© 2004 Device Engineering Inc.
DS-MP-00429 Rev. F
03/11/2004
2 of 12
Functional Description:
Modes:
The BD429 operates in either a 429 mode or a 422 mode as controlled by the 429/422´ pin.
429 Mode:
In 429 mode, the serial data is presented on the DATA(A) and DATA(B) inputs in the dual rail
format defined in the MARK 33 Digital Information Transfer System – ARINC Specification 429-10. The
driver is enabled by the SYNC and CLOCK inputs. The output voltage level is programmed by the V
REF
input and is normally tied to +5VDC along with V
1
to produce output levels of +5 volts, 0 volts, and –5 volts
on each output for ±10 volts differential outputs. *See figure 4.
422 Mode:
In 422 mode, the serial data is presented on DATA(A) input. The driver is enabled by the
SYNC and CLOCK inputs. The outputs swings between 0 volts and +5 volts if V
REF
is at +5VDC. *See
figure 5.
Output Resistance:
The driver output resistance is 75Ω ±20% at room temperature; 37.5Ω on each out-
put. The outputs are also fused for failsafe protection against shorts to aircraft power. The output slew
rate is controlled by external timing capacitors on C
A
and C
B
. Typical values are 75pF for 100 KHz data
and 500pF for 12.5 KHz data.
General Description:
The BD429 ARINC Line Driver Circuit is a bipolar monolithic IC designed to meet the requirements of several
general aviation serial data bus standards. These include the differential bipolar RZ types such as ARINC
429, ARINC 571, and ARINC 575, as well as the differential NRZ types such as the RS-422 standard.
429/422'
NOTE 1
SYNC
NOTE 2
CLOCK
NOTE 2
DATA(A)
NOTE 2
DATA(B)
NOTE 2
A
OUT
B
OUT
COMMENTS
4
2
9
M
O
D
E
H
H
H
H
H
H
L
X
H
H
H
H
X
L
H
H
H
H
X
X
L
H
H
L
X
X
L
H
L
H
0
0
0
0
+V
REF
-V
REF
0
0
0
0
-V
REF
+V
REF
NULL
NULL
NULL
NULL
LOGIC 1
LOGIC 0
4
2
2
M
O
D
E
L
L
L
L
L
X
H
H
X
L
H
H
X
X
L
H
X
X
X
X
+V
REF
+V
REF
0
+V
REF
0
0
+V
REF
0
NULL
NULL
LOGIC 0
LOGIC 1
NOTES:
1. The 429/422' pin is internally pulled up to V
1
through a 10kΩ resistor. So, if no external connection is made to this pin, it will
force the chip into the 429 mode.
2. X = Don’t care.
Table 1: Truth Table