ST STM32F446 Series User Manual

RM0390 Rev 4 1085/1328
RM0390 USB on-the-go full-speed/high-speed (OTG_FS/OTG_HS)
1264
the physical support to USB connectivity.
The full-speed OTG PHY includes the following components:
• FS/LS transceiver module used by both host and device. It directly drives transmission
and reception on the single-ended USB lines.
• Integrated ID pull-up resistor used to sample the ID line for A/B device identification.
• DP/DM integrated pull-up and pull-down resistors controlled by the OTG_FS core
depending on the current role of the device. As a peripheral, it enables the DP pull-up
resistor to signal full-speed peripheral connections as soon as V
BUS
is sensed to be at
a valid level (B-session valid). In host mode, pull-down resistors are enabled on both
DP/DM. Pull-up and pull-down resistors are dynamically switched when the role of the
device is changed via the host negotiation protocol (HNP).
• Pull-up/pull-down resistor ECN circuit. The DP pull-up consists of two resistors
controlled separately from the OTG_FS as per the resistor Engineering Change Notice
applied to USB Rev2.0. The dynamic trimming of the DP pull-up strength allows for
better noise rejection and Tx/Rx signal quality.
• V
BUS
sensing comparators with hysteresis used to detect V
BUS
valid, A-B session valid
and session-end voltage thresholds. They are used to drive the session request
protocol (SRP), detect valid startup and end-of-session conditions, and constantly
monitor the V
BUS
supply during USB operations.
• V
BUS
pulsing method circuit used to charge/discharge V
BUS
through resistors during
the SRP (weak drive).
Caution: To guarantee a correct operation for the USB OTG FS peripheral, the AHB frequency should
be higher than 14.2 MHz.
31.4.5 Embedded full speed OTG PHY
(a)
The full-speed OTG PHY includes the following components:
• FS/LS transceiver module used by both host and device. It directly drives transmission
and reception on the single-ended USB lines.
• integrated ID pull-up resistor used to sample the ID line for A/B device identification.
• DP/DM integrated pull-up and pull-down resistors controlled by the OTG_HS core
depending on the current role of the device. As a peripheral, it enables the DP pull-up
resistor to signal full-speed peripheral connections as soon as V
BUS
is sensed to be at
a valid level (B-session valid). In host mode, pull-down resistors are enabled on both
DP/DM. Pull-up and pull-down resistors are dynamically switched when the peripheral
role is changed via the host negotiation protocol (HNP).
• Pull-up/pull-down resistor ECN circuit. The DP pull-up consists of 2 resistors controlled
separately from the OTG_HS as per the resistor Engineering Change Notice applied to
USB Rev2.0. The dynamic trimming of the DP pull-up strength allows to achieve a
better noise rejection and Tx/Rx signal quality.
• V
BUS
sensing comparators with hysteresis used to detect V
BUS
valid, A-B session valid
and session-end voltage thresholds. They are used to drive the session request
protocol (SRP), detect valid startup and end-of-session conditions, and constantly
monitor the V
BUS
supply during USB operations.
a. The content of this section applies only to USB OTG HS.

ST STM32F446 Series Specifications

General

Brand	ST
Model	STM32F446 Series
Category	Microcontrollers
Language	English