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TE0320 is provided with a slide switch S2S1B.
Slide switch S2 S1B conditions the value of signal PS_EN.
In this way, S2 S1B conditionally/unconditionally enables the 1.2 V and 2.5 V power rails.

Figure 33: Slide switch S2 S1B (angle view).

Figure 34: Slide switch S2 S1B schematic.


Figure 35: When slide switch S2 S1B = FX2 PON, signal PS_EN is set to signal FX2_PS_EN driven by the EZ-USB FX2LP USB FX2 microcontroller under user control.

When S2 S1B is turned on (FX2 PON), the 1.2 V and 2.5 V power rails are controlled by the USB (EZ-USB FX2LP USB FX2) microcontroller. At start-up, the USB microcontroller switches off the 1.2 V and 2.5 V power rails and starts up the module in low-power mode. After enumeration, the USB microcontroller firmware switches the 1.2 V and 2.5 V power rails on, if enough current is available from the USB bus.

When S2 S1B is turned off, the 1.2 V and 2.5 V power rails are always enabled.

S2 S1B position	Default position	Effect on 1.2 V and 2.5 V rails
FX2 PON (on)		1.2 V and 2.5 V rails controlled by USB FX2 microcontroller (signal FX2_PS_EN) PS_EN = FX2_PS_EN = 1 or 0
PON (off)		1.2 V and 2.5 V rails always enabled (PS_EN = 1) PS_EN ≠ FX_PS_EN = 1 or 0

Table 14: Slide switch S2 S1B settings overview (1.2 V and 2.5 V rails only).

Signal FX2_PS_EN

To command signal FX2_PS_EN, read the reference firmware code.
IOD = 0x03; // Enable PS_EN and disable PROG_B
OED = 0x03; // Configure PS_EN and PROG as outputs

When slide switch S2 S1B is in the left position ( = FX2 PON : power rails conditionally on depending on signal FX2_PS_EN), signal PS_EN is set to signal FX2_PS_EN (PS_EN = FX2_PS_EN) driven by the EZ-USB FX2LP USB FX2 microcontroller under user control (IOD and OED of fw.c).

Figure 38: S2 S1B on position FX2 PON (PS_EN = FX2_PS_EN = 1 or 0 ).  

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• • FPGA core logic (1.2V)
  • DDR SDRAM (2.5V)
  • FPGA bank 3 (2.5V)
  • VREF (2.5V)
  • VCCCIO0 (2.5V) FPGA bank 0 (if R131+R132- assembly)

Slide Switch

...

S1B = PON 

Summary table

Table 14 summarizes all switching options implied by slide switch S2 S1B and firmware signal FX2_PS_EN (under the standard assembly option).

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⁽²⁾ R131 unsoldered / R132 soldered

Table 40: Slide switch S2 S1B settings overview ( 1.2V , 2.5V, VCCIO0).

 Alternate Assembly Options for Slide Switch

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S1B

Slide switch S2 S1B can be replaced by one resistors in the following cases:

• cost sensitive applications
• applications where just one position of S2 S1B is required
• application where switching of S2 S1B is not allowed.

Assembly option when resistor R17 not populated and R19 populated is equivalent to slide switch S2 S1B permanently set to PON.

Figure 41: assembly option: S2 S1B = PON.

Assembly option when resistor R17 populated and R19 not populated is equivalent to slide switch S2 S1B permanently set to FX2 PON.

Figure 42: Assembly option: S2 S1B = FX2 PON.