Ublox SARA-N210, System Integration Manual

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SARA-N2 series - System Integration Manual
UBX-17005143 - R06 Design-in Page 54 of 82
2.11.2 Guidelines for VCC supply circuit design
The power supply ratings, average and pulse, must be considered in the design of the VCC supply
circuit on the application device integrating SARA-N211 module, implementing proper circuits
providing adequate maximum voltage and current to the VCC supply input of the modules, according
to the specific potentially explosive gas atmosphere category subdivision where the apparatus is
intended for use.
Table 25 lists the maximum input and equivalent parameters that must be considered in the sub-
division IIC, the sub-division IIB and the sub-division IIA for SARA-N211 modules.
Parameter SARA-N211
Ui 4.2 V
Ii 0.5 A
Ci 68.1
µ
F
Li 8.5
µ
H
Table 25: Maximum input and equivalent parameters for sub-division IIC
Primary and secondary cells and batteries
Cells and batteries incorporated into equipment with intrinsic safety “i” protection to potentially
explosive gas atmosphere shall conform to the requirements of the IEC 60079-0
[15] ,
IEC 60079-11 [16] ATEX standards.
Shunt voltage limiters
For Level of Protection “ia”, the application of controllable semiconductor components as shunt
voltage limiting devices, for example transistors, thyristors, voltage/current regulators, etc., may be
permitted if both the input and output circuits are intrinsically safe circuits or where it can be shown
that they cannot be subjected to transients from the power supply network. In circuits complying with
the above, two devices are considered to be an infallible assembly.
For Level of Protection “ia”, three independent active voltage limitation semiconductor circuits may
be used in associated apparatus provided the transient conditions of the clause 7.5.1 of IEC 60079-11
standard are met. These circuits shall also be tested in accordance with the clause 10.1.5.3 of the IEC
60079-11 standard
[16] .
Series current limiters
The use of three series blocking diodes in circuits of Level of Protection “ia” is permitted, however,
other semiconductors and controllable semiconductor devices shall be used as series current-limiting
devices only in Level of Protection “ib” or “ic” apparatus. However, for power limitation purposes, Level
of Protection “ia” apparatus may use series current limiters consisting of controllable and non-
controllable semiconductor devices.
The use of semiconductors and controllable semiconductor devices as current-limiting devices for
spark ignition limitation is not permitted for Level of Protection “ia” apparatus because of their
possible use in areas in which a continuous or frequent presence of an explosive atmosphere may
coincide with the possibility of a brief transient which could cause ignition. The maximum current that
may be delivered may have a brief transient but will not be taken as Io, because the compliance with
the spark ignition test of the clause 10.1 of IEC 60079-11 standard
[16] would have established the
successful limitation of the energy in this transient.