19-4450; Rev 0; 2/09 MAX9792A Evaluation Kit The MAX9792A evaluation kit (EV kit) demonstrates the MAX9792A IC, which combines a mono Class D power amplifier, a DirectDrive® stereo headphone amplifier, and a 120mA, 4.75V low-dropout regulator (LDO) for notebook, tablet PC, and portable media player applications. Maxim’s DirectDrive technology eliminates the need for bulky DC-blocking capacitors at the output of the headphone amplifier. The EV kit is configured for a 12dB speaker amplifier gain and a 0dB headphone amplifier gain. It is designed to operate from a 4.5V to 5.5V speaker supply and an optional separate 2.7V to 5.5V headphone supply. The EV kit is capable of delivering up to 3W into a 3Ω speaker and 180mW into a 32Ω headphone load. Features ♦ No DC-Blocking Output Capacitors Required at Headphone Output ♦ Speaker and Headphone Operation Speaker: 3W Mono Class D Output Headphone: 180mW Stereo DirectDrive Output ♦ Wake-on-Beep Function ♦ 120mA, 4.75V LDO ♦ Lead(Pb)-Free and RoHS Compliant ♦ Fully Assembled and Tested Ordering Information PART TYPE MAX9792AEVKIT+ EV Kit +Denotes lead(Pb)-free and RoHS compliant. Component List DESIGNATION QTY DESCRIPTION REQUIRED COMPONENTS C1, C5, C6, C25–C28 7 1µF ±10%, 10V X7R ceramic capacitors (0603) Murata GRM188R71A105K C3, C4, C29 3 1µF ±10%, 50V X7R ceramic capacitors (0805) Murata GRM21BR71H105K C7, C8, C9 C10, C30, C31 3 3 0.1µF ±10%, 16V X7R ceramic capacitors (0603) Murata GRM188R71C104K 10µF ±10%, 10V X7R ceramic capacitors (0805) Murata GRM21BR71A106K R1 1 20kΩ ±1% resistor (0603) R3, R4, R13 3 40.2kΩ ±1% resistors (0603) U1 1 Speaker and headphone amplifiers with LDO (28 TQFN-EP*) Maxim MAX9792AETI+ — 1 PCB: MAX9792A Evaluation Kit+ *EP = Exposed pad. DirectDrive is a registered trademark of Maxim Integrated Products, Inc. DESIGNATION QTY DESCRIPTION OPTIONAL COMPONENTS AVDD, HPVDD, PGND, SPOUT+, SPOUT- 5 Binding posts C13, C14, C19, C20, C23, C24, C33 0 Not installed, ceramic capacitors (0603) C16 0 Not installed, ceramic capacitor (0805) HPINL 1 White side-entry phono jack HPINR, SPIN 2 Red side-entry phono jacks HPL, HPR, PGND, SENSE, SPO+, SPO- 0 Not installed, small PCB test points HPOUT 1 3.5mm stereo headphone jack JU1, JU2, JU3 3 3-pin headers JU4, JU5 2 2-pin headers L3, L4 0 Not installed, inductors (6.4mm x 6mm x 1.5mm) R7, R8 2 0Ω ±5% resistors (0805) R11, R12, R15 0 Not installed, resistors (0603) — 5 Shunts (JU1–JU5) ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX9792A General Description Evaluates: MAX9792A MAX9792A Evaluation Kit Component Supplier SUPPLIER PHONE Murata Electronics North America, Inc. WEBSITE 770-436-1300 www.murata-northamerica.com Note: Indicate that you are using the MAX9792A when contacting this component supplier. Quick Start Detailed Description of Hardware Required Equipment The MAX9792A EV kit demonstrates the MAX9792A IC in a 28-pin TQFN package with an exposed pad. The IC combines a mono Class D amplifier, a stereo DirectDrive headphone amplifier, and a 120mA, 4.75V LDO for notebook, tablet PC, and portable media player applications. The EV kit demonstrates Maxim’s DirectDrive technology, which eliminates bulky DCblocking capacitors at the headphone amplifier output. The MAX9792A IC features adjustable gain. • One 5V, 3A DC Supply • One 3Ω speaker • One stereo headphone • Two audio signal sources: one mono and another stereo Procedure The MAX9792A EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) Verify that shunts are installed as follows: JU1: Pins 2-3 (speaker amplifier enabled) JU2: Pins 1-2 (headphone amplifier enabled) JU3: Pins 1-2 (LDO enabled) JU4: Installed (HPVDD connected to AVDD) JU5: Installed (wake-on-beep function disabled) 2) Set the power-supply output to 5V. 3) Disable the power-supply output. 4) Connect the power-supply ground to the PGND binding post and the power-supply positive output to the AVDD binding post. 5) Verify that the audio source output is disabled. 6) Connect the stereo audio source’s right channel to the HPINR phono jack and the left channel to the HPINL phono jack. 7) Connect the mono audio source to the SPIN phono jack. The MAX9792A EV kit is configured for a 12dB speaker amplifier gain and 0dB headphone amplifier gain. The gains can be adjusted by modifying the corresponding gain-setting resistors (R1, R3, and R4). R1 sets the speaker amplifier gain while R3 and R4 set the headphone amplifier gain. The EV kit is designed to operate from a 4.5V to 5.5V speaker supply providing 3A. To use the LDO, AVDD must range from 4.9V to 5.5V. An optional separate 2.7V to 5.5V headphone supply can power the headphone amplifier. The EV kit is capable of delivering up to 3W into a 3Ω speaker, 180mW into a 32Ω headphone load, and 120mA from the 4.75V LDO output. In applications where the speaker leads exceed 225mm, replace resistors R7 and R8 with surfacemount 0805 ferrite beads and install surface-mount 0603 capacitors for C13 and C14. Refer to the Optional Ferrite Bead Filter section of the MAX9791/MAX9792 IC data sheet for more information. The speaker outputs do not require an output filter as the MAX9792A relies on the inherent inductance of the speaker coil and the natural filtering of an attached speaker. For optimum results, use a speaker with a series inductance > 10µH. The EV kit layout shows an optional speaker output filter for evaluation purposes only. 8) Plug the headphone into the HPOUT headphone jack. 9) Connect the speaker across the SPOUT+ and SPOUT- binding posts. 10) Enable the power-supply output. 11) Enable the audio sources. 12) Verify that the headphones and speakers are playing the audio source signals. 2 _______________________________________________________________________________________ MAX9792A Evaluation Kit LDO Shutdown Jumper JU3 enables or disables the LDO (LDO_EN). To use the LDO, AVDD must range between 4.9V and 5.5V. See Table 3 for jumper JU3 configuration to shut down or enable the LDO. Optional Headphone Supply Configuration Jumper JU4 configures the source for the headphone power supply (HPVDD). To power HPVDD using AVDD, install a shunt on jumper JU4. To use an optional separate supply for HPVDD, do not install a shunt on jumper JU4 and connect a 2.7V to 5.5V supply across the HPVDD and PGND binding posts. See Table 4 for jumper JU4 configuration. Wake-on-Beep Jumper JU5 controls the MAX9792A EV kit’s wake-onbeep feature. A qualified BEEP signal overrides HP_EN and SPKR_EN enabling the speaker and headphone amplifiers. Refer to the Wake-on-Beep section of the MAX9791/MAX9792 IC data sheet for more information. To use the wake-on-beep feature, remove the shunt from jumper JU5, connect a user-supplied BEEP signal across the BEEP and nearby PGND PCB pads. Note: Do not leave the BEEP pin unconnected. The LDO must be enabled to use the wake-on-beep feature. See Table 5 for jumper JU5 configuration. Table 2. Headphone Amplifier (JU2) SHUNT POSITION Connected to AVDD Enabled 2-3 Connected to PGND Disabled *Default position. Table 3. LDO (JU3) SHUNT POSITION LDO_EN PIN SPEAKER AMPLIFIER 1-2 Connected to AVDD Disabled 2-3* Connected to PGND Enabled 4.75V LDO 1-2* Connected to AVDD Enabled 2-3 Connected to PGND Disabled *Default position. Table 4. Headphone Supply (JU4) SHUNT POSITION Installed* Not installed HPVDD PIN Connected to AVDD HPVDD POWERSUPPLY SOURCE AVDD supply Connected to HPVDD Optional separate 2.7V binding post to 5.5V supply *Default position. Table 5. Wake-on-Beep (JU5) SHUNT POSITION BEEP PIN Not installed WAKE-ON-BEEP FEATURE Connected to PGND Disabled Connected to BEEP PCB pad Enabled with a usersupplied BEEP output; the LDO must be enabled (see Table 4) Table 1. Speaker Amplifier (JU1) SPKR_EN PIN HEADPHONE AMPLIFIER HP_EN PIN 1-2* Installed* SHUNT POSITION Evaluates: MAX9792A Speaker/Headphone Amplifier Shutdown Jumpers JU1 and JU2 enable or disable the speaker amplifier (SPKR_EN) and headphone amplifier (HP_EN), respectively. See Tables 1 and 2 for jumper JU1 and JU2 configuration to shut down or enable the respective amplifier. *Default position. *Default position. _______________________________________________________________________________________ 3 Evaluates: MAX9792A MAX9792A Evaluation Kit Speaker and Headphone Gain Setting The default gain-setting resistor (R1) configures the speaker amplifier gain to 12dB, while the default gainsetting resistors (R3 and R4) configure the headphone amplifier gain to 0dB. The gain can be changed by replacing these resistors with other surface-mount 0603 resistors. Use ±1% tolerance resistors for optimum performance. See Table 6 and the following equations to select new gain-setting resistors in kilohms for the corresponding channel: Table 6. Component Function CHANNEL RIN Speaker R1 Headphone right R3 Headphone left R4 ⎛ 20kΩ ⎞ RINSPKR [kΩ] = − 4 × ⎜ ⎟ ⎝ A VSPKR ⎠ where AVSPKR is the desired speaker voltage gain and RINSPKR is the speaker amplifier’s input resistor (R1). ⎛ 40.2kΩ ⎞ RINHP [kΩ] = − ⎜ ⎟ ⎝ A VHP ⎠ where AVHP is the desired headphone voltage gain and RINHP is the headphone amplifier input resistors (R3 or R4). 4 _______________________________________________________________________________________ MAX9792A Evaluation Kit Evaluates: MAX9792A Figure 1. MAX9792A EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX9792A MAX9792A Evaluation Kit Figure 2. MAX9792A EV Kit Component Placement Guide—Component Side 6 _______________________________________________________________________________________ MAX9792A Evaluation Kit Evaluates: MAX9792A Figure 3. MAX9792A EV Kit PCB Layout—Component Side _______________________________________________________________________________________ 7 Evaluates: MAX9792A MAX9792A Evaluation Kit Figure 4. MAX9792A EV Kit PCB Layout—Layer 2 8 _______________________________________________________________________________________ MAX9792A Evaluation Kit Evaluates: MAX9792A Figure 5. MAX9792A EV Kit PCB Layout—Layer 3 _______________________________________________________________________________________ 9 Evaluates: MAX9792A MAX9792A Evaluation Kit Figure 6. MAX9792A EV Kit PCB Layout—Solder Side 10 ______________________________________________________________________________________ MAX9792A Evaluation Kit Evaluates: MAX9792A Figure 7. MAX9792A 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 ____________________ 11 © 2009 Maxim Integrated Products SPRINGER Maxim is a registered trademark of Maxim Integrated Products, Inc.