hi TI
Problem Description:
The output of lmv358idr of on-board operational amplifier is abnormal, which is inconsistent with the specification (the full-scale output is only 4.5V, which can not reach the 5V voltage close to VCC power supply)
Specific verification method:
1. There is an open circuit between TW1 and TW2. At this time, the input of pin 5 of the operational amplifier is pulled up to VCC2 (5V) through 2K resistance. At this time, the theoretical value of pin 7 output should be 5v-20mv = 4.98v, and the actual test is only about 4.6V. There are about 10 circuit boards tested, and the phenomenon is consistent.
2. When a fixed resistance is connected between TW1 and TW2, when the output is below 4.6V, there is no problem with the input and output. When the input exceeds 4.6V, the output is saturated and does not increase with the increase of the output.
3. The circuit is simulated with Tina, and the simulation results are no problem.
