Themis NanoPAK, User Manual

Page: 48 / 156

2-16
Themis Computer
NanoPAK
®
User Manual Version 1.0
external battery or an internal battery.
• An external battery may have either the exact voltage required by COMEx-
press
®
specification, (fixed range mode), or a voltage between 9V and 36V,
(wide range mode). In the latter case, an LDO DC/DC converter steps down
the external battery input to 3V. This condition is set by solder bead SB21 set-
ting as indicated in
Table 2-7 and in Table A-5, "Solder Bead Settings," on page
A-11 of Appendix A.
• When an internal battery is used, two options are offered depending on the
design operating temperature. For the normal operating range between -20°C
Figure 2-12. Standby Power Diagram
VCC_RTC (2Vmin -3.3Vmax)
+
-
LDO
(on 69-pin connector)
External VBat
(Fixed range 2.5Vmin 3.3V max)
(Wide range 9Vmin 36V max)
SB2
1
4
2
3
JP1
JP6
Caution: When the “fixed range mode” is set, the LDO DC/DC converter is not
present in the circuit. Therefore, a “wide range” voltage applied to the external bat-
tery circuit will cause excessively high voltages to be applied to the power rails and
will cause damage to the components of the SBC. When the “fixed range mode” is
set, ensure that only in-spec voltage is applied to the external battery circuit, (2.5V
min to 3.3V max).
Table 2-7. External Standby Voltage Settings
Solder Beads
Setting
Wide Range
(9V to 36V) Fixed Range
(3.3V)
SB21 1-2, 3-4 2-3