I input a 1 Vp-p signal for an experiment and it was output as is Is there any problem if I use the IC as is?
A3 There is a problem. To make the input signal 1 Vp-p in the external video signal mode, the level of the internal video signal (character signal) must be adjusted accordingly. Perform the following setting. 1. Internal video signal amplitude control bitVPD = 0 2. Voltage applied to Vcnt pin 2.5 V Item 1 above can be changed by a command, but item 2 requires modification of the hardware. The voltage of the pin cannot be changed by a command. – Forcibly apply 2.5 V to the VCNT pin from an external source. – Insert a resistor between Vcnt and VDD (+5 V) to adjust the voltage applied to Vcnt to 2.5 V. The level of VBSO pin is determined by a voltage-dividing resistor connected between the Vcnt pin and VDD (+5V). The above two methods may be used to adjust the voltage applied to the Vcnt pin to 2.5 V. Reference document: OSD LSIs User’s Manual Figure 2-9 in “2.2.
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