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OTP LED is ON when connecting TX-SDK board and XEM3001 module

Other Parts Discussed in Thread: LMV321

Hi,

Whenever I connect Tx-SDK board and XEM3001 board the OTP led is turned high. This happens when there is no power supply connection given to the TX-SDK-V2 board and the FPGA is programmed with TX_EN and sLA as high. Is it happens usually? When I checked the +3.3 V supply rail it reads 2.45 V

I am afraid there is a short in the board.. Any information will be appreciated.

Regards,

Fathima

NET "FPGA_MODE" LOC = P119;NET "OTP_LED" LOC = P205;NET "FPGA_TX_EN" LOC = P148;NET "FPGA_ARST" LOC = P146;NET "FPGA_S_LA" LOC = P140;NET "FPGA_S_DATA" LOC = P138;NET "FPGA_S_CLK" LOC = P135;NET "FPGA_S_RD" LOC = P143;NET "SYS_RST_N" LOC = P194;NET "START" LOC = P191;NET "LOCKED_OUT" LOC = P204;NET "FPGA_PSR_EN" LOC = P132;NET "FPGA_SDI" LOC = P130;NET "FPGA_SCLKI" LOC = P114;NET "FPGA_SCSI" LOC = P126;NET "FPGA_SW_RST" LOC = P111;NET "FPGA_SPI_EN" LOC = P124;NET "FPGA_OTP" LOC = P116;NET "data<0>" LOC = P196;NET "data<1>" LOC = P197;NET "Y<0>" LOC = P203;NET "Y<1>" LOC = P200;NET "Y<2>" LOC = P199;NET "Y<3>" LOC = P198;
NET "hi_in<0>" LOC = "P79";NET "hi_in<1>" LOC = "P57";NET "hi_in<2>" LOC = "P58";NET "hi_in<3>" LOC = "P78";NET "hi_in<4>" LOC = "P61";NET "hi_in<5>" LOC = "P62";NET "hi_in<6>" LOC = "P63";NET "hi_in<7>" LOC = "P64";NET "hi_out<0>" LOC = "P81";NET "hi_out<1>" LOC = "P85";NET "hi_inout<0>" LOC = "P67";NET "hi_inout<1>" LOC = "P68";NET "hi_inout<2>" LOC = "P72";NET "hi_inout<3>" LOC = "P74";NET "hi_inout<4>" LOC = "P86";NET "hi_inout<5>" LOC = "P87";NET "hi_inout<6>" LOC = "P90";NET "hi_inout<7>" LOC = "P92";NET "hi_inout<8>" LOC = "P93";NET "hi_inout<9>" LOC = "P94";NET "hi_inout<10>" LOC = "P95";NET "hi_inout<11>" LOC = "P96";NET "hi_inout<12>" LOC = "P97";NET "hi_inout<13>" LOC = "P100";NET "hi_inout<14>" LOC = "P101";NET "hi_inout<15>" LOC = "P102";
NET "clk1" LOC = "P80";NET "SYS_CLK2" LOC = "P77";

  • Hi Fathima,

    If you look at the schematic of how the OTP LED is biased, if the FPGA_OTP is 3.3V (instead of high impedance or ground), then the LED will be on. The reason the 3.3V supply is 2.45V is because there is an ESD diode from pin 3 of the LMV321 to pin 5 (3.3V).

    Hope it helps,

    Charles