BL4S100 User’s Manual
120
A
PPENDIX
B. P
OWER
S
UPPLY
Appendix B describes the power circuitry provided on the
BL4S100.
B.1 Power Supplies
Power is supplied to the BL4S100 boards via the Micro-Fit connector at J17. The
BL4S100 is protected against reverse polarity by a diode at D27 as shown in Figure B-1.
Figure B-1. BL4S100 Power Supply
The input voltage range is from 9 V to 36 V. A switching power regulator is used to provide
+5 V for the BL4S100 logic circuits. In turn, the reg5 V DC power supply is used
to drive reg1.8 V and +3.3 V power supplies.
The digital ground and the analog ground share a single split ground plane on the board,
with the analog ground connected at a single point to the digital ground by a 0
resistor
(R63). This is done to minimize digital noise in the analog circuits and to eliminate the
possibility of ground loops. External connections to analog ground are made on a screw-
terminal header at J15.
LINEAR POWER
REGULATOR
POWER
IN
J17
C25
10 µF
LM1117T
U10
+3.3 V
3
1
2
1
3
B240
D27
47 µF
C56
330 µF
+5 V
L3
C93
150 µH
D18
B240
SWITCHING POWER REGULATOR
U17
LM2576
RAW
1
4
2
C48
10 µF
LINEAR POWER
REGULATOR
C79
10 µF
+1.8 V
TPS76918
U16
1
2
5