Texas Instruments | Using the PGA Function in TSC210x/AIC26/AIC28/DAC26 Devices | Application notes | Texas Instruments Using the PGA Function in TSC210x/AIC26/AIC28/DAC26 Devices Application notes

Texas Instruments Using the PGA Function in TSC210x/AIC26/AIC28/DAC26 Devices Application notes
Application Report
SLAA253 – June 2005
Using the Programmable Gain Amplifier Function in
TSC210x/AIC26/AIC28/DAC26 Devices
Wendy X. Fang ......................................................................................................... DAP Group, HPA
ABSTRACT
TI’s touch screen and audio codec/DAC devices, such as TSC2100, TSC2101,
TSC2102, TLV320AIC26 (AIC26), TLV320AIC28, and TLC320DAC26, have one or
more audio-band programmable gain amplifiers (PGA) in their input circuitry. This
application report describes how to implement this PGA function using the
TLV320DAC26 as an example.
The Texas Instruments touch screen and audio codec/DAC devices, such as TSC2100, TSC2101,
TSC2102, TLV320AIC26 (AIC26), TLV320AIC28, and TLC320DAC26, have one or more audio-band
programmable gain amplifiers (PGA) in their input circuitry. The input signal through the PGA can be
mixed with the digital-to-analog converter (DAC) results or can be directly fed to the device’s output
drivers/amplifiers; the latter can be seen as a separate PGA.
Consider the TLV320DAC26 (DAC26) as an example, and refer to Figure 1, the DAC26 functional block
diagram. In this diagram, the PGA-related blocks are enclosed in yellow boxes. The features of the
DAC26 PGA include gain ranges from –35.5 dB to 12 dB in 0.5-dB steps with soft-stepping logic. The gain
is programmable using a standard SPI bus; input can be fed into the PGA through the MICIN or AUX pin
and with single-ended mode; output can drive a 8-Ω/325-mW speaker or headphone. Power supplies
range from 2.7-V to 3.6-V, analog and from 1.1-V to 3.6-V, digital. See the TLV320DAC26 data sheet
(SLAS428 ) for details of the audio input/output features.
SLAA253 – June 2005
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
1
www.ti.com
DRVDD DRVSS AVDD AVSS DVDD DVSS IOVDD
0 to -63.5 dB
(0.5 dB steps)
High Power
HPL
Programmable
PLL
DAC
Digital
Filters
DAC
Digital
Bass,
Midrange,
Treble,
EQ
Processing
MCLK
Low Power
High Power
HPR
Low Power
VGND
MICBIAS
MICIN
2.0 V / 2.5 V
+
−
AUX
Digital Audio
Serial
Interface
M
U
X
Control
Interface
SPI Serial
Interface and
Data
Processing
PWD
LRCK
BCLK
DIN
SS
SCLK
MOSI
MISO
RESET
OSC
Figure 1. DAC26 Function Block Diagram
The following steps describe the physical connections and setups for using the separate PGA function,
with the DAC26 EVM as the tool.
Connections:
1. Connect a single-ended audio input signal to the DAC26 MICIN or AUX pin.
2. Connect an audio output device to the HPL and/or HPR pins (the other end of the connection can be to
VGND if in capacitorless mode or to the analog ground if in capacitor-coupling mode).
DAC26 Control Registers’ Settings:
1. Start the DAC26EVM software on your PC, and the graphic user interface (GUI) shown in Figure 2
appears.
2
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
SLAA253 – June 2005
www.ti.com
Figure 2. DAC26 EVM GUI With Page2 Registers Read
2. As an example, to connect the AUX to the analog sidetone PGA, set the D13–D12 of Page2/Reg00h
to 01b.
3. To power up the PGA, set the D13 of Page2/Reg05h to 0b (and if in the capacitorless output mode,
also power up the VGND ).
4. To unmute the PGA, set the D15 of Page2/Reg03h to 0b.
The preceding settings are reflected in the Page2 registers’ contents shown in Figure 2. Inside the
Register Reading box, the right column is the register content, and the left column identifies the register,
where the 0 to 6 lines correspond to Page2/Reg00h to 06h and the 7 to 10 lines correspond to
Page2/Reg1Bh to 1Eh. Note the settings in registers 00h, 03h, and 05h.
Figure 3 displays the audio input and output signals of the PGA where channel 1 (Ch1) is the input signal,
and channel 2 (Ch2) and channel 3 (Ch3) are the outputs from the PGA (HPL and HPR pins of DAC26).
In Figure 3-a to Figure 3-d, the PGA gain was set to 9.5 dB, 3 dB, 0 dB, and –9.5 dB, respectively.
SLAA253 – June 2005
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
3
www.ti.com
3a: PGA Gain = 9.5 dB
3b: PGA Gain = 3 dB
3a: PGA Gain = 0 dB
3b: PGA Gain = −9.5 dB
Figure 3. PGA Gains
The PGA function with the same or similar features can also be obtained through TSC2100, TSC2101,
TSC2102, TLV320AIC26 (AIC26), and TLC320AIC28 (AIC28), depending on the input circuitry and the
output drivers.
Example: Using the CP_IN PGA and output to receiver driver OUT32P/OUT32N of TSC2101 (AIC28). To
have the CP_IN route to the OUT32P/N, no ADC, DAC, PLL, or I2S mode needs to be powered or set,
because only the bypass route from the CP_IN pin to the OUT32P/N pins are involved.
Therefore, the only control registers that need to be set up for this channel to work are described as
follows:
1. Keep all registers on page 2 as the power-up/reset default.
2. Set Page2/Reg20h to 8200h (to select SPK1 at differential and route CP_IN to the OUT32P/N).
3. Set Page2/Reg1Fh to 457Ch (to power up the CP_IN PGA and set it at 0 dB).
4. Set Page2/Reg05h to EFFCh (to power up the OUT32 driver).
4
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
SLAA253 – June 2005
www.ti.com
5. Set Page2/Reg20h to 8202h (to unmute the OUT32 driver).
In the following illustrations, a single-ended sine wave was input to the CP_IN pin (and another end was
wired to the analog ground). In Figure 4, the CELL_IN PGA was set to 0 dB, to –6 dB in Figure 5, and to 4
dB in Figure 6.
Figure 4. CP_IN to OUT32P/N Path, PGA Gain = 0 dB
Figure 5. CP_IN to OUT32P/N Path, PGA Gain = –6 dB
SLAA253 – June 2005
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
5
www.ti.com
Figure 6. CP_IN to OUT32P/N Path, PGA Gain = 4 dB
References
1. TLV320DAC26, Low Power Stereo Audio DAC With Headphone/Speaker Amplifier data sheet
(SLAS428)
2. TSC2101, Audio CODEC With Integrated Headphone, Speaker Amplifier and Touch Screen Controller
data sheet (SLAS392)
6
Using the Programmable Gain Amplifier Function in TSC210x/AIC26/AIC28/DAC26 Devices
SLAA253 – June 2005
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
orders and should verify that such information is current and complete. All products are sold subject to TI’s terms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,
copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process
in which TI products or services are used. Information published by TI regarding third-party products or services
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction
of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for
such altered documentation.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
product or service voids all express and any implied warranties for the associated TI product or service and
is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Following are URLs where you can obtain information on other Texas Instruments products and application
solutions:
Products
Applications
Amplifiers
amplifier.ti.com
Audio
www.ti.com/audio
Data Converters
dataconverter.ti.com
Automotive
www.ti.com/automotive
DSP
dsp.ti.com
Broadband
www.ti.com/broadband
Interface
interface.ti.com
Digital Control
www.ti.com/digitalcontrol
Logic
logic.ti.com
Military
www.ti.com/military
Power Mgmt
power.ti.com
Optical Networking
www.ti.com/opticalnetwork
Microcontrollers
microcontroller.ti.com
Security
www.ti.com/security
Telephony
www.ti.com/telephony
Video & Imaging
www.ti.com/video
Wireless
www.ti.com/wireless
Mailing Address:
Texas Instruments
Post Office Box 655303 Dallas, Texas 75265
Copyright  2005, Texas Instruments Incorporated
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising