
17
Figure1-17
TL494
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.
Figure1-18
Anti-reverse-insertion circuit