PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 61

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Functional Description
®
2.4.2
IOM
-2 Interface Connections
Output Driver Selection
The type of the IOM output is selectable via bit ODS (ADF2 register). Thus when inactive (not
transmitting) IDP0, 1 are either high impedance (ODS=1) or open drain "1" (ODS=0).
Normally the IOM-2 interface is operated in the "open drain" mode (ODS=0) in order to take
advantage of the bus capability. In this case pull-up resistors (1 k – 5 k ) are required on
IDP0 and IDP1.
IOM
®
Direction Control
For test applications, the direction of IDP0 and IDP1 can be reversed during certain timeslots
within the IOM-2 frame. This is performed via the IDC bit in the SQXR register. For normal
operation SQXR:IDC should be set to "0".
In IOM-2 terminal mode these pull-up resistors can also be connected to FSC2/X1 pins instead
of V
in order to reduce the power dissipation.
DD
Semiconductor Group
61