Telit Wireless Solutions LN940 WWAN M.2, User Manual

Page: 31 / 56

3.3.5. Dynamic Power Reduction
With the SAR (Specific Absorption Rate) regulatory requirement met for the
design of Tablets and Ultrabooks in which the antenna is in the base of the unit
the DPR# is available to trigger the reduction of radio transmit power.
The signal to DPR# is provided to trigger by the proximity sensor of the host.
The required value of the transmit power reduction may vary by different host
designs. The assertion and deassertion of DPR is asynchronous to any system
clock. All transients resulting from the proximity sensor is required to de-
bounce by system circuitry.
In conjunction with the DPR signal a full power control tool is available to the
host to adjust the RF transmit power level of LN940 WWAN M.2 Module.
The DPR pin has 10Kohm pull-up resister on the LN940 WWAN M.2 Module.
Table 3.3.5 DPR interface
Signal Name Pin Voltage
Level Description
DPR# 25 3.3V This is an “Active Low”,
input signal. When the state
is
“Low” the SAR power
back off is enabled. When
the state is
“High” the SAR
power back off is disabled,
internally pulled up.