LARA-R2 series - System Integration Manual
UBX-16010573 - R02
Objective Specification
Design-in
Page 81 of 148
2.2.3
Interface supply (V_INT)
2.2.3.1
Guidelines for V_INT circuit design
LARA-R2 series provide the
V_INT
generic digital interfaces 1.8 V supply output, which can be mainly used to:
Indicate when the module is switched on (see sections 1.6.1, 1.6.2 for more details)
Pull-up SIM detection signal (see section 2.5 for more details)
Supply voltage translators to connect digital interfaces of the module to a 3.0 V device (see section 2.6.1)
Pull-up DDC (I
2
C) interface signals (see section 2.6.4 for more details)
Supply a 1.8 V u-blox 6 or subsequent GNSS receiver (see section 2.6.4 for more details)
Supply an external device, as an external 1.8 V audio codec (see section 2.7.1 for more details)
V_INT
supply output pin provides internal short circuit protection to limit start-up current and protect the device
in short circuit situations. No additional external short circuit protection is required.
Do not apply loads which might exceed the limit for maximum available current from
V_INT
supply (see
the
LARA-R2 series
Data Sheet
[1]) as this can cause malfunctions in internal circuitry.
Since the
V_INT
supply is generated by an internal switching step-down regulator, the
V_INT
voltage
ripple can range as specified in the
LARA-R2 series
Data Sheet
[1]: it is not recommended to supply
sensitive analog circuitry without adequate filtering for digital noise.
V_INT
can only be used as an output: do not connect any external supply source on
V_INT
.
ESD sensitivity rating of the
V_INT
supply pin is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level could be required if the line is externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible point.
It is recommended to provide direct access to the
V_INT
pin on the application board by means of an
accessible test point directly connected to the
V_INT
pin.
2.2.3.2
Guidelines for V_INT layout design
V_INT
supply output is generated by an integrated switching step-down converter, used internally to supply the
generic digital interfaces. Because of this, it can be a source of noise: avoid coupling with sensitive signals.
