...
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.
When S2 is turned on (closed, 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 (open, PON), the 1.2 V and 2.5 V power rails are always enabled.
S2 position | Default position | Effect on 1.2 V and 2.5 V rails |
---|---|---|
FX2 PON (on, closed) | 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, open) | 1.2 V and 2.5 V rails always enabled (PS_EN = 1) PS_EN ≠ FX_PS_EN = 1 or 0 |
...
Port D Pin | Alternate Function | Alternate Function is Selected By... | Alternate Function is Described in... |
---|---|---|---|
PD.7:0 | FD[15:8] | IFCFG1 = 1 and any WORDWIIDE bit = 1 | Slave FIFOs chapter 9 on page 99 |
Table from EZ-USB(R) Technical Reference Manual (EZ-USB_TRM.pdf).
Power-rail 3.3V is not controlled by signal PS_EN and is unconditionally enabled.
Figure 37: Power rails 3.3V 3 V could not be enabled/disabled by signal PS_EN.
According to the corresponding assembly option, power rail VCCCIO0 can depend or not on the 2.5V 5 V power rail.
Figure 37: example of VCCIO0 assembly not dependent on 2.5V 5 V power rail. The other way is also possible.
...
...
Full power operation (PS_EN = 1): 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 rails 1.2 .5V V and 12.2V 5 V are unconditionally enabled.
Figure 39: S2 on position PON (PS_EN ≠ FX2_PS_EN = x; PS_EN = high ).
...
power rail | S2= PON | S2 = FX2 PON and | S2 = FX2 PON and |
---|---|---|---|
1.2V | on | on | off |
2.5V | on | on | off |
VCCCIO0 (= 2.5V) | on | on | off |
VCCCIO0 (= 3.3V) | on | on | on |
(1) R131 soldered populated / R132 unsolderedunpopulated
(2) R131 unsoldered unpopulated / R132 solderedpopulated
Table 40: Slide switch S2 settings overview ( 1.2V 2 V , 2.5V5 V, VCCIO0).
...