Figure 9.
Connecting an external supply voltage
The 5 V (VBUS) of the USB port is connected to three low-dropout regulators, which supply:
•
Digital components
•
RF components
•
External power amplifier
For the digital components a 3.3 V supply is provided. RF components are supplied by 3.6 V and the external
power amplifier is supplied by 4.1 V.
Table 12.
Typical voltage levels
Voltage domain
Typical voltage level
3V3
3.33
VSUP
3.67
VPA
4.1
Table 13.
Components connected to 5 V
5 V
Schematic page
Component
Pin name
Pin number
Supply
U9, U10, U11
VI
6
Supply
U9, U10
EN
1
USB_Interface
U13
VCC
12
UM2353
Power supply
UM2353
-
Rev 2
page 16/48
Summary of Contents for ST25RU3993-EVAL
Page 25: ...Figure 16 Schematic of UHF RFID reader device UM2353 Rev 2 page 25 48 UM2353...
Page 26: ...Figure 17 Schematic of external power amplifier UM2353 Rev 2 page 26 48 UM2353...
Page 28: ...Figure 20 Schematic of USB supply UART bridge UM2353 Rev 2 page 28 48 UM2353...
Page 29: ...Figure 21 Schematic of microcontroller UM2353 Rev 2 page 29 48 UM2353...
Page 30: ...Figure 22 Schematic of supply LDOs UM2353 Rev 2 page 30 48 UM2353...
Page 31: ...Figure 23 Schematic of external interfaces and connections UM2353 Rev 2 page 31 48 UM2353...
Page 32: ...Figure 24 Schematic of BT classic module UM2353 Rev 2 page 32 48 UM2353...
Page 33: ...Figure 25 Schematic of RF shield UM2353 Rev 2 page 33 48 UM2353...
Page 39: ...8 4 GND layer Figure 30 Layout GND layer UM2353 GND layer UM2353 Rev 2 page 39 48...