Texas Instruments DRV601EVM User manual

User's GuideSLOU215 – January 2008
DRV601EVM
This user’s guide describes the operation of the DRV601EVM stereo line driver evaluation module andprovides measurement data and design information such as the schematic, bill of materials, andprinted-circuit board layout.
Contents1 Overview ...................................................................................................................... 22 Quick Setup Guide........................................................................................................... 33 Shutdown ..................................................................................................................... 54 Component Selection ....................................................................................................... 55 Layout Recommendations .................................................................................................. 76 DRV601EVM Performance ................................................................................................. 87 Related Documentation from Texas Instruments ...................................................................... 198 Design Documentation .................................................................................................... 19
List of Figures
1 DRV601EVM ................................................................................................................. 22 DRV601 Functional Block Diagram ....................................................................................... 33 DRV601EVM Physical Structure ........................................................................................... 34 Power-Up/Down Sequence ................................................................................................. 55 Second-Order, Active Low-Pass Filter .................................................................................... 66 THD+N vs Voltage (600 Ω)................................................................................................. 97 THD+N vs Voltage (600 Ω)................................................................................................. 98 THD+N vs Voltage (100-k Ωload) ........................................................................................ 109 THD+N vs Voltage (100- Ωload) Linear Scale ......................................................................... 1010 THD+N vs Voltage (600- ΩLoad) ........................................................................................ 1111 THD+N vs Voltage (100-k ΩLoad) ....................................................................................... 1112 THD+N vs Frequency (600- ΩLoad) ..................................................................................... 1213 THD+N vs Frequency (600- ΩLoad) Using X7R Input Capacitors .................................................. 1214 FFT Spectrum With –60-dBFS Tone .................................................................................... 1315 Idle Noise FFT Spectrum (BTL) .......................................................................................... 1316 Channel Separation ........................................................................................................ 1417 Channel Separation, 10x Lower Feedback Impedance ............................................................... 1518 Frequency Response ...................................................................................................... 1519 Phase Response ........................................................................................................... 1620 Pop/Click (Enable) ......................................................................................................... 1721 Pop/Click (Disable) ......................................................................................................... 1822 DRV601EVM PCB Component Placement Top ........................................................................ 2123 PCB Top Layer ............................................................................................................. 2124 PCB Bottom Layer ......................................................................................................... 22
List of Tables
1 DRV601 Features ............................................................................................................ 22 Recommended Supply Voltage ............................................................................................ 53 DRV601EVM Specification ................................................................................................. 64 General Test Specifications ................................................................................................ 8PurePath Digital, DirectPath, FilterPro are trademarks of Texas Instruments.
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1 Overview
Overview
5 Electrical Data ................................................................................................................ 86 Audio Performance .......................................................................................................... 87 Physical Specifications ...................................................................................................... 88 DRV601EVM Parts List .................................................................................................... 209 PCB Specifications ......................................................................................................... 20
The DRV601EVM customer evaluation module (EVM) demonstrates the integrated circuits DRV601RTJfrom Texas Instruments (TI).
The DRV601 is a stereo line driver designed to allow the removal of the DC-blocking capacitors forreduced component count and cost. The DRV601 is ideal for single-supply electronics where size andcost are critical design parameters ().
The DRV601 is capable of driving 2 Vrms into a 600- Ωload at 3.3-V supply. The DRV601 has externalgain-setting resistors, that support a gain range of -1 V/V to -10 V/V and line outputs that have ±8 kV IECESD protection. The DRV601 has independent shutdown control for the left and right audio channels.
This EVM is configured with two RCA phone input connectors and two RCA phone output connectors.Power supply is connected via a two-pin 2,54-mm pin header.
The EVM is configured with a gain of –2 V/V.
Table 1. DRV601 Features
KEY PARAMETERS
Supply Voltage 1.8 V to 4.5 VNumber of Channels 2Load Impedance Minimum 600 ΩOutput Voltage 2 Vrms / 600 Ω< 0.005% THDDYR > 108 dBGain –2 V/V
This EVM is designed for evaluating applications such as A/V receivers, DVD receivers, DVDminicomponent systems, home theater in a box (HTIB) designs, or set-top boxes.
This document covers EVM specifications, audio performance and power efficiency measurementsgraphs, and design documentation that includes schematics, parts list, layout, and mechanical design.
Figure 1. DRV601EVM
Gerber (layout) files are available at the TI Web site .
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1.1 DRV601EVM Features
Functional Block Diagram
Rin
SVDD
SVDD
SVSS
SVSS
Audio In - R
Audio In - L
SGND
Audio Out - R
Audio Out - L
Short
Circuit
Protection
Charge
Pump
Bias
Circuitry
SDx
C1N
C1P
PVSS
Rin
Rfb
Rfb
1.2 PCB Key Map
2 Quick Setup Guide
Quick Setup Guide
•Two-channel evaluation module, a double-sided, plated-through printed-circuit board (PCB) layout.•2-V
RMS
line output•Output capacitor-less.
•Shutdown button
Figure 2. DRV601 Functional Block Diagram
The physical structure of the DRV601EVM is shown in Figure 3 .
Figure 3. DRV601EVM Physical Structure
This section describes the DRV601EVM board in regards to power supply and system interfaces. Itprovides information regarding handling and unpacking, absolute operating conditions, and a descriptionof the factory default switch and jumper configuration.
The following is a step–by–step guide to configuring the DRV601EVM for device evaluation.
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2.1 Electrostatic Discharge Warning
2.2 Unpacking the EVM
Quick Setup Guide
Many of the components on the DRV601EVM are susceptible to damage by electrostatic discharge (ESD).Customers are advised to observe proper ESD handling precautions when unpacking and handling theEVM, including the use of a grounded wrist strap at an approved ESD workstation.
CAUTION
Failure to observe ESD handling procedures may result in damage to EVMcomponents.
On opening the DRV601EVM package, ensure that the following items are included:•1 DRV601EVM board with one DRV601RTJ•1 pc. PurePath Digital™ CD-ROM
If either of these items is missing, contact the Texas Instruments Product Information Center nearest youto inquire about a replacement.
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2.3 Power Supply Setup
3 Shutdown
DVDD
SHUTDOWN
> 50 sm> 50 sm
4 Component Selection
4.1 Charge Pump
Shutdown
To power up the EVM, one power supply is needed. The power supply is connected to the EVM using a2-pin, 2,54-mm pin header, J10.
Table 2. Recommended Supply Voltage
Description Voltage Limitations Current Requirement Cable
Power supply 1.8 V to 4.5 V 0.3 A
CAUTION
Applying voltages above the limitations given in Table 2 may cause permanentdamage to your hardware.
For minimum click and pop during power on and power off, the shutdown pin should be kept low. Thepreferred power-up/down sequence is shown in Figure 4 .
Figure 4. Power-Up/Down Sequence
The charge pump flying capacitor, C13, serves to transfer charge during the generation of the negativesupply voltage. The PVSS capacitor must be at least equal to the charge pump capacitor in order to allowmaximum charge transfer. Low ESR capacitors are an ideal selection, and a value of 1 µF is typical.Capacitor values smaller than 1 µF can be used, but the maximum output can be reduced. It is thereforerecommended to validate the design with thorough testing.
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4.2 Decoupling Capacitors
4.3 Supply Voltage Limiting at 4.5 V
4.4 Using the DRV601 as a Second-Order Low-Pass Filter
C1
R1 R3
R2
C2
+
-
C3
Component Selection
The DRV601 is a DirectPath™ line driver amplifier that requires adequate power supply decoupling toensure that the noise and total harmonic distortion (THD) are low. A good low equivalent-series-resistance(ESR) ceramic capacitor, C12, typical 1 µF, placed as close as possible to the device V
DD
leads worksbest. Placing this decoupling capacitor close to the DRV601 is important for the performance of theamplifier. For filtering lower frequency noise signals, a 10- µF or greater capacitor placed near the audioamplifier also helps, but is not required in most applications because of the high PSRR of this device.
The charge pump circuit does apply ripple current on the V
DD
line, and a LC or RC filter may be needed ifnoise-sensitive audio devices share the V
DD
supply.
The DRV601 has a build-in charge pump which serves to generate a negative rail for the line driver.Because the line driver operates from a positive and negative voltage supply, circuitry has beenimplemented to protect the devices in the amplifier from an overvoltage condition. Once the supply isabove 4.5 V, the DRV601 can shut down in an overvoltage protection mode to prevent damage to thedevice.
Many of the audio DACs used today require an external low-pass filter, to remove band noise. This ispossible with the DRV601, and the EVM is configured as a 40-kHz second-order, active Butterworth filter.The topology chosen is the MFB Single-Ended. Further, the DRV601 needs a ac-coupling capacitor toremove dc-content from the source.
Figure 5. Second-Order, Active Low-Pass Filter
The component values can be calculated with the help of the TI FilterPro™ program available on:http://focus.ti.com/docs/toolsw/folders/print/filterpro.html
In Table 3 , various proposals for the filter and gain settings can be found.
Table 3. DRV601EVM Specification
Gain High Pass Low Pass C1 C2 C3 R1 R2 R3
–1 V/V 16 Hz 40 kHz 100 pF 680 pF 1 µF 10 kR 10 kR 24 kR-1.5 V/V 19 Hz 40 kHz 68 pF 680 pF 1 µF 8.2 kR 12 kR 30 kR-2 V/V 11 Hz 40 kHz 33 pF 330 pF 1 µF 15 kR 30 kR 47 kR–2 V/V 11 Hz 30 kHz 47 pF 470 pF 1 µF 15 kR 30 kR 43 kR–3.33 V/V 12 Hz 40 kHz 33 pF 470 pF 1 µF 13 kR 43 kR 43 kR-10 V/V 15 Hz 30 kHz 22 pF 1 nF 2.2 µF 4.7 kR 47 kR 27 kR
The resistor values should be low value to get low noise, but should be high value to get a small sizeac-coupling capacitor. With the proposed values, 15k, 30k, and47k, a DYR of 105 dB can be achievedwith a small 1- µF input ac-coupling capacitor.
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5 Layout Recommendations
5.1 Exposed Pad on the DRV601RJT Package
5.2 SGND and PGND Connections
Layout Recommendations
The exposed metal pad on the DRV601RTJ package can be soldered to a pad on the PCB in order toimprove reliability. The pad on the PCB should be allowed to float and not be connected to ground orpower. Connecting this pad to power or ground prevents the device from working properly because it isconnected internally to PVSS.
The SGND and PGND pins of the DRV601 must be routed separately back to the decoupling capacitor inorder to provide proper device operation. If the SGND pins are connected directly to each other, the partfunctions without risk of failure, but the noise and THD performance can be reduced.
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6 DRV601EVM Performance
DRV601EVM Performance
This section provides general test specifications, electrical data, audio performance data, and physicalspecifications.
Table 4. General Test Specifications
(1)
GENERAL TEST SPECIFICATIONS NOTES
Supply Voltage 3.3 VLoad Impedance 600 ΩInput Signal 1-kHz SineMeasurement Filter AES17
(1)
These test conditions are used for all tests, unless otherwise specified.
Table 5. Electrical Data
(1)
ELECTRICAL DATA SPECIFICATIONS NOTES/CONDITIONS
Output Voltage, 600 Ω2.2 Vrms 1 kHz, unclipped (< 1% THD), T
A
= 25 °COutput Voltage, 100 k Ω2.3 Vrms 1 kHz, unclipped (< 1% THD), T
A
= 25 °CSupply Current < 10 mA 1 kHz, 2 m Vrms output voltageSupply Current < 20 mA 1 kHz, 2 m Vrms output voltage into 600 Ω
(1)
All electrical and audio specifications are typical values.
Table 6. Audio Performance
AUDIO PERFORMANCE NOTES/CONDITIONS
THD+N, 600 Ω0.02 Vrms < 0.099 % 1 kHz (Noise-limited)THD+N, 600 Ω0.2 Vrms < 0.009 % 1 kHz (Noise-limited)THD+N, 600 Ω2 Vrms < 0.006 % 1 kHzTHD+N, 100 k Ω0.02 Vrms < 0.099 % 1 kHz (Noise-limited)THD+N, 100 k Ω0.2 Vrms < 0.009 % 1 kHz (Noise- limited)THD+N, 100 k Ω2 Vrms < 0.005 % 1 kHzDynamic Range > 105 dB Ref: 2 Vrms, A-weighted, AES17 filterNoise Voltage < 12 µVrms A-weighted, AES17 filterDC Offset < 5m mV No signal, 600- ΩloadChannel Separation > 97 dB 1 kHz, 2 VrmsFrequency Response: 20 Hz to 20 kHz +0.5/–1 dB 2 Vrms/600 Ω
Table 7. Physical Specifications
(1)
PHYSICAL SPECIFICATIONS NOTES/CONDITIONS
PCB Dimensions 50 x 60 x 25 Width x Length x Height (mm)Total Weight 35g Components + PCB + Mechanics
(1)
All electrical and audio specifications are typical values.
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6.1 THD+N vs Voltage (600- ΩLoad)
10m 420m 50m 100m 200m 500m 1 2
V - Output Voltage - Vrms
O
0.001
10
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
THD+N - Total Harmonic Distortion Plus Noise - %
4.5 V DVDD
3.3 V DVDD
1.8 V DVDD
0.001
10
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
THD+N - Total Harmonic Distortion Plus Noise - %
250m 4500m750m 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.751
V - Output Voltage - Vrms
O
1.8 V DVDD
3.3 V DVDD
4.5 V DVDD
DRV601EVM Performance
Figure 6. THD+N vs Voltage (600 Ω)
The THD+N from 10m Vrms to approximately 0.5 Vrms is dominated by noise.
Figure 7. THD+N vs Voltage (600 Ω)
Here the THD+N versus output voltage is shown with linear scale, this makes it easier to see whereclipping occurs. Clipping is often defines as THD+N=1%. For the DRV601 this is 2.25 Vrms with a 3.3-Vsupply and 600- Ωload.
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6.2 THD+N vs Voltage (100-k Ωload)
0.001
10
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
THD+N - Total Harmonic Distortion Plus Noise - %
10m 420m 50m 100m 200m 500m 1 2
V - Output Voltage - Vrms
O
3.3 V DVDD
4.5 V DVDD
1.8 V DVDD
0.001
10
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
THD+N - Total Harmonic Distortion Plus Noise - %
250m 4500m 750m 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.751
V - Output Voltage - Vrms
O
1.8 V DVDD
3.3 V DVDD
4.5 V DVDD
DRV601EVM Performance
Figure 8. THD+N vs Voltage (100-k Ωload)
The THD+N in the range from 10mVrms to 1Vrms is completely dominated by noise.
Figure 9. THD+N vs Voltage (100- Ωload) Linear Scale
Here the THD+N versus output voltage is shown with linear scale; this makes it easier to see whereclipping occurs. Clipping is often defines as THD+N = 1%. For the DRV601 this is over 2.25 Vrms with a3.3-V supply and 100-k Ωload.
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