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?