BMD-34 / 38 EVK - User guide
UBX-19033356 - R05
Hardware description
Page 6 of 20
C1-Public
2
Hardware description
Design files for each of the BMD-3xx evaluation boards may be requested from the
Figure 2: Assembly drawing (Top view)
2.1
Power
The BMD-34 evaluation board has five possible power sources as listed below:
•
USB from the debug interface
•
USB peripheral on the BMD-34 itself
•
CR2032 coin cell battery
•
2.54 mm through-hole connector for connecting 3.3 V
•
Lithium Polymer (LiPo) battery input
These power sources use protection diodes to prevent reverse voltage to any supply. This
allows them to be used simultaneously. Solder jumpers are provided to allow by-passing any
of the protection diodes eliminating the voltage drop across them.
⚠
Care should be taken to not damage the supplies when the protection is by-passed.
2.1.1
Powering the board
During typical debugging, power will be provided by VBUS on the USB debug interface to
supply 5 V to the 3.3 V LDO regulator and to the shield connector. The 3.3 V LDO regulator will
then power
VIO
,
VSHLD
, and
VBMD
.
When powering the board from the CR2032 coin cell (3VDC), the external power header, or the
LiPo header, USB can be left disconnected. In this configuration, the interface IC is held in reset
to conserve power.
☞
Only if the power protection diodes are left intact can the USB be safely connected at the
same time as the coin cell or external power is still applied, which allows for easy
programming of the module.
