SEMTECH SC604A Technical data

1

United States Patents: 6,504,422, 6,794,926

www.semtech.com

POWER MANAGEMENT

OBJECTIVE -NOVEMBER
9, 2000

SC604A

Low Noise, High Efficiency

Regulated White LED Driver

Features

June 27, 2005

Description

Applications

Typical Application Circuit

The SC604A is a very high efficiency charge pump white
LED driver driver from the mAhXLife

TM

family of products,

optimized for Li-Ion battery applications.

The four (4) LED outputs are current matched for consis­tent LED brightness. Extremely low battery current is
achieved by automatically reconfiguring the charge pump
to match circuit conditions. Using four LEDs, each at
20mA for a total I

OUT

= 80mA, the SC604A can use less

than 83mA from the supply for most of the battery life.

Patented low noise mode switching circuitry and constant
output current allow the use of extremely small input and
output capacitors.

 Very high efficiency over 90% of battery life
 Peak efficiency over 92%
 Current regulation for up to 4 LEDs
 Digital 3 bit output control logic
 Current matching tolerance of ±3% typical
 Wide current range per LED [0.5mA - 30mA]
 High available total LED current = 4



I

LED

= 120mA

 Low Shutdown Current: 1µA typical
 Soft start / In-rush current limiting
 Short circuit protection
 MLP-16 [4x4] Package
 Fixed frequency 250kHz
 1x, 1.5x and 2x charge pump modes of operation

 Cellular phones
 LED backlighting
 PDA power supplies
 Portable devices

 Electronic books
 Wireless web appliances
 LCD Modules

Patent Pending

VIN

EN

CTRL0

CTRL1

BATTERY

1µF

CTRL2

GND

ILED1
ILED2
ILED3

ILED4

VOUT

C1+

C1-

C2+ C2-

SC604A

1µF

1µF

1µF

ISET

查询SC604A供应商

2

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SC604A

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Absolute Maximum Ratings

Electrical Characteristics

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GTS

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DAEL

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DAEL

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Unless specified: TA = -40°C to 85°C, V

IN

= 2.85V to 5.5V, C1 = C2 = 1.0µF (ESR = 0.03Ω). Typical values @ T

A

=25°C, LED VF = 3.4V.

This device is ESD sensitive. Use of standard ESD handling precautions is required.

Note: (1) By JESD51 standards

Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not implied.

3

 2005 Semtech Corp. www.semtech.com

SC604A

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Electrical Characteristics (Cont.)

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V

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V

tnerruChgiHtupnII

HI

VHIV=

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01

µ

A

tnerrucwoLtupnII

LI

V

LI

DNG=01

µ

A

Notes:
(1) Guaranteed by design

Unless specified: T

A

= -40°C to 85°C, V

IN

= 2.85V to 5.5V, C1 = C2 = 1.0µF (ESR = 0.03Ω). Typical values @ T

A

=25°C, LED VF = 3.4V.

4

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Definitions

I

LED

Accuracy

The LED current is determined by the R

SET

resistor (I

LED

vs. R

SET

data is found on pages 9 and 10). This term

does not include the tolerance of the resistor R

SET

. If
maximum accuracy is required, a precision resistor is
needed. To calculate the error I

LED-ERR

[%], use the formula

I

LED-ERR

[%] = ±

Current Matching

Current Matching refers to the difference in current from

one LED to the next. The ∆I between any two LEDs will

meet this requirement. To calculate the error I

LED-LED-ERR

,
first identify the highest and lowest value of the 4 LED
currents, and use the formula:

I

LED-LED-ERR

[%] =

or

which reduces to ±

1x Mode, 1.5x Mode and 2x Mode

1x Mode, 1.5x Mode and 2x Mode all refer to the charge
pump configuration. These modes boost the battery input
voltage and ensure there is enough voltage at V

OUT

so
that the regulated current will flow through the LEDs and
return via the I

LED

pins.

I

LED

()

MEASURED

I

LED

-

I

LED

%

100

IMAX

IMAX + IMIN

-1

100%

2

IMIN

IMAX + IMIN

-1

100%

2

IMIN

100%

IMAX

IMINIMAX

+

Input Current

The total input current of the SC604A is a function of
the sum of the LED currents, the charge pump mode
and the quiescent current. The quiescent current trend
is charted on page 12 and used to calculate IIN in the
following examples.

I

IN

= I

OUT

 Mode + IQ =

(I

LED1+ILED2+ILED3+ILED4

)



Mode + I

Q

Example 1:

Mode = 1x, IQ = 2.4mA,

I

LED1+ILED2+ILED3+ILED4

= 4



15mA = 60mA

Answer 1:

I

IN

= I

OUT



Mode + IQ = 60mA



1 + 2.4mA =

62.4mA

Example 2:

Mode = 1.5x, IQ = 2.4mA,

I

LED1+ILED2+ILED3+ILED4

= 4



15mA = 60mA

Answer 2:

I

IN

= I

OUT



Mode + I

Q

= 60mA



1.5 + 2.4mA =

92.4mA

Mode Transition Voltage

Mode transition voltage refers to the input voltage at
the point just before the charge pump changes from a
weaker mode to a stronger mode. V

TRANS1X

is the

transition from 1x to 1.5x mode, and V

TRANS1.5X

is the

transition from 1.5x to 2x mode. Equations for V

TRANS1X

and V

TRANS1.5X

are given on page 7.

5

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

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Pin Descriptions

ECIVEDEGAKCAP

)1(

RTLMIA406CS61-PLM

TRTLMIA406CS

)2(

61-PLM

BVE406CSdraoBnoitaulavE

Notes:

(1) Available in tape and reel only. A reel contains 3000 devices.

(2) Available in lead-free package only. This product is fully WEEE and

RoHS compliant.

Ordering Information

Pin Configuration

Note: (1) The CTRL word must match the outputs in use.

TOP VIEW

MLPQ16: 4X4 16 LEAD

ISET VOUT VIN C1+

ILED1 ILED2 ILED3 ILED4

EN

CTRL0

CTRL1

CTRL2

GND

C2+

C2-

C1-

TOP VIEW

1

2

3

4

12

11

10

9

16 15 14

13

5678

T

6

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SC604A

POWER MANAGEMENT

Block Diagram

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)1(

sutatStuptuO

2LRTC1LRTC0LRTC4DEL3DEL2DEL1DEL

000 FFOFFOFFONO

001 FFOFFONOFFO

010 FFONOFFOFFO

011NOFFOFFOFFO

100 FFOFFONONO

101 FFONONONO

110 NONONONO

111 FFOFFOFFOFFO

Table 1 - LED Enable Logic

VIN

CTRL0

EN

VOUT

7

2

1

6

C1+

C2-

C2+

C1-

8

mAhXLife Fractional Charge Pump
[1x, 1.5x, 2x]

Schmitt Buffer

Schmitt Buffer

250kHz
Oscillator
& Delay Cl k

Mode Select
[1x, 1.5x, 2x
Start up, Shutdown]

Current Brightness Control

Current Sense FETs
and Amplifier(s)

Current Set Detect

1.22V Bandgap
Voltage

GND

ISET

CTRL1

I

L

ED3 ILED2 ILED1ILED4

CTRL2

Schmitt Buffer

Schmitt Buffer

Ouput Selection
Logic

9

10

11

3

4

12

5

13

14

15

16

TM

Notes:
(1) The sequencing of Enable and logic state CTRL{2,1,0} = [1, 1, 1] will affect quiescent state current. IQ = 100µA if Enable transitions high before
CTRL{2,1,0} transitions to [1, 1, 1]. IQ = 400µA if Enable transitions high after CTRL{2,1,0} transitions to [1, 1, 1]. If Enable = high and CTRL{2,1,0}= [1, 1,
1] is to be used for an extended period of time, it is recommended that Enable = High when change to the [1, 1, 1] state to achieve the lower IQ level.

7

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Applications Information

Designing for Lowest Possible Battery Current

The SC604A efficiency and battery current are shown in
the plots that follow on page 8. For this example, 4 LEDs
are matched at 15mA each. The battery current remains
low at 63mA well into the Li-Ion battery range as indicated
in the plot by a boundary box. The SC604A uses 1x mode
(I

IN=IOUT+IQ

) for part of the input voltage range, conserving
significant energy from the battery. A similar four (4)
output device uses only 1.5x mode (I

IN

= I

OUT

 1.5+I

Q

)
over the input voltage range. This means that the
SC604A will have about 25% higher efficiency than a

1.5x only charge pump. Where the competition drops
off at 3V, the SC604A uses 2x mode to extend the
operating range down to a battery voltage of only 2.85V.

The input voltages at which the mode transitions occur
are dependent on the forward voltage V

F

of the LED used

and the LED current I

LED

. To keep the battery current low
and in the 1x mode for as long as possible, it is best to
choose an LED with a lower V

F

.

The mode transition voltages V

TRANS1X

and V

TRANS1.5X

can

be estimated by the following equations:

V

TRANS1X

= VF + V

ILED

+ [(# of LEDs used)  I

LED

 1.2]

V

TRANS1.5X

= VF + V

ILED

+ [(# of LEDs used)  I

LED

 16]

1.5

where, V

F

is the forward LED voltage measured from

anode to cathode, V

ILED

is the voltage at the ILED pin,
typically V

ILED

= 100mV, I

LED

is the LED current.

Power efficiency can now be estimated for comparison
with the intended battery voltage range.

Efficiency [%] =

Detailed Description

The SC604A contains a fractional charge pump, mode
selection circuit, output selection logic, current setting
detection circuit, and four current sense circuits. All are
depicted in the block diagram on page 6.

The fractional charge pump multiplies the input voltage
a multiple of 1, 1.5 or 2 times the input voltage. The
charge pump switches at a fixed 250kHz whenever the
mode is 1.5x or 2x. The charge pump does not switch
during 1x mode, saving power and improving efficiency.

The mode selection circuit automatically selects the mode
as 1x, 1.5x or 2x based on circuit conditions such as LED
voltage, input voltage and load current. 1x is the most
efficient mode, followed by 1.5x and 2x modes. At lower
voltages a stronger mode may be needed to maintain
regulation, if so, the mode will change first to 1.5x and
then to 2x. 2x mode usually operates for a much shorter
run time compared to 1x mode, and 2x mode maintains
the output until the battery is discharged to 2.85V or
less. The LED requiring the highest voltage drop will
determine the output voltage needed to drive all outputs
with adequate bias. Comparing all cathodes and
regulating VOUT for the LED with the lowest cathode
voltage ensures sufficient bias for all LEDs.

Output selection logic enables control over the LED
outputs for on and off functions with eight (8) different
output states. The states are defined in Table 1 on page

6.

The current set and detection circuit uses an external
resistor and a 1.22V reference to program the LED
current.

Four (4) current regulating circuits sink matched currents
from the LEDs. LEDs with matched forward voltage will
produce the best possible matched currents. For best

matching performance it is recommended that the ∆Vf

between LEDs be under 250mV. (For more information

on ∆Vf considerations refer to Semtech application

notes).

V

OUTIOUT

100%

VIN(I

OUT

Mode + I

Q

(

8

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Efficiency Comparison for 4 LEDs with 15mA Each and LED = 3.5V

40

50

60

70

80

90

100

3.23.33.43.53.63.73.83.94.04.14.2

VIN [V]

Efficiency [%]

Competition 1.5x mode

Semt e ch 1x mo de

90% of Li-Ion battery life

Semtech 1.5x mode

Battery Current Comparison for 4 LEDs at 15mA Each with LED = 3.5V

50

60

70

80

90

100

110

3.23.33.43.53.63.73.83.94.04.14.2

VIN [V]

Battery Current [mA]

90% of Li-Ion battery life

Competition 1.5x mode

Semt e ch 1x mo de

Semtech 1.5x mode

9

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

There are four methods for setting and adjusting the LED current
outlined here. The methods are:

1) R

SET

only

2) Analog Reference V

ADJ

3) NMOS switched parallel resistors

4) PWM Input

Method 1. The most basic means of setting the LED current is

with a resistor connected from ISET to GND, as shown in the
application circuit on Page 1. The resistor R

SET

establishes the
reference current needed for a constant LED current. Values of
R

SET

for a fixed LED current are given in Table 2 and also in the

below graph, “Typical R

SET

Resistance vs. LED Current”. Methods
2 and 3 on page 10 are for setting the LED current allow for
brightness control.

Table 2 - Resistor Value Selection

RRRRR

TESTES

TES

TESTES

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eulaV

eulaVeulaV

]Am[DELI]Am[DELI

]Am[DELI

]Am[DELI]Am[DELIRRRRR

TESTES

TES

TESTES

k[k[

k[

k[k[ ΩΩΩΩΩ]]

]

]]

ktseraeNktseraeN

ktseraeN

ktseraeNktseraeN ΩΩΩΩΩ

dradnatSdradnatS

dradnatS

dradnatSdradnatS

eulaVeulaV

eulaV

eulaVeulaV

dradnatSdradnatS

dradnatS

dradnatSdradnatS

eulaVeulaV

eulaV

eulaVeulaV

ecnereffiD%ecnereffiD%

ecnereffiD%

ecnereffiD%ecnereffiD%

5.0139139%0.0

1174074%2.0-

2732732%0.0

3551451%6.0-

50.491.39%0.1-

015.745.74%0.0

5138.136.13%7.0-

020.420.42%0.0

035.615.61%0.0

Methods for Setting LED Current

Typical R

SET

Resistance vs. LED Current

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0.511.522.5 33.544.555.566.577.5 88.599.510

LED Current [mA]

R

SET

Resistance [kΩ]

10

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

V

JDA

]V[I

DEL

]Am[V

JDA

]V[I

DEL

]Am[

000.02.03006.08.41

001.07.72007.03.21

002.01.52008.07.9

003.05.22009.01.7

004.00.02000.11.2

005.03.71051.10.1

Table 3 - Analog Voltage for LED Current Control

Figure 1 - Analog Voltage for LED Current Control

Figure 2 - 3 Bit LED Current Control with Open Drain

Method 2. The example circuit in Figure 1 uses a 16.5kΩ resistor

and an analog input DC voltage, V

ADJ

, which varies from 1.2V to 0V
to control LED current from 1mA to 30mA. Table 3 shows the
resulting output. If necessary, the analog V

ADJ

voltage can be
sourced from a voltage higher than 1.2V, but the source must be
divided down so that the V

ADJ

mode will not exceed 1.2V. For lower
current applications and for higher resolution, a larger resistor
may be substituted in this circuit. PWM applications are also
possible with this circuit by application of RC filtering. (Consult
with Semtech for detailed application support).

Methods for Setting LED Current (Cont.)

Method 3. The circuit in Figure 2 uses open drain NMOS transistors
to set an equivalent resistance for R

SET

. Parallel combinations are
switched on and off for R1, R2 and R3. R4 is always connected,
so that a minimum value of LED current can be maintained at

1.5mA.

11

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

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ssenthgirB

lortnoC

1dohteMR

TES

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Note: 1) “N” is the number of NMOS transistors used for brightness control.

Table 4 - Summary of LED Current Control

Figure 3 - PWM Example Circuit

Method 4. LED current may also be controlled by applying a PWM

signal to any of the CTRL2, CTRL1 and CTRL0 inputs. The circuit in
Figure 3 turns 4 LEDs on and off by applying a PWM signal to the
CTRL0 input. This circuit uses resistor R

SET

to set the on state
current and the average LED current is then proportional to the
percentage of on-time when the CTRL0 pin is a logic low. Average
LED current is approximately equal to:

I

AVG

= (tON  I

LED_ON

)/(tON + t

OFF

)

The recommended PWM frequency is between 100Hz and 500Hz.
Due to start up delay and ramp up time, frequency >500Hz will
result in error in the average value of I

LED

. Frequency <100Hz can

naturally cause the LEDs to blink visibly.

In PWM applications where ILED4 is not used, keep ILED4 pin 13
open. Connecting ILED4 to ground can result in the charge pump
operating in open loop mode. Connecting ILED4 to VIN will work
but will cause shutdown current IQ to increase to approximately
VIN / 100k.

Methods for Setting LED Current (Cont.)

12

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

OVP Event with LED Open Circuit

Mode Transition Voltage vs. LED Voltage

Startup with 4 LEDs at 20 mA

Efficiency vs. Load at Low Battery

Efficiency vs. Load at High Battery

Quiescent Current Trend

Typical Characteristics

50

60

70

80

90

100

020406080100120

Total Load Current [mA]

Efficiency [%]

VIN = 3.8V

V

IN = 4. 0V

VIN = 4.2V

50

60

70

80

90

100

0 20406080100120

Total Load Current [mA]

Efficiency [%]

VIN = 3.6V

VIN = 2.8V

V

IN = 3.4V

0

1

2

3

4

5

0 20 40 60 80 100 120

Total Output Current [mA]

Quiescent Current [mA]

Trend for 4 LEDs

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

0 5 10 15 20 25 30 35

LED Current [mA]

Input Voltage [V]

V

f = 3.6V

V

f = 3.4V

V

f = 3.2V

1X to 1. 5X Mode for 4 LEDs

13

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Battery Current for 4 LEDs at 0.5mA

Efficiency for 4 LEDs at 0.5mA

Efficiency for 4 LEDs at 20mA

Battery Current for 4 LEDs at 10mA

Efficiency for 4 LEDs at 10mA

Battery Current for 4 LEDs at 20mA

Typical Characteristics with 4 LEDs

50

60

70

80

90

100

3.23.43.63.844.2

Input Voltage [V]

Efficiency [%]

LED = 3.37V

30

40

50

60

70

80

3.23.43.63.844.2

Input Voltage [V]

Battery Current [mA]

LED = 3.37V

50

60

70

80

90

100

3.23.43.63.844.2

Input Voltage [V]

Efficiency [%]

LED = 3.45V

40

60

80

100

120

140

3.23.43.63.84.04.2

Input Voltage [V]

Battery Current [mA]

LED = 3.45V

1.5

2

2.5

3

3.5

4

3.23.43.63.844.2

Input Voltage [V]

Battery Current [mA]

LED = 2.91V

LED = 2.91V

20

30

40

50

60

70

3.23.43.63.844.2

Input Voltage [V]

Efficiency [%]

14

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Typical Characteristics with 4 LEDs

Ripple in 1x Mode for 4 LEDs at 20mA Each

Ripple in 1.5x Mode for 4 LEDs at 20mA Each

Ripple in 2x Mode for 4 LEDs at 20mA Each

15

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Evaluation Board Schematic

C1

1.0uF

1 2

C2

1.0uF

1 2

RSET

TBD

1 2

D4

1 2

D3

1 2

D2

1 2

D1

1 2

C4

1.0uF
1

2

J4

1 2

J3

1 2

J2

1 2

J1

1 2

R1

1ohm

12

R4

1ohm

12

R3

1ohm

12

R2

1ohm

12

CNTRL1

CNTRL0

JP4

1 2

JP3

1 2

JP2

1 2

JP1

1 2

SC604

EN

1

CTRL02CTRL13CRTL2

4

ISET

5

VOUT

6

C2+11GND

12

ILED4

13

ILED3

14

ILED2

15

ILED1

16

C2-

10

VIN

7

C1-

9

C1+

8

JP6

ENABLE

123

C2+

1

C2-

1

C1-

1

C1+

1

R4+1R4-

1

R3+1R3-

1

R2+

1

LED4

1

R2-

1

LED31LED2

1

R1+

1

LED1

1

OFF

ON

R1-

1

BATTERY +

VBAT

1

BATTERY -

GND

1

CTRL2

1

2

3

RIN

0.22

1 2 CTRL1

1

2

3

CTRL0

1

2

3

CNTRL2

JP5

Input Resist ance Bypa ss

1 2

J5

Input Jacks

POS

1

NEG

2

VBAT

BATTE RY -

GND

1

ENABLE

LOWLOWLOW HIGHHI GHHIG H

C1-

C6

10uF

1

2

VBAT

VOUT

1

JP7

Connect RSET pot.

1 2

1M

POT_3296W-105

1 3

2

VOUT

RSET

C3

1.0uF
1

2

Analog C ontrol

VADJ

1

C1+

RADJ

16.5k

1 2

C2-

C2+

Evaluation Board Bill of Materials

Evaluation Board Gerber Plots

Reference Value Comment

U1 SC604A Component references in bold are the only essential design components.
C1,C2,C3,C4 1.OµF Bucket, input and output capacitors. Ceramic, low ESR type, 6.3V rating or higher.
C6 10µF This extra capacitor supports usage of long power leads from benchtop supply.
D1,D2,D3,D4 - Add LEDs to meet the requirements of the application.
J1, J2, J3, J4 - Jumpers in series with each LED.

JP1,JP2,JP3,JP4 - Jumpers to bypass each 1Ω sense resistor and bypass J1, J2, J3 and J4.

JP5 - Jumper for bypassing the R4 input resistor.
JP6 - Enable jumper.
JP7 - Connects RSET potentiometer. Remove this jumper when using a fixed value R1.
CTRL0,CTRL1,CTRL2 - Jumpers provide High/Low settings for the control bits.
RSET - RSET resistor

3296W-105 Evaluation board has 1MΩ potentiometer in place of R1.
R4 0.22Ω Series input resistor for studying effects of input resistance.
RADJ 16.5kΩ Resistor for analog brightness control. Apply test signal of 0 to 1.2V at VADJ test point.

J5 - Banana jacks for power supply.

Top View

Bottom View

SC604A

16

 2005 Semtech Corp. www.semtech.com

POWER MANAGEMENT

17

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Outline Drawing- MLP-16 [4x4]

.003

.010

.074

16

.012

.085

-

.000

.031

(.008)

0.08

0.30

16

.014

.089

0.25

1.90

.040

-

.002-0.00

0.80

2.25

0.35

2.15

-

0.05

1.00

(0.20)

.004 0.10

1.90 2.15 2.25

0.65 BSC.026 BSC

0.45.018 .026.022 0.55 0.65

.089.085.074

D/2

E1

2

A

A1

1

LxN

bbb C A B

A2

bxN

e

SEATING
PLANE

C

E/2

D1

N

e/2

aaa C

CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).

COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.

1.

2.

NOTES:

A D

E

B

-

--

-

INCHES

N

bbb

aaa

A2

A1

E1

D1

DIM

L

e

E

D

A

b

MIN MAX

MILLIMETERS

MINMAX NOM

.153 .157 .161 3.90 4.00 4.10

.153 .157 .161 3.90 4.00 4.10

INDICATOR

(LASER MARK)

PIN 1

DIMENSIONS

NOM

yyww = Datecode (Example: 0452)

Marking Information

604A

yyww

18

 2005 Semtech Corp. www.semtech.com

SC604A

POWER MANAGEMENT

Land Pattern MLP-16pin [4x4]

P

Y

K

C

Z

P

Y

X

G

K

H

.189

.026
.016
.041

.106
.091
.091

4.80

0.40

1.05

0.65

2.30

2.30

2.70

DIM

(3.75)

MILLIMETERS

DIMENSIONS

(.148)

INCHES

THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.

NOTES:

1.

2x G

H

2x (C)

2x Z

X

Semtech Corporation

Power Management Products Division

200 Flynn Road, Camarillo, CA 93012

Phone: [phone] FAX [phone]

Contact Information

Visit us at: www.semtech.com