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ADG1409 for switching power supply

Question asked by Joaquim on Jul 30, 2012
Latest reply on Aug 9, 2012 by Joaquim

Hi all,

 

I want to switch two power supply (+5V and +12V) with an ADG1409 mux to 4 differents outputs. Please see attached image.

 

I use U15 to select the power supply. With A0_1 == A1_1 == 0 in DA pin I will have +5V, and with  A0_1 == 0 nad A1_1 == 1, I'll have +12V in the DA pin.

 

The U10 is for switch the 5V or 12V to another output. With A0_0 == A1_0 == 0 the selected power supply will mux in the +EXC1 signal, A0_0 == 0 and A1_0 == 1, +EXC2, etc.

 

The +12V is used for supply both mux and for the each +EXC signals. The voltage of logical signal control of both MUX is +3.3V.

 

The problem is that I haven't any voltage in DA pin of U15 when control pins are selected. For example, when EN = 3.3V, A0_1 = 3.3V and A1_1 = 0V, the DA output is 0V.

 

I have checked:

 

1. hi and lo voltage in control pins, they are ok.

2. the +5V and 12V are present on S1A and S2A of U15.

 

Can anybody help me please?

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