2-9
2.1.2.2
RTC (Real Time Clock) circuit
The FW82371EB incorporates an RTC function.
The RTC includes the hardware for clock and calendar functions and the battery backup type CMOS-RAM that can manage the
hardware setup information.
Operation is compatible with the MC146818.
To actuate the RTC, it is necessary to install the battery and the oscillator externally.
The oscillatory frequency is 32.768kHz, fixed. The clock is also of the backup type.
VCC(RTC)
L16
RTCVCC
RTCX2
R20
10M
22p
22p
X2
32. 768KHz
RTC
FW82371EB
RTCX1
N19
This system uses a lithium battery to back up the RTC circuit.
The battery (BT_1) is a charge-disabled coin type primary battery that maintain a voltage of about +3.0V.
When the power supply is ON, +3V (+3.3V) is turned to the RTCVCC voltage via D_1. When the power supply is OFF, the
battery voltage is used as the RTCVCC voltage via D_2.
The C_1 capacitor is a backup capacitor to be used during the replacement of battery.
The battery backup time is only about 2 minutes, and therefore care must be taken at the time of replacement.
R_2
100
R_1
1K
+3V
TP1
0. 1u
C_1
680uF
D_2
M A704
BT_1
RTCVCC
+
D_1
M A 704
C R 2450
Содержание JS-170FR Series
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Страница 101: ...3 17 LCD DISPLAY TEST 6 Video Test ENTER 1 OK or 2 NG ...
Страница 134: ...4 JS 170FR PCB s 4 1 Main PCB 4 1 1 Main PCB Schematic Diagram 1 10 4 1 ...
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Страница 144: ...4 1 2 Main PCB Parts Location 4 11 ...
Страница 145: ...4 2 MB PCB 4 2 1 MB PCB Schematic Diagram 4 17 ...
Страница 146: ...4 18 4 2 2 MB PCB Parts Location ...
Страница 148: ...4 3 Peripheral PCB 4 3 1 Peripheral PCB Schematic Diagram 4 20 ...
Страница 149: ...4 21 4 3 2 Peripheral PCB Parts Location ...
Страница 152: ...5 2 Main PCB 75 Peripherals ...
Страница 153: ...5 3 Power Supply Peripherals ...
Страница 154: ...5 4 Customer Display Peripherals ...
Страница 155: ...5 5 LCD Peripherals ...
Страница 156: ...5 6 Inverter PCB Peripherals ...
Страница 161: ...Printed in Japan ...