Texas Instruments TRF7970A BoosterPack, Руководство пользователя

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TRF7970A
www.ti.com SLOS743L – AUGUST 2011 – REVISED MARCH 2017
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Detailed Description
Copyright © 2011–2017, Texas Instruments Incorporated
(1) x = Don't care
6.3.2 Supply Regulator Settings
The input supply voltage mode of the reader needs to be selected. This is done in the Chip Status Control
register (0x00). Bit 0 in register 0x00 selects between 5-V or 3-V input supply voltage. The default
configuration is 5 V, which reflects an operating supply voltage range of 4.3 V to 5.5 V. If the supply
voltage is below 4.3 V, the 3-V configuration should be used.
As V
DD_RF
is increased, the system can become more susceptible to noise coupling on the RX lines. For
minimum noise coupling, TI recommends using the value of 0x00. For improved range, higher V
DD_RF
voltages may be set, but complete system testing is required to determine the value which provides
optimal performance.
The various regulators can be configured to operate in automatic or manual mode. This is done in the
Regulator and I/O Control register (0x0B), as shown in
Table 6-1 and Table 6-2 .
Table 6-1. Supply Regulator Setting: 5-V System
REGISTER
ADDRESS
(hex)
OPTION BITS SETTING IN REGULATOR CONTROL REGISTER
(1)
COMMENTS
B7 B6 B5 B4 B3 B2 B1 B0
Automatic Mode (default)
0B 1 x x x x x 0 0 Automatic regulator setting 400-mV difference
Manual Mode
0B 0 x x x x 1 1 1 V
DD_RF
= 5 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 1 1 0 V
DD_RF
= 4.9 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 1 0 1 V
DD_RF
= 4.8 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 1 0 0 V
DD_RF
= 4.7 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 0 1 1 V
DD_RF
= 4.6 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 0 1 0 V
DD_RF
= 4.5 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 0 0 1 V
DD_RF
= 4.4 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 0 0 0 V
DD_RF
= 4.3 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
(1) x = Don't care
Table 6-2. Supply Regulator Setting: 3-V System
REGISTER
ADDRESS
(hex)
OPTION BITS SETTING IN REGULATOR CONTROL REGISTER
(1)
COMMENTS
B7 B6 B5 B4 B3 B2 B1 B0
Automatic Mode (default)
0B 1 x x x x x 0 0 Automatic regulator setting 400-mV difference
Manual Mode
0B 0 x x x x 1 1 1 V
DD_RF
= 3.4 V, V
DD_A
= 3.4 V, V
DD_X
= 3.4 V
0B 0 x x x x 1 1 0 V
DD_RF
= 3.3 V, V
DD_A
= 3.3 V, V
DD_X
= 3.3 V
0B 0 x x x x 1 0 1 V
DD_RF
= 3.2 V, V
DD_A
= 3.2 V, V
DD_X
= 3.2 V
0B 0 x x x x 1 0 0 V
DD_RF
= 3.1 V, V
DD_A
= 3.1 V, V
DD_X
= 3.1 V
0B 0 x x x x 0 1 1 V
DD_RF
= 3.0 V, V
DD_A
= 3.0 V, V
DD_X
= 3.0 V
0B 0 x x x x 0 1 0 V
DD_RF
= 2.9 V, V
DD_A
= 2.9 V, V
DD_X
= 2.9 V
0B 0 x x x x 0 0 1 V
DD_RF
= 2.8 V, V
DD_A
= 2.8 V, V
DD_X
= 2.8 V
0B 0 x x x x 0 0 0 V
DD_RF
= 2.7 V, V
DD_A
= 2.7 V, V
DD_X
= 2.7 V
The regulator configuration function adjusts the regulator outputs by default to 400 mV below V
IN
level, but
not higher than 5 V for V
DD_RF
, 3.4 V for V
DD_A
and V
DD_X
. This ensures the highest possible supply
voltage for the RF output stage while maintaining an adequate PSRR (power supply rejection ratio).