Regulator Circuit - Epson LQ 1050 - B/W Dot-matrix Printer Technical Manual

2.3.2.6 +5V Regulator Circuit
Figure 2-18 shows the +5 VDC regulator circuit An NJ M2355 switching regulator IC is used for
constant-frequency pulse-width modulation. The circuit shown below employs an NJ M2355 configured
as a chopper-style switching regulator circuit.
This IC has a built-in oscillator. The oscillation frequency is determined by external components
connected to pins 2 and 3. Therefore, R22, and C9 cause the circuit to oscillate at about 30 kHz. The
oscillator waveform is shown in Figure 2-19.
+
o
I
o
NJM 2355 (7A)
R
19 33K
N I
- c 12
o.
Figure 2-18. +5V Regulator Circuit
Figure 2-19. Oscillator Waveform
012
A1015
13
R
2. w
2-21
-
D3
: R14
10V
03
4