Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 66 of 143
2.2.1.3 Guidelines for VCC supply circuit design using a LDO linear regulator
The use of a linear regulator is suggested when the difference from the available supply rail source and the
VCC value is low. The linear regulators provide high efficiency when transforming a 5 VDC supply to a
voltage value within the module VCC normal operating range.
The characteristics of the Low Drop-Out (LDO) linear regulator connected to the VCC pins should meet the
following prerequisites to comply with module VCC requirements summarized in Table 7:
Power capabilities: the LDO linear regulator with its output circuit must be capable of providing a
voltage value to the VCC pins within the specified operating range and must be capable of delivering
to the VCC pins the maximum peak / pulse current consumption during Tx burst at maximum Tx power
specified in the TOBY-L3 series Data Sheet [1].
Power dissipation: the power handling capability of the LDO linear regulator must be checked to limit
its junction temperature to the maximum rated operating range (i.e. check the voltage drop from the
maximum input voltage to the minimum output voltage to evaluate the power dissipation of the
regulator).
Figure 23 and the components listed in Table 19 show an example of a power supply circuit where the VCC
module supply is provided by an LDO linear regulator capable of delivering the required current with a
suitable power handling capability.
It is recommended to consider configuring the LDO linear regulator to generate a voltage supply value
slightly below the maximum limit of the module VCC normal operating range (e.g. ~4.1 V for the VCC, as
in the circuits illustrated in Figure 23 and Table 19). This reduces the power on the linear regulator and
improves the thermal design of the circuit.
5V
C1
R1
IN OUT
ADJ
GND
1
2
4
5
3
C2
R2
R3
U1
SHDN
TOBY-L3 series
71
VCC
72
VCC
70
VCC
GND
C3
Figure 23: Example of high reliability VCC supply application circuit using an LDO linear regulator
Reference
Description
Part Number - Manufacturer
C1, C2
10 µF Capacitor Ceramic X5R 0603 20% 6.3 V
GRM188R60J106ME47 - Murata
C3
330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m
T520D337M006ATE045 - KEMET
R1
47 k Resistor 0402 5% 0.1 W
RC0402JR-0747KL - Yageo Phycomp
R2
9.1 k Resistor 0402 5% 0.1 W
RC0402JR-079K1L - Yageo Phycomp