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are output via JK402, JK401 respectively.
- Power Supply block
Configuration: IC402 (DC/DC converter), IC403 (1.8V regulator),
IC404 (1.9V regulator), IC411 (OP Amp), IC413 (negative power
regulator), Q403, Q404, Q405, Q411, Q412 (transistor), L401, C408,
C453, C454, D406~D409, BAT401, IP401, IP402 (circuit protection
device) and so on.
Function:
+15V input is made step-down to +3.3V by DC/DC converter circuit
that consists of IC402, L401, Q412 and C408, and is supplied to
each IC power. And, it monitors +3.3V output voltage and turns
ON Q411 to block +15V input when over voltage is supplied.
+15V input is dropped to +9.4V by Q403 and is supplied to RS232C
driver with the inverted voltage (about 9.1V) generated in IC413,
C453 and C454.
+3.3V generated in DC/DC converter is converted to 1.8V in the
back board or IC403 and Q405 via Q404 and supplied to IC101
core power, and also is converted to 1.9V in IC404 via the back-
flow prevention diode D407 and supplied to IC101 clock block
power.
BAT401, which is a lithium battery for memory backup, is
connected to the power supply of IC301, IC302 (SRAM) via D408,
D409.
IC411 compares BAT401 output voltage to the reference voltage
(about 2.8V) and drives LED (BATALM) that indicates dropping of
backup voltage.
IP401and IP402 block the line respectively when over current
flows to +15V and +3.3V line.
10. BACK BOARD CIRCUIT OPERATION
The back board (BB) connects signals between all cards in KX-TDA100. It also supplies power
from the power supply unit to the cards.
CONNECTORS EXPLANATION
(1) Power Supply Unit Connector: CN100
(2) Free Slot Connectors: CN102-CN106
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