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19-3296; Rev 1; 2/05
MAX9770 Evaluation Kit
General Description
The MAX9770 evaluation kit (EV kit) is a fully assembled and tested circuit board that uses the MAX9770, a lowEMI, filterless class D, bridge-tied-load (BTL) speaker amplifier with an 80mW stereo DirectDriveTM headphone amplifier. Designed to operate from a 2.5V to 5.5V power supply, the EV kit is capable of delivering 1.2W into an 8 load with efficiency up to 85%.
Features
Filterless Operation Class D Amplifier Passes FCC Class B Radiated Emissions 2.5V to 5.5V Single-Supply Operation 0.1A (typ) IC Shutdown Current Drives 1.2W into 8 Speaker Drives 80mW into 16 Headphone Low 0.015% THD+N
Evaluates: MAX9770/MAX9771
Ordering Information
PART MAX9770EVKIT TEMP RANGE 0C to +70C IC PACKAGE 28 TQFN*
Selectable Gain Options Selectable 3-Way Input Mixer/Multiplexer Selectable Switching Frequency Also Evaluates MAX9771 Surface-Mount Construction Fully Assembled and Tested
*Package code is T2855N-1.
Component List
DESIGNATION QTY DESCRIPTION 10F 20%, 6.3V X5R ceramic capacitor (0805) Taiyo Yuden JMK212BJ106MG or TDK C2012X5R0J106M 1F 10%, 10V X7R ceramic capacitors (0603) TDK C1608X7R1A105K 0.047F 10%, 25V X7R ceramic capacitor (0603) TDK C1608X7R1E473K 0.47F 10%, 10V X5R ceramic capacitors (0603) Taiyo Yuden LMK107BJ474KA or TDK C1608X5R1A474K 0.1F 10%, 25V X7R ceramic capacitor (0603) Murata GRM188R71E104J or TDK C1608X7R1E104K 100pF 5%, 50V C0G ceramic capacitor (0402) Murata GRP1555C1H101J or Taiyo Yuden UMK105CG101JW DESIGNATION C14, C15, C20 C16-C19, C21, C22 L1, L2 J1 JU1-JU6 JU7 JU8 OUT+, OUT-, FOUT1+, FOUT1-, HPOUTR, HPOUTL, TP1 R1 R2, R3 T1 U1 None None QTY 0 0 0 1 6 1 1 DESCRIPTION Not installed, ceramic capacitors (0402) Not installed, ceramic capacitors (0603) Not installed, power inductors 3.5mm surface-mount stereo headphone jack 3-pin headers 5-pin header 2-pin header
C1
1
C2, C4-C7
5
C3
1
C8-C11
4
0
Not installed, test points
1 0 0 1 8 1
49.9 1% resistor (0402) Not installed, resistors (0603) Not installed, common-mode choke MAX9770ETI (28-pin 5mm x 5mm thin QFN) Shunts MAX9770/MAX9771 PC board
C12
1
C13
1
________________________________________________________________ Maxim Integrated Products
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For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX9770 Evaluation Kit Evaluates: MAX9770/MAX9771
Component Suppliers
SUPPLIER Murata Taiyo Yuden PHONE 770-436-1300 800-348-2496 FAX 770-436-3030 847-925-0899 www.murata.com www.t-yuden.com WEBSITE
TDK 847-803-6100 847-390-4405 www.component.tdk.com Note: Indicate that you are using the MAX9770 when contacting these component suppliers.
Quick Start
The MAX9770 EV kit is fully assembled and tested. Follow the steps listed below to verify board operation. Do not turn on the power supply until all connections are completed.
7) Connect the positive terminal of the power supply to the VDD pad and the power-supply ground terminal to the GND pad. 8) Connect the audio source to VRIN1 and VLIN1. 9) Turn on the power supply. 10) Turn on the audio source. 11) Plug the headphone into J1 for headphone mode.
Recommended Equipment
* 2.5V to 5.5V, 1A power supply (suggested supply of 3.3V) * Audio source (i.e., CD player, cassette player, etc.) * 8 speaker * Stereo headphone with 3.5mm plug
Detailed Description
The MAX9770 EV kit features the MAX9770 low-EMI filterless class D amplifier IC, designed to drive a BTL mono speaker or a stereo headphone with an AC stereo/mono input source in portable audio applications. The EV kit operates from a DC power supply that can provide 2.5V to 5.5V and 1A of current. The EV kit accepts only a single-ended audio input. The audio input source is amplified to drive 1.2W into an 8 speaker. The MAX9770 is designed to pass FCC class B emissions without additional filtering when using 10cm of cable to connect the speaker. In applications where more margin and/or cable length are required, output capacitors C14, C15, and common-mode choke T1 can be added to reduce radiated emission. Connect the speaker to FOUT1+/FOUT1- test points. Table 1 lists the cable length vs. the required output components. The filtered outputs (FOUT2+, FOUT2-) require installation of filtering components L1, L2, C16-C19, C21, R2, and R3.
Procedure
1) Install shunts across jumpers JU1 (pins 1 and 2, GAIN1 = high) and JU2 (pins 2 and 3, GAIN2 = low) (speaker gain = 9dB, headphone gain = -2dB). 2) Install shunts across jumpers JU3 (pins 1 and 2, SEL1 = high), JU4 (pins 2 and 3, SEL2 = low), and JU5 (pins 2 and 3, SELM = low) (stereo inputs VRIN1 and VLIN1 are enabled). 3) Install a shunt across pins 1 and 2 of jumper JU6 (the EV kit is enabled). 4) Install a shunt across pins 1 and 4 of jumper JU7 (SYNC = high, spread-spectrum mode). 5) Install a shunt across jumper JU8 (automatic switchover to headphone operation is enabled). 6) Connect the speaker across the OUT+ and OUTtest points.
Table 1. Cable Length vs. Suggested Output Components
CABLE LENGTH X (cm) X < 10 10 < X < 15 15 < X < 30 X>30 OUTPUT CAPACITORS C14 AND C15 -- Required (100pF) Required (100pF) -- COMMON-MODE CHOKE T1 -- -- Required -- LCR FILTER L1, L2, C16-C19, C21, R2, R3 -- -- -- Required OUTPUT SPEAKER CONNECTED BETWEEN OUT+, OUTOUT+, OUTFOUT1+, FOUT1FOUT2+, FOUT2-
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MAX9770 Evaluation Kit
The EV kit outputs (OUT+, OUT-) can be connected directly to a speaker load without any filtering. However, a filter can be added to ease evaluation by recovering the audio signal. See Table 2 for the recommended filtering component values for an 8 load and 30kHz cutoff frequency.
Evaluates: MAX9770/MAX9771
Table 2. Recommended Filtering Components for Outputs with 8 Load
COMPONENT L1, L2 C16, C17 C18, C19 C21 R2, R3 RECOMMENDED VALUE 15H 0.033F 0.068F 0.15F 22
Jumper Selection
Output Gain Selection Jumpers JU1 and JU2 control the GAIN1 and GAIN2 pins of the MAX9770 IC. The MAX9770 can be configured to automatically switch between two gain settings depending on whether the EV kit is in speaker or headphone mode. By driving one or both gain inputs with the HPS pin, the gain of the output changes when a headphone is inserted/removed. See Table 3 for output gain settings.
Table 3. JU1 and JU2 Jumpers Selection
SPEAKER MODE GAIN (HPS = 0) (dB) 6 3 6 9 6 0 9 (default) 3 6 HEADPHONE MODE GAIN (HPS = 1) (dB) -2 1 4 1 1 1 -2 (default) 4 7 JU1 SHUNT POSITION Open Open Pins 2 and 3 Pins 1 and 2 Open Pins 1 and 2 Pins 1 and 2 Pins 2 and 3 Pins 2 and 3 GAIN1 PIN GAIN1 = HPS, connect pin 2 of JU1 to pin 1 of JU8 GAIN1 = HPS, connect pin 2 of JU1 to pin 1 of JU8 GAIN1 = low GAIN1 = high GIAN1 = HPS, connect pin 2 of JU1 to pin 1 of JU8 GAIN1 = high GAIN1 = high GAIN1 = low GAIN1 = low JU2 SHUNT POSITION Pins 2 and 3 Pins 1 and 2 Open Open Open Pins 1 and 2 Pins 2 and 3 Pins 1 and 2 Pins 2 and 3 GAIN2 PIN
GAIN2 = low GAIN2 = high GAIN2 = HPS, connect pin 2 of JU2 to pin 1 of JU8 GAIN2 = HPS, connect pin 2 of JU2 to pin 1 of JU8 GAIN2 = HPS, connect pin 2 of JU2 to pin 1 of JU8 GAIN2 = high GAIN2 = low GAIN2 = high GAIN2 = low
Note: JU8 is closed.
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MAX9770 Evaluation Kit Evaluates: MAX9770/MAX9771
Input Selection Jumpers JU3, JU4, and JU5 control the SEL1, SEL2, and SELM pins of the MAX9770 IC. See Table 4 for JU3, JU4, and JU5 functions.
Table 4. JU3, JU4, and JU5 Jumpers Selection
JU3 SHUNT POSITION Pins 2 and 3 (SEL1 = low) Pins 2 and 3 (SEL1 = low) Pins 2 and 3 (SEL1 = low) Pins 2 and 3 (SEL1 = low) Pins 1 and 2 (SEL1 = high) Pins 1 and 2 (SEL1 = high) Pins 1 and 2 (SEL1 = high) Pins 1 and 2 (SEL1 = high) JU4 SHUNT POSITION Pins 2 and 3 (SEL2 = low) Pins 2 and 3 (SEL2 = low) Pins 1 and 2 (SEL2 = high) Pins 1 and 2 (SEL2 = high) Pins 2 and 3 (SEL2 = low) Pins 2 and 3 (SEL2 = low) Pins 1 and 2 (SEL2 = high) Pins 1 and 2 (SEL2 = high) JU5 SHUNT POSITION Pins 2 and 3 (SELM = low) Pins 1 and 2 (SELM = high) Pins 2 and 3 (SELM = low) Pins 1 and 2 (SELM = high) Pins 2 and 3 (SELM = low) Pins 1 and 2 (SELM = high) Pins 2 and 3 (SELM = low) Pins 1 and 2 (SELM = high) INPUT SELECTION All inputs are disabled VMONO (mono) VRIN2/VLIN2 (stereo) VRIN2/VLIN2 (stereo), VMONO (mono) VRIN1/VLIN1 (stereo) (default) VRIN1/VLIN1 (stereo), VMONO (mono) VRIN1/VLIN1 (stereo), VRIN2/VLIN2 (stereo) VRIN1/VLIN1 (stereo), VRIN2/VLIN2 (stereo), VMONO (mono)
Note: Refer to Table 2 of the MAX9770 IC data sheet for the multiplex/mixer settings.
Shutdown Mode (SHDN) Jumper JU6 controls the shutdown pin (SHDN) of the MAX9770 IC. See Table 5 for shunt positions.
Table 5. JU6 Jumper Selection
SHUNT POSITION Pins 1 and 2 (default) Pins 2 and 3 SHDN PIN Connected to VDD Connected to GND EV KIT FUNCTION EV kit enabled Shutdown mode
Switching Frequency Mode (SYNC) Jumper JU7 provides an option to select the switching frequency of the MAX9770 IC. See Table 6 for the various shunt positions.
Table 6. JU7 Jumper Selection
SHUNT POSITION Pins 1 and 2 Pins 1 and 3 Pins 1 and 4 (default) Pins 1 and 5 SYNC = low SYNC = floating SYNC = high SYNC = external clock input SYNC PIN INTERNAL OSCILLATOR SWITCHING FREQUENCY 1.1MHz 1.45MHZ 1.22MHz 120kHz (spread-spectrum mode) Synchronized to the incoming clock frequency
4
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MAX9770 Evaluation Kit Evaluates: MAX9770/MAX9771
VDD
GND
VDD
C1 10F C2 1.0F 2 26 GND C1P 10 C5 1.0F OUT19 C14 OPEN OUT+ OUT+ 18 C15 OPEN HPOUTR 3 6 1 4 JU8 2 VDD HPOUTL 1 JU6 2 3 3 4 2 1 TP1 XGND (BYPASS) SYNC 1 C20 OPEN VDD 1 2 JU3 3 VDD 1 2 JU4 VDD 3 1 2 JU5 3 2 JU7 C13 100pF 5 4 3 J1 R3 OPEN 1 4 T1 2 3 FOUT1+ L2 OPEN C17 OPEN C19 OPEN C21 OPEN C22 OPEN FOUT2+ FOUT1L1 OPEN C16 OPEN C18 OPEN
VRIN1
C8 0.47F C9 0.47F C10 0.47F C11 0.47F C6 1.0F
VDD 28 IN1_R
R2 OPEN
VRIN2
27
IN2_R
C1N OUT-
9
FOUT2-
VLIN1
25
IN1_L U1
VLIN2
24
IN2_L
MAX9770
VMONO
23
MONO
HPOUTR
GND
VDD 20 C12 0.1F PVDD
HPS HPOUTL
17
PGND
5 8 C4 1.0F
SVSS CPVSS
SHDN
15
R1 49.9 1%
SYNC VDD 1 2 VDD 3 1 JU2 2 3 C3 0.047F VDD 7 C7 1.0F CPVDD JU1
16
VDD
22
GAIN1
SEL1
12
21 1
GAIN2 BIAS
SEL2
13
SELM
14
11
CPGND
NOTE: C20 IS ONLY REQUIRED FOR MAX9771.
Figure 1. MAX9770 EV Kit Schematic _______________________________________________________________________________________ 5
MAX9770 Evaluation Kit Evaluates: MAX9770/MAX9771
Figure 2. MAX9770 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX9770 EV Kit PC Board Layout--Component Side
Figure 4. MAX9770 EV Kit PC Board Layout--Layer 2 (GND)
Figure 5. MAX9770 EV Kit PC Board Layout--Layer 3 (VDD)
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MAX9770 Evaluation Kit Evaluates: MAX9770/MAX9771
Figure 6. MAX9770 EV Kit PC Board Layout--Solder Side
Figure 7. MAX9770 EV Kit Component Placement Guide-- Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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