Hello SSita,
The maximum output power is mentioned in the ST25R3916 Datasheet. It depends on many factors like supply voltage and proper selection of the matching circuit.
The easiest was to estimate the output power is to measure the Power consumed by the ST25R3916 and then calculate the output power by P_out = P_in - P_d.
P_d ... dissipated power in the IC.
This is an example which does not relate to any demoboard.
Since the P_In depends on your power supply , please measure and calculate those values accordingly.
VDD = 5V ... supply voltage of the ST25R3916
I_VDD = 200mA ... Current consumption during Tx
I_rdy 20mA ... Current consumption during ready mode
R_dson 1.6Ohm ... typcial driver resistance
VDD_RF 4.7V ... regulated driver supply
P_rdy ... power dissipated by the analog and digital circuit
P_reg ... power dissipated by the internal regulator
P_drv ... power dissipated by the driver during Tx
P_in = VDD * I_VDD = 5 * 0.2 = 1W
P_d = P_rdy + P_reg + P_drv
P_rdy = VDD * I_rdy = 5*0.02 = 0.1W
P_reg = (VDD - VDD_RF)*(I_VDD-I_rdy) = 0.3*0.18 = 0.054W
P_drv = (I_VDD-I_rdy)*(I_VDD-I_rdy)*R_dson*2 = 0.18*0.18*1.6*2=0.10368W
P_out = 1 - (0.1+0.054+1.0368) = 1 - 0.25768 = 0.74232W
By lowering the target matching impedance and increasing the VDD the I_VDD can be increased. Also the dissipated power inside the IC will increase.
br Travis
