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PPENDIX
C.1 Power Supplies
Power is supplied to the Jackrabbit board from an external source through either header J1
or header J4. J1 is a 3-pin straight header with a pitch of 0.1". V
ground on pins 1 and 3. The symmetry allows for a 3-pin cable to be connected either way.
The Jackrabbit board itself is protected against reverse polarity by a Shottky diode at D2
as shown in Figure C-1. The Shottky diode has a low forward voltage drop, 0.3 V, which
keeps the minimum DCIN required to power the Jackrabbit lower than a normal silicon
diode would allow.
J1
1
2
3
Figure C-1. Jackrabbit Power Supply Schematic
The external power, +RAW, is provided to any daughterboard connected to the Jackrabbit
via pin 38 of header J4. +RAW is not protected against reversed polarity, such as could
happen if the cable was connected to header J1 offset by one pin. This absence of protec-
tion is intentional so as to provide the maximum possible voltage to any daughterboard
connected to the Jackrabbit.
Capacitor C1 provides surge current protection for the voltage regulator, and allows the
external power supply to be located some distance away from the Jackrabbit board. A
switching power supply or a linear power supply option is provided, depending on the
Jackrabbit model.
User's Manual
C. P
+RAW DCIN
D2
1N5819
C1
10 µF
SWITCHING POWER SUPPLY
LM2575
14
15
8
1
12
M
OWER
ANAGEMENT
is on pin 2 between
in
LINEAR POWER SUPPLY
Vcc
7805
U1
3
1
C2
2
100 nF
7
U2
17
4
2
330 µH
18
1
3
L1
D1
10
1N5819
Vcc
C3
330 µF
45
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