RA(6)
RA(5)
RA(0)
Don’t Care
7-bit Register Address
Read
8-bit Register Data
SS
SCLK
MOSI
MISO
Hi-Z
Hi-Z
D(7)
D(6)
D(0)
Hi-Z
Hi-Z
Power Supply
Figure 2-51. SPI Timing Diagram for Register Read
2.9
Power Supply
The four supply pins are LDOin, DVdd, AVdd and IOVDD.
•
IOVdd - The IOVdd pin supplies the digital IO cells of the device. The voltage of IOVdd can range from
1.1 to 3.6V and is determined by the digital IO voltage of the rest of the system.
•
DVdd - This pin supplies the digital core of the device. Lower DVdd voltages cause lower power
dissipation. If efficient switched-mode power supplies are used in the system, system power can be
optimized using low DVdd voltages. the full clock range is only supported with DVdd in the range of
1.65 to 1.95V. Also, operation with DVdd down to 1.26V is possible. (See
)
•
AVdd - This pin is either a supply input to the device, or if the internal LDO is used it is used to
connect an external capacitor. It supplies the analog core of the device. The analog core voltage
(AVdd) should be in the range of 1.5 to 1.95V for specified performance. For AVdd voltages above
1.8V, the internal common mode voltage can be set to 0.9V (Pg 1, Reg 10, D(6)=0, default) resulting in
500mVrms full-scale voltage internally. For AVdd voltages below 1.8V, the internal common mode
voltage should be set to 0.75V (Pg 1, Reg 10, D(6)=1), resulting in 375mVrms internal full scale
voltage.
NOTE:
At powerup, AVdd is weakly connected to DVdd. This coarse AVdd generation must be
turned off by writing Pg 1, Reg 1, D(3) = 1 at the time AVdd is applied, either from internal
LDO or through external LDO.
•
LDOin - The LDOin pin serves two main functions. It serves as supply to the internal LDO as well as to
the analog-output amplifiers of the device. The LDOin voltage can range from 1.9V to 3.6V.
2.9.1 System Level Considerations
While there is flexibility in supplying the device through multiple options of power supplies, care must be
taken to stay within safe areas when going to standby and shutdown modes.
In summary, the lowest shutdown current is achieved when all supplies to the device are turned off,
implying that all settings must be reapplied to the device after bringing the power back up. In order to
retain settings in the device, the DVdd voltage and either internally or externally the AVdd voltage also
must be maintained. In this case the TLV320DAC3203 exhibits shutdown currents of below 1.5
μ
A.
2.9.1.1
Supply from single voltage rail (1.8V).
If a single 1.8V rail is used, generating the 1.8V from a higher battery voltage via a DC-DC converter
results in good system-level efficiency. In this setup, the headphone output voltage is limited to 500mV
rms
,
and the maximum headphone output power is 15mW into 16
Ω
.
69
SLAU434 – May 2012
TLV320DAC3203 Application
Copyright © 2012, Texas Instruments Incorporated