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TE0320 is provided with a slide switch S2. S2 conditionally / unconditionally enables the 1.2 V and 2.5 V power rails.


Figure 33: Slide switch S2 (angle view).

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

S2 position

Effect on 1.2 V and 2.5 V rails

FX2 PON (on)(1)

1.2 V and 2.5 V rails controlled by USB FX2 microcontroller (signal FX2_PS_EN)

PON (off)

1.2 V and 2.5 V rails always enabled

 (1) default: FX2 PON

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

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

Slide switch S2 conditions the value of signal PS_EN.

  • When slide switch S2 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 driven by the EZ-USB FX2LP USB FX2 microcontroller under user control.

    Figure 34: Slide switch S2 schematic.


    Figure 35: When slide switch S2 = FX2 PON, signal PS_EN is set to signal FX2_PS_EN driven by the EZ-USB FX2LP USB FX2 microcontroller under user control.
  • Signal PS_EN enables (high) or disables (low) power rails 2.5V and 1.2V.

    Figure 36: Power rails 2.5V and 1.2V could be enabled/disabled by signal PS_EN.
  • According to the corresponding assembly option, power rail VCCCIO0 can depend or not on the 2.5V power rail.

    Figure 37: example of VCCIO0 assembly not dependent on 2.5V power rail. The other way is also possible.

  • Power-rail 3.3V is not controlled by signal PS_EN and is unconditionally enabled. 
      
    Figure 38: Power rails 3.3V could not be enabled/disabled by signal PS_EN.

Table 14 summarizes all switching options implied by slide switch S2 under the standard assembly option.

power rail

S2= PON

S2 = FX2 PON and
PS_EN = FX2_PS_EN = 1

S2 = FX2 PON and
PS_EN = FX2_PS_EN = 0

1.2V

on

on

off

2.5V

on

on

off

VCCCIO0 (= 2.5V)
R131+R132- assembly (2)

on

on

off

VCCCIO0 (= 3.3V)
R131-R132+ assembly (3)

on

on

on

(2) R131 soldered / R132 unsoldered

(3) R131 unsoldered / R132 soldered

Table 14: Slide switch S2 settings overview ( 1.2V , 2.5V, VCCIO0).

Slide Switch S2 = FX2 PON

When slide switch S2 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 driven by the EZ-USB FX2LP USB FX2 microcontroller under user control.

Figure 35: S2 on position FX2 PON (PS_EN = FX2_PS_EN = x ).

  1. Dynamic full power operation (PS_EN = high): when the EZ-USB FX2LP USB FX2 microcontroller sets signal PS_EN = FX2_PS_EN = high, power rails 2.5V and 1.2V are enabled.
    This setting can be useful for .
  2. Dynamic low power operation (PS_EN = low): when the EZ-USB FX2LP USB FX2 microcontroller resets signal PS_EN = FX2_PS_EN = low, the following components are switched off:
  • FPGA core logic (1.2V)
  • DDR SDRAM (2.5V)
  • FPGA bank 3 (2.5V)
  • VREF (2.5V)
  • VCCCIO0 (2.5V) FPGA bank 0

Slide Switch S2 = FX2 PON 

When slide switch S2 is in the right position (PON = power rails unconditionally on), signal PS_EN is set to power rail 3.3V. Thus power rails 2.5V and 1.2V are unconditionally enabled.


Figure 34: S2 on position PON.




 

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