LARA-R6 series - Data sheet

UBX-21004391 - R09

Interfaces

Page 11 of 41

C1-Public

2 Interfaces

2.1 Power management

2.1.1 Module supply input (VCC)

LARA-R6 series modules must be supplied through the three VCC pins by a DC power supply. Voltage

must be stable, because during operation the current drawn from VCC can vary by some order of

magnitude, especially due to the surging consumption profile of the GSM system (described in the

system integration manual [2]). It is important that the system power supply circuit can support peak

power.

LARA-R6 series modules provide separate supply inputs over the three VCC pins:

•

VCC pins #52 and #53 represent the supply input for the internal RF power amplifiers, demanding

most of the total current drawn by the module when RF transmission is enabled

•

VCC pin #51 represents the supply input for the internal baseband Power Management Unit and

the internal transceiver, demanding a minor part of the total current drawn by the module when

RF transmission is enabled

2.1.2 Generic digital interfaces supply output (V_INT)

LARA-R6 series modules provide a 1.8 V supply rail output on the V_INT pin, which is internally

generated when the module is switched on. The same voltage domain is used internally to supply the

generic digital interfaces of the modules (as the UARTs, I2C, I2S, GPIOs). The V_INT supply output

can be used in place of an external discrete regulator.

☞ It is recommended to provide accessible test point directly connected to the V_INT input pin.

2.2 Antenna interfaces

2.2.1 Antenna RF interfaces

The modules have two RF pins with a characteristic impedance of 50 . The primary antenna pin

(ANT1) supports both Tx and Rx, providing the main antenna interface, while the secondary antenna

pin (ANT2) supports Rx only for the LTE / 3G Rx diversity configuration.

2.2.2 Antenna detection

The ANT_DET pin is an Analog to Digital Converter (ADC) input with a current source provided by

LARA-R6 series modules to sense the external antenna(s) presence (as an optional feature). It

evaluates the resistance from ANT1 and ANT2 pins to GND by means of an external antenna

detection circuit implemented on the application board. For more details, see the system integration

manual [2] and the AT commands manual [1].

2.3 System functions

2.3.1 Module power-on

When LARA-R6 series modules are not powered, they can be switched on as following:

•

Applying a voltage at the VCC module supply input within the operating range (see Table 12), and

then forcing a low level at the PWR_ON input pin, which is normally set high by an internal pull-up,

for a valid time period (see section 4.2.9, module switch on).