Part Number: LM2902DR, Cycle: 2549+5 This is a very mature product model. Currently, 100% of the defective products are pre-tested using this cycle. The defect phenomenon is: addrpriocold_3A_-40V_cold. After debugging and ABA cross-validation, it was confirmed that the root cause lies in the abnormality of component N11. Comparative measurements on pin 14 of N11 showed that the normal unit voltage is 6.4V and the faulty unit voltage is 6.0V. The voltage at this pin is significantly lower in the faulty unit. We need to confirm whether there has been any change to this chip and the possible causes of the problem. Thank you
Hi RuiPing,
The high level output voltage of the LM2902 is specified with a minimum of VCC-1.5V at 25C with a 10Kohm load. Under the other datasheet conditions (VCC = MAX = 26V for the LM2902), with load greater than 10kOhms operating across the full temperature range, the typical high level output voltage is 24V (VCC-2V).
With a 7V supply voltage, a high level output voltage of 6V instead of 6.4V is within the specifications of this device.
Given that this issue occurs at low temperatures (Based on the test name "addrpriocold_3A_-40V_cold"), you may be able to improve the VOH level by changing the value of the pullup resistance, as described in section 5.2 of Application Design Guidelines for LM324 and LM358 Devices (Rev. B).
Let me know if you have any questions.
Best,
Alex Curtis
