2.0 port connectors. One of these five

connectors, J1, is a Type-B connector designed to interface with an upstream USB host or hub. The

remaining connectors, J2, J3, J4, and J5 are Type-A connectors for connection to downstream devices or

hubs. Standard size connectors were used on the EVM design but USB micro connectors can be used, if

desired.

The USB ports can be attached via a standard USB cable to any USB 2.0 host, hub, or device. The

TUSB4041 will automatically connect to any upstream USB 2.0 host or hub at HS.

2.2.1

USB Port Connector - Power

VBUS is received from the upstream host or hub on J1. The TUSB4041 can be configured as a self-

powered or bus-power hub, just setting SW3 in the required option.

When the EVM is set for self-power there is not any significant current draw by the EVM from VBUS. The

TUSB4041 does monitor the VBUS input after filtering through a resistor divider network of a 90.9-k

Ω, 1%

resistor, R2, and a 10-k

Ω, 1% resistor, R3. VBUS cannot be directly connected to the TUSB4041 device.

A bulk capacitor of at least 1

μF is required on the upstream port VBUS input to comply with the USB

specification. The TUSB4041PAPEVM uses a 10-

μF capacitor, C35.

VBUS, sourced by the 5-V wall power input, J6, is provided to the downstream port connectors. The USB

2.0 specification limits the current consumption of a USB 2.0 device to 500 mA at 5 V. The current-limiting

parameter of the TPS2001C device, U7, is configured to 2.2 A to avoid any spurious overcurrent events

due to bus-powered HDD spin-up power fluctuations or unnecessary limiting during USB charging. A

production implementation could place stricter limits on this power consumption. An overcurrent event on

any of the downstream port connectors will be reported to the TUSB4041 via the OVERCURxZ inputs.

2.2.2

USB Port Connector – Noise Filtering

Each downstream VBUS output has a 150-

μF bulk capacitor (C70, C71, C76, C79) as recommended by

the TPS2001C data manual (SLVSAU6) to prevent in-rush current events on the downstream devices. In

addition, there are ferrite beads and small capacitors on the VBUS lines to reduce noise and address

ESD/EMI concerns.

The TUSB4041PAPEVM also implements optional isolation using two small noise-filtering capacitors and

a 1-M

Ω resistor between the earth ground of each connector and the digital ground of the EVM, this is not

a requirement but should be used if ground isolation is desired.

3

SLLU227 – September 2015

TUSB4041PAP Evaluation Module

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