ANNA-B112 - System integration manual
UBX-18009821 - R09
System description
Page 9 of 66
C1-Public
Supply interfaces
1.4.1
Main supply input
The ANNA-B112 module uses an integrated DC/DC converter or LDO to transform the supply voltage
presented at the
VCC
pin into a stable system core voltage. Due to this, the ANNA-B112 module is
compatible for use in battery powered designs.
While using ANNA-B112 with a battery, it is important that the battery type can handle the peak
power of the module. In case of battery supply, consider adding extra capacitance on the supply line
to avoid capacity degradation. See the ANNA-B112 data sheet [2]
supply requirement and current consumption.
Table 2: Summary of voltage supply requirements
☞
The current requirement in Table 2 considers using the u-connectXpress software with UART
communication. But it does not include any additional I/O current. Any use of external
push buttons, LEDs, or other interfaces will add to the total current consumption of the
ANNA-B112 module. The peak current consumption of the entire design must be considered in
battery powered solutions.
1.4.2
Digital I/O interfaces reference voltage
On the ANNA-B112 module, the I/O voltage level is the same as the supply voltage and
is internally
connected to the supply input
VCC
.
When using ANNA-B112 module with a battery, the I/O voltage level will vary with the battery output
voltage, depending on the charge of the battery. Level shifters might be needed depending on the I/O
voltage of the host system.
1.4.3
VCC application circuits
The power for ANNA-B112 module is provided through the VCC pins, which can be one of the following:
•
Switching Mode Power Supply (SMPS)
•
Low Drop Out (LDO) regulator
•
Battery
The SMPS is the ideal choice when the available primary supply source has higher value than the
operating supply voltage of the ANNA-B112 module. The use of SMPS provides the best power
efficiency for the overall application and minimizes current drawn from the main supply source.
⚠
While selecting SMPS, ensure that AC voltage ripple at switching frequency is kept as low as
possible. Layout shall be implemented to minimize impact of high frequency ringing.
The use of an LDO linear regulator is convenient for a primary supply with a relatively low voltage
where the typical 85-90% efficiency of the switching regulator leads to minimal current saving. Linear
regulators are not recommended for high voltage step-down as they will dissipate a considerable
amount of energy.
DC/DC efficiency should be evaluated as a tradeoff between active and idle duty cycle of the specific
application. Although some DC/DC can achieve high efficiency at extremely light loads, a typical
DC/DC efficiency quickly degrades as idle current drops below a few mA, which greatly reduces the
battery life.
Rail
Voltage requirement
Current requirement (peak)
VCC
1.7 V – 3.6 V
15 mA
