SI57X-EVB Datasheet, PDF(4/34 Page) Silicon Laboratories – Si57X/598/599 ANY FREQUENCY I2C PROGRAMMABLE XO/VCXO EVALUATION BOARD

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SI57X-EVB Datasheet, PDF (4/34 Pages) Silicon Laboratories – Si57X/598/599 ANY FREQUENCY I2C PROGRAMMABLE XO/VCXO EVALUATION BOARD

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Si57x-EVB

1.3. Reset Circuit

The Si57x-EVB MCU may be reset by pressing momentary pushbutton SW1. It may also be held in reset by

installing a jumper at J7. MCU outputs are open drain and are tri-stated during reset. They remain tri-stated unless

otherwise directed under program control.

There is no hardware reset for the Si57x/598/599 itself. The Si57x/598/599 is reset only on power-up or through

software. Pressing the Si57x-EVB motherboard pushbutton SW1 in an attempt to reset the Si57x/598/599 may

result in unexpected behavior.

1.4. USB

A 4-pin USB receptacle is provided at location J15. The Si57x-EVB, via the MACâs USB Function Controller, is

compatible with USB Specification 2.0. When the USB link is in use the MCU drives LED D7.

1.5. MCU

The MCU, Silicon Laboratories P/N C8051F320, provides the following functions:

ï® Supports I2C communication to the DUT on behalf of the host PC per the Si57x-EVB software

ï® Drives a number of status indicator LEDs (see Table 2)

ï® Supplies 3.3 V to peripheral ICs on the motherboard but not to the DUT

The MCU comes pre-loaded with firmware. While there is a provision for in-circuit programming at connector J12

located on the back, this should not be necessary. The host PC operates the Si57x/598/599 software and

communicates to the Si57x/598/599 through the MCU via USB connector J15. When the USB link is in use, LED

D7 should be illuminated.

As mentioned earlier, the MCU may be reset by pressing momentary pushbutton (SW1) or held in reset by

installing a jumper at J7.

1.5.1. Status Signals

There are seven LEDs on the Si57x-EVB that report visual status as listed in Table 2 and as highlighted in Figure 2.

Upon power up, D1âD2 and only one of D3âD5 should be illuminated. D6 and D7 are only illuminated when in use.

Table 2. Si57x-EVB LEDs

Reference

Designation

Color Signal or Status Indicated

Comments

Red 5 V present

Red MCU 3.3 V present

Red VREG 3.3 V selected

Red VREG 2.5 V selected

Red VREG 1.8 V selected

Green OE active

Green USB active

Connected to filtered 5 V

Connected to MCU 3.3 V output

Under MCU control

Rev. 0.2

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