USB333X datasheet(38/85 Pages) MICROCHIP

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USB333x

DS00001880A-page 38

 2009 - 2015 Microchip Technology Inc.

5.8.2

RESISTIVE CHARGER DETECTION

To support the detection and identification of different types of USB chargers the USB333x provides integrated pull-up

resistors, RCD, on both DP and DM. These pull-up resistors along with the single ended receivers can be used to deter-

mine the type of USB charger attached. Reference information on implementing charger detection is provided in Section

8.2, "USB Charger Detection".

5.9

USB Audio Support (USB3331, USB3336, and USB3338)

The USB333x provides two low resistance analog switches that allow analog audio to be multiplexed over the DP and

DM terminals of the USB connector. The audio switches are shown in Figure 5-1. The electrical characteristics of the

USB Audio Switches are provided in Table 4-11.

During normal USB operation the switches are off. When USB Audio is desired the switches can be turned “on” by

enabling the SpkLeftEn, SpkRightEn, or MicEn bits in the Carkit Control register as described in Section 6.7.2. These

bits are disabled by default.

The RESETB pin must be high when using the analog switches so that the VDD33 supply is present. If the VDD33 sup-

ply is applied externally and RESETB is held low the switches will be off.

TABLE 5-9:

USB CHARGER SETTING VS. MODES

Charger Detection Modes

Device Connect Detect

(The Connect Detect setting in Table 5-1 must be followed)

1001

Device Charger Detection

0000

Device USB Operation

0000

Charging Host Port, no charging device attached and SE0

(VdatDet = 0)

0111

Charging Host Port, charging device attached (VdatDet = 1)

0111

Charging Host Port USB Operation

0111

Note:

The Resistive Charger Detection has been superseded by the Active Analog Charger Detection detailed

above. It is recommended that new designs use the Active Analog Charger Detection.

TABLE 5-10:

USB WEAK PULL-UP ENABLE

RESETB

DP Pullup Enable

DM Pullup Enable

ChargerPullupEnableDP

ChargerPullupEnableDM

Note:

ChargerPullupEnableDP

and ChargerPullupEnableDM are enabled in the USB IO & Power Management

Note:

The USB333x supports “USB Digital Audio” through the USB protocol in ULPI and USB Serial modes

described in Section 6.0, "ULPI Operation".

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