Products > Test Equipment
A strange "7106" chip
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siealex:
Recently I bought a couple of 7106 chips in the QFP44 case. Markings on them look like:
"i" logo
ICL7106
CM44
L0907DWZD
Today I mounted one of them into a burnt meter.
This chip looks like a 7106, swims like a 7106, quacks like a 7106 (yes, it's perfectly compatible), so... it must be a 7106, right?
BUT...
1. Pin 33 is the "Low Battery" segment driver (in the datasheet for 7106: NC). It lights up at approx. 6 V. I accidentally measured the output signal on a wrong pin (33 instead of 32) and found out that pin 33 acts like a segment driver.
2. Pin 5 is "HOLD"!!! Yep, hold, like on modern cheapo meters. Short it to the battery positive with a switch (my meter has this switch) and you get a hold. In the same datasheet: NC as well.
3. Pins 1 and 2 emit square pulses at approx. 3 Hz (one pulse per ADC cycle), the duty cycle on pin 1 depends on the analog input value (0..50%), on pin 2 is constant (approx. 25%). In the datasheet: both NC. Are they some test outputs of the integrator circuitry?
4. The power consumption is approx. 0.3 mA in voltage mode (according to the datasheet, 1.0..1.8 mA). This is typical for 7126/7136/7137 chips, not 7106.
What chip is this?


magic:
I recall some commie block company made a clone 7106 years ago, there are probably clone 7106 made in China today.
Something has to go into all those $5 manual ranging DMMs...

I think I have seen some Internsil variant with HOLD and BATTERY LOW, but I can't find it now. I thought it was ICL7126, but it's not.
So dunno, maybe it isn't exactly based on any original part.
siealex:
Its surprisingly similar to the AME7106 datasheet.
https://html.alldatasheet.com/html-pdf/55556/AME/AME7106/250/5/AME7106.html
Pins 1 and 2 are integrator status outputs (1 is high during deintegration, 2 during integration, during the auto-zero phase both are low), 33 is Battery Low (output), 5 is HOLD (input).

BUT: my chip has the Intersil logo on it ("i" with a long triangle below) and ICL marking.
magic:
Good find.

Regarding the logo, it's just a bit of paint, it means nothing.

You can buy FT232 clones with FTDI logo.
You can buy DS18B20 clones with Dallas logo.
You can buy 74 series logic clones with NXP or TI logo.

This is normal business practice in China ;D
Either some manufacturers are doing it or you can custom order ICs without markings and then print anything on them.
iMo:
The 7106 family has been copied by many.. Interesting is the info in the AME's DS - the Ordering info - the Temp range - chips max temperature from 70 to 77C step 1C :)
A pity there is not a pin called "6.5digits".. :D
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