The TPS2540/40A and TPS2541/41A are a combination of current-limited USB port power switch with a USB 2.0 high-speed data line (D+/D-) switch and a USB charging port identification circuit. Applications include notebook PCs and other intelligent USB host devices. The wide bandwidth (2.6 GHz) data-line switch also features low capacitance and low on resistance, allowing signals to pass with minimum edge and phase distortion. The TPS2540/40A/41/41A monitors D+ and D-, providing the correct hand-shaking protocol with compliant client devices.
The TPS2540/40A/41/41A supports the following charging logic schemes:
- USB 2.0 BC1.2
- Chinese Telecom Standard YD/T 1591-2009
- Divider Mode, compliant with Apple devices such as iPod and iPhone
CTL1-CTL3 logic inputs are used to select one of the various charge modes provided by the TPS2540/40A and TPS2541/41A . These charge modes allow the host device to actively select between Dedicated Charging Port (DCP) (wall-adapter emulation), Charging Downstream Port (CDP) (active USB 2.0 data communications with 1.5-A support), or Standard Downstream Port (SDP) USB 2.0 Mode (active USB 2.0 data communications with 500-mA support). The TPS2540/40A/41/41A also integrates an auto-detect feature that supports both DCP schemes for Battery Charging Specification (BC1.2) and the Divider Mode without the need for outside user interaction.
The TPS2540A auto detect mode also has a longer detach detection time, so that it can support certain unique non-compliant devices. The TPS2540/40A/41/41A power-distribution switch is intended for applications where heavy capacitive loads and short-circuits are likely to be encountered, incorporating a 73-mΩ, N-channel MOSFET in a single package. Constant-current mode is used when the output load exceeds the current-limit threshold. ILIM_SEL logic input selects one of two current-limit thresholds, each one being individually adjustable via an external resistor. Additional USB switch features include a de-glitched output fault reporting (FAULT), and a logic-level enable EN (TPS2540/40A) or OUT discharge control DSC (TPS2541). With the TPS2540/40A, the mode “000” is used to force an output discharge.