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.
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 | 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 |
(2) R131 soldered / R132 unsoldered
(3) R131 unsoldered / R132 soldered
Table 14: Slide switch S2 settings overview ( 1.2V , 2.5V, VCCIO0).
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 ).
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.