User's Guide

User’s Guide Multipurpose Interface Board
2110059 Rev 1.0 Proprietary and Confidential Page 91
10.3. Power Supply
The MIB requires a 12V DC, 1 Amp power supply. An AC adapter (part number 1900000) is
provided with the OEM Developer’s Toolkit.
This power is converted by the MIB into the 5V (and 7V for the SB220) supply needed by the
modems. It is not designed to support more than one modem connected to the MIB at any time.
There is a power switch on the MIB that controls delivery of both the 5V and 7V supplies to the
modem connectors but DOES NOT control the 5V supply to the MIB’s own logic. The MIB’s
logic is on whenever the 12V supply is connected.
The normal initial setup has jumper J21 (Power Select) set on pins 1 and 2 which will deliver
power to the modem from the MIB’s power source.
10.3.1. Voltage Adjustment
A trim-pot is provided to make fine adjustments to the 5V supply, accommodating cable loss and
allowing you to test the modem under various power conditions.
NOTE
At this time the 5V power adjustment will also affect the 5V supply to the MIB’s own
logic. Extreme settings may cause failures of the MIB that should not be interpreted as
failures of the modem.
There is protection circuitry intended to prevent the trim-pot from setting values high enough to
damage the MIB or modem. The range is approximately 5V +5%/–10%.
The 5V supply can be measured at test point TP3 or at pin 1 of the power select jumper (J21).
The 7V supply does not have adjustment controls.
10.3.2. Using Power from Host (DTE)
For users testing a host connection to a SB302, it is possible to power the modem from the host
(DTE) device rather than the MIB. To do this, connect the host to the 2x8-pin block
(J9 SB301/302 To Host) and set jumper J21 (Power Select) to pins 2 – 3 (+5V Host).
At this time, there is no provision for a similar host connection to the SB300 or SB320. These
modems do however derive power from the source set by jumper J21 (Power Select) so this must
be set to pins 1 – 2 for normal operation. A workaround to allow host power to supply the modem
is to patch the host power to pins 1 and 2 of the SB301/302 host connector block (J9) and set the
power select jumper (J21) to pins 2 – 3.
The MIB’s 12V power supply must remain on to deliver power to the RS-232 / HCMOS
conversion logic. The DTE/DCE serial lines are converted to RS-232, made available at the Serial
Breakout Box, and then converted back to HCMOS at each end.
10.4. Connections
This section provides information on the use of the various connectors on the MIB.
10.4.1. PC Host (DTE) RS-232 Serial Connection
There are two 9-pin D connectors (female) provided on the MIB to connect to standard RS-232
serial ports on a host terminal, usually a PC.