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Hello：
Batch 2221 LM2904DGKR abnormal description: After the main control chip LM5026 of the whole machine detects a fault, the RES output (internal current source current is 7.5-12.5ua) charges the C126 capacitor with a voltage of 2.5V, and pin 3 of IC104 (LM2904DGKR) detects this voltage and compares it with pin 2 (1.17V ) for comparison, and output a high level to the subsequent circuit. When the ambient temperature is 100 ℃, the leakage current of pin 3 is large, so the voltage here cannot rise. Eventually lead to the failure of the functional circuit here. After changing to batch 2144, the input signal level is normal and the circuit works. The partial schematic diagram of the circuit is shown in Figure 1, in which IC104 is the device LM2904DGKR.
Waveform comparison
Ambient temperature 100℃
CH2 abnormal 2221 batch 3 pin (IN+) to 4 pin (GND) waveform as shown in the figure
The normal 2144 batch 3-pin (IN+) to 4-pin (GND) waveform is shown in the figure
After scanning, the customer found that the silk screen and internal circuit diagrams of the two batches of materials were different.
2221 batch silk screen, and DPA diagram, as follows
Other batches of 2144 batches of silk screen and DPA pictures are as follows
Please help confirm，Thanks！！！
Hi Jerry：
Thank you for your reply
1、Here are the two stickers on the reels from the devices include both the 2221 and 2144 batches. After scanning, the customer found that the silk screen and internal circuit diagrams of the two batches of materials were different.
Would you please help explain this difference，Thanks！！！
2、For the schematic diagram, R160 is 30k and R161 is 4k，Customer Feedback This is a mass production project，Except for batch 2221, other batches are normal.
Would you please check the schematic diagram for any problems and points that need improvement, Thanks！！！
Hi Ron：
Customers say PIN2 has no negative voltage.
This picture only shows the difference between the 2221 and 2144 batches LM2904
Customer found some problems between 2 batches and then do some experiment
The picture show that customer test 3-pin (IN+) to 4-pin (GND) waveform for 2 batches under ambient temperature 100℃.
abnormal voltage
normal voltage
When the ambient temperature is 100 ℃, the leakage current of pin 3 is large, so the voltage here cannot rise. Eventually lead to the failure of the functional circuit here.
