Integration Manual

LISA-U series - System Integration Manual
3G.G2-HW-10002-A3 Preliminary System description
Page 20 of 160
The VCC pins are directly connected to the RF power amplifiers and to the integrated Power Management Unit
(PMU) within the module: all supply voltages needed by the module are generated from the VCC supply by
integrated voltage regulators.
V_BCKP is the Real Time Clock (RTC) supply. When the VCC voltage is within the valid operating range, the
internal PMU supplies the Real Time Clock and the same supply voltage will be available to the V_BCKP pin. If
the VCC voltage is under the minimum operating limit (for example, during not powered mode), the Real Time
Clock can be externally supplied via the V_BCKP pin (see section 1.5.4).
When a 1.8 V or a 3 V SIM card type is connected, LISA-U series modules automatically supply the SIM card via
the VSIM pin. Activation and deactivation of the SIM interface with automatic voltage switch from 1.8 to 3 V is
implemented, in accordance to the ISO-IEC 7816-3 specifications.
The same voltage domain used internally to supply the digital interfaces is also available on the V_INT pin, to
allow more economical and efficient integration of the LISA-U series modules in the final application.
The integrated Power Management Unit also provides the control state machine for system start up and system
reset control.
1.5.2 Module supply (VCC)
The LISA-U series modules must be supplied through the VCC pins by a DC power supply. Voltages must be
stable: during operation, the current drawn from VCC can vary by some orders of magnitude, especially due to
surging consumption profile of the GSM system (described in the section 1.5.3). It is important that the system
power supply circuit is able to support peak power (refer to LISA-U1 series Data Sheet [1] and LISA-U2 series
Data Sheet [2] for the detailed specifications).
Name
Description
Remarks
VCC
Module power supply input
VCC pins are internally connected, but all the available pads
must be connected to the external supply in order to
minimize the power loss due to series resistance.
Clean and stable supply is required: low ripple and low
voltage drop must be guaranteed.
Voltage provided must always be above the minimum limit of
the operating range.
Consider that during a GSM call there are large current spikes
in connected mode.
GND
Ground
GND pins are internally connected but a good (low
impedance) external ground can improve RF performance: all
available pads must be connected to ground.
Table 6: Module supply pins
VCC pins ESD sensitivity rating is 1 kV (Human Body Model according to JESD22-A114F). Higher
protection level can be required if the line is externally accessible on the application board. Higher
protection level can be achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor
array) on the line connected to this pin, close to accessible point.
The voltage provided to the VCC pins must be within the normal operating range limits as specified in the
LISA-U1 series Data Sheet [1] and LISA-U2 series Data Sheet [2]. Complete functionality of the module is only
guaranteed within the specified minimum and maximum VCC voltage normal operating range.
The module cannot be switched on if the VCC voltage value is below the specified normal operating
range minimum limit. Ensure that the input voltage at VCC pins is above the minimum limit of the
normal operating range for more than 3 s after the start of the module switch-on sequence.