User guide

Si471x-EVB
6 Preliminary Rev. 0.4
3.2. Si471x Base Board
3.2.1. Power Supply Network
Figure 5. Power Supply Block Diagram
The EVB can be powered from 3 different kinds of power supplies:
1. USB power supply via J79
2. Ext DC power supply via power jack J78
3. Three separate power supplies (Vdd, Vio, Vmcu) via terminal block J76
The EVB has three different rails: Vdd, Vio, and Vmcu. Vdd and Vio are routed directly to the daughter board to
power the Vdd and Vio pins on the Si471x chip, while Vmcu is used to power the entire base board.
USB Power Supply & EXT DC Power Supply
Switch SW1 is used to select between the USB supply and Ext DC supply.
There are 2 modes that the user can use with the USB or the EXT DC supply:
1. Fixed +3.3 V
2. Adjustable Vdd and Vio
SW1
J78
EXT
LDO
1.25-3.9V
(R73)
LDO
1.25-7V
(R74)
Jumper
J68
Jumper
J69
DAUGHTER BOARD
Si471x
VIO
10
11
VDD
ADJ
TB
+3.3V
LDO
+3.3V
(U17)
J79
USB
J77
Terminal
Block (TB)
Gnd
Vdd
Vio
Vm
ADJ
+3.3V
TB
+3.3V
TB
Vmcu
Jumper
J61
VIO
VDD