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Table from EZ-USB(R) Technical Reference Manual (EZ-USB_TRM.pdf)
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Signal PS_EN enables (1) or disables (0) power rails 1.2 V, 1.5 V and 2.5 V.
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Power-rail 3.3V is not controlled by signal PS_EN and is unconditionally enabled.
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Info |
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According to the corresponding assembly option, power rail VCCCIO0 (enabled by PS_EN and switch S1B ) can depend or not on the power rail 2.5V. |
VCCIO0 voltage can be configured in 3 ways:
(1) See Spartan-6 documentation fo VCCIO power range.
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Others options of VCCIO0 power supply are not supported and can damage the FPGA! |
See the figure below to locate R102 and R103 on PCB.
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See section "FPGA I/O banks power supply" here.
When Dip switch S1B 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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Full power operation (PS_EN = 1): when Dip switch S1B is in the right position (PON = power rails unconditionally on), signal PS_EN is set to power rail 3.3V. Thus power rails 1.2 V, 1.5 V and 2.5 V are unconditionally enabled.
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The table below summarizes all switching options implied by Dip switch S1B and firmware signal FX2_PS_EN (under the standard assembly option).
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(1) R102 unpopulated / R103 populated (2) R102 populated / R103 unpopulated |