Vdc Regulator Circuit - Epson LQ-510 Technical Manual

REV.-A

2.2.6 +5 VDC REGULATOR CIRCUIT

Figure 2-25 shows the + 5 VDC Regulator Circuit. The + 5 VDC is generated from the + 24 VDC by a chopper-
type switching regulator circuit utilizing a TL494. Through pin 13 of the output control terminal, the TL494
can cause the IC to operate in either push-pull or parallel mode. In the illustration, pin 13 is LOW, and parallel
action is in effect. In other words, the operation of the IC's two output transistors will be exactly alike.
The IC incorporates an internal oscillating circuit. The oscillating frequency is determined by the external
inputs to pins 5 and 6. In this circuit, the frequency, set by R29 and C25, is about 27K Hz.
LQ-510
Figure 2-25. +5 VDC Regulator Circuit
PRINCIPLES OF OPERATION
2-21