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User’s Guide
SWRU321A
– May 2013
Page 18/32
The EM domain may be powered using various power sources; USB powered (regulated to 3.3
V), battery powered (regulated to 2.1 V or unregulated) and using an external power supply
(regulated to 2.1 V or unregulated).
When battery powered or powered by an external source, the EM power domain is by default
regulated to 2.1 V using a step down converter. The step down converter may be bypassed by
mounting a jumper on J502 (Figure 13), powering the EM domain directly from the source. When
J502 is not mounted, the EM power domain is regulated to 2.1 V. The maximum current
consumption of the EM power domain is then limited by the regulator to 410 mA.
Figure 13
– Mount a jumper on J502 to bypass EM domain voltage regulator
6.3.3 3.3 V Domain
The 3.3 V domain is a sub domain of the EM domain. The 3.3 V domain is regulated to 3.3 V
using a buck-boost converter, irrespective of the source powering the EM domain. Signals in the
3.3V domain (controlled by the EM)
are prefixed “HV_” for High Voltage in the schematics.
Two EB peripherals are in the 3.3 V domain, the LCD and the SD card slot, as listed in Table 5.
These peripherals are connected to the EM domain via level shifters U401 and U402.
The 3.3 V domain may be switched on (off) completely by the mounted EM board by pulling
signal LV_3.3V_EN to a logical 1 (0). See Table 14 in section 6.11.1 for details about the
mapping between the EM and signals onboard the SmartRF06EB.
6.4 LCD
The SmartRF06EB comes with a 128x64 pixels display from Electronic Assembly (DOGM128E-6)
[4]. The LCD display is available to mounted EM via a SPI interface, enabling software
development of user interfaces and demo use. Table 6 shows an overview of the I/O signals
related to the LCD.
The recommended operating condition for the LCD display is a supply voltage between 3.0 V and
3.3 V. The LCD display is powered from the 3.3 V power domain (HI_VDD). The min (max)
operating temperature is -20 (+70)
˚C.
The LCD connector on SmartRF06EB is very tight to ensure proper contact between
the EM and the LCD. Be extremely cautious when removing the LCD to avoid the
display from breaking.
NOTE:
Mounting a jumper on J502 will not have any effect if the SmartRF06EB is powered
over USB (when the power source selection switch, S502, is in “USB” position).
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