TE0320 is provided with a slide switch S2.
Slide switch S2 conditions the value of signal PS_EN.
In this way, S2 conditionally/unconditionally enables the 1.2 V and 2.5 V power rails.
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title | Slide switch S2 schematic |
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title | 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 |
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Figure 33: Slide switch S2 (angle view).When S2 is turned on (closed, FX2 PON), the power rails 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 1enables (switches on) power rails 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 (switched on).
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When S2 is turned on (FX2 PON), make sure that no signals are applied to the input pins when power-rails are disabled by the USB microcontroller (at start-up). |
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title | Slide switch S2 settings overview (power rails 1.2 V and 2.5 V only) |
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S2 position | Default position | Effect on 1.2 V and 2.5 V rails |
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FX2 PON (on, closed) | | Power rails 1.2 V and 2.5 V | |
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controlled by USB FX2 microcontroller (signal FX2_PS_EN) PS_EN = FX2_PS_EN = 1 or 0 | PON (off, open) | | Power rails 1.2 V and 2.5 V |
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(PS_EN = 1) PS_EN ≠ FX_PS_EN = 1 or 0
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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
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title | Table from EZ-USB(R) Technical Reference Manual |
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Table from EZ-USB(R) Technical Reference Manual (EZ-USB_TRM.pdf) Port D Pin | Alternate Function | Alternate Function is Selected By... | Alternate Function is Described in... |
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PD.7:0 | FD[15:8] | IFCFG1 = 1 and any WORDWIIDE bit = 1 | Slave FIFOs chapter 9 on page 99 |
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Signal PS_EN
VCCIO0 assembly options
According to the corresponding assembly option, power rail VCCCIO0 can depend or not on the power rail 2.5V.
Voltage VccIO for bank B0 shall span from 2.5 V to 3.3 V. VccIO can be supplied either externally or internally to the micromodule.
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Spartan-3 I/Os are not 5 V tolerant. Applying more than the recommended operating voltages at any pin, results in a damaged FPGA (see Xilinx Answer AR#19146). |
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title | example of VCCIO0 assembly not dependent on power rail 2.5V. The other way is also possible |
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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).
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title | S2 on position FX2 PON (PS_EN = FX2_PS_EN = |
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- Dynamic full power operation (PS_EN = high1): when the EZ-USB FX2LP USB FX2 microcontroller sets signal PS_EN = FX2_PS_EN = high, power rails 1.2 .5V V and 12.2V 5 V are enabled.
This setting can be useful for . - Dynamic low power operation (PS_EN = low0): 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 (if R131+R132- assembly)
Slide Switch S2 = PON
Full power operation ((PS_EN = high1): 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.Image Removed
Figure 34:
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title | S2 on position PON (PS_ |
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EN ≠ . Signal PS_EN
- Signal PS_EN enables (high) or disables (low) power rails 2.5V and 1.2V.
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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.
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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.
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Figure 37: example of VCCIO0 assembly not dependent on 2.5V power rail. The other way is also possible.
Summary table
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Summary table
The table below Table 14 summarizes all switching options implied by slide switch S2 and firmware signal FX2_PS_EN (under the standard assembly option).
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title | Slide switch S2 settings overview ( 1.2 V , 2.5 V, VCCIO0) |
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power rail | S2= PON (PS_EN = 1) (PS_EN ≠ FX2_PS_EN) (Full power)
| S2 = FX2 PON and PS_EN = FX2_PS_EN = 1
(Dynamic full power)
| S2 = FX2 PON and PS_EN = FX2_PS_EN = 0
(Dynamic low power)
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1.2V | on | on | off | 2.5V | on | on | off | VCCCIO0 (= 2.5V) R131+R132- assembly (1) | on | on | off | VCCCIO0 (= 3.3V) R131-R132+ assembly (2) | on | on | on |
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Table 14: Slide switch S2 settings overview ( 1.2V , 2.5V, VCCIO0).
Alternate Assembly Options for Slide Switch S2
Slide switch S2 can be replaced by one resistors in the following cases:
- cost sensitive applications
- applications where just one position of S2 is required
- application where switching of S2 is not allowed.
Assembly option when resistor R17 not populated and R19 populated is equivalent to slide switch S2 permanently set to PON.
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title | Assembly option: S2 = PON |
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Assembly option when resistor R17 populated and R19 not populated is equivalent to slide switch S2 permanently set to FX2 PON.
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title | Assembly option: S2 = FX2 PON |
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Any other assembly options of R17 and R19 are not allowed. |
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