000-000C55545-101

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SLGC55545

Standard Downstream Port (SDP)

An SDP is a traditional USB port that follows USB 2.0/3.0 and supplies a maximum of 500 mA per port for USB 2.0 and 900 mA

per port for USB 3.0. USB 2.0 communications is supported, and the host controller must be active to allow charging.

Charging Downstream Port (CDP)

A CDP is a USB port that follows USB 2.0/3.0 BC1.2 (draft) and supplies a minimum of 1.5 A per port. It provides power and

meets USB 2.0/3.0 requirements for device enumeration. USB 2.0/3.0 communications is supported, and the host controller must

be active to allow charging. What separates a CDP from an SDP is the host-charge handshaking logic that identifies this port as

a CDP. A CDP is identifiable by a compliant BC1.2 (draft) client device and allows for additional current draw by the client device.

The CDP hand-shaking process is two steps. During step one the portable equipment outputs a nominal 0.6 V output on its D+

line and reads the voltage input on its D- line. The portable device concludes it is connected to an SDP if the voltage is less than

the nominal data detect voltage of 0.3 V. The portable device concludes that it is connected to a Charging Port if the D- voltage

is greater than the nominal data detect voltage of 0.3V and less than 0.8 V.

The second step is necessary for portable equipment to determine between a CDP and a DCP. The portable

device outputs a nominal 0.6 V output on its D- line and reads the voltage input on its D+ line. The portable

device concludes it is connected to a CDP if the data line being read remains less than the nominal data detect

voltage of 0.3 V. The portable device concludes it is connected to a DCP if the data line being read is greater

than the nominal data detect voltage of 0.3V and less than 0.8 V.

Dedicated Charging Port (DCP)

A DCP is a special type of wall-adapter used in charging applications that uses a micro-B connector to connect to portable devices.

A DCP only provides power and does not support data connection to an upstream port. As shown in following sections, a DCP

is identified by the electrical characteristics of its data lines. The SLGC55545 emulates DCP in two charging states, namely DCP

Forced and DCP Auto. In DCP Forced state the device will support one of the following two DCP charging schemes: Divider1 or

Shorted. In DCP Auto state, the SLGC55545 charge detection state machine is enabled which will selectively implement charging

schemes involved with the Shorted, Divider1, Divider2, and 1.2 V modes.

Shorted DCP mode complies with BC1.2 and Chinese Telecommunications Industry Standard YD/T 1591-2009,

Divider and 1.2V modes are used to charge devices that do not comply with BC1.2 DCP standard.

High-Bandwidth Data Line Switch

The SLGC55545 passes the D+ and D- data lines through the device to enable monitoring and handshaking while supporting

charging operation. A wide bandwidth signal switch is used, allowing data to pass through the device without corrupting signal

integrity. The data line switches are turned on in any of CDP or SDP operating modes. The EN input also needs to be at logic

High for the data line switches to be enabled.

Note:

1. While in CDP mode, the data switches are ON even while CDP handshaking is occurring.

2. The data line switches are OFF if EN is low, or if in DCP mode (BC1.2 (draft), Divider mode or Auto-detect). They are not

automatically turned off if the power switch (VIN to VOUT) is doing current limiting. With SLGC55545, the data line switches are

also off when in “000” mode.

3. The data switches are for USB 2.0 differential pair only. In the case of a USB 3.0 host, the super speed differential pairs must

be routed directly to the USB connector without passing through the SLGC55545.