diff --git a/embassy-stm32/src/usb_otg/usb.rs b/embassy-stm32/src/usb_otg/usb.rs
index c7f19f6e..e602bcb7 100644
--- a/embassy-stm32/src/usb_otg/usb.rs
+++ b/embassy-stm32/src/usb_otg/usb.rs
@@ -828,6 +828,30 @@ impl<'d, T: Instance> embassy_usb_driver::Bus for Bus<'d, T> {
                 critical_section::with(|_| crate::pac::PWR.cr2().modify(|w| w.set_usv(true)));
             }
 
+            #[cfg(stm32f7)]
+            {
+                // Enable ULPI clock if external PHY is used
+                let ulpien = !self.phy_type.internal();
+                critical_section::with(|_| {
+                    crate::pac::RCC.ahb1enr().modify(|w| {
+                        if T::HIGH_SPEED {
+                            w.set_usb_otg_hsulpien(ulpien);
+                        } else {
+                            w.set_usb_otg_hsen(ulpien);
+                        }
+                    });
+
+                    // Low power mode
+                    crate::pac::RCC.ahb1lpenr().modify(|w| {
+                        if T::HIGH_SPEED {
+                            w.set_usb_otg_hsulpilpen(ulpien);
+                        } else {
+                            w.set_usb_otg_hslpen(ulpien);
+                        }
+                    });
+                });
+            }
+
             #[cfg(stm32h7)]
             {
                 // If true, VDD33USB is generated by internal regulator from VDD50USB