Texas Instruments DRV602EVM2 User manual

User's GuideSLOU248A – December 2008 – Revised January 2009
DRV602EVM2
DRV602EVM2
This user’s guide describes the operation of the DRV602 evaluation module. This document also providesmeasurement data and design information including a schematic, bill of materials, and printed circuit board(PCB) layout drawings.
Contents1 Overview ...................................................................................................................... 22 Quick Setup................................................................................................................... 33 On/Off Sequence ............................................................................................................ 44 Component Selection ....................................................................................................... 45 Layout Recommendations .................................................................................................. 76 DRV602EVM2 Performance ............................................................................................... 77 Related Documentation from Texas Instruments ...................................................................... 128 Design Documentation .................................................................................................... 12
List of Figures
1 DRV602EVM2 Functional Block Diagram ................................................................................ 32 Power-Up/-Down Sequence ................................................................................................ 43 Second-Order, Active Low-Pass Filter .................................................................................... 54 Differential Input, Second-Order Active Low-Pass Filter ............................................................... 65 THD+N versus Voltage ..................................................................................................... 86 THD+N versus Frequency .................................................................................................. 97 FFT Spectrum with –60-dBFS Tone ...................................................................................... 98 Channel Separation ........................................................................................................ 109 Frequency Response ...................................................................................................... 1010 Pop/Click (Enable) ......................................................................................................... 11DirectPath is a trademark of Texas Instruments.Blu-ray Disc is a trademark of Blu-ray Disc Association.All other trademarks are the property of their respective owners.
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1 Overview
Overview www.ti.com
11 Pop/Click (Disable) ......................................................................................................... 1112 DRV602EVM2 Schematic: DRV602 ..................................................................................... 1213 DRV602EVM2 Schematic: On/Off and Regulator ..................................................................... 1214 DRV602EVM2 PCB Component Placement ............................................................................ 1515 DRV602EVM2 PCB Top Layer ........................................................................................... 1616 DRV602EVM2 PCB Bottom Layer ....................................................................................... 16
List of Tables
1 Key Parameters .............................................................................................................. 32 Recommended Supply Voltage ............................................................................................ 43 DRV602EVM2 Filter Specifications ....................................................................................... 54 General Test Conditions .................................................................................................... 75 Electrical Data ................................................................................................................ 76 Audio Performance Analog Input .......................................................................................... 87 Physical Specifications ...................................................................................................... 88 Related Documentation.................................................................................................... 129 Bill of Materials ............................................................................................................. 1310 PCB Specifications ......................................................................................................... 14
The DRV602EVM2 customer evaluation module (EVM) demonstrates the capabilities and operation of theDRV602 integrated circuit from Texas Instruments.
The DRV602 is a 2-V
RMS
pop-free stereo line driver designed to allow removal of the output dc-blockingcapacitors in audio applications to reduce component count and overall cost. The device is ideal forsingle-supply electronics where size and cost are critical design parameters.
Designed using TI’s patented DirectPath™ technology, the DRV602 is able to drive 2 V
RMS
into a 2.5-k Ωload with 3.3-V supply voltage. The device has differential inputs and uses external gain-setting resistorsthat support a gain range of ±1 V/V to ±10 V/V, and line outputs that have ±8 kV IEC electrostaticdischarge (ESD) protection. The DRV602 also has built-in shutdown control for pop-free on/off control.
Using the DRV602 in audio product applications can reduce component counts considerably compared totraditional methods of generating a 2-V
RMS
output. The DRV602 does not require a power supply greaterthan 3.3 V to generate its 5.6-V
PP
output, nor does it require a split-rail power supply. The DRV602integrates its own charge pump to generate a negative supply rail that provides a clean, pop-free,ground-biased 2-V
RMS
output. The DRV602 is available in a 14-pin TSSOP package.
This EVM is configured with two RCA phono input connectors for analog input; the output signal isavailable on two RCA phono connectors. The power supply is connected via a two-pin, 2,54-mm header.
This evaluation board is designed for testing applications such as set-top boxes, LCD/PDP TVs, Blu-rayDisc™ DVD players, DVD mini-component systems, home theater-in-a-box (HTIB) systems, orsoundcards.
This document presents EVM specifications, audio performance measurements graphs, and designdocumentation that includes complete circuit descriptions, schematic diagrams, a parts list, and PCBlayout design. Gerber (layout) files are available from the TI web site at www.ti.com .
Throughout this document, the abbreviation EVM and the term evaluation module are synonymous withthe DRV602EVM2.
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1.1 DRV602EVM2 Features
R_IN
L_IN L_OUT
R_OUT
DRV602PW
ON/OFF
+5 V
Linear
Regulator
2 Quick Setup
2.1 Electrostatic Discharge Notice
www.ti.com Quick Setup
The DRV602EVM2 has these features:•Two-channel evaluation module (double-sided, plated-through PCB layout)•2-V
RMS
line output•No output capacitor required•Shutdown button
Figure 1 illustrates the functional diagram for the EVM. Table 1 summarizes the key parameters.
Figure 1. DRV602EVM2 Functional Block Diagram
Table 1. Key Parameters
Key Parameters Specification/Unit
Supply Voltage 5 VNumber of Channels TwoLoad Impedance 2.5 k Ω(min)Output Voltage > 2 V
RMS
Dynamic Range > 102 dB
This section describes the DRV602EVM2 board with regard to the power supply and system interfaces. Itprovides information about handling and unpacking the DRV602EVM2, absolute operating conditions, anda description of the factory default switch and jumper configurations.
The following subsections provide a step-by-step guide to configuring the DRV602EVM2 for deviceevaluation.
CAUTION
Many of the components on the DRV602EVM2 are susceptible to damage byelectrostatic discharge (ESD). Customers are advised to observe proper ESDhandling precautions when unpacking and handling the EVM, including the useof a grounded wrist strap at an approved ESD workstation.
Failure to observe proper ESD handling procedures may result in damage toEVM components.
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2.2 Unpacking the EVM
2.3 Power-Supply Setup
3 On/Off Sequence
PVDD
Enable
> 50 sm> 50 sm
4 Component Selection
4.1 Charge Pump
On/Off Sequence www.ti.com
Upon opening the DRV602EVM2 package, ensure that the following items are included:•One DRV602EVM2 evaluation board, including:– One DRV602PW device
If either item is missing, please contact the Texas Instruments Product Information Center nearest you toinquire about a replacement.
A single power supply is required to power up the EVM. The power supply is connected to the EVM boardusing a two-pin, 2,54-mm header (J10). Table 2 lists the recommended supply voltage.
Table 2. Recommended Supply Voltage
Description Voltage Limitations Current Requirement Cable
Power supply 5 V 0.10 A —
CAUTION
Applying voltages above the limitations given in Table 2 may cause permanentdamage to your hardware.
For minimum click and pop interference during device power on and power off, the DRV602 Enable pin(pin 5) should be held low, primarily because of pre-charging of the ac-coupled input capacitors. Thepreferred power-up/-down sequence is shown in Figure 2 .
Figure 2. Power-Up/-Down Sequence
This sequence is ensured by the onboard supply monitor, U13.
The charge pump flying capacitor, C18, 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 allowa maximum charge transfer. Low equivalent series resistance (ESR) capacitors are an ideal selection, witha typical value of 1 µF. Capacitor values less than 1 µF can be used, but the maximum output can bereduced. It is therefore recommended to validate the design with thorough testing.
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4.2 Power-Supply Decoupling Capacitors
4.3 Using the DRV602 as a Second-Order, Low-Pass Filter in Single-Ended Input Mode
R2
R1R3
C2CX
C1
C3
DRV602
www.ti.com Component Selection
The DRV602 is a DirectPath™ line driver amplifier that requires adequate power-supply decoupling toensure that noise and total harmonic distortion (THD) are low. A good low ESR ceramic capacitor, C17(1 µF typical), placed as close as possible to the device VDD leads is the best option. Placing thisdecoupling capacitor close to the DRV602 device is important for amplifier performance. For filteringlower-frequency noise signals, a 10- µF or greater capacitor placed near the audio amplifier may also help,but is not required in most applications because of the high PSRR of the DRV602.
The charge pump circuit does apply ripple current on the VDD line, and an LC or RC filter may be neededif noise-sensitive audio devices share the VDD supply.
Several audio digital-to-audio converters (DACs) used in typical consumer applications require an externallow-pass filter to remove out-of-band noise. This function is also possible with the DRV602; the EVM isconfigured as a 40-kHz, second-order active Butterworth filter to accomplish this filtering using an MFB(Multiple Feed Back) topology. Furthermore, the DRV602 requires an ac-coupling capacitor to remove dccontent from the source.
The recommended component values can be calculated with the help of the TI FilterPro active filter designprogram available at http://focus.ti.com/docs/toolsw/folders/print/filterpro.html on the TI web site. Figure 3illustrates the circuit design for this configuration.
Figure 3. Second-Order, Active Low-Pass Filter
Figure 3 uses the component references also used in the FilterPro software. Various recommendation forfilter and gain settings are listed in Table 3 .
Table 3. DRV602EVM2 Filter Specifications
C1’ C2’ C3’ R1’ R2’ R3’FilterPro
C23 C21 C13 R11 R15 R13
Gain High Pass Low Pass C24 C22 C14 R12 R16 R14
–1 V/V 16 Hz 40 kHz 100 pF 680 pF 1 µF 10 k Ω10 k Ω24 k Ω–1.5 V/V 19 Hz 40 kHz 68 pF 680 pF 1 µF 8.2 k Ω12 k Ω30 k Ω–2 V/V 11 Hz 40 kHz 15 pF 150 pF 1 µF 33 k Ω68 k Ω100 k Ω–2 V/V 11 Hz 30 kHz 47 pF 470 pF 1 µF 15 k Ω30 k Ω43 k Ω–3.33 V/V 12 Hz 40 kHz 33 pF 470 pF 1 µF 13 k Ω43 k Ω43 k Ω–10 V/V 15 Hz 30 kHz 22 pF 1 nF 2.2 µF 4.7 k Ω47k Ω27 k Ω
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4.4 Using the DRV602 as a Differential Input, Second-Order Low-Pass Filter
R2
R2
R1R3C1
C1
C3
R1R3
C3
-In
+In
C2
DRV602
Component Selection www.ti.com
The resistor values should be low value to achieve low noise, but should be of high enough value toobtain a small size ac-coupling capacitor. With the proposed values of 33 k Ω, 68 k Ω, and 100 k Ω, adynamic range (DYR) of 102 dB can be achieved with a small 1- µF input ac-coupling capacitor.
The MFB filter structure demands an op amp that is unity-gain stable at high frequencies; this requirementcan be relaxed by adding the C
X
capacitor value to be equal to C1. The DRV602 is unity-gain stable, butstray capacitance and inductance from the PCB layout can affect the phase margin. Therefore, werecommend adding C
X
.
The single-ended input, second-order filter described in Section 4.3 can easily be extended to have adifferential input, as shown in Figure 4 .
Figure 4. Differential Input, Second-Order Active Low-Pass Filter
C
2
can be split into separate capacitors to ground with the double value; this technique increases thecommon-mode filtering. Another capacitor, C
X
, set equal to C
1
can continue to be used from the negativeinput to ground to limit the high-frequency gain to 2.
As with the single-ended input, the differential input filter component values can be calculated with thehelp of the TI FilterPro active filter design program available on the TI web site.
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5 Layout Recommendations
5.1 SGND and PGND Connections
6 DRV602EVM2 Performance
www.ti.com Layout Recommendations
The SGND and GND pins of the DRV602 must be routed separately back to the decoupling capacitor inorder to facilitate proper device operation. If the SGND pins are connected directly to each other, thedevice functions without risk of failure, but noise and THD performance can be reduced.
On the DRV602EVM2, a star ground routing pattern is used; the star point is located directly below theDRV602 device itself.
This section discusses the DRV602EVM2 overall performance in key parametric areas. Table 4 throughTable 7 summarize the EVM specifications.
Note: All electrical and audio specifications are typical values.
Table 4. General Test Conditions
(1)
General Test Conditions Notes
Supply voltage 5.0 VLoad impedance 2.5 k ΩInput signal 1 kHz sineMeasurement filter AES17
(1)
These test conditions are used for all tests, unless otherwise specified.
Table 5. Electrical Data
Electrical Data Notes/Conditions
Output voltage, 2500 Ω2.2 V
RMS
1 kHz, THD+N = 1%, T
A
= +25 °COutput voltage, 100 k Ω2.3 V
RMS
1 kHz, THD+N = 1%, T
A
= +25 °C1 kHz, V
O
= 2 mV
RMS
at 2.5 k Ω, includingSupply current < 20 mA
linear regulator and LED1 kHz, V
O
= 2 V
RMS
at 2.5 k Ω, includingSupply current < 20 mA
linear regulator and LED
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6.1 THD+N versus Voltage (Analog Input)
100 m 500 m 15
Voltage (V )
RMS
10
1
0.1
0.01
0.001
0.0001
THD+N (%)
20 Hz
1 kHz
20 kHz
DRV602EVM2 Performance www.ti.com
Table 6. Audio Performance Analog Input
Audio Performance Analog Input Notes/Conditions
THD+N, 2.5 k Ω0.02 V
RMS
< 0.150 % 20 Hz to 20 kHz (Noise limited)THD+N, 2.5 k Ω0.2 V
RMS
< 0.015 % 2 Hz to 20 kHz (Noise limited)THD+N, 2.5 k Ω2 V
RMS
< 0.060 % 2 Hz to 20 kHzTHD+N, 100 k Ω0.02 V
RMS
< 0.150 % 20 Hz to 20 kHz (Noise limited)THD+N, 100 k Ω0.2 V
RMS
< 0.015 % 20 Hz to 20 kHz (Noise limited)THD+N, 100 k Ω2 V
RMS
< 0.050 % 20 Hz to 20 kHzDynamic range > 102 dB Ref: 3 V
RMS
, A-weighted, AES17 filterNoise voltage < 18 µV
RMS
A-weighted, AES17 filterDC offset < 5 mV No signal, 2.5-k ΩloadChannel separation > 90 dB 1 kHz, V
RMS
Frequency response: 20 Hz to 20 kHz ±0.5 dB 2 V
RMS
/ 2.5 k Ω
Table 7. Physical Specifications
Physical Specifications Notes/Conditions
PCB dimensions 60 ×60 ×25 mm Width ×Length ×Height (mm)Total weight 40 g Components + PCB + Mechanics
Up to approximately 1 V
RMS
, THD+N is dominated by the noise element, as shown in Figure 5 .
Figure 5. THD+N versus Voltage
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6.2 THD+N vs Frequency
10
1
0.1
0.01
0.001
0.0001
THD+N (%)
20 100 500 1 k 5 k 10 k 20 k
Frequency (Hz)
2 VRMS
0.2 VRMS
Load: 2.5 kW
6.3 FFT Spectrum with –60dBFS Tone
0
20
40
60
80
100
120
140
160
-
-
-
-
-
-
-
-
dB (dB)
0510 15 20 25
Frequency (kHz)
www.ti.com DRV602EVM2 Performance
Figure 6 illustrates characteristic performance for THD+N versus frequency.
Figure 6. THD+N versus Frequency
For the FFT plot shown in Figure 7 , the reference voltage is 2 V
RMS
and the FFT size is 16 k.
Figure 7. FFT Spectrum with –60-dBFS Tone
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6.4 Channel Separation
10
0
10
20
30
40
50
60
70
80
90
100
110
120-
-
-
-
-
-
-
-
-
-
-
-
dB (dB)
20 100 500 1 k 5 k 10 k 20 k
Frequency (Hz)
Left-to-Right
Right-to-Left
0 dB
6.5 Frequency Response
20 500100 1 k 5 k 10 k 50 k 200 k
Frequency (Hz)
10
5
0
5
10
15
20
25
30
35
40
-
-
-
-
-
-
-
-
dB (dB)
DRV602EVM2 Performance www.ti.com
Figure 8 illustrates the channel separation. The output signal and the reference voltage are both 2 V
RMS
,while the load is 2.5 k Ω.
Figure 8. Channel Separation
In Figure 9 , the measurement bandwidth filter is set to 500 kHz with a load of 2.5 k Ω.
Figure 9. Frequency Response
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