DIODES PAM8945 EVB EV Board User Guide

DIODES PAM8945 EVB EV Board

Specifications

• Built-In Battery Tracking
• Automatic Gain Control (AGC)
• High-Efficiency Integrated Boost Converter Over 85%
• 4W into a 4Ω Load At 10% THD
• 3.3W into a 4Ω Load At 1% THD
• Operates from 2.8V to 5.2V
• Efficient Class-D Prolongs Battery Life
• Minimized ON/OFF Pop Noise
• Superior Low Noise
• High PSRR (Power Supply Rejection Ratio)
• DC Input Protection
• Auto-Recovery Short-Circuit Protection
• Thermal Shutdown
• Available in 1.5mm X 2.0mm 12-ball WCSP

Product Usage Instructions

EV Board Operational Sequence

1. Preset the power supply to between 2.8V and 5.2V.
2. Turn off the power supply.
3. Connect power supply to EV board power.
4. Connect audio input from audio input jack.
5. Connect the Speaker to the output jack.
6. Turn on the power supply.

EV Board BOM List

EMK107B7105KA-T

FAQ

• Q: Can the PAM8945 EVB operate below 2.8V?
  • A: No, the PAM8945 EVB operates within the voltage range of 2.8V to 5.2V.
• Q: What is the purpose of the AGC feature?
  • A: The Automatic Gain Control (AGC) feature helps in automatically adjusting the audio signal strength to maintain a consistent output level.

Revision Information

This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. PAM8945 Document number: DSxxxxx Rev. 1 – 0 1 of 7

• www.diodes.com
• January. 2016
• © Diodes Incorporated

Key Features

• Built-In Battery Tracking Automatic Gain Control (AGC)
• High-Efficiency Integrated Boost Converter Over 85%
• 4W into an 4Ω Load At 10% THD
• 3.3W into an 4Ω Load At 1% THD
• Operates from 2.8V to 5.2V
• Efficient Class-D Prolongs Battery Life
• Minimized ON/OFF Pop Noise
• Superior Low Noise
• High PSRR
• DC Input Protection
• Auto-Recovery Short-Circuit Protection
• Thermal Shutdown
• Available in 1.5mm X 2.0mm 12-ball WCSP

EV Board Schematic

PAM8945 EB58AB Description

The PAM8945 is a high efficiency Class-G audio power amplifier with an integrated boost converter. It drives up to 4W (10% THD+N) into an 4Ω speaker. With 85% typical efficiency, the PAM8945 helps extend battery life when playing audio The built-in boost converter generates the voltage rail for the output stage. This provides a louder audio output than a stand-alone amplifier connected directly to the battery. It also maintains a consistent loudness, regardless of battery voltage. The PAM8945 features battery tracking AGC function which adjusts the Class-D gain to limit battery current at lower battery voltage

EV Board View

EV board operational sequence:

• a. Preset the power supply to between 2.8V and 5.2V.
• b. Turn off the power supply.
• c. Connect power supply to EV board power.
• d. Connect audio input from audio input jack.
• e. Connect the Speaker to the output jack
• f. Turn on the power supply

EV Board BOM List

Item| Value| Type| Rating| Description| Vender and port
---|---|---|---|---|---

C9,C10

|

1uF

| X5R/X7R,

Ceramic/0603

|

10V

|

Input coupling CAP

| Taiyo Yuden

EMK107B7105KA-T

C8

|

1uF

| X5R/X7R,

Ceramic/0603

|

10V

| VBAT decoupling

CAP

| Taiyo Yuden

EMK107B7105KA-T

C6

|

10uF

| X5R/X7R,

Ceramic/0805

|

10V

| VBAT decoupling

CAP

| Taiyo Yuden

LMK107BBJ106MALT

C7

|

1uF

| X5R/X7R,

Ceramic/0805

|

10V

| VBAT decoupling

CAP

| Taiyo Yuden

LMK107BBJ105MAL T

C2,C5

|

10uF

| X5R/X7R,

Ceramic/0805

|

10V

| PVDD     decoupling

CAP

| Taiyo Yuden

LMK107BBJ106MALT

C11

|

2.2uF

| X5R/X7R,

Ceramic/0805

|

10V

| PVDD     decoupling

CAP

| Taiyo Yuden

LMK107B7225KA-T

C12

|

220uF

| |

10V

| VBAT decoupling

CAP

|

Taiyo Yuden

R3

| |

0805

| | VBAT Connection

resistance

|

L1

|

2.2uH

|

3.4A

| | | SWPA4020S2R2NT

sunlord

IC1| | PAM8945| | | DIODES
FB1,FB2| | 1A| |

EMI

Components

|
C3,C4| | 220pF/10V| |

External Components Selection

Input Capacitors (C9,C10)

1. Form a high pass filter with Ri, and the cut off frequency is fc=1/2ΠRi*Ci
2. Have a tolerance of 10% or better for matching: any mismatch in capacitance causes an importance mismatch at the corner frequency.
3. Low leakage current needed, 1uF, X5R/X7R ceramic

Power Supply decoupling Caps (C6, C7,C8,C12)

1. Low ESR for good THD, PSRR
2. C6,C7, C8 Additional 1uF /10uF or greater for low frequency noise filtering and serves as a local storage capacitor for supplying current during large signal transients on the amplifier outputs
3. VBAT decoupling need place electrolytic capacitor 220uF/10
4. Need place very closed to the IC

PCB Layout Guidelines

Grounding

1. Use plane grounding or separate grounds.
2. Do not use one line connecting power GND and analog GND
3. Output noise grounds must tie to system ground at the power in exclusively.
4. Signal currents for the inputs need to be returned to quite ground.

This ground only ties to the signal components and the GND pin.

Power Supply

1. VBET and Boost Converter need to be separated and tied together at the system power supply.
2. Recommend that the all the trace could be routed as short and thick as possible.
3. Any barricade placed in the trace could result in the bad performance of the amplifier.

Components Placement

1. The power supply capacitors (C6,C7) need to place very close to the L1 pins.
2. The power supply capacitors (C8) need to place very close to the PAM8945 VBATpins.
3.  Input capacitors (C9,C10) place closed to input pin as near as possible

PCB Layout Example

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