Canon ZR70 MC A Service Manual page 85

• Backup Lithium Battery
LI3V power from the lithium battery is input to pin 3 of the IC102, and it is output from pin 12 as power to the MODE microcom-
puter. Thus, the MODE microcomputer performs data backup and clock operation when main power supply is not connected.
When the voltage of the lithium battery decreases below 2.6 V (or when the lithium battery is not loaded), the IC102 outputs the "L"
signal form pin 2. Upon receipt of this signal at the time of power-on, the MODE microcomputer sends it to the FR microcomputer,
which then issue a lithium battery low-level warning indication.
• Main Power Supply
Main power (DC-JACK/BATTERY) is supplied to pin 13 of IC102. Through the internal regulator in IC102, the main power thus
supplied is converted to 3V power, which is output as E3V from pin 14 of IC102. Furthermore, through the internal switch, the
main power is converted to LI3V, which is output from pin 12 of IC102 as a power voltage for driving the MODE MI-COM.
Supplied with the main power, IC102 outputs the "L" signal from its pin 4. When the MODE MI-COM receives the "L" signal and
the two signals output from pin 4 of IC103, it recognizes that the power supply is loaded. Then the MODE MI-COM performs
initialization to set up a standby state. In this state, the MODE MI-COM carries out detection of start-related switch signals. Upon
detection of these switch signals, the MODE MI-COM delivers the VTR ON(H) signal from its pins 52. When the VTR ON(H)signal
is output, each circuit power is made active.
When each circuit power is made active, 3V power is input to pins 5/7 of IC102. 3V power is output as the power for the MODE
MI-COM from pin 12 of IC102 to save its power consumption.
CHAPTER 2. TECHNICAL DESCRIPTION
2-4
ZR70 MC A, ZR65 MC A, ZR60 A