Si501/2/3/4-EVB
2. MCU
The Silicon Laboratories MCU, P/N C8051F380, is mounted on the back side of the board at U6. The MCU
provides the following functions:
Supports USB communication to host PC
Supports single-wire communication (C1) to the DUT on behalf of the host PC per the EVB GUI Software
Supplies 3.3 V to peripheral ICs (the serial number generator and the C1 voltage level shifter)
3. Power Supply
The Si501/2/3/4-EVB can be powered from USB or from an external voltage supply. This is to support temperature
testing without a USB connection. The power supply consists of a Maxim MAX8869 adjustable voltage regulator
that steps down the USB +5 V or an external +5V power supply to one of a selectable 1.8, 2.5, or 3.3 V. VDD
selection is made via jumper P2. The supply voltage for all the device sites, both Si504 and eval sites, can be
adjusted to one of three settings: 3.3 V, 2.5gV, or 1.8 V by jumper P2. (Note that all four locations share the same
supply voltage, so any supply voltage change will affect all devices at sites U1, U2, U3, and U4.) The default
setting, connecting pins 2 and 3 as shown above, is 3.3 V. Moving the jumper to connect pins 1 and 2 results in
2.5 V. Removing the jumper altogether will result in 1.8 V supply voltage. The voltage regulator may be bypassed
by connecting VDD directly to the VDD P1 connection point.
4. LEDs
Two green indicator LEDs are driven by the on-board MCU. A "Ready" LED (D1) is illuminated to indicate the EVB
is recognized by the EVB GUI software and ready for use. A "USB" LED (D2) is illuminated whenever USB
communications are actively in progress.
Rev. 0.1
9
SILICON [ SILICON ]
