TCA9548A: Defect serie of this compontents?

No.

Please show the schematic, and specify what the defect is.

Hi

Schematic is linked to in the bottom of this side about the module: https://wiki.dfrobot.com/Gravity__Digital_1-to-8_I2C_Multiplexer_SKU_DFR0576

As part of error searching I connected a esp32 wroom to the Gravity module (linked above), and 4x BME280 sensors. This worked. Then I desolder the TCA9548 and hand soldered a new one on under microscope. The new one was taken from tape. I only disconnected usb power, alle other connections was kept. With new TCA it did not work. Then I put the old TCA back on and it worked again.

I stille have 5 ic's in not  opened tape.

I get 10new from rs-online tomorrow. I will make above test again, and then replace on our own pcb's. Above test was to make sure that it was not something else in hw or sw. 

I have never seen more defective new ic before. I have been in production where 10^9 components where mounted....

Br David 

What exactly do you mean with "did not work"? Does it acknowledge writes to its configuration register?

All chips sold by TI are tested. Did you buy those chips from an authorized distributor?

All data/signal in is ok, no data/signal out. No contract with ic.

IT test when produced, not when sold. You are saying they are not produced by IT? Which do you thing is IT.