Ubx-13004618 - R28 - Ublox TOBY-L2 Series System Integration Manual
Lte/dc-hspa+/egprs modules
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2.2.1.3 Guidelines for supply circuit design using a Low Drop-Out linear regulator
The use of a linear regulator is suggested when the difference from the available supply rail and the
VCC or the 3.3Vaux value is low. The linear regulators provide high efficiency when transforming a 5
VDC supply to a voltage value within the module VCC or 3.3Vaux normal operating range.
The characteristics of the Low Drop-Out (LDO) linear regulator connected to VCC or 3.3Vaux pins
should meet the following prerequisites to comply with the module VCC or 3.3Vaux requirements
summarized in
Table
Power capabilities: the LDO linear regulator with its output circuit must be capable of providing a
voltage value to the VCC or 3.3Vaux pins within the specified operating range and must be capable
of delivering to VCC or 3.3Vaux pins the maximum peak / pulse current consumption during Tx
burst at maximum Tx power specified in TOBY-L2 or MPCI-L2 Data Sheet
Power dissipation: the power handling capability of the linear regulator must be checked to limit
its junction temperature to the maximum rated range (i.e. check the voltage drop from the max
input voltage to the minimum output voltage to evaluate the power dissipation of the regulator).
Figure 35
and the components listed in
VCC or 3.3Vaux module supply is provided by an LDO linear regulator capable of delivering the required
current, with proper power handling capability.
It is recommended to configure the LDO linear regulator to generate a voltage supply value slightly
below the maximum limit of the module VCC or 3.3Vaux normal operating range (e.g. ~4.1 V for the
VCC and ~3.44 V for the 3.3Vaux as in the circuits described in
the power on the linear regulator and improves the thermal design of the circuit.
5V
2
IN
OUT
U1
C1
R1
1
ADJ
SHDN
GND
3
5V
2
IN
OUT
U1
C1
R1
1
ADJ
SHDN
GND
3
Figure 35: Suggested schematic design for the VCC and 3.3Vaux supply application circuit using an LDO linear regulator
Reference
Description
C1, C2
10 µ F Capacitor Ceramic X5R 0603 20% 6.3 V
C3
330 µ F Capacitor Tantalum D_SIZE 6.3 V 45 m
R1
47 k Resistor 0402 5% 0.1 W
R2
9.1 k Resistor 0402 5% 0.1 W
R3
3.9 k Resistor 0402 5% 0.1 W
R4
3.3 k Resistor 0402 5% 0.1 W
R5
1.8 k Resistor 0402 5% 0.1 W
U1
LDO Linear Regulator ADJ 3.0 A
Table 17: Suggested components for VCC and 3.3Vaux supply application circuit using an LDO linear regulator
UBX-13004618 - R28
TOBY-L2 and MPCI-L2 series - System Integration Manual
7:
Table 17
70
4
71
72
R2
C2
C3
5
R3
4
24
39
41
R4
C2
C3
5
52
R5
show an example of a power supply circuit, where the
Figure 35
TOBY-L2 series
VCC
VCC
VCC
GND
MPCI-L2 series
3.3Vaux
2
3.3Vaux
3.3Vaux
3.3Vaux
3.3Vaux
GND
Part Number – Manufacturer
GRM188R60J106ME47 – Murata
T520D337M006ATE045 – KEMET
RC0402JR-0747KL – Yageo Phycomp
RC0402JR-079K1L – Yageo Phycomp
RC0402JR-073K9L – Yageo Phycomp
RC0402JR-073K3L – Yageo Phycomp
RC0402JR-071K8L – Yageo Phycomp
LT1764AEQ#PBF – Linear Technology
Design-in
[1]
[2].
and
Table
17). This reduces
Page 73 of 164
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