User's Manual

TRF7960
TRF7961
SLOU186F–AUGUST 2006–REVISED AUGUST 2010 www.ti.com
5.1.3 Supply Regulator Configuration
The supply regulators can be automatically or manually configured by the control bits. The available
options are shown in Table 5-1 through Table 5-4. Table 5-1 shows a 5-V system and the manual-mode
regulator settings. Table 5-2 shows manual mode for selection of a 3-V system. Table 5-3 and Table 5-4
show the automatic-mode gain settings for 5-V and 3-V systems.
The automatic mode is the default configuration. In automatic mode, the regulators are automatically set
every time the system is activated by asserting the EN input HIGH. The internal regulators are also
automatically reconfigured every time the automatic regulator selection bit is set HIGH (on the rising
edge).
The user can re-run the automatic mode setting from a state in which the automatic setting bit is already
high by changing the automatic setting bit from high to low to high. The regulator-configuration algorithm
adjusts the regulator outputs 250 mV below the V
IN
level, but not higher than 5 V for V
DD_RF
, 3.5 V for
V
DD_A
, and 3.4 V for V
DD_X
. This ensures the highest possible supply voltage for the RF output stage while
maintaining an adequate PSRR (power supply rejection ratio). As an example, the user can improve the
PSRR if there is a noisy supply voltage from V
DD_X
by increasing the target voltage difference across the
V
DD_X
regulator as shown for automatic regulator settings in Table 5-3 and Table 5-4.
Table 5-1. Supply-Regulator Setting – Manual – 5-V System
Byte Option Bits Setting in Control Register Action
Address
B7 B6 B5 B4 B3 B2 B1 B0
00 1 5-V system
0B 0 Manual regulator setting
0B 0 1 1 1 V
DD_RF
= 5 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 1 1 0 V
DD_RF
= 4.9 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 1 0 1 V
DD_RF
= 4.8 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 1 0 0 V
DD_RF
= 4.7 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 0 1 1 V
DD_RF
= 4.6 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 0 1 0 V
DD_RF
= 4.5 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 0 0 1 V
DD_RF
= 4.4 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
0B 0 0 0 0 V
DD_RF
= 4.3 V, V
DD_A
= 3.5 V, and V
DD_X
= 3.4 V
Table 5-2. Supply-Regulator Setting – Manual – 3-V System
Byte Option Bits Setting in Control Register Action
Address
B7 B6 B5 B4 B3 B2 B1 B0
00 0 3V system
0B 0 Manual regulator setting
0B 0 1 1 1 V
DD_RF
= 3.4 V, V
DD_A
, and V
DD_X
= 3.4 V
0B 0 1 1 0 V
DD_RF
= 3.3 V, V
DD_A
, and V
DD_X
= 3.3 V
0B 0 1 0 1 V
DD_RF
= 3.2 V, V
DD_A
, and V
DD_X
= 3.2 V
0B 0 1 0 0 V
DD_R
F = 3.1 V, V
DD_A
, and V
DD_X
= 3.1 V
0B 0 0 1 1 V
DD_RF
= 3.0 V, V
DD_A
, and V
DD_X
= 3.0 V
0B 0 0 1 0 V
DD_RF
= 2.9 V, V
DD_A
, and V
DD_X
= 2.9 V
0B 0 0 0 1 V
DD_RF
= 2.8 V, V
DD_A
, and V
DD_X
= 2.8 V
0B 0 0 0 0 V
DD_RF
= 2.7 V, V
DD_A
, and V
DD_X
= 2.7 V
12 System Description Copyright © 2006–2010, Texas Instruments Incorporated
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