National Semiconductor LM48860 Technical data

February 14, 2008

LM48860 Ground-Referenced, Ultra Low Noise, Fixed Gain Stereo Headphone Amplifier

General Description

The LM48860 is a ground referenced, fixed-gain audio power amplifier capable of delivering 40mW per channel of continuous average power into a 16Ω single-ended load with less than 1% THD+N from a 3V power supply.

The LM48860 features a new circuit technology that utilizes a charge pump to generate a negative reference voltage. This allows the outputs to be biased about ground, thereby eliminating output-coupling capacitors typically used with normal single-ended loads.

Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM48860 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement.

The LM48860 features a low-power consumption shutdown mode selectable for either channel separately. This is accomplished by driving either the SD_RC nel) or SD_LC (Shutdown Left Channel) (or both) pins with logic low, depending on which channel is desired shutdown. Additionally, the LM48860 features an internal thermal shutdown protection mechanism.

The LM48860 contains advanced pop & click circuitry that eliminates noises which would otherwise occur during turn-on and turn-off transitions.

The LM48860 has an internal fixed gain of 1.5V/V.

(Shutdown Right Chan-

Key Specifications

■ PSRR at 217Hz (V

■ Stereo Power Output at V

RL = 16Ω, THD+N = 1%

■ Shutdown Current

■ Internal Fixed Gain

■ Operating Voltage

= 3.0V)

= 3V,

40mW (typ)

0.1μA (typ)

1.5V/V (typ)

2.0V to 5.5V

Features

Fixed logic levels with supply voltage

■

Ground referenced outputs

■

High PSRR

■

Available in space-saving micro SMD package

■

Ultra low current shutdown mode

■

Improved pop & click circuitry eliminates noises during

■

turn-on and turn-off transitions No output coupling capacitors, snubber networks,

■

bootstrap capacitors, or gain-setting resistors required Shutdown either channel independently

■

Applications

Mobile Phones

■

MP3 Players

■

PDAs

■

Portable electronic devices

■

Notebook PCs

■

80dB (typ)

Boomer® is a registered trademark of National Semiconductor Corporation.

Typical Application

LM48860

FIGURE 1. Typical Audio Amplifier Application Circuit

30006889

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Connection Diagram

LM48860

LM48860TL Pinout

(BUMP DOWN VIEW )

Order Number LM48860TL

See NS Package Number TLA12XXX

Top View

Pin Descriptions

Pin Name Function

A1 RIN Right Channel Input

A2 SGND Signal Ground

A3 LIN Left Channel Input

B1 ROUT Right Channel Output

B2 SD_LC Active Low Shutdown, Left Channel

B3 LOUT Left Channel Output

C1 V

C2 SD_RC Active-Low Shutdown, Right Channel

C3 V

D1 CCP- Negative Terminal - Charge Pump Flying Capacitor

D2 PGND Power Ground

D3 CCP+ Positive Terminal - Charge Pump Flying Capacitor

SS(CP)

Charge Pump Voltage Output

Supply Voltage

30006813

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Absolute Maximum Ratings (Notes 2, 2)

If Military/Aerospace specified devices are required,

LM48860

please contact the National Semiconductor Sales Office/

Junction Temperature 150°C Thermal Resistance

θJA (typ) TLA12XXX (Note 11)

Distributors for availability and specifications.

Supply Voltage 6.0V Storage Temperature −65°C to +150°C

Input Voltage

-0.3V to V

Power Dissipation (Note 3) Internally Limited

Operating Ratings

Temperature Range

≤ TA ≤ T

MIN

Supply Voltage (VDD) 2.0V ≤ VDD ≤ 5.5V

MAX

ESD Rating(Note 4) 2000V ESD Rating (Note 5) 200V

Electrical Characteristics VDD = 3V (Notes 1, 2)

The following specifications apply for VDD = 3V and 16Ω load unless otherwise specified. Limits apply to TA = 25°C.

LM48860

Symbol Parameter Conditions

VDD = 3.0V, VIN = 0V, inputs terminated

Quiescent Power Supply Current Full Power Mode

both channels enabled

VDD = 5.0V, VIN = 0V, inputs terminated both channels enabled

SD_LC = SD_RC= GND 0.1 1 µA (max)

Shutdown Current

SD_LC = SD_RC= GND, VDD = 5.0V

ΔA

Output Offset Voltage

Voltage Gain

Channel-to-channel Gain

RL = 32Ω, VIN = 0V

1 %

Matching

Input Resistance

THD+N = 1% (max); f = 1kHz,

Output Power

RL = 16Ω, (two channels in phase)

THD+N = 1% (max); f = 1kHz,

RL = 32Ω, (two channels in phase)

PO = 20mW, f = 1kHz, RL = 16Ω

THD+N

Total Harmonic Distortion + Noise

(two channels in phase)

PO = 25mW, f = 1kHz, RL = 32Ω (two channels in phase)

= 200mVPP, Input Referred

RIPPLE

PSRR

Power Supply Rejection Ratio Full Power Mode

f = 217Hz 80 73 dB (min)

f = 1kHz 75 dB

f = 20kHz 60 dB

SNR Signal-to-Noise Ratio

RL = 32Ω, P f = 1kHz, BW = 20Hz to 22kHz,

= 50mW,

OUT

A-weighted

∈

TALK

Shutdown Input Voltage High

Shutdown Input Voltage Low

Crosstalk

Output Noise

VDD = 2.0V to 5.5V

RL = 16Ω, PO = 1.6mW, f = 1kHz

A-weighted filter, VIN = 0V

Typical

(Note 6)

4 5.5 mA (max)

4.2 mA

0.1 1 µA (max)

0.7 5.5

–1.5

40 35 mW (min)

50 40 mW (min)

0.025

0.014

105 dB

59.3°C/W

−40°C ≤ TA ≤ 85°C

Limit

(Note 7)

Units

(Limits)

mV (max)

15 25

kΩ (min)

kΩ (max)

1.2 V (min)

0.45 V (max)

V/V

μV

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LM48860

Symbol Parameter Conditions

Typical

(Note 6)

LM48860

Limit

(Note 7)

Units

(Limits)

VSD = GND

OUT

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 T allowable power dissipation is P derating curves for additional information.

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 = +25ºC, 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: θJA value is measured with the device mounted on a PCB with a 1.5” x 1.375”, 1oz copper heatsink.

Output Impedance

Input Leakage ±0.1 nA

= (T

DMAX

- TA) / θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM48860, see power

JMAX

Input Terminated Input not terminated SD_LC = SD_RC = GND

30 30

, θJA, and the ambient temperature, TA. The maximum

JMAX

kΩ (min)

External Components Description

(Figure 1)

Components Functional Description

Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a high passpass filter with Ri at fC = 1/(2RiC1). Refer to the section Proper Selection of External Components, for an

explanation of how to determine the value of C1.

Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a high passpass filter with Ri at fC = 1/(2RiC2). Refer to the Power Supply Bypassing section for an explanation of how to

determine the value of C2.

Output capacitor. Low ESR ceramic capacitor (≤100mΩ)

Flying capacitor. Low ESR ceramic capacitor (≤100mΩ)

Tantalum capacitor. Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply

Bypassing section for information concerning proper placement and selection of the supply bypass capacitor.

Ceramic capacitor. Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply

Bypassing section for information concerning proper placement and selection of the supply bypass capacitor.

kΩ

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Typical Performance Characteristics

LM48860

THD+N vs Output Power

VDD = 3V, RL = 16Ω

f = 1kHz, 22kHz BW, one channel enabled

300068d2

THD+N vs Output Power

VDD = 3V, RL = 32Ω

f = 1kHz, 22kHz BW, one channel enabled

THD+N vs Output Power

VDD = 3V, RL = 16Ω, f = 1kHz

22kHz BW, two channels in phase

30006824

THD+N vs Output Power

VDD = 3V, RL = 32Ω, f = 1kHz

22kHz BW, two channels in phase

300068d3

THD+N vs Output Power

VDD = 3.6V, RL = 16Ω

f = 1kHz, 22kHz BW, one channel enabled

300068c8

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30006825

THD+N vs Output Power

VDD = 3.6V, RL = 16Ω, f = 1kHz

22kHz BW, two channels in phase

300068c9

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