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3.0 LM87 Evaluation Board Hardware Details
The schematic for the LM87 evaluation board is shown in FIGURE 2. The backup battery (BT1) for the
Chassis Intrusion circuitry has not been installed on the evaluation board. The recommended battery is a
Panasonic BR2330-1HE with 3V nominal cell voltage and 255 mAh capacity.
3.1 JP3
JP3, a four-pin header is provided for access to the SMBus and the power supply (V+ and GND) lines and
is described in TABLE 2.
Table 1 JP3 Description
Pin Number
Description
1
V+
2
SDA
3
SCL
4
GND
This header may be used for daisy chaining multiple boards together by connecting the V+, SDA, SCL and
GND pins of the different boards.
3.2 JP5
The two pin header JP5 allows the disconnection of the on board voltage regulator, (an LP2950CZ-3.3)
from the parallel printer port connection. The board is shipped with a jumper in place, allowing the board to
derive all of its power from the parallel printer port.
Table 2 JP5 Power Supply Input Header Description
Pin Number
Description
1
Input of the LP2950CZ-3.3
2
Parallel printer port rectifier
circuitry
3.3 JP1
The output of the LP2950CZ-3.3 is connected to the load circuitry through JP1. This allows the user to
optionally power the LM87 and other circuitry with a voltage other than 3.3V. When daisy chaining boards
it may be necessary to supply an external power source connected to pin 1 of JP1. When using an external
supply, ensure that the voltage does not exceed the specifications of any of the Vcc powered circuitry.
Table 1 JP1 Power Supply Output Header Description
Pin Number
Description
1
Vcc powered circuitry
2
Output of the LP2950CZ-3.3