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Test Point Functions
REF
TP1/TP2
TP4/TP6
TP3, 8,9,10
TP5
TP6
TP7
TP3, 8, 9, 10
TP11
TP21
TP13
TP14
TP17/18
AN‐1590, Rev. New
NAME
BUSB
1553 Bus B connection (secondary of transformer)
BUSA
1553 Bus A connection (secondary of transformer)
GND
Board Ground
VCONT
Connection to measure of input analog amplitude control, note that
J5 should be open. J4 should be open when inputting a voltage.
UPDATE
Test point for Update signal indicates when MIL‐STD‐1553B word has
been received
VSEL
This pin monitors voltage on the VSEL pin control on the output
amplitude.
High = SPI control 0‐24V
Float = Analog Control
Low = SPI Control, 0‐5.1V
GND
Board Ground
3V3
VLOGIC Supply, connect power supply here
VDD
VLOGIC after supply filter
IRQ
INTERRUPT
ACTIVE
Produces pulse just before 1553 message starts, can be used to
trigger scope.
TXDO/RXDO
USB data.
TXA, nTXA
Connect external 1553 data here if not using the on board message
generator for BUSA. Need to cut links TXA and nTXA.
TXB, nTXB
Connect external 1553 data here if not using the on board message
generator for BUSB. Need to cut links TXB and nTXB.
HOLT INTEGRATED CIRCUITS
DESCRIPTION
10/10/14
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