User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 245
www.energymicro.com
Figure 15.5. OTG Dual Role Device (5V)
USB_DP
USB_DM
Micro-AB
VBUS
D+
D-
ID
USB_VBUS
EFM32
USB_VREGI
USB_VREGO
(ESD Protection)
VDD
USB_ID
GND
5V
USB_VBUSEN
GPIO (over-current)
Power switch +
over-current detection
V
in
V
out
EN
OC
15.3.2.5 OTG Dual Role Device (5V step-up regulator)
An OTG Dual Role Device (5V step-up regulator) configuration is shown in Figure 15.6 (p. 245) . When
5V is not available, an external 5V step-up regulator is needed. In this configuraton, the voltage for the
EFM32 must be in the range 3.0V - 3.6V. In this mode the voltage regulator is bypassed by connecting
both the input and output to the external supply. This effectively causes the PHY to be powered directly
from the external 3.0 - 3.6 V supply. The voltage regultor should be disabled when operating in this mode.
For overcurrent detection a regular GPIO input pin with interrupt is used. The application should turn
off or limit VBUS power when overcurrent is detected. In OTG mode, the maximum VBUS decoupling
capacitance is 6.5 uF.
In this configuration, the VREGO sense circuit should be left disabled.
Figure 15.6. OTG Dual Role Device (5V step-up regulator)
USB_DP
USB_DM
Micro-AB
VBUS
D+
D-
ID
USB_VBUS
EFM32
USB_VREGO
USB_VREGI
(ESD Protection)
VDD
USB_ID
GND
3.0V – 3.6V
USB_VBUSEN
GPIO (over-current)
EN
V
out
V
in
OC
5V step-up
15.3.2.6 Host
A host configuration is shown in Figure 15.7 (p. 246) . In this example a 5V step-up regulator is used.
If 5V is available, a power switch can be used instead, as shown in Figure 15.5 (p. 245) . The host
configuration is equal to OTG Dual Role Device, except for the USB_ID pin which is not used and the
USB connector which is a USB Standard-A Connector. In host mode, the minimum VBUS decoupling
capacitance is 96 uF.