EPSON FX-890/2190 Revision B
Operating Principles Overview 48
TYPE-B IF circuit
Specification: Level 2
Current consumption 0.5 A max.
SSI is supported.
Transmission rates supported are 600/1200/2400/4800/
9600/19200 [bps].
Data reception rate (between TYPE B and Main Circuit
Board) is 2 MB/s at peak.
Data receiving system: DMA
Data reception timing: Based on TYPE-B specification
RESET IC IC13
Power ON reset
• Device: Reset IC LA5623M (Sanyo) equivalent
reset circuit 2
• Detecting voltage: 4.2
± 0.2 V (logic system)
• Processing: Generates a hardware reset, and there is
delay of 60 ms (min.) at turning High from
Low.
Power OFF detection
• Device: Reset IC LA5623M (Sanyo) equivalent
reset circuit 1
• Detecting voltage:1.25
± 0.05 V (keeps watch on power
system by resistor division)
• Processing: Divides 42 V source voltage by resistance
at 1.4/30, and keeps watch on.
Generates NMI interrupt request when
42V source voltage is 28.0 V (min. 26.4
V).
Oscillating circuit
Element: Ceramic oscillator
Frequency: 48.00 MHz
Oscillation stabilization time: 10 ms or less
Table 2-2. Major Elements on MAIN Board (continued)
Elements Location Function
CR Motor Driver IC15
Drive voltage: 42 V ± 5%
Drive IC: SLA7024M (Sanken)
Drive system: Constant-current unipolar drive
Excitation method: 2-2 phase /1-2 phase (quadrangular) /1-2
phase (circular) /W1-2 phase driving
Current detection resistance:0.68 Ω, 2 W
Current value setting:Setting with D/A port of the CPU
D/A reference voltage (= 3.3
± 0.3 V)
The maximum of 8-bit current setting
register for D/A (= d'255)
Current setting resolution:3.3/255/
0.68=0.019A
QPIT compensation: D/A circuit is compensated to ensure
current accuracy (
± 5% at the maximum
current and
± 10% at the minimum
current).
PF Motor Driver IC9
Drive voltage: 42 V± 5%
Drive system: Constant-current bipolar drive
Drive IC: A3972 (Sanken)
Excitation method:1-2 phase
Phase change: The ASIC generates the control signal of
the drive IC based on the trigger signal
(CPU output).
Current value setting: Setting with D/A converter of drive
IC. Any setting number is available.
Current detection resistance:0.56Ω ± 1%, 1 W
Output at reset: SLEEP signal (G/A output) Low. (Output
current off)
Head Driver
QM1,
QM2,
QM3
Drive voltage: 42 V ± 5%
Drive system: Constant voltage drive
Drive Tr: SMA4037 (Sanken) 3A
Control method: Controlled by ASIC based on print timing
signal (CPU output)
At reset: G/A output L (head drive off)
QPIT compensation: The voltage detecting circuit is
compensated to ensure the accuracy of
head energization time.
Table 2-2. Major Elements on MAIN Board (continued)
Elements Location Function
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