
45
Data Device Corporation
www.ddc-web.com
BU-6474X/6484X/6486X
J-07/05-0
+3.3 VOLT ISOLATION TRANSFORMERS
In selecting isolation transformers to be used with the Mini-ACE
Mark3, there is a limitation on the maximum amount of leakage
inductance. If this limit is exceeded, the transmitter rise and fall
times may increase, possibly causing the bus amplitude to fall
below the minimum level required by MIL-STD-1553. In addition,
an excessive leakage imbalance may result in a transformer
dynamic offset that exceeds 1553 specifications.
The maximum allowable leakage inductance is a function of the
coupling method. For Transformer Coupled applications, it is a
maximum of 5.0 H. For Direct it is a maximum of 10.0 H, and
is measured as follows:
The side of the transformer that connects to the Mark3 is defined
as the "primary" winding. If one side of the primary is shorted to
the primary center-tap, the inductance should be measured
across the "secondary" (stub side) winding. This inductance
must be less than 5.0 H (Transformer Coupled) and 10.0 H
(Direct Coupled). Similarly, if the other side of the primary is
shorted to the primary center-tap, the inductance measured
across the "secondary" (stub side) winding must also be less
than 5.0 H (Transformer Coupled) and 10.0 H (Direct
Coupled).
The difference between these two measurements is the "differ-
ential" leakage inductance. This value must be less than 1.0 H
(Transformer Coupled) and 2.0 H (Direct Coupled).
Beta Transformer Technology Corporation (BTTC), a subsidiary
of DDC, manufactures transformers in a variety of mechanical
configurations with the required turns ratios of 1:3.75 direct cou-
pled, and 1:2.7 transformer coupled. TABLE 46 provides a listing
of these transformers.
For further information, contact BTTC at 631-244-7393 or at
www.bttc-beta.com.
TABLE 46. BTTC TRANSFORMERS FOR USE WITH +3.3 VOLT Mini-ACE Mark3
MLP-2233
DSS-1003
Dual epoxy transformer, side by side, surface mount (SMT), transformer coupled or direct coupled depending on
pins selected,
0.960” x 0.575” x 0.165” max. height, -55°C to +130°C operating temperature
MLP-2033
Single epoxy transformer, surface mount (SMT), transformer coupled,
0.400” x 0.400” x 0.185” max. height, -55°C to +120°C operating temperature.
BTTC PART NO.
TRANSFORMER CONFIGURATION
Single epoxy transformer, surface mount (SMT), direct coupled,
0.400” x 0.400” x 0.185” max. height, -55°C to +120°C operating temperature.
Notes:
1. SMT (Surface Mount) body package size (a” x b”) does not include leads.
2. The list of approved transformers for use with SSRT Mark3 is constantly being updated. Please see the Beta Transformer Technology Corporation
web site (www.bttc-beta.com) for the latest transformer configuration information.