Page History

...

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

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 (PS_EN = FX2_PS_EN) driven by the EZ-USB FX2LP USB FX2 microcontroller under user control (IOD and OED of fw.c). 

Figure 35: S2 on position FX2 PON (PS_EN = FX2_PS_EN = high or low ).

Figure 36: Slide switch S2 schematic.


Figure 37: 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.

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

...

Signal PS_EN

• 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.

• 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.

VCCIO assembly

...

options

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.

Summary table

...

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

...