LM49101TMEVAL - National Semiconductor

LM49101 March 23, 2009

Mono Class AB Audio Subsystem with a True Ground

Headphone Amplifier and Earpiece Switch

General Description

The LM49101 is a fully integrated audio subsystem with a

mono power amplifier capable of delivering 540mW of con-

tinuous average power into an 8Ω BTL speaker load with 1%

THD+N using a 3.3V supply. The LM49101 includes a sepa-

rate stereo headphone amplifier that can deliver 44mW per

channel into 32Ω loads using a 2.75V supply.

The LM49101 has four input channels. A pair of single-ended

inputs and a fully differential input channel with volume control

and amplification stages. Additionally, a bypass differential

input is available that connects directly to the mono speaker

outputs through an analog switch without any amplification or

volume control stages. The LM49101 features a 32–step dig-

ital volume control on the input stage and an 8–step digital

volume control on the headphone output stage.

The digital volume control and output modes, programmed

through a two-wire I2C compatible interface, allows flexibility

in routing and mixing audio channels.

The LM49101 is designed for cellular phones, PDAs, and

other portable handheld applications. The high level of inte-

gration minimizes external components. The True Ground

headphone amplifier eliminates the physically large DC block-

ing output capacitors reducing required board space and

reducing cost.

Key Specifications

■ Supply Voltage (VDDLS) 2.7V ≤ VDDLS ≤ 5.5V

■ Supply Voltage (VDDHP) 1.8V ≤ VDDHP ≤ 2.9V

■ I2C Supply Voltage 1.7V ≤ I2CVDD ≤ 5.5V

■ Output power

VDDLS = 5V, VDDHP = 2.75V

1% THD+N

RL = 8Ω speaker 1.3W (typ)

RL = 32Ω headphone 45mW (typ)

■ Output Power

VDDLS = 3.3V, VDDHP = 2.75V

1% THD+N

RL = 8Ω speaker 540W (typ)

RL = 32Ω headphone 40mW (typ)

■ PSRR:

VDD = 3.3V, 217Hz ripple, Mono In 90dB (typ)

■ Shutdown power supply current 0.01μA (typ)

Features

■Differential mono input and stereo single-ended input

■Separate earpiece (receiver) differential input

■Analog switch for a separate earpiece path

■32-step digital volume control (-80 to +18dB)

■Three independent volume channels (Left, Right, Mono)

■Separate headphone volume control

■Flexible output for speaker and headphone output

■True Ground headphone amplifier eliminates large DC

blocking capacitors reducing PCB space and cost.

■Hardware reset function

■RF immunity topology

■“Click and Pop” suppression circuitry

■Thermal shutdown protection

■Micro-power shutdown

■I2C control interface

■Available in space-saving microSMD package

Applications

■Portable electronic devices

■Mobile Phones

■PDAs

Boomer® is a registered trademark of National Semiconductor Corporation.

LM49101Mono Class AB Audio Subsystem with a True Ground Headphone Amplifier and

Earpiece Switch

Typical Application

30086203

FIGURE 1. Typical Audio Application Circuit

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LM49101

Connection Diagrams

25 Bump micro SMD Package

30086202

Top View

(Bump Side Down)

Order Number LM49101TM, LM49101TMX

See NS Package Number TMD25BCA

micro SMD Markings

30086204

Top View

XY - Date Code

TT - Die Traceability

G- Boomer Family

L4 - LM49101TM

Ordering Information

Order

Number

Package Package DWG

Transport Media MSL Level Green Status Features

LM49101TM 25 Bump micro

SMD TMD25BCA 250 units on tape and reel 1 RoHS and no Sb/Br

LM49101TMX 25 Bump micro

SMD TMD25BCA 3000 units on tape and reel 1 RoHS and no Sb/Br

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LM49101

Bump Descriptions

Bump Name Pin Function Type

A1 CPGND Charge pump ground terminal Ground

A2 VSSCP Negative charge pump power supply Power Output

A3 HPR Right headphone output Analog Output

A4 VDDHP Headphone amplifier power supply Power Input

A5 MIN+ Positive input pin for the mono, differential input Analog Input

B1 C1N Negative terminal of the charge pump flying capacitor Analog Output

B2 C1P Positive terminal of the charge pump flying capacitor Analog Output

B3 HPL Left headphone output Analog Output

B4 HPGND Headphone signal ground Ground

B5 MIN- Negative input pin for the mono, differential input Analog Input

C1 VDDCP Charge pump power supply Power Input

C2 SDA I2C data Digital Input

C3 GND Ground Ground

C4 RIN Single-ended input for the right channel Analog Input

C5 LIN Single-ended input for the left channel Analog Input

D1 BYPASS_IN- Earpiece negative input, bypass volume control and amplifier Analog Input

D2 I2CVDD I2C power supply Power Input

D3 SCL I2C clock Digital Input

D4 HW RESET

Hardware reset function, active low. When pin is low (<0.6V) the

LM49101 goes into shutdown mode and will remain in shutdown

mode until pin goes to logic high (>1.6V) and is activated by I2C

control. When reset all registers are set to the default value of 0.

Digital Input

D5 BYPASS_IN+ Earpiece positive input, bypass volume control and amplifier Analog Input

E1 MONO+ Positive loudspeaker output Analog Output

E2 VDDLS Main power supply Power Input

E3 GND Ground Ground

E4 MONO- Negative loudspeaker output Analog Output

E5 BIAS Half-supply bias, capacitor bypassed Analog Output

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LM49101

Absolute Maximum Ratings (Notes 1, 2)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Supply Voltage (Loudspeaker,

VDDLS) 6.0V

Supply Voltage (Headphone, VDDHP) 3.0V

Storage Temperature −65°C to +150°C

Voltage at Any Input Pin GND − 0.3 to VDD LS + 0.3

Power Dissipation (Note 3) Internally Limited

ESD Rating (Note 4) 2000V

ESD Rating (Note 5) 200V

Junction Temperature (TJMAX)150°C

Soldering Information

Vapor Phase (60sec.) 215°C

Infrared (15sec.) 220°C

See AN-1112 “Micro SMD Wafer Level Chip Scale

Package”

Thermal Resistance

θJA (Note 8) 51°C/W

Operating Ratings

Temperature Range

TMIN ≤ TA ≤ TMAX −40°C ≤ TA ≤ 85°C

Supply Voltage (VDDLS) 2.7V ≤ VDDLS ≤ 5.5V

Supply Voltage (VDDHP) 1.8V ≤ VDDHP ≤ 2.9V

VDDHP ≤ VDDLS

Supply Voltage (VDDCP) VDDCP = VDD HP

Supply Voltage (I2CVDD)1.7V ≤ I2CVDD ≤ 5.5V

I2CVDD ≤ VDDLS

Electrical Characteristics VDDLS = 3.3V, VDDHP = 2.75V (Notes 1, 2)

The following specifications apply for VDDLS = 3.3V, VDDHP = 2.75V, TA = 25°C, all volume controls set to 0dB, unless otherwise

specified. LS = Loudspeaker, HP = Headphone, EP = Earpiece.

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 6)

Limits

(Note 7)

IDD Quiescent Power Supply Current

VIN = 0, No Load

EP Receiver

(Output Mode Bit EP Bypass = 1) 0.03 0.045 mA (max)

LS only (Mode 1), GAMP_SD = 0

VDDLS

VDDHP

2.5

4.2 mA (max)

LS only (Mode 1), GAMP_SD = 1

VDDLS

VDDHP

HP only (Mode 8), GAMP_SD = 0

VDDLS

VDDHP

VDDLS +VDDHP

1.6

3.1

2.0

4.5

6.45

mA (max)

HP only (Mode 8), GAMP_SD = 1

VDDLS

VDDHP

2.8

3.3

LS+HP (Mode 10), GAMP_SD = 0

VDDLS

VDDHP

VDDLS +VDDHP

2.8

3.1

3.8

4.5

mA (max)

ISD Shutdown Current Power_On = 0 0.01 2 µA (max)

VOS Output Offset Voltage

VIN = 0V, Mode 10

LS output, RL = 8Ω BTL

HP output, RL = 32Ω SE

2.5

0.5

mV (max)

POOutput Power

LS output, Mode 1, RL = 8Ω BTL

THD+N = 1%, f = 1kHz, LS_Gain = 6dB 540 480 mW (min)

HP output, Mode 8, RL = 32Ω SE

THD+N = 1%, f = 1kHz 44 40 mW (min)

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LM49101

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 6)

Limits

(Note 7)

THD+N Total Harmonic Distortion + Noise

LS output, f = 1kHz, RL = 8Ω BTL

PO = 250mW, Mode 1, LS_Gain = 6dB 0.065 %

HP output, f = 1kHz, RL = 32Ω SE

PO = 20mW, Mode 8 0.015 %

SNR Signal-to-Noise Ratio

LS output, f = 1kHz, Mode 1

VREF = VOUT (1%THD+N)

Vol. Gain & LS_GAIN = 0dB

A-Wtg, LIN & RIN AC terminated

105 dB

HP output, f = 1kHz, Mode 8

VREF = VOUT (1%THD+N)

Vol. Gain = 0dB, A-weighted

LIN & RIN AC terminated

100 dB

PSRR Power Supply Rejection Ratio

VRIPPLE on VDDLS = 200mVPP, fRIPPLE = 217Hz, CB = 2.2μF

All inputs AC terminated to GND, output referred

LS: Mode 1, 5, 9, 13, RL = 8Ω BTL 90 dB (max)

LS: Mode 2, 6, 10 ,14, RL = 8Ω BTL 75 dB (max)

HP: Mode 4, 5, 6, 7, RL = 32Ω SE 85 dB (max)

HP: Mode 8, 9, 10, 11, RL = 32Ω SE 81 dB (max)

CMRR Common-Mode Rejection Ratio

f = 217Hz, VCM = 1VP-P

LS: RL = 8Ω BTL, Mode 1

HP: RL = 32Ω SE, Mode 4

XTALK Crosstalk HP PO = 20mW

f = 1kHz, Mode 8 72 dB

ZIN MIN, LIN, and RIN Input Impedance

Maximum Gain setting 12.5 10

KΩ (min)

KΩ (max)

Maximum Attenuation setting 110 90

130

KΩ (min)

KΩ (max)

RON On Resistance Analog Switch On 3.4 Ω

VOL Digital Volume Control Range Maximum Gain

Maximum Attenuation

–80 dB

VOL Volume Control Step Size Error ±0.02 dB

TWU Wake-Up Time from Shutdown CB = 2.2μF, HP, Normal Turn-On Mode 30 ms

CB = 2.2μF, HP, Fast Turn-On Mode 15 ms

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LM49101

Electrical Characteristics VDDLS = 5.0V, VDDHP = 2.75V (Notes 1, 2)

The following specifications apply for VDDLS = 5.0V, VDDHP = 2.75V, TA = 25°C, all volume controls set to 0dB, unless otherwise

specified. LS = Loudspeaker, HP = Headphone, EP = Earpiece.

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 6)

Limits

(Note 7)

IDD Quiescent Power Supply Current

VIN = 0, No Load

EP Receiver

(Output Mode Bit EP Bypass = 1) 0.05 0.07 mA (max)

LS only (Mode 1), GAMP_SD = 0

VDDLS

VDDHP

2.9

4.4 mA (max)

LS only (Mode 1), GAMP_SD = 1

VDDLS

VDDHP

2.1

HP only (Mode 8), GAMP_SD = 0

VDDLS

VDDHP

VDDLS+VDDHP

1.8

3.1

2.15

4.5

6.6

mA (max)

HP only (Mode 8), GAMP_SD = 1

VDDLS

VDDHP

1.3

3.1

LS+HP only (Mode 10), GAMP_SD = 0

VDDLS

VDDHP

VDDLS+VDDHP

3.1

4.1

4.5

8.35

mA (max)

ISD Shutdown Current Power_On = 0 0.01 2 µA (max)

VOS Output Offset Voltage

VIN = 0V, Mode 10

LS output, RL = 8Ω BTL

HP output, RL = 32Ω SE

2.5

0.5

mV (max)

POOutput Power

LS output, Mode 1, RL = 8Ω BTL

THD+N = 1%, f = 1kHz, LS_Gain = 6dB 1.3 W

HP output, Mode 8, RL = 32Ω SE

THD+N = 1%, f = 1kHz 45 mW

THD+N Total Harmonic Distortion + Noise

LS output, f = 1kHz, RL = 8Ω BTL

PO = 600mW, Mode 1, LS_Gain = 6dB 0.055 %

HP output, f = 1kHz, RL = 32Ω SE

PO = 20mW, Mode 8 0.015 %

SNR Signal-to-Noise Ratio

LS output, f = 1kHz, Mode 1

VREF = VOUT (1%THD+N)

Vol. Gain & LS_GAIN = 0dB

A-Wtg, LIN & RIN AC terminated

108 dB

HP output, f = 1kHz, Mode 8

VREF = VOUT (1%THD+N)

Vol. Gain = 0dB, A-weighted

LIN & RIN AC terminated

100 dB

PSRR Power Supply Rejection Ratio

VRIPPLE on VDDLS = 200mVPP, fRIPPLE = 217Hz, CB = 2.2μF

All inputs AC terminated to GND, output referred

LS: Mode 1, 5, 9, 13, RL = 8Ω BTL 90 dB

LS: Mode 2, 6, 10, 14, RL = 8Ω BTL 74 dB

HP: Mode 4, 5, 6, 7, RL = 32Ω SE 84 dB

HP: Mode 8, 9, 10, 11, RL = 32Ω SE 79 dB

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LM49101

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 6)

Limits

(Note 7)

CMRR Common-Mode Rejection Ratio

f = 217Hz, VCM = 1VP-P

LS: RL = 8Ω BTL, Mode 1

HP: RL = 32Ω SE, Mode 4

XTALK Crosstalk HP PO = 20mW

f = 1kHz, Mode 8 72 dB

ZIN MIN, LIN, and RIN Input Impedance

Maximum Gain setting 12.5 10

KΩ (min)

KΩ (max)

Maximum Attenuation setting 110 90

130

KΩ (min)

KΩ (max)

RON On Resistance Analog Switch On 2 Ω

VOL Digital Volume Control Range Maximum Gain

Maximum Attenuation

–80 dB

VOL Volume Control Step Size Error ±0.02 dB

TWU Wake-Up Time from Shutdown CB = 2.2μF, HP, Normal Turn-On Mode 30 ms

CB = 2.2μF, HP, Fast Turn-On Mode 15 ms

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LM49101

I2C Interface 2.2V ≤ I2C_VDD ≤ 5.5V, (Notes 1, 2)

The following specifications apply for VDDLS = 5.0V and 3.3V, 2.2V ≤ I2C_VDD ≤ 5.5V, TA = 25°C, unless otherwise specified.

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 4)

Limits

(Notes 7, 9)

t1I2C Clock Period 2.5 µs (min)

t2I2C Data Setup Time 100 ns (min)

t3I2C Data Stable Time 0 ns (min)

t4Start Condition Time 100 ns (min)

t5Stop Condition Time 100 ns (min)

t6I2C Data Hold Time 100 ns (min)

VIH I2C Input Voltage High 0.7xI2CVDD V (min)

VIL I2C Input Voltage Low 0.3xI2CVDD V (max)

I2C Interface 1.7V ≤ I2C_VDD ≤ 2.2V, (Notes 1, 2)

The following specifications apply for VDDLS = 5.0V and 3.3V, TA = 25°C, 1.7V ≤ I2C_VDD ≤ 2.2V, unless otherwise specified.

Symbol Parameter Conditions

LM49101 Units

(Limits)

Typical

(Note 6)

Limits

(Notes 7, 9)

t1I2C Clock Period 2.5 µs (min)

t2I2C Data Setup Time 250 ns (min)

t3I2C Data Stable Time 0 ns (min)

t4Start Condition Time 250 ns (min)

t5Stop Condition Time 250 ns (min)

t6I2C Data Hold Time 250 ns (min)

VIH I2C Input Voltage High 0.7xI2CVDD V (min)

VIL I2C Input Voltage Low 0.3xI2CVDD V (max)

Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability

and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in

the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and the

device should not be operated beyond such conditions. All voltages are measured with respect to the ground pin, unless otherwise specified

Note 2: The Electrical Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified

or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature, TA. The maximum

allowable power dissipation is PDMAX = (TJMAX - TA) / θJA or the number given in Absolute Maximum Ratings, whichever

Note 4: Human body model, applicable std. JESD22-A114C.

Note 5: Machine model, applicable std. JESD22-A115-A.

Note 6: Typical values represent most likely parametric norms at TA = +25°C, and at the Recommended Operation Conditions at the time of product

characterization and are not guaranteed.

Note 7: Datasheet min/max specification limits are guaranteed by test or statistical analysis.

Note 8: The given θJA is for an LM49101 mounted on a demonstration board.

Note 9: Refer to the I2C timing diagram, Figure 2.

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LM49101

Typical Performance Characteristics

THD+N vs Frequency

VDDLS = 3.3V, RL = 8Ω BTL, PO = 250mW

Mode 1 (Mono), 80kHz BW

30086219

THD+N vs Frequency

VDDLS = 3.3V, RL = 8Ω BTL, PO = 250mW

Mode 2 (Left + Right), 80kHz BW

30086220

THD+N vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, RL = 32Ω SE,

PO = 5mW/Ch, Mode 4 (Mono), 80kHz BW

30086221

THD+N vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, RL = 32Ω SE,

PO = 5mW/Ch, Mode 8 (Left/Right ), 80kHz BW

30086222

THD+N vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, RL = 8Ω BTL, RL = 32Ω SE,

PO = 250mW BTL, PO = 5mW/Ch SE, Mode 5 (Mono)

LS (EP Mode) = 0, 80kHz BW

30086226

THD+N vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, RL = 8Ω BTL, RL = 32Ω SE,

PO = 250mW BTL, PO = 5mW/Ch SE, Mode 10 (L/R)

LS (EP Mode) = 0, 80kHz BW

30086229

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LM49101

THD+N vs Frequency

VDDLS = 5V, RL = 8Ω BTL, PO = 600mW,

Mode 1 (Mono), 80kHz BW

30086223

THD+N vs Frequency

VDDLS = 5V, RL = 8Ω BTL, PO = 600mW,

Mode 2 (Let + Right), 80kHz BW

30086224

THD+N vs Frequency

VDDLS = 5V, VDDHP = 2.75V, RL = 32Ω SE,

PO = 20mW/Ch, Mode 4 (Mono), 80kHz BW

30086225

THD+N vs Frequency

VDDLS = 5V, VDDHP = 2.75V, RL = 32Ω SE,

PO = 20mW/Ch, Mode 8 (Left/Right), 80kHz BW

30086228

THD+N vs Frequency

VDDLS = 5V, VDDHP = 2.75V, RL = 8Ω BTL, RL = 32Ω SE,

PO = 600mW BTL, PO = 20mW/Ch SE, Mode 5 (Mono)

LS (EP Mode) = 0, 80kHz BW

30086227

THD+N vs Frequency

VDDLS = 5V, VDDHP = 2.75V, RL = 8Ω BTL, RL = 32Ω SE,

PO = 600mW BTL, PO = 20mW/Ch SE, Mode 10 (L/R)

LS (EP Mode) = 0, 80kHz BW

30086230

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LM49101

THD+N vs Output Power

VDDLS = 3.3V & 5V, f = 1kHz, RL = 8Ω BTL

Mode 1 (Mono), 80kHz BW

30086243

THD+N vs Output Power

VDDLS = 3.3V & 5V, f = 1kHz, RL = 8Ω BTL

Mode 2 (Left + Right), 80kHz BW

30086244

THD+N vs Output Power

VDDLS = 3.3V, VDDHP = 1.8V & 2.75V, f = 1kHz,

RL = 32Ω SE, Mode 4 (Mono), 80kHz BW

30086245

THD+N vs Output Power

VDDLS = 3.3V, VDDHP = 1.8V & 2.75V, f = 1kHz,

RL = 32Ω SE, Mode 8 (Left/Right), 80kHz BW

30086246

THD+N vs Output Power

VDDLS = 3.3V & 5V, VDDHP = 2.75V, f = 1kHz,

RL = 8Ω BTL, Mode 5 (Mono), 80kHz BW

30086242

THD+N vs Output Power

VDDLS = 3.3V, VDDHP = 1.8V & 2.75V, f = 1kHz,

RL = 32Ω SE, Mode 10 (Left/Right), 80kHz BW

30086247

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LM49101

PSRR vs Frequency

VDDLS = 3.3V, VRIPPLELS = 200mVPP, RL = 8Ω BTL,

Mode 1 (Mono), 80kHz BW

30086211

PSRR vs Frequency

VDDLS = 3.3V, VRIPPLELS = 200mVPP, RL = 8Ω BTL,

Mode 2 (Left + Right), 80kHz BW

30086213

PSRR vs Frequency

VDDLS = 5V, VRIPPLELS = 200mVPP, RL = 8Ω BTL,

Mode 1 (Mono), 80kHz BW

30086212

PSRR vs Frequency

VDDLS = 5V, VRIPPLELS = 200mVPP, RL = 8Ω BTL,

Mode 2 (Left + Right), 80kHz BW

30086214

PSRR vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, VRIPPLEHP = 200mVPP,

RL = 32Ω SE, Mode 4 (Mono), 80kHz BW

30086215

PSRR vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, VRIPPLEHP = 200mVPP,

RL = 32Ω SE, Mode 8 (Left/Right), 80kHz BW

30086217

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LM49101

PSRR vs Frequency

VDDLS = 3.3V, VDDHP = 2.75V, VRIPPLEHP = 200mVPP,

RL = 32Ω SE, Mode 4 (Mono), 80kHz BW

30086248

PSRR vs Frequency

VDDLS = 3.3V, VDDHP = 2.75V, VRIPPLEHP = 200mVPP,

RL = 32Ω SE, Mode 8 (Left/Right), 80kHz BW

30086249

Power Dissipation vs Output Power

VDDLS = 3.3V & 5V, VDDHP = 2.75V, RL = 8Ω BTL,

Mode 3 (Mono + Left + Right), 80kHz BW

30086235

Power Dissipation vs Output Power

VDDLS = 5V, VDDHP = 1.8V & 2.75V, RL = 32Ω SE,

Mode 12 (Mono + Left/ Right), 80kHz BW

30086236

Crosstalk vs Frequency

VDDLS = 3.3V, VDDHP = 1.8V, VIN = 1VPP,

RL = 32Ω SE, Mode 8 (Left/Right), 80kHz BW

30086231

Crosstalk vs Frequency

VDDLS = 3.3V, VDDHP = 2.75V, VIN = 1VPP,

RL = 32Ω SE, Mode 8 (Left/Right), 80kHz BW

30086232

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LM49101

Supply Current vs Supply Voltage (VDDLS)

VDDHP = 2.75V, No Load, Gain_SD = 0 & 1

LS (EP_Mode) = 0 & 1, Mode 1

30086237

Supply Current vs Supply Voltage (VDDLS)

VDDHP = 2.75V, No Load, Gain_SD = 0 & 1

LS (EP_Mode) = 0 & 1, Mode 2

30086239

Supply Current vs Supply Voltage (VDDHP)

VDDLS = 3.3V, No Load, Gain_SD = 0 or 1

HPR_SD = 0 & 1, Modes 4, 8, 15

30086238

Supply Current vs Supply Voltage (VDDLS)

VDDHP = 2.75V, No Load, Gain_SD = 0 or 1

LS (EP_Mode) = 0 & 1, Mode 15

30086240

Output Power vs Supply Voltage (VDDLS)

VDDHP = 2.75V, RL = 8Ω BTL,

Mode 1

30086234

Output Power vs Supply Voltage (VDDHP)

VDDLS = 3.3V, RL = 32Ω SE,

Mode 4

30086233

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LM49101

Application Information

I2C COMPATIBLE INTERFACE

The LM49101 is controlled through an I2C compatible serial

interface that consists of a serial data line (SDA) and a serial

clock (SCL). The clock line is uni-directional. The data line is

bi-directional (open drain). The LM49101 and the master can

communicate at clock rates up to 400kHz. Figure 2 shows the

I2C interface timing diagram. Data on the SDA line must be

stable during the HIGH period of SCL. The LM49101 is a

transmit/receive slave-only device, reliant upon the master to

generate the SCL signal. Each transmission sequence is

framed by a START condition and a STOP condition (Figure

3). Each data word, device address and data, transmitted

over the bus is 8 bits long and is always followed by an ac-

knowledge pulse (Figure 4). The LM49101 device address is

11111000.

I2C INTERFACE POWER SUPPLY PIN (I2CVDD)

The LM49101's I2C interface is powered up through the

I2CVDD pin. The LM49101's I2C interface operates at a volt-

age level set by the I2CVDD pin which can be set independent

to that of the main power supply pin VDDLS. This is ideal

whenever logic levels for the I2C interface are dictated by a

microcontroller or microprocessor that is operating at a lower

supply voltage than the VDDLS voltage.

I2C BUS FORMAT

The I2C bus format is shown in Figure 4. The START signal,

the transition of SDA from HIGH to LOW while SCL is HIGH,

is generated, alerting all devices on the bus that a device ad-

dress is being written to the bus.

The 7-bit device address is written to the bus, most significant

bit (MSB) first, followed by the R/W bit. R/W = 0 indicates the

master is writing to the slave device, R/W = 1 indicates the

master wants to read data from the slave device. Set R/W =

0; the LM49101 is a WRITE-ONLY device and will not re-

spond to the R/W = 1. The data is latched in on the rising edge

of the clock. Each address bit must be stable while SCL is

HIGH. After the last address bit is transmitted, the master de-

vice releases SDA, during which time, an acknowledge clock

pulse is generated by the slave device. If the LM49101 re-

ceives the correct address, the device pulls the SDA line low,

generating an acknowledge bit (ACK).

Once the master device registers the ACK bit, the 8-bit reg-

ister data word is sent. Each data bit should be stable while

SCL is HIGH. After the 8-bit register data word is sent, the

LM49101 sends another ACK bit. Following the acknowl-

edgement of the register data word, the master issues a

STOP bit, allowing SDA to go high while SCL is high.

300862s0

FIGURE 2. I2C Timing Diagram

300862s1

FIGURE 3. Start and Stop Diagram

www.national.com 16

LM49101

300862s2

FIGURE 4. Start and Stop Diagram

TABLE 1. Chip Address

A7 A6 A5 A4 A3 A2 A1 A0

Chip

Address 1 1 1 1 1 0 0 0

TABLE 2. Control Registers

General Control 0 0 1 GAMP_SD (1) LS

(EP_Mode) (2) 0Turn_On

_Time (3) Power_On (4)

Output Mode Control 0 1 EP

Bypass (5) HPR_SD (6) Mode_ Control (7)

Output Gain Control 1 0 0 Input_Mute (8) LS_Gain (9) HP_Gain (10)

Mono Input Volume

Control 1 0 1 Mono_Vol (11)

Left Input Volume

Control 1 1 0 Left_Vol (11)

Right Input Volume

Control 1 1 1 Right_Vol (11)

Notes: All registers default to 0 on initial power-up.

1. GAMP_SD: Is used to shut down gain amplifiers not in use

and reduce current consumption. See Table 3.

2. LS (EP_Mode): Loudspeaker power amplifier bias current

reduction. See Table 3.

3. Turn_On_Time: Reduces the turn on time for faster acti-

vation. See Table 3.

4. Power_On: Master Power on bit. See Table 3.

5. EP Bypass: Earpiece bypass mode to allow BYPASS in-

puts to drive speaker outputs. See Table 4

6. HPR_SD: Will shutdown one channel of the headphone

amplifier. See Table 4.

7. Mode_Control: Sets the output mode. See Table 4.

8. Input Mute: Controls muting of the inputs except the BY-

PASS inputs. See Table 5.

9. LS_Gain: Sets the gain of the loudspeaker amplifier to 0dB

or 6dB. See Table 5.

10. HP_Gain: Sets the headphone amplifier output gain. See

Table 5.

11. Mono_Vol/Left_Vol/Right_Vol: Sets the input volume for

Mono, Left and Right inputs. See Table 6.

17 www.national.com

LM49101

TABLE 3. General Control Register

Bit Name Value Description

0 Power_On

This bit is a master shutdown control bit and sets the device to be on or off.

Value Status

0 Master power off, device disable.

1 Master power on, device enable.

1 Turn_On_Time

This bit sets the turn on time of the device.

Value Status

0 Normal Turn-on time

1 Fast Turn-on time

3 LS (EP Mode)

This bit enables EP Mode reducing loudspeaker output stage bias current by 500μA.

Value Status

0 Normal loudspeaker power amplifier operation.

1Enables EP Mode reducing loudspeaker output stage bias current

by 500μA.

4 GAMP_SD

This bit is used to reduce IDD by shutting down gain amplifiers not in use.

0 Normal operation of all gain amplifiers.

Disables the input gain amplifiers that are not in use to reduce

current from VDDLS. Recommended for Output Modes 1, 2, 4, 5,

8, 10.

www.national.com 18

LM49101

TABLE 4. Output Mode Control Register (see key below table)

Bits Field Description

3:0 Mode_Control These bits determine how the input signals are mixed and routed to the outputs.

D3 D2 D1 D0

Headphone Loudspeaker

D3D2D1D0Mode Left

Headphone

Right

Headphone

0000 0 SD SD SD

0001 1 SD SD GM x M

0010 2 SD SD 2 x (GL x L + GR x R)

0011 3 SD SD 2 x (GL x L + GR x R)

+ GM x M

0100 4GM x M/2 GM x M/2 SD

0101 5 GM x M/2 GM x M/2 GM x M

0110 6 GM x M/2 GM x M/2 2 x (GL x L + GR x R)

0111 7 GM x M/2 GM x M/2 2 x (GL x L + GR x R)

+ GM x M

1000 8GL x L GR x R SD

1001 9 GL x L GR x R GM x M

1010 10 GL x L GR x R 2 x (GL x L + GR x R)

1011 11 GL x L GR x R 2 x (GL x L + GR x R)

+ GM x M

1100 12 GL x L + GM x

M/2

GR x R + GM x

M/2 SD

1101 13 GL x L + GM x

M/2

GR x R + GM x

M/2 GM x M

1110 14 GL x L + GM x

M/2

GR x R + GM x

M/2 2 x (GL x L + GR x R)

1111 15 GL x L + GM x

M/2

GR x R + GM x

M/2

2 x (GL x L + GR x R)

+ GM x M

4 HPR_SD

This bit sets the headphone amplifiers to normal mode or mono mode.

Value Status

0 Normal stereo headphone operation.

1 Disable right headphone output.

5 EP Bypass

This bit is used to control the analog switch to have the BYPASS inputs drive the loudspeaker outputs.

Value Status

0 Normal output mode operation with analog switch off.

1Loudspeaker and headphone amplifiers go into shutdown mode and Bypass (Receiver) path

enable with the analog switch on.

M : MIN, Mono differential input

L : LIN, Left single-ended input

R : RIN, Right single-ended input

SD : Shutdown

GM : Mono_Vol setting determined by the Mono Input Volume Control register, See Table 6.

GL : Left_Vol setting determined by the Left Input Volume Control register, See Table 6.

GR : Right_Vol setting determined by the Right Input Volume Control register, See Table 6.

19 www.national.com

LM49101

TABLE 5. Output Gain Control Register

Bits Field Description

2:0 HP_GAIN

These bits set the gain of the headphone output amplifiers.

Value Gain (dB)

000 0

001 –1.2

010 –2.5

011 –4.0

100 –6.0

101 –8.5

110 –12

111 –18

3 LS_GAIN

This bit sets the loudspeaker output amplifier gain.

Value Status

0 Loudspeaker output amplifier gain is set to 0dB.

1 Loudspeaker output amplifier gain is set to 6dB.

4 INPUT MUTE

This bit will set all the inputs except the BYPASS inputs to be in Mute mode.

Value Status

0 Normal operation of all inputs.

Mutes all inputs except BYPASS with over 80dB of attenuation

with out adjusting the volume settings. This bit can be used to

mute the inputs to eliminate noise or transients from other

systems and ICs. See the section Input Mute Bit in the

Application Information section for a detailed explanation.

www.national.com 20

LM49101

TABLE 6. Input Volume Control Registers

Bits Fields Description

4:0 Mono_Vol

Right_Vol

Left_Vol

These bits set the input volume for each input volume register listed.

Volume Step Value Gain (dB)

1 00000 –80.0

2 00001 –46.5

3 00010 –40.5

4 00011 –34.5

5 00100 –30.0

6 00101 –27.0

7 00110 –24.0

8 00111 –21.0

9 01000 –18.0

10 01001 –15.0

11 01010 –13.5

12 01011 –12.0

13 01100 –10.5

14 01101 –9.0

15 01110 –7.5

16 01111 –6.0

17 10000 –4.5

18 10001 –3.0

19 10010 –1.5

20 10011 0.0

21 10100 1.5

22 10101 3.0

23 10110 4.5

24 10111 6.0

25 11000 7.5

26 11001 9.0

27 11010 10.5

28 11011 12.0

29 11100 13.5

30 11101 15.0

31 11110 16.5

32 11111 18.0

21 www.national.com

LM49101

HW RESET FUNCTION

The LM49101 can be globally reset without using the I2C con-

trols. When the HW RESET pin is set to a logic low the

LM49101 will enter into shutdown, the mode control bits of the

Output Mode Control register, volume control registers and

Power_On bits will be set to the default value of zero. The

other bits will retain their values. The LM49101 cannot be ac-

tivated until the HW RESET pin is set to a logic high voltage.

When the HW RESET is set to a logic high then the I2C con-

trols can activate and set the register control bits.

GAMP_SD BIT

The GAMP_SD bit allows for reduced power consumption.

When set to '1' the gain amplifiers on unused inputs will be

shutdown saving approximately 0.4mA per input in shutdown.

For example, in Mode 1 only the mono inputs are in use. Set-

ting GAMP_SD to '1' will shut down the gain amplifiers for the

left and right inputs reducing current draw from the VDDLS

supply by approximately 0.8mA. The GAMP_SD bit does not

need to be set each time when changing modes as the

LM49101 will automatically activate and deactivate the need-

ed inputs based on the mode selected.

When operating with GAMP_SD set to '1', a transient may be

observed on the outputs when changing modes. During pow-

er up, the LM49101 uses a start up sequence to eliminate any

pops and clicks on the outputs. The volume control circuitry

is powered up first followed by the other internal circuitry with

the output amplifiers being powered up last. If a mode change

requires a gain amplifier to turn on then a potential transient

may be created that is amplified on the already active outputs.

To eliminate unwanted noise on the outputs the Power_On

bit should be used to turn off the LM49101 before changing

modes, perform a mode change, then turn the LM49101 back

on. This procedure will cause the LM49101 to follow the start

up sequence.

LS (EP_MODE) BIT

The LS (EP_Mode) bit selects the amount of bias current in

the loudspeaker amplifier. Setting the LS (EP_Mode) bit to a

'1' will reduce the amount of current from the VDDLS supply

by approximately 0.5mA. The THD performance of the loud-

speaker amplifier will be reduced as a result of lower bias

current. See the performance graphs in the Typical Perfor-

mance Characteristics section above.

TURN_ON_TIME BIT

The Turn_On_Time bit determines the delay time from the

Power_On bit set to '1' and the internal circuits ready. For

input capacitor values up to 0.47μF the Turn_On_Time bit can

be set to fast mode by setting the bit to a '1'. When the input

capacitor values are larger than 0.47μF then the

Turn_On_Time bit should be set to '0' for normal turn-on time

and higher delay. This allows sufficient time to charge the in-

put capacitors to the ½ VDDLS bias voltage.

POWER_ON BIT

The Power_On bit is the master control bit to activate or de-

activate the LM49101. All registers can be loaded indepen-

dent of the Power_On bit setting as long as the IC is powered

correctly. Cycling the Power_On bit does not change the val-

ues of any registers nor return all bits to the default power on

value of zero. The Power_On bit only determines whether the

IC is on or off.

EP BYPASS BIT

The EP Bypass bit is used to set the LM49101 to earpiece

mode. When this bit is set the analog switch is activated and

the rest of the IC blocks except for the I2C circuitry will go into

shutdown for minimal current consumption.

HPR_SD BIT

The HPR_SD bit will deactivate the right headphone output

amplifier. This bit is provided to reduce power consumption

when only one headphone output is needed.

MODE_CONTROL BITS

The LM49101 includes a comprehensive mixer multiplexer

controlled through the I2C interface. The mixer/multiplexer al-

lows any input combination to appear on any output of

LM49101. Multiple input paths can be selected simultane-

ously. Under these conditions, the selected inputs are mixed

together and output on the selected channel. Table 4 shows

how the input signals are mixed together for each possible

input selection.

INPUT MUTE BIT

The Input Mute bit will mute all inputs except the Bypass in-

puts when set to a '1'. This allows complete and quick mute

of the Mono, Left, and Right inputs without changing the Vol-

ume Control registers or HP_Gain bits. The volume and

HP_Gain bits retain their values when the Input Mute is en-

abled or disabled.

The Input Mute bit can be used to mute all the inputs when

other chips in a system, such as the baseband IC, create

transients causing unwanted noise on the outputs of the

LM49101. This added feature eliminates the need for power

cycling the LM49101.

LS_GAIN BIT

The loudspeaker amplifier can have an additional gain of 0dB

or 6dB by using the LS_Gain bit. The Mono input has 6dB of

attenuation before the volume control (see Figure 1) while the

Left and Right inputs do not. The LS_Gain bit is used to ac-

count for the different attenuation levels for each input and to

achieve maximum output power. To obtain maximum output

power on the loudspeaker outputs, the LS_Gain bit should be

se to '1' for Modes 1, 5, 9, 13.

HP_GAIN BITS

The headphone outputs have an additional, single volume

control set by the three HP_Gain bits in the Output Gain Con-

trol register. The HP_Gain volume setting controls the output

level for both the left and the right headphone outputs.

VOLUME CONTROL BITS

The LM49101 has three independent 32-step volume con-

trols, one for each of the inputs. The five bits of the Volume

Control registers sets the volume for the specified input chan-

nel.

SHUTDOWN FUNCTION

The LM49101 features the following shutdown controls.

Bit D4 (GAMP_SD) of the GENERAL CONTROL register

controls the gain amplifiers. When GAMP_SD = 1, it disables

the gain amplifiers that are not in use. For example, in Modes

1, 4 and 5, the Mono inputs are in use, so the Left and Right

input gain amplifiers are disabled, causing the IDD to be min-

imized.

Bit D0 (Power_On) of the GENERAL CONTROL register is

the global shutdown control for the entire device. Set

Power_On = 0 for normal operation. Power_On = 1 overrides

any other shutdown control bit.

www.national.com 22

LM49101

DIFFERENTIAL AMPLIFIER EXPLANATION

The LM49101 features a differential input stage, which offers

improved noise rejection compared to a single-ended input

amplifier. Because a differential input amplifier amplifies the

difference between the two input signals, any component

common to both signals is cancelled. An additional benefit of

the differential input structure is the possible elimination of the

DC input blocking capacitors. Since the DC component is

common to both inputs, and thus cancelled by the amplifier,

the LM49101 can be used without input coupling capacitors

when configured with a differential input signal.

BRIDGE CONFIGURATION EXPLAINED

By driving the load differentially through the MONO outputs,

an amplifier configuration commonly referred to as “bridged

mode” is established. Bridged mode operation is different

from the classical single-ended amplifier configuration where

one side of the load is connected to ground.

A bridge amplifier design has a few distinct advantages over

the single-ended configuration, as it provides differential drive

to the load, thus doubling output swing for a specified supply

voltage. Four times the output power is possible as compared

to a single-ended amplifier under the same conditions. This

increase in attainable output power assumes that the ampli-

fier is not current limited or clipped.

A bridge configuration, such as the one used in LM49101,

also creates a second advantage over single-ended ampli-

fiers. Since the differential outputs are biased at half-supply,

no net DC voltage exists across the load. This eliminates the

need for an output coupling capacitor which is required in a

single supply, single-ended amplifier configuration. Without

an output coupling capacitor, the half-supply bias across the

load would result in both increased internal IC power dissipa-

tion and also possible loudspeaker damage.

POWER DISSIPATION

Power dissipation is a major concern when designing a suc-

cessful amplifier, whether the amplifier is bridged or single-

ended. A direct consequence of the increased power

delivered to the load by a bridge amplifier is an increase in

internal power dissipation. The power dissipation of the

LM49101 varies with the mode selected. The maximum pow-

er dissipation occurs in modes where all inputs and outputs

are active (Modes 6, 7, 8, 9, 10, 11, 13, 14, 15). The power

dissipation is dominated by the Class AB amplifier. The max-

imum power dissipation for a given application can be derived

from the power dissipation graphs or from Equation 1.

PDMAX = 4*(VDD)2/(2π2RL) (1)

It is critical that the maximum junction temperature (TJMAX) of

150°C is not exceeded. TJMAX can be determined from the

power derating curves by using PDMAX and the PC board foil

area. By adding additional copper foil, the thermal resistance

of the application can be reduced from the free air value, re-

sulting in higher PDMAX. Additional copper foil can be added

to any of the leads connected to the LM49101. It is especially

effective when connected to VDD, GND, and the output pins.

Refer to the application information on the LM49101 refer-

ence design board for an example of good heat sinking. If

TJMAX still exceeds 150°C, then additional changes must be

made. These changes can include reduced supply voltage,

higher load impedance, or reduced ambient temperature. In-

ternal power dissipation is a function of output power. Refer

to the Typical Performance Characteristics curves for

power dissipation information for different output powers and

output loading.

POWER SUPPLY BYPASSING

As with any amplifier, proper supply bypassing is critical for

low noise performance and high power supply rejection. The

capacitor location on both the bypass and power supply pins

should be as close to the device as possible. Typical appli-

cations employ a 5V regulator with 10µF tantalum or elec-

trolytic capacitor and a ceramic bypass capacitor which aid in

supply stability. This does not eliminate the need for bypass-

ing the supply nodes of the LM49101. The selection of a

bypass capacitor, especially CB, is dependent upon PSRR

requirements, click and pop performance, system cost, and

size constraints.

GROUND REFERENCED HEADPHONE AMPLIFIER

The LM49101 features a low noise inverting charge pump that

generates an internal negative supply voltage. This allows the

headphone outputs to be biased about GND instead of a

nominal DC voltage, like traditional headphone amplifiers.

Because there is no DC component, the large DC blocking

capacitors (typically 220μF) are not necessary. The coupling

capacitors are replaced by two small ceramic charge pump

capacitors, saving board space and cost. Eliminating the out-

put coupling capacitors also improves low frequency re-

sponse. In traditional headphone amplifiers, the headphone

impedance and the output capacitor from a high-pass filter

that not only blocks the DC component of the output, but also

attenuates low frequencies, impacting the bass response.

Because the LM49101 does not require the output coupling

capacitors, the low frequency response of the device is not

degraded by external components. In addition to eliminating

the output coupling capacitors, the ground referenced output

nearly doubles the available dynamic range of the LM49101

headphone amplifiers when compared to a traditional head-

phone amplifier operating from the same supply voltage.

HEADPHONE & CHARGE PUMP SUPPLY VOLTAGE

(VDDHP & VDDCP)

The headphone outputs are centered at ground by using dual

supply voltages for the headphone amplifier. The positive

power supply is set by the voltage on the VDDHP pin while the

negative supply is created with an internal charge pump. The

negative supply voltage is equal in magnitude but opposite in

voltage to the voltage on the VDDCP pin.

INPUT CAPACITOR SELECTION

Input capacitors may be required for some applications, or

when the audio source is single-ended. Input capacitors block

the DC component of the audio signal, eliminating any conflict

between the DC component of the audio source and the bias

voltage of the LM49101. The input capacitors create a high-

pass filter with the input resistors RIN. The -3dB point of the

high-pass filter is found using Equation (2) below.

f = 1 / 2πRINCIN (Hz) (2)

Where the value of RIN is given in the Electrical Characteris-

tics Table as ZIN.

When the LM49101 is using a single-ended source, power

supply noise on the ground is seen as an input signal. Setting

the high-pass filter point above the power supply noise fre-

quencies, 217Hz in a GSM phone, for example, filters out the

noise such that it is not amplified and heard on the output.

23 www.national.com

LM49101

Capacitors with a tolerance of 10% or better are recommend-

ed for impedance matching and improved CMRR and PSRR.

CHARGE PUMP FLYING CAPACITOR (C1)

The flying capacitor (C1), see Figure 1, affects the load regu-

lation and output impedance of the charge pump. A C1 value

that is too low results in a loss of current drive, leading to a

loss of amplifier headroom. A higher valued C1 improves load

regulation and lowers charge pump output impedance to an

extent. Above 2.2μF, the RDS(ON) of the charge pump switches

and the ESR of C1 and Cs3 dominate the output impedance.

A lower value capacitor can be used in systems with low max-

imum output power requirements.

CHARGE PUMP HOLD CAPACITOR (CS3)

The value and ESR of the hold capacitor Cs3 directly affects

the ripple on VSSCP. Increasing the value of Cs3 reduces out-

put ripple. Decreasing the ESR of Cs3 reduces both output

ripple and charge pump output impedance. A lower value ca-

pacitor can be used in systems with low maximum output

power requirements.

SELECTION OF INPUT RESISTORS

The Bypass_In inputs connect to the loudspeaker output

through an FET switch when EP Bypass is active (see Figure

5). Because THD through this path is mainly dominated by

the switch impedance variation, adding input resistors (R3 and

R4 in Figure 5) will help reduce impedance effects resulting in

improved THD. For example, a change in the switch

impedance from 2Ω to 3Ω is a 67% change in impedance. If

10Ω input resistors are used then the impedance change is

from 12Ω to 13Ω, only 7.7% impedance variation. The analog

switch impedance is typically 2Ω to 3.4Ω. The switch

impedance change is a result of heating and the increase in

RDS(ON) of the FETs.

The value of the input resistors must be balanced against the

amount of output current and the load impedance on the loud-

speaker outputs. A higher value input resistor reduces the

effects of switch impedance variation but also causes voltage

drop and reduced power to the load on the loudspeaker out-

puts.

The current through the FET switch should not exceed 500mA

or die heating may cause thermal shut down activation and

potential IC damage.

MINIMUM POWER OPERATION

The LM49101 has several options to reduce power consump-

tion and is designed to conserve power when possible. When

a speaker only mode is selected the headphone sections are

shutdown and the current drawn from the VDDHP/VDDCP

power supply will be zero. When a headphone mode is se-

lected the current drawn from the VDDLS supply is also re-

duced by shutting down unused circuitry. See the various

Supply Current vs Supply Voltage graphs in the Typical Per-

formance Characteristics section.

To reduce power consumption further, the additional control

bits GAMP_SD, LS (EP Mode), and HPR_SD are provided.

When low power consumption is more important than the

THD performance of the loudspeaker the LS (EP_mode) bit

should be set to '1' saving approximately 0.5mA from the

VDDLS supply. The GAMP_SD bit should be set on to save

approximately 0.4mA for each input shut down. For modes

where only the mono input is used, up to 0.8mA can be saved

from the VDDLS supply. Also, the HPR_SD bit can be used to

shut down the right headphone channel reducing power con-

sumption when only one amplifier headphone output is need-

ed.

Additionally, the supply voltages for the different VDD pins

(VDDLS, VDDHP, and VDDCP) can be set to the minimum

needed values to obtain the output power levels required by

the design. By reducing the supply voltage the total power

consumption will be reduced.

For best system efficiency, a DC-DC converter (buck) can be

used to power the VDDHP and VDDCP voltages from the

VDDLS supply instead of a linear regulator. DC-DC converters

achieve much higher efficiency (> 90%) than even a low

dropout regulator (LDO).

www.national.com 24

LM49101

Demo Board Circuit

30086201

FIGURE 5. Demo Board Circuit

Demonstration Board

The demonstration board (see Figure 5) has connection and

jumper options to be powered partially from the USB bus or

from external power supplies. Additional options are to power

the I2C logic and loudspeaker amplifier (VDDLS) from a single

power supply or separate power supplies. The headphone

amplifier and charge pump can also be powered from the

same supply as long as the voltage limits for each power sup-

ply are not exceeded, although the option is not built into the

board. See theOperating Ratings for each supply's range lim-

it. When powered from the USB bus the I2CVDD will be set to

3.3V and the VDDLS will be set to 5V. Jumper headers J13 and

J12 must be set accordingly. If a single power supply for

I2CVDD and VDDLS is desired then header J5 should be used

with a jumper added to header J11 to connect I2CVDD to the

external supply voltage connected to J5 (see Figure 5).

Connection headers J1 and J2 are provided along with the

stereo headphone jack J4 for easily connection and monitor-

ing of the headphone outputs.

25 www.national.com

LM49101

LM49101 microSMD Demo Board Views

30086209

Composite View

30086205

Silk Screen

30086206

Top Layer

30086208

Internal Layer 1

30086207

Internal Layer 2

30086210

Bottom Layer

www.national.com 26

LM49101

LM49101 Reference Demo Board Bill Of Materials

TABLE 7. Bill Of Materials

Designator Vlaue Tolerance Part Description Comment

R1, R25.1kΩ5% 1/10W, 0603 Resistors

R3, R410Ω 1% 1/10W, 0603 Resistors

R5100kΩ5% 1/10W, 0805 Resistor

CIN1, CIN2

CIN3, CIN4

1μF10% 1206, X7R Ceramic Capacitor

CS1, CS4

CS5, CB

2.2μF10% Size A, Tantalum Capacitor

CS2 0.1μF10% 0805, 16V, X7R Ceramic Capacitor

CS3, C12.2μF10% 0603, 10V, X7R Ceramic Capacitor

U1 LM49101TM

J1, J2, J3

J5, J7, J8

J9, J10, J14

0.100" 1x2 header, vertical mount Input, Output, VDD, GND

J11, J12, J13 0.100" 1x3 header, vertical mount VDD Selects, VDD, I2CVDD,

GND

J6 16 pin header I2C Connector

J4 Headphone Jack

SW1 Momentary Push Switch RESET function

PCB Layout Guidelines

This section provides practical guidelines for mixed signal

PCB layout that involves various digital/analog power and

ground traces. Designers should note that these are only

"rule-of-thumb" recommendations and the actual results will

depend heavily on the final layout.

General Mixed Signal Layout

Recommendations

SINGLE-POINT POWER AND GROUND CONNECTIONS

The analog power traces should be connected to the digital

traces through a single point (link). A "Pi-filter" can be helpful

in minimizing high frequency noise coupling between the ana-

log and digital sections. It is further recommended to put

digital and analog power traces over the corresponding digital

and analog ground traces to minimize noise coupling.

PLACEMENT OF DIGITAL AND ANALOG COMPONENTS

All digital components and high-speed digital signals traces

should be located as far away as possible from analog com-

ponents and circuit traces.

AVOIDING TYPICAL DESIGN AND LAYOUT PROBLEMS

Avoid ground loops or running digital and analog traces par-

allel to each other (side-by-side) on the same PCB layer.

When traces must cross over each other do it at 90 degrees.

Running digital and analog traces at 90 degrees to each other

from the top to the bottom side as much as possible will min-

imize capacitive noise coupling and cross talk.

27 www.national.com

LM49101

Revision History

Rev Date Description

0.01 10/18/08 Initial released.

www.national.com 28

LM49101

Physical Dimensions inches (millimeters) unless otherwise noted

25 Bump micro SMD Package

NS Package Number TMD25BCA

X1 = 2.040±0.030mm X2 = 2.066±0.030mm, X3 = 0.600±0.075mm

29 www.national.com

LM49101

Notes

LM49101Mono Class AB Audio Subsystem with a True Ground Headphone Amplifier and

Earpiece Switch

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