You advanced hello, recently I in measuring a board, the board is mainly control LCD main control board,

Description: observation circuit, this design is through the Gamma IC manufacturing different voltage source, provided to the OPA (MC33174) of reverse signal, then the output of the OPA concatenated 100 ohm is connected to a "K27 (SOT23-6)", K27 is encapsulation shell can see the words, I use the electric meter with diodes resistance gear and gear measurement, and refer to relevant specifications speculation on the Internet should be 2 n7002kdw double N - (MOS), don't know what is wrong? Hand draw circuit is measured by the meter to draw also I help me confirm whether there is a problem?

In addition to ask, why not OPA output drive LCD directly, why through K27 components, design considerations?


https://photos.app.goo.gl/Cq1XyQ6NTsgn8RKUA