Epson TM U200D Technical Reference - Page 58

TM-U200D/U200PD Technical Manual +5V DC control circuit The +5V regulator circuit switches the +24V power input and converts it to +5V. The switching regulator IC (U1) switches the +24V input, smooths it via C1, and outputs +5V. Power for the RS-232 is generated by the internal charge-up circuit on the RS-232 interface driver. U5 30 WDTOUT P80 WDTOUT 73 +24COM SW P51/T04 74 CRCOM SW P52/T05 76 PFCOM SW P53/INT1/TI4 CN1 F1 +30V 11 GND 22 N . C 33 F . G 4 SH F . G R59 Q24 +5V Q27 Q1 D47 G N D Q2 D48 D6 P.G Q3 D49 +24DT C12 C11 L1 GND R9 + _ C10 R17 1M FG C13 GND R5 D4 G N D +24DT U2 5 VIN 3 VOUT 2 SW 4 SEN R6 + _ C14 1 GND + _ C45 + _ C16 +24A HEAD COM A / C COM DKD COM D3 R7 U3 5 VIN 2 SW 3 VOUT G N 4 SEN D 1 + C6 _ C7 +24B CR COM GND D5 U4 5 VIN 2 SW 3 VOUT G N 4 SEN D 1 GND + C8 _ C9 SW1 +5I 1 2 Power switch R42 + _ C2 U1 10 IN C3 1 OUT 6 LIN G 5 + _ C1 +24C PF COM {5 V 1 C5 GND + _ C41 GND 1 Figure 2-18 Power supply circuit diagram Control Circuitry Reset circuit The reset circuit is used to prevent the CPU from operating erratically and the print head from printing unexpectedly during the period of unstable voltage immediately after the power is turned on. To accomplish this, the OUT terminal output (pin5) of the reset IC (U9) is supplied to the CPU (U5) as the -RESET input signal (pin 21). The reset IC (U9) monitors the +5V voltage. When the voltage is 4.5V or more, the reset is released for the CPU and other components, and the printer becomes ready. In addition, the C terminal (pin 4) of the reset IC (U9) is connected to the reset signal (DSR signal or pin 25 input signal) from the host interface via DIP switches 2-3 and 2-4. If a reset signal is applied to this pin, the reset IC output goes low and the CPU and other components are reset. The reset signals differ depending on the interface specifications: Rev. B Mechanism Configuration and Operating Principles