DSP 104-plus, Справочное руководство

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26 158004.B00
is present then the battery pin on the J3 connector must be connected to GND,
to prevent it floating. The battery pin is called BATT and is pin 28. A ground pin
exists on the adjacent pin, pin 27.
The calendar/clock circuitry draws approximately 2uA from the battery when the
TP400 is powered down and draws no current when operating normally (i.e. powered
up).
The TCDEVPLUS has a 3.6V NiMH rechargeable battery installed. This connects to
the BATT input via an enable/disable jumper, as described in the TCDEVPLUS
manual. The TCDEVPLUS NiMH battery should be sufficient for the clock to operate
for several months in the absence of the +5V power supply. The jumper E2 is
provided on the TCDEVPLUS that can be used to disconnect the battery in order to
extend the battery life or to deliberately corrupt the contents of the CMOS SRAM. The
battery should be disconnected while the TP400/TCDEVPLUS is in storage.
Figure 2 gives a suitable circuit for a rechargeable battery back-up circuit.
NOTE: This circuit is suitable only when using a NiMH or Nicad battery of the type
used on the TCDEVPLUS. The circuit shown in Figure 2 is not suitable for Lithium or
other non-rechargeable battery types. The diode and the resistor must be omitted if a
lithium battery is used.
FIGURE 2 - RECOMMENDED BATTERY BACK-UP CIRCUIT
3.7 KEYBOARD AND MOUSE
The TP400 uses an AT or PS/2 type keyboard. Your supplier can provide a suitable
keyboard. Alternatively, USB keyboards can be used - see section 3.14 for details of
the USB ports.
In many applications the familiar desktop keyboard is inappropriate. A variety of
industrial keyboards and keypads are available - contact DSP Design for details. The
TP400 will work without a keyboard if required.
Users should avoid plugging in the keyboard or mouse when the TP400 is powered
on.
VCC
BATT
NiMH
3.6V
10K Ohm