TOBY-L1 and MPCI-L1 series - System Integration Manual
UBX-13001482 - R04
Advance Information
Design-in
Page 41 of 90
2.2.1.4
Guidelines for VCC supply circuit design using a rechargeable Li-Ion or Li-Pol battery
Rechargeable Li-Ion or Li-Pol batteries connected to the
VCC
pins on TOBY-L1 should meet the following
prerequisites to comply with the module’s
VCC
requirements summarized in Table 7:
•
Maximum pulse and DC discharge current
: the rechargeable Li-Ion battery with its output circuit must be
capable of extensively delivering the maximum current pulses to the
VCC
pins specified in
TOBY-L1 series
Data Sheet
[1]. The maximum discharge current is not always reported in battery data sheets, but the
maximum DC discharge current is typically almost equal to the battery capacity in Amp-hours divided by 1
hour.
•
DC series resistance
: the rechargeable Li-Ion battery with its output circuit must be capable of avoiding a
VCC voltage drop below the operating range specified in
TOBY-L1 series Data Sheet
[1] during transmit.
2.2.1.5
Guidelines for VCC supply circuit design using a primary (disposable) battery
The characteristics of a primary (non-rechargeable) battery connected to the
VCC
pins on TOBY-L1 should meet
the following prerequisites to comply with the module’s
VCC
requirements summarized in Table 7:
•
Maximum pulse and DC discharge current
: the non-rechargeable battery with its output circuit must be
capable of extensively delivering the maximum current pulses to the
VCC
pins specified in
TOBY-L1 series
Data Sheet
[1]. The maximum discharge current is not always reported in battery data sheets, but the
maximum DC discharge current is typically almost equal to the battery capacity in Amp-hours divided by 1
hour.
•
DC series resistance
: the non-rechargeable battery with its output circuit must be capable of avoiding a
VCC voltage drop below the operating range specified in
TOBY-L1 series Data Sheet
[1] during transmit.
2.2.1.6
Additional guidelines for VCC supply circuit design
To reduce voltage drops, use a low impedance power source. The resistance of the power supply lines
(connected to the
VCC / 3.3Vaux
and
GND
pins of the module) on the application board and battery pack
should also be considered and minimized: cabling and routing must be as short as possible to minimize power
losses.
Three pins are allocated to
VCC
supply and five pins to
3.3Vaux
supply. Another twenty pins are designated for
GND
connection. Even if all the
VCC / 3.3Vaux
pins and all the
GND
pins are internally connected within the
module, it is recommended to properly connect all of them to supply the module to minimize series resistance
losses.
To reduce voltage ripple and noise, which should improve RF performance especially if the application device
integrates an internal antenna, place the following bypass capacitors near the
VCC / 3.3Vaux
pins:
•
68 pF capacitor with Self-Resonant Frequency in the 800/900 MHz range (e.g. Murata GRM1555C1H680J)
to filter EMI in the LTE band 13
•
15 pF capacitor with Self-Resonant Frequency in 1800/1900 MHz range (e.g. Murata GRM1555C1E150J)
to filter EMI in the LTE band 4
•
10 nF capacitor (e.g. Murata GRM155R71C103K) to filter digital logic noise from clocks and data sources
•
100 nF capacitor (e.g. Murata GRM155R61C104K) to filter digital logic noise from clocks and data sources
A bypass capacitor with large capacitance and low ESR (e.g. KEMET T520D337M006ATE045, 330 µF, 45 m
Ω
)
can be used to avoid
VCC
or
3.3Vaux
spikes, but it is not strictly required.
The necessity of each part depends on the specific design, but it is recommended to provide all the
VCC
and
3.3Vaux
bypass capacitors described in Figure 22 and Table 13 if the application device integrates an
internal antenna.
