Texas Instruments TRF7970A Manual page 17

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6.3.1 Supply Arrangements
Regulator Supply Input: V
The positive supply at V
input sources for three internal regulators with the output voltages V
bypass capacitors for supply noise filtering must be used (per reference schematics).
V must be the highest voltage supplied to the TRF7970A.
IN
RF Power Amplifier Regulator: V
The V (pin 3) regulator is supplying the RF power amplifier. The voltage regulator can be set for
DD_RF
either 5-V or 3-V operation. External bypass capacitors for supply noise filtering must be used (per
reference schematics). When configured for 5-V manual-operation, the V
from 4.3 V to 5 V in 100-mV steps. In 3-V manual-operation, the output can be programmed from 2.7 V to
3.4 V in 100-mV steps. The maximum output current capability for 5-V operation is 150 mA and for 3-V
operation is 100 mA.
Analog Supply Regulator: V
Regulator V (pin 1) supplies the analog circuits of the device. The output voltage setting depends on
DD_A
the input voltage and can be set for 5-V and 3-V operation. When configured for 5-V manual-operation,
the output voltage is fixed at 3.4 V. External bypass capacitors for supply noise filtering must be used (per
reference schematics). When configured for 3-V manual-operation, the V
to 3.4 V in 100-mV steps (see
The configuration of V
V output current should not exceed 20 mA.
DD_X
Digital Supply Regulator: V
The digital supply regulator V
can also be used to supply external electronics within the reader system. When configured for 3-V
operation, the output voltage can be set from 2.7 to 3.4 V in 100-mV steps. External bypass capacitors for
supply noise filtering must be used (per reference schematics).
The configuration of the V
The V
DD_X
By default, the regulators are set in automatic regulator setting mode. In this mode, the regulators are
automatically set every time the system is activated by setting EN input High or each time the automatic
regulator setting bit, B7 in register 0x0B is set to a 1. The action is started on the 0 to 1 transition. This
means that, if the user wants to rerun the automatic setting from a state in which the automatic setting bit
is already high, the automatic setting bit (B7 in register 0x0B) should be changed: 1-0-1.
By default, the regulator setting algorithm sets the regulator outputs to a "Delta Voltage" of 400 mV below
V , but not higher than 5 V for V
IN
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IN
(pin 2) has an input voltage range of 2.7 V to 5.5 V. V
IN
DD_RF
DD_A
Table 6-2).
and V
DD_A DD_X
DD_X
(pin 32) provides the power for the internal digital building blocks and
DD_X
and V
DD_A DD_X
output current should not exceed 20 mA.
and 3.4 V for V
DD_RF
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SLOS743L – AUGUST 2011 – REVISED MARCH 2017
NOTE
NOTE
regulators are not independent from each other. The
NOTE
regulators are not independent from each other.
and V .
DD_A DD_A
TRF7970A
TRF7970A
provides the supply
IN
, V , and V . External
DD_RF DD_A DD_X
output voltage can be set
DD_RF
output can be set from 2.7 V
DD_A
Detailed Description 17