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

REV.-A
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.
C3746 013
L2
+
o
012
A1015
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I
NJM 2355 (7A)
9
R 13
D3
2. w
IW
‘:” 1
Cll t
1000U’
03
10V
lo5t
R 19 33K
( )
VA1$
- c 12
N
I
o.
IM +N
C7
o
4
Figure 2-18. +5V Regulator Circuit
—
—
- +5#v
: R14
- 3. 3K
_ GND
20ys/ DI V
Figure 2-19. Oscillator Waveform
2-21
,.