101-0654 Rabbit Semiconductor, 101-0654 Datasheet - Page 70

• Manufacturer Part Number: 101-0654
• Description: INTERFACE OP6800 W/ETHERNET 512K
• Manufacturer: Rabbit Semiconductor

Specifications of 101-0654

• Module/board Type: Single Board Computer Module
• For Use With/related Products: OP6800
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The Demonstration Board has an onboard LM7805 linear regulator for the circuits on the
Demonstration Board only. Its major drawback is its inefficiency, which is directly propor-
tional to the voltage drop across it. The voltage drop creates heat and wastes power.
You may wish to use a switching power supply in your applications where better effi-
ciency is desirable. The LM2575 is an example of an easy-to-use switching voltage regu-
lator. This part greatly reduces the heat dissipation of the regulator. The drawback in using
a switching voltage regulator is its higher cost.
m
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Figure C-3. Demonstration Board Power Supply
Capacitor C1 provides surge current protection for the voltage regulator, and allows the
external power supply to be located some distance away.
Be careful to limit the current draw in any prototype circuits you build on the prototyping
area of the Demonstration Board to avoid operating the linear regulator outside its recom-
mended limits. The LEDs and buzzer together can draw up to 70 mA, which still leaves
some current capacity for your own circuits (see Table C-1) if you plan to use them with
the LEDs and the buzzer.
If you need additional current from the linear regulator beyond that specified in Table C-1,
consider adding a heat sink to the linear regulator (remember to use silicone grease
between the tab and the heat sink), or use a lower voltage power supply.
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MiniCom (OP6800)