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I am having trouble with the 7107 IC. I have 5 of them on my PCB: 3 being used as current measurement and the other 2 are being used as a voltage measurement.

Only one of the 5 are displaying readings on the 7-segment display (may not be calibrated correctly but is showing something). The other 4 are the 7-segments are all blank. I have attached the circuit diagram below.

I have check the all 7-segments are working with the test feature on pin 37. The clock is oscillating at 40-43KHz (check with oscilloscope). The difference I am seeing with respects to the one working versus the others is that 100nF connected to cref+ and cref- on the working unit is pulsing about 1.3V, the others have no pulse or very low (mV) pulses.

I really starting to believe I have a bad batch of IC's. Please provide any tips or recommendations. Thanks in advance.

enter image description here

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You are almost surely seeing the display 'blank' because you're ignoring the most significant digit (AB4 is open). The meters are in overrange (displaying + or - 1bbb where b is blank).

The 7107 works much better with a negative supply (+/-5V is ideal). If you want to use it with a single +5V supply you have to pay a lot of attention to the common mode range of the inputs, so it has to be more than 1V or something like that (read the datasheet) relative to analog COMMON.

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    \$\begingroup\$ @JOHNDOE See the data sheet - it shows a charge-pump circuit using a CMOS inverter chip, a couple diodes, capacitors to generate a -ve voltage. \$\endgroup\$ – glen_geek Nov 5 '18 at 16:40
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    \$\begingroup\$ As @glen_geek said. Or use a TPS60400DBVT, ICL7660 etc. charge pump to generate -5V regulated (my usual choice). \$\endgroup\$ – Spehro Pefhany Nov 5 '18 at 16:53
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    \$\begingroup\$ So a negative 5 on pin 26 will make it work. Wish I knew this before I made the board. Hehehe guess I am always learning \$\endgroup\$ – JOHNDOE Nov 5 '18 at 17:10
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    \$\begingroup\$ Some learning is more painful than others. And the painful varieties are often avoided if you read the entire data sheet. \$\endgroup\$ – WhatRoughBeast Nov 5 '18 at 18:46
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    \$\begingroup\$ Note that you probably only need a single charge pump for the set of DVM chips if you use one like the 7660. The draw from the minus supply is only about 1mA each. \$\endgroup\$ – Spehro Pefhany Nov 5 '18 at 18:52

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