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DP-4X SIGNAL POWER SUPPLY SHUTDOWN CIRCUIT EXPLANATION
(Continued from page 10)
D214 Left Hand Input Circuits:
The left hand input to D214 is connected to the collector of Q205. This transistor works as an inverter. Its
base inputs are monitoring DC voltages for shorts.
Q205 base input circuits.
•
D115:
1.
The left hand input monitors the 5.7V line for shorts.
2.
The right hand input monitors the 35V line for shorts.
•
D116:
1.
The left hand input monitors the 10.5V line for shorts.
2.
The right hand input monitors the 3.3V line for shorts.
The Emitter of Q205 pull up voltage is supplied through D213. The left hand input to D213 is 5.7V and the
right hand input is 10.5V. This assures the emitter voltage is always present and allows Q205 to monitor
these voltages without fail. If either the 10.5V or the 3.3V line is shorted, this transistor will still function.
D214 Right Hand Input Circuit:
The right hand input to D214 is connected to the anode of ZD204. This monitors the DC voltage 3.3V for an
over voltage condition. If this voltage rises too much, the zener will fire generating a high on its anode and
through D214 to the Common Action Circuit.
D217 input circuits.
•
D217 Left Hand Input:
1.
ZD202. This monitors the DC voltage 5.7V for an over voltage condition. If this voltage rises too
much, the zener will fire generating a high on its anode and through D217 to the Common Action
Circuit.
•
D217 Right Hand Input:
1.
ZD203. This monitors the DC voltage 10.5V for an over voltage condition. If this voltage rises too
much, the zener will fire generating a high on its anode and through D217 to the Common Action
Circuit.
D218 input circuits.
•
D218 Left Hand Input:
1.
ZD205. This monitors the DC voltage -5.6V for a loss or short. If this voltage disappears, the posi-
tive voltage fed through R241 will pull the cathode of zener diode ZD205 high. The zener will fire
generating a high on its anode and through D218 to the Common Action Circuit.
•
D218 Right Hand Input:
1.
This monitors the PROT_OVP inputs also labeled as (E) to the connector PPS1 pin 47. There are a
total of 7 inputs fed to this pin described in the previous 9 pages. If this voltage goes high, the high
will be directed through D218 to the Common Action Circuit.
•
D220 input circuits.
The anode of diode D220 is connected to the collector of Q206. This transistor works as an inverter. Its base
input is monitoring the PROT_OCP inputs also identified as (F) from the connector PPS1 pin 45. These
inputs will be Low in nature. There are a total of 5 inputs fed to this pin described in the previous 9 pages.
•
See references to (F) on the PROT_OVP and PROT_OCP SHUTDOWN DIAGRAM.
See references to (E) on the PROT_OVP and PROT_OCP SHUTDOWN DIAGRAM.
PAGE 01-11
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