National Semiconductor LM4860 Technical data

August 2000

LM4860
Series 1W Audio Power Amplifier with Shutdown Mode

LM4860 1W Audio Power Amplifier with Shutdown Mode

General Description

The LM4860 is a bridge-connected audio power amplifier
capable of delivering 1W of continuous average power to an
8Ω load with less than 1% THD+N over the audio spectrum
from a 5V power supply.

Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components using surface mount packaging. Since
the LM4860 does not require output coupling capacitors,
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems.

The LM4860 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism. It also includes two head­phone control inputs and a headphone sense output for
external monitoring.

The unity-gain stable LM4860 can be configured by external
gain setting resistors for differential gains of up to 10 without
the use of external compensation components. Higher gains
may be achieved with suitable compensation.

Key Specifications

n THD+N at 1W continuous average

output power into 8Ω: 1% (max)

n Instantaneous peak output power:
n Shutdown current: 0.6µA (typ)

Features

n No output coupling capacitors, bootstrap capacitors, or

snubber circuits are necessary

n Small Outline (SO) packaging
n Compatible with PC power supplies
n Thermal shutdown protection circuitry
n Unity-gain stable
n External gain configuration capability
n Two headphone control inputs and headphone sensing

output

Applications

n Personal computers
n Portable consumer products
n Cellular phones
n Self-powered speakers
n Toys and games

Typical Application Connection Diagram

>

2W

Small Outline Package

Order Number LM4860M

See NS Package Number M16A

01198801

FIGURE 1. Typical Audio Amplifier Application Circuit

The Boomer®registered trademark is licensed to National Semiconductor for audio integrated circuits by Rockford Corporation.
Patents pending.

Top View

01198802

© 2004 National Semiconductor Corporation DS011988 www.national.com

Absolute Maximum Ratings (Note 2)

If Military/Aerospace specified devices are required,

LM4860

please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage 6.0V

Storage Temperature −65˚C to +150˚C

Input Voltage −0.3V to V

Power Dissipation Internally limited

ESD Susceptibility (Note 4) 3000V

ESD Susceptibility (Note 5) 250V

Junction Temperature 150˚C

DD

0.3V

+

Small Outline Package

Vapor Phase (60 sec.) 215˚C

Infrared (15 sec.) 220˚C

See AN-450 “Surface Mounting and their Effects on Product

Reliability” for other methods of soldering surface mount
devices.

Operating Ratings

Temperature Range

T

≤ TA≤ T

MIN

MAX

Supply Voltage 2.7V ≤ VDD≤ 5.5V

−20˚C ≤ TA≤

Soldering Information

Electrical Characteristics

(Notes 1, 2) The following specifications apply for VDD= 5V, RL=8Ω unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4860 Units

Typical Limit

(Note 6) (Note 7)

V

DD

I

DD

I

SD

V

OS

P

O

THD+N Total Harmonic Distortion + Noise P

PSRR Power Supply Rejection Ratio V

V

od

V

IH

V

IL

V

OH

V

OL

Note 1: All voltages are measured with respect to the ground pins, unless otherwise specified.

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee specific performance limits. Electrical Characteristics state DC andAC electrical specifications under particular test conditions which
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given, however, the typical value is a good indication of device performance.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation is P
+150˚C, and the typical junction-to-ambient thermal resistance, when board mounted, is 100˚C/W.

Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor.

Note 5: Machine Model, 200 pF– 240 pF discharged through all pins.

Note 6: Typicals are measured at 25˚C and represent the parametric norm.

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.

Note 9: Shutdown current has a wide distribution. For Power Management sensitive designs, contact your local National Semiconductor Sales Office.

Supply Voltage 2.7 V (min)

5.5 V (max)

Quiescent Power Supply Current VO= 0V, IO= 0A (Note 8) 7.0 15.0 mA (max)

Shutdown Current V

pin2=VDD

(Note 9) 0.6 µA

Output Offset Voltage VIN= 0V 5.0 50.0 mV (max)

Output Power THD+N = 1% (max);f=1kHz 1.15 1.0 W (min)

= 1 Wrms; 20 Hz ≤ f ≤ 20 kHz 0.72 %

O

= 4.9V to 5.1V 65 dB

DD

Output Dropout Voltage VIN=0Vto5V,Vod=(Vo1−Vo2) 0.6 1.0 V (max)

HP-IN High Input Voltage HP-SENSE = 0V to 4V 2.5 V

HP-IN Low Input Voltage HP-SENSE = 4V to 0V 2.5 V

HP-SENSE High Output Voltage IO= 500 µA 2.8 2.5 V (min)

HP-SENSE Low Output Voltage IO= −500 µA 0.2 0.8 V (max)

, θJA, and the ambient temperature TA. The maximum

DMAX

=(T

JMAX−TA

)/θJAor the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4860, T

JMAX

+85˚C

(Limits)

JMAX

=

www.national.com 2

High Gain Application Circuit

LM4860

01198803

FIGURE 2. Stereo Amplifier with AVD=20

Single Ended Application Circuit

*CSand CBsize depend on specific application requirements and constraints. Typical values of CSand CBare 0.1 µF.

**Pin 2, 6, or 7 should be connected to V

***These components create a “dummy” load for pin 8 for stability purposes.

to disable the amplifier or to GND to enable the amplifier. These pins should not be left floating.

DD

01198804

FIGURE 3. Single-Ended Amplifier with AV=−1

www.national.com3

External Components Description

(Figures 1, 2)

LM4860

Components Functional Description

1. R

2. C

3. R

4. C

i

i

f

S

Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also
forms a high pass filter with C

at fC= 1/(2π RiCi).

i

Input coupling capacitor which blocks DC voltage at the amplifier’s input terminals. Also creates a
highpass filter with R

at fC= 1/(2π RiCi).

i

Feedback resistance which sets closed-loop gain in conjunction with Ri.

Supply bypass capacitor which provides power supply filtering. Refer to the Application Information
section for proper placement and selection of supply bypass capacitor.

5. C

B

Bypass pin capacitor which provides half supply filtering. Refer to Application Information section for
proper placement and selection of bypass capacitor.

(Note 10) Used when a differential gain of over 10 is desired. Cfin conjunction with Rfcreates a low-pass filter

6. C

f

which bandwidth limits the amplifier and prevents high frequency oscillation bursts. f

Note 10: Optional component dependent upon specific design requirements. Refer to the Application Information section for more in formation.

Typical Performance Characteristics

THD+N vs Frequency THD+N vs Frequency

= 1/(2π RfCf)

C

01198809 01198810

THD+N vs Frequency THD+N vs Output Power

01198811 01198812

www.national.com 4

Typical Performance Characteristics (Continued)

THD+N vs Output Power THD+N vs Output Power

01198813 01198814

LM4860

Supply Current vs Time

in Shutdown Mode

Power Derating Curve

01198815

Supply Current vs

Supply Voltage

01198816

LM4860 Noise Floor

vs Frequency

01198817

01198818

www.national.com5

Typical Performance Characteristics (Continued)

LM4860

Supply Current Distribution

vs Temperature

Output Power vs
Load Resistance

01198819

Power Dissipation

vs Output Power

01198820

Output Power vs

Supply Voltage

Open Loop

Frequency Response

01198821

01198823

01198822

Power Supply

Rejection Ratio

01198824

www.national.com 6

Application Information

BRIDGE CONFIGURATION EXPLANATION

As shown in Figure 1, the LM4860 has two operational
amplifiers internally, allowing for a few different amplifier
configurations. The first amplifier’s gain is externally config­urable, while the second amplifier is internally fixed in a
unity-gain, inverting configuration. The closed-loop gain of

(1)

to Riwhile

f

O1

and

the first amplifier is set by selecting the ratio of R
the second amplifier’s gain is fixed by the two internal 40 kΩ
resistors. Figure 1 shows that the output of amplifier one
serves as the input to amplifier two which results in both
amplifiers producing signals identical in magnitude, but out
of phase 180˚. Consequently, the differential gain for the IC
is:

=2*(Rf/Ri)

A

vd

By driving the load differentially through outputs V

, an amplifier configuration commonly referred to as

V

O2

“bridged mode” is established. Bridged mode operation is
different from the classical single-ended amplifier configura­tion where one side of its 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. Consequently, 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 amplifier is not current limited or clipped. In
order to choose an amplifier’s closed-loop gain without caus­ing excessive clipping which will damage high frequency
transducers used in loudspeaker systems, please refer to
the Audio Power Amplifier Deslgn section.

A bridge configuration, such as the one used in Boomer
Audio Power Amplifiers, also creates a second advantage
over single-ended amplifiers. Since the differential outputs,

and VO2, are biased at half-supply, no net DC voltage

V

O1

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 in a single supply single-ended amplifier, the
half-supply bias across the load would result in both in­creased internal IC power dissipation and also permanent
loudspeaker damage. An output coupling capacitor forms a
high pass filter with the load requiring that a large value such
as 470 µF be used with an 8Ω load to preserve low fre­quency response. This combination does not produce a flat
response down to 20 Hz, but does offer a compromise
between printed circuit board size and system cost, versus
low frequency response.

POWER DISSIPATION

Power dissipation is a major concern when designing a
successful 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. Equation 1 states the maximum
power dissipation point for a bridge amplifier operating at a
given supply voltage and driving a specified output load.

=4*(VDD)2/(2π2R

P

DMAX

L)

Since the LM4860 has two operational amplifiers in one
package, the maximum internal power dissipation is 4 times
that of a single-ended amplifier. Even with this substantial
increase in power dissipation, the LM4860 does not require
heatsinking. From Equation 1, assuming a 5V power supply
and an 8Ω load, the maximum power dissipation point is 625

mW. The maximum power dissipation point obtained from
Equation 1 must not be greater than the power dissipation
that results from Equation 2:

P

=(T

DMAX

JMAX−TA

For the LM4860 surface mount package, θ

= 150˚C. Depending on the ambient temperature, TA,

T

JMAX

)/θ

JA

JA

(2)

= 100˚C/W and

of the system surroundings, Equation 2 can be used to find
the maximum internal power dissipation supported by the IC
packaging. If the result of Equation 1 is greater than that of
Equation 2, then either the supply voltage must be de­creased or the load impedance increased. For the typical
application of a 5V power supply, with an 8Ω load, the
maximum ambient temperature possible without violating the
maximum junction temperature is approximately 88˚C, pro­vided that device operation is around the maximum power
dissipation point. Power dissipation is a function of output
power and thus, if typical operation is not around the maxi­mum power dissipation point, the ambient temperature can
be increased. Refer to the Typical Performance Charac-
teristics curves for power dissipation information for lower
output powers.

POWER SUPPLY BYPASSING

As with any power 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. As displayed in the Typical Performance Charac-
terIstIcs section, the effect of a larger half-supply bypass
capacitor is improved low frequency THD+N due to in­creased half-supply stability. Typical applications employ a
5V regulator with 10 µF and a 0.1 µF bypass capacitors
which aid in supply stability, but do not eliminate the need for
bypassing the supply nodes of the LM4860. The selection of
bypass capacitors, especially C

, is thus dependant upon

B

desired low frequency THD+N, system cost, and size con­straints.

SHUTDOWN FUNCTION

In order to reduce power consumption while not in use, the
LM4860 contains a shutdown pin to externally turn off the
amplifier’s bias circuitry. The shutdown feature turns the
amplifier off when a logic high is placed on the shutdown pin.
Upon going into shutdown, the output is immediately discon­nected from the speaker. There is a built-in threshold which
produces a drop in quiescent current to 500 µA typically. For
a 5V power supply, this threshold occurs when 2V–3V is
applied to the shutdown pin. A typical quiescent current of

0.6 µA results when the supply voltage is applied to the
shutdown pin. In many applications, a microcontroller or
microprocessor output is used to control the shutdown cir­cuitry which provides a quick, smooth transition into shut­down. Another solution is to use a single-pole, single-throw
switch that when closed, is connected to ground and enables
the amplifier. If the switch is open, then a soft pull-up resistor
of 47 kΩ will disable the LM4860. There are no soft pull­down resistors inside the LM4860, so a definite shutdown
pin voltage must be appliied externally, or the internal logic
gate will be left floating which could disable the amplifier
unexpectedly.

HEADPHONE CONTROL INPUTS

The LM4860 possesses two headphone control inputs that
disable the amplifier and reduce I

to less than 1 mA when

DD

either one or both of these inputs have a logic-high voltage
placed on their pins.

LM4860

www.national.com7

Application Information (Continued)

Unlike the shutdown function, the headphone control func-

LM4860

tion does not provide the level of current conservation that is
required for battery powered systems. Since the quiescent
current resulting from the headphone control function is
1000 times more than the shutdown function, the residual
currents in the device may create a pop at the output when
coming out of the headphone control mode. The pop effect
may be eliminated by connecting the headphone sensing
output to the shutdown pin input as shown in Figure 4. This
solution will not only eliminate the output pop, but will also
utilize the full current conservation of the shutdown function
by reducing I
shutdown. This configuration also allows the designer to use
the control inputs as either two headphone control pins or a
headphone control pin and a shutdown pin where the lowest
level of current consumption is obtained from either function.

Figure 5 shows the implementation of the LM4860’s head­phone control function using a single-supply headphone am­plifier. The voltage divider of R1 and R2 sets the voltage at
the HP-IN1 pin to be approximately 50 mV when there are
no headphones plugged into the system. This logic-low volt­age at the HP-IN1 pin enables the LM4860 to amplify AC
signals. Resistor R3 limits the amount of current flowing out
of the HP-IN1 pin when the voltage at that pin goes below
ground resulting from the music coming from the headphone
amplifier. The output coupling cap protects the headphones
by blocking the amplifier’s half-supply DC voltage. The ca­pacitor also protects the headphone amplifier from the low
voltage set up by resistors R1 and R2 when there aren’t any
headphones plugged into the system. The tricky point to this
setup is that the AC output voltage of the headphone ampli­fier cannot exceed the 2.0V HP-IN1 voltage threshold when
there aren’t any headphones plugged into the system, as­suming that R1 and R2 are 100k and 1k, respectively. The
LM4860 may not be fully shutdown when this level is ex­ceeded momentarily, due to the discharging time constant of
the bias-pin voltage. This time constant is established by the
two 50k resistors (in parallel) with the series bypass capaci­tor value.

When a set of headphones are plugged into the system, the
contact pin of the headphone jack is disconnected from the
signal pin, interrupting the voltage divider set up by resistors

to 0.6 µA. The amplifier will then be fully

DD

R1 and R2. Resistor R1 then pulls up the HP-IN1 pin,
enabling the headphone function and disabling the LM4860
amplifier. The headphone amplifier then drives the head­phones, whose impedance is in parallel with resistor R2.
Since the typical impedance of headphones are 32Ω, resis­tor R2 has negligible effect on the output drive capability.
Also shown in Figure 5 are the electrical connections for the
headphone jack and plug. A 3-wire plug consists of a Tip,
Ring, and Sleave, where the Tip and Ring are signal carrying
conductors and the Sleave is the common ground return.
One control pin contact for each headphone jack is sufficient
to indicate to control inputs that the user has inserted a plug
into a jack and that another mode of operation is desired.

For a system implementation where the headphone amplifier
is designed using a split supply, the output coupling cap, C
and resistor R2 of Figure 5, can be eliminated. The function­ality described earlier remains the same, however.

In addition, the HP-SENSE pin, although it may be con­nected to the SHUTDOWN pin as shown in Figure 4, may
still be used as a control flag. It is capable of driving the input
to another logic gate or approximately 2 mA without serious
loading.

01198807

FIGURE 4. HP-SENSE Pin to SHUTDOWN Pin Connection

C

www.national.com 8

Application Information (Continued)

LM4860

FIGURE 5. Typical Headphone Control Input Circuitry

HIGHER GAIN AUDIO AMPLIFIER

The LM4860 is unity-gain stable and requires no external
components besides gain-setting resistors, an input coupling
capacitor, and proper supply bypassing in the typical appli­cation. However if a closed-loop differential gain of greater
than 10 is required, then a feedback capacitor is needed, as
shown in Figure 2, to bandwidth limit the amplifier. The
feedback capacitor creates a low pass filter that eliminates
unwanted high frequency oscillations. Care should be taken
when calculating the −3 dB frequency in that an incorrect
combination of R

and Cfwill cause rolloff before 20 kHz. A

f

typical combination of feedback resistor and capacitor that
will not produce audio band high frequency rolloff is R
100 kΩ and C

= 5 pF. These components result in a −3 dB

f

f

point of approximately 320 kHz. Once the differential gain of
the amplifier has been calculated, a choice of R

can then be calculated from the formula stated in the

and C

f

will result,

f

External Components Description section.

VOICE-BAND AUDIO AMPLIFIER

Many applications, such as telephony, only require a voice­band frequency response. Such an application usually re­quires a flat frequency response from 300 Hz to 3.5 kHz. By
adjusting the component values of Figure 2, this common
application requirement can be implemented. The combina­tion of R

and Ciform a highpass filter while Rfand Cfform a

i

lowpass filter. Using the typical voice-band frequency range,
with a passband differential gain of approximately 100, the
following values of R

, and Cffollow from the equa-

i,Ci,Rf

tions stated in the External Components Description sec­tion.

01198808

R

=10kΩ,Rf= 510k, Ci= 0.22 µF, and Cf=15pF

i

Five times away from a −3 dB point is 0.17 dB down from the
flatband response. With this selection of components, the
resulting −3 dB points, f

and fH, are 72 Hz and 20 kHz,

L

respectively, resulting in a flatband frequency response of

±

better than

0.25 dB with a rolloff of 6 dB/octave outside of
the passband. If a steeper rolloff is required, other common
bandpass filtering techniques can be used to achieve higher
order filters.

SINGLE-ENDED AUDIO AMPLIFIER

Although the typical application for the LM4860 is a bridged

=

monoaural amp, it can also be used to drive a load single­endedly in applications, such as PC cards, which require that
one side of the load is tied to ground. Figure 3 shows a
common single-ended application, where V

is used to

O1

drive the speaker. This output is coupled through a 470 µF
capacitor, which blocks the half-supply DC bias that exists in
all single-supply amplifier configurations. This capacitor,
designated C

in Figure 3, in conjunction with RL, forms a

O

highpass filter. The −3 dB point of this highpass filter is
1/(2πR
product of R

), so care should be taken to make sure that the

LCO

and COis large enough to pass low frequen-

L

cies to the load. When driving an 8Ω load, and if a full audio
spectrum reproduction is required, C
470 µF. V

, the output that is not used, is connected

O2

should be at least

O

through a 0.1 µF capacitor to a 2 kΩ load to prevent insta­bility. While such an instability will not affect the waveform of

, it is good design practice to load the second output.

V

O1

www.national.com9

Application Information (Continued)

AUDIO POWER AMPLIFIER DESIGN

LM4860

Design a 500 mW/8Ω Audio Amplifier

Given:
Power Output: 500 mWrms
Load Impedance: 8Ω
Input Level: 1 Vrms(max)
Input Impedance: 20 kΩ
Bandwidth: 20 Hz-20 kHz
A designer must first determine the needed supply rail to

obtain the specified output power. Calculating the required
supply rail involves knowing two parameters, V
the dropout voltage. The latter is typically 0.7V. V
be determined from equation 3.

For 500 mW of output power into an 8Ω load, the required

is 2.83V. A minimum supply rail of 3.53V results from

V

opeak

adding V

and Vod. But 3.53V is not a standard voltage

opeak

that exists in many applications and for this reason, a supply
rail of 5V is designated. Extra supply voltage creates dy­namic headroom that allows the LM4860 to reproduce peaks
in excess of 500 mW without clipping the signal. At this time,
the designer must make sure that the power supply choice
along with the output impedance does not violate the condi­tions explained in the Power Dissipation section.

±

0.25 dB

opeak

and also

opeak

can

Once the power dissipation equations have been addressed,
the required differential gain can be determined from Equa­tion 4.

From equation 4, the minimum Avdis: Avd=2
Since the desired input impedance was 20 kΩ, and with an

of 2, a ratio of 1:1 of Rfto Riresults in an allocation of Ri=

A

vd

=20kΩ. Since the Avdwas less than 10, a feedback

R

f

capacitor is not needed. The final design step is to address
the bandwidth requirements which must be stated as a pair
of −3 dB frequency points. Five times away from a −3 dB
point is 0.17 dB down from passband response which is

±

better than the required

0.25 dB specified. This fact results
in a low and high frequency pole of 4 Hz and 100 kHz
respectively. As stated in the External Components sec-

in conjunction with Cicreate a highpass filter.

tion, R

i

C

≥ 1/(2π *20kΩ * 4 Hz) = 1.98 µF; use 2.2 µF.

i

The high frequency pole is determined by the product of the
desired high frequency pole, f
With a A

= 2 and fH= 100 kHz, the resulting GBWP =

vd

, and the differential gain, Avd.

H

100 kHz which is much smaller than the LM4860 GBWP of
7 MHz. This figure displays that if a designer has a need to
design an amplifier with a higher differential gain, the
LM4860 can still be used without running into bandwidth
problems.

www.national.com 10

Physical Dimensions inches (millimeters) unless otherwise noted

LM4860 1W Audio Power Amplifier with Shutdown Mode

Small Outline Package (M)

Order Number LM4860M

NS Package Number M16A

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.

For the most current product information visit us at www.national.com.

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:

1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use

2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.

provided in the labeling, can be reasonably expected to result
in a significant injury to the user.

BANNED SUBSTANCE COMPLIANCE

National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship
Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned
Substances’’ as defined in CSP-9-111S2.

National Semiconductor
Americas Customer
Support Center

Email: [e-mail]
Tel: [phone]

www.national.com

National Semiconductor
Europe Customer Support Center

Fax: [phone]

Email: [e-mail]
Deutsch Tel: [phone]
English Tel: [phone]
Français Tel: [phone]

National Semiconductor
Asia Pacific Customer
Support Center

Email: [e-mail]

National Semiconductor
Japan Customer Support Center

Fax: [phone]
Email: [e-mail]
Tel: [phone]