ETS2228 Maintenance Manual
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Page 17, Total 43
Figure 6 TL494
The differential amplifier can work within the range from AC -0.2V to 0.2V. The time overflow
controller has a fixed offset to assure the stable output in case of the changed external input. The external
oscillating circuit can be set through Rt/Ct (The working frequency to be set is 100KHZ).
3 .
Power supply anti-reverse-insertion circuit and external
interface
D305 and D301 fulfill the anti-reverse=insertion function of the external power supply. EXT_DC
signal: Whether or not the external power supply exists; V_BATT signal: Battery voltage;
VREG_PHONE signal: Voltage of the second-time power supply.