Circuit Description; Internal Operation; Power-On-Reset Signal Generation Circuit - Sharp PC-1600 Service Manual

-
P C-1600
3. Block diagram
0 0,
-
0
A o - A,
FROM
CE· 1 600P
{PRINTER)
107N, WR, RD,
RSTN
Vcc (+5V)
Vp (+6V)
50P CONNECTOR

4. Circuit description

4-1. Internal operation

Since the floppy disk controller
2.5" floppy disk drive unit and directly interfaced with the
bus line, data line and control signals are directly con-
nected.
So, only the power-on-reset signal generation circuit and
the amp's 5VC (+5V) supply regulator circuit are provided
for circuit.

4-2. Power-on-reset signal generation circuit

RSTN
VCC
Fig. 1 Raset circuit
8
3
3
~ POWER ON
RESET
CIRCUIT
REGURATED
POWER
~
SUPPLY
CIRCUIT
is contained within the
VCC
R5
REST
0 0
- 7
0
A A,
o -
CSO, WR, RD,
REST
+5V
5VB
5VC
+6V
FDU-250 MICRO FLOPPY DISK DRIVE UNIT
POWER ON
~y
I
I
VCC
-:---+/lJ.
,
Delay
____
@ ::
.;__-;
Reset ~
period~
Fig.2 Raset timings
Fig. 1 shows the reset circuit and Fig. 2 shows its timings.
R5 is acharge current regulating resistor C3 which is used
for pullup and delay. D4 is a diode which is used to bypass
the charge in C3 to VCC line when VCC is off.
-99-
1ff' ~
R!W
FDC
&
WO
LOGIC f--;l
WG R!W AMP
~
LSI
RD
~
GATE
ARREY
r SOLENOID
SOLENOID
,
CONTROL
CIRCUIT
~
rr1
MOTOR
CONTROL
CIRCUIT
I
, System reset
n
, ,
t
U
ERASE
j
(+5)
VCC
0
H
L
H
L