EPSON Stylus PHOTO 895/785EPX
Revision A
Operating Principles
Electrical Circuit Operating Principles
51
2.2.2.5 ASF Motor Drive Circuit
The motor driver IC on the MAIN board drives the ASF motor. This product uses 4-
phase 200-pole hybrid type stepping motor and performs constant current bi-polar
drive.
CPU (IC2) converts ASF motor phase control signal to LB1946 micro step drive form
and outputs to motor driver IC (IC10) LB1946 from each port. Based on this signal,
IC10 determines the phase mode.
The current value on each phase is determined by CPU (IC2) and outputs from each
port to driver IC (IC10). Motor driver IC generates motor driver waveform based on
these input signals and controls the motor. If the printer does not receive any data from
PC for 5 minutes, CPU set the motor drive current to 0 via each port and the motor
drive is turned off to save the power consumption.
Figure 2-23. ASF Motor Driver Circuit Block Diagram
2.2.2.6 Reset and EEPROM circuits
Unlike the previous products, this product uses IC in which reset circuit and EEPROM
are united.
Reset Circuit
Reset circuit RTC9822 (IC6), which monitors three types of voltage; logic group
(+3.3V, +5V) and power group (+42V), is mounted on the C408MAIN board.
Each reset circuit monitors the voltage of +3.3V, +5V and +42V and prevents the
operation failure of printer by resetting CPU and ASIC if any failure is detected. It
is possible for this IC to monitor the +3.3V, +5V and +42V lines by one IC and
performs resetting on each voltage. Following circuit diagram shows the structure
of reset circuit.
Figure 2-24. Reset EEPROM Circuit Diagram
+3.3V line reset circuit
The 3.3V line is monitored at the VDD port of IC6. It outputs the reset signal
from the FRST port to the CPU ASIC if the irregular voltage (2.5V or less) is
detected.
CLK
DATA
SET
VREF1
VREF2
MD
CR1
CR2
E1
E2
ST
GND
NC
NC
NC
OUTA
OUTA-
OUTB
VBB
VBB
VCC
NC
NC
NC
NC
NC
NC
OUTB-
1
3
4
ASF_SCLK
ASF_DAT
ASF_LAT
C_P47
C_P25
2
7
5
8
9
14
1
28
2
4
5
10
11
13
21
23
27
16
24
25
18
3
12
20
15
17
19
26
22
23
21
3
22
27
+5V
CN11
Rotor
+42V
+5V
E01A22CA
(IC2)
LB1946
(IC10)
+5V
+42V
+3.3V
+3.3V
14
12
8
10
128
129
130
133
VDD
VI5
VDD2
VEX
7
1
6
VSS
MON
IRQ
CE
CLK
DI
DO
EXO
FRST
RST
5
4
3
2
135
126
134
C_P20
C_P21
C_P22
C_P23
NMILVL
MRES
RESET
RTC9822
(IC6)
CPU-
ASIC2in1
(IC2)
9
13
11