# USB power management

Source: [https://docs.qualcomm.com/doc/80-88500-4/topic/111_USB_power_management.html](https://docs.qualcomm.com/doc/80-88500-4/topic/111_USB_power_management.html)

The USB power management helps assess the impact of power supply and consumption in the
    system when USB is being used.

The USB controller driver controls the power states of various device and host operating
      modes.

The table lists the power modes allowed by the USB software only. Other software drivers may
      prevent the system from entering lower power modes.

| Operating mode | Conditions | Power collapse (HS PHY) | Power collapse (SS PHY) | XO shutdown | XO shutdown + VDD minimization |
| --- | --- | --- | --- | --- | --- |
| Device | USB bus suspend | X | X | X | X |
| Device | USB disconnected | √ | √ | √ | √ |
| Device | USB charger connected | √ | √ | √ | √ |
| Host | USB bus suspend without a device connected | X | X | √ | X |
| Host | USB bus suspend with a <br>SS-USB device connected | X | X | √ | X |
| Host | USB bus suspend with a <br>HS-USB device connected | X | X | √ | X |
| √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode | √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode | √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode | √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode | √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode | √ – USB software allows the power mode<br><br><br>X – USB software prevents the power mode |
|  |  |  |  |  |  |
|  |  |  |  |  |  |

The table lists the voltage supplied to the USB device nodes for power consumption in both
      high speed and super speed modes.

| Voltage rail | Voltage level | Voltage level | Voltage level | Used in device node | Comments |
| --- | --- | --- | --- | --- | --- |
| Voltage rail | Max(V) | Nominal(V) | Nominal(V) | Used in device node | Comments |
| VREG L12 | 1.8 | 1.7 | 0 | <ul class="ul" id="USB_power_management_111__ul_qxb_krx_bxb"><br>                <li class="li">usb2_phy0</li><br><br>                <li class="li"> usb2_phy1</li><br><br>              </ul> | 1.8 V regulator used by both HS-PHYs in the system |
| VREG L2 | 3.3 | 3.05 | 0 | <ul class="ul" id="USB_power_management_111__ul_p41_lrx_bxb"><br>                <li class="li">usb2_phy0</li><br><br>                <li class="li">usb2_phy1</li><br><br>              </ul> | 3.3 V regulator used by both HS-PHYs in the system |
| VREG L18 | 1.2 | 1.2 | 0 | <ul class="ul" id="USB_power_management_111__ul_ugr_lrx_bxb"><br>                <li class="li">usb_qmp_dp_phy</li><br><br>                <li class="li">usb_qmp_phy</li><br><br>              </ul> | SS-PHY VDD core |
| VREG L5 (VDDMX) | 880 | 880 | 880 | <ul class="ul" id="USB_power_management_111__ul_u1p_mrx_bxb"><br>                <li class="li">usb2_phy0</li><br><br>                <li class="li">usb2_phy1</li><br><br>                <li class="li">usb_qmp_dp_phy</li><br><br>                <li class="li"> usb_qmp_phy</li><br><br>              </ul> | HS-PHY/SS-PHY VDD core |
|  |  |  |  |  |  |

Note: For more information, see <cite class="cite">Linux USB Implementation Guide</cite>
      (80-NF283-1).

**Parent Topic:** [USB](https://docs.qualcomm.com/doc/80-88500-4/topic/106_USB.html)

Last Published: Aug 18, 2023

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