Datasheet SP6682 Datasheet (Sipex)

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Page 1

High Efficiency Charge Pump Regulator

FEATURES

■ Ideal For White LED Driver

■ Low Profile, Inductorless Regulator

■ X1.5 and X2 Modes for Highest Efficiency

■ +2.7V to +5.5V Input Voltage Range

■ Fast Turn-On Time, 175µS

■ 1mA Quiescent Current

■ <1.5µA Shutdown Current

■ Built-in 600kHz Oscillator

■ Programmable Output Current or Voltage

■ PWM Dimming Control with Enable Pin

■ Shutdown to Disconnect Output from Input

■ Soft Start to Eliminate In-Rush Current

■ Industry Standard 10-pin MSOP Package

and Small 10-pin DFN Package

SP6682

for White LEDs

OUT

C1P

SP6682

10 Pin DFN

MODE

Now Available in Lead Free Packaging

APPLICATIONS

■ Next Generation Mobile Phones

■ PDAs

■ 3.3V to 5.0V Conversion

■ Digital Still Cameras

■ Digital Camcorders

■ Palmtop Computers

■ Color LCD Modules

C2P

C1N

GND

C2N

EN/PWM

DESCRIPTION

The SP6682 is a current regulated charge pump ideal for converting a Li-Ion battery input for driving white LED used in backlighting color displays. The charge pump automatically switches between X1.5 and X2 modes based on the input voltage, providing improved efficiency over traditional methods using charge pump doubler followed by LDO. This input voltage threshold can be externally programmed for optimized efficiency at specific output voltages and currents. The SP6682 operates with an internal 600kHz clock, enabling the use of small external components. Output current or voltage can be accurately regulated by modulating the switcher between the charge pump and output capacitor. In shutdown mode, the IC disconnects the output from the input and draws less than 1.5µA current. The SP6682 is offered in a 10-pin MSOP package, and a small 10-Pin DFN Package.

TYPICAL APPLICATION SCHEMATIC

SP6682

C2P

C1N

GND

C2N

EN/PWM

2.7 - 4.2V

Lithium-Ion

ENABLE/PWM DIMMING

2.2µF

R3 1M

0.1µF

C1P

OUT

MODE

2.2µF

0.1µF

2.2µF

White LED

R6 20

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ABSOLUTE MAXIMUM RATINGS

VIN, V VIN - V Output Current (I Power Dissipation per Package - 10-pin MSOP

(derate 8.84mW/°C above +70°C) ................. 720mW

Junction Temperature .................................... +125°C

Storage Temperature ...................... -65°C to +150°C

ESD Rating. ................................................ 2kV HBM

, V

MODE

OUT

and EN/PWM................. -0.3V to 6V

OUT

........................................................... 0.7V

) ...................................... 300mA

OUT

These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

ELECTRICAL CHARACTERISTICS

Unless otherwise specified: VIN =+2.7V to +5.0V, C1=C2=C4=C5=2.2µF (ceramic, ESR=0.03Ω), C3=0.1µF (ceramic) and T

PARAMETER MIN TYP MAX UNITS CONDITIONS

Input Voltage 2.7 5.5 V

Quiescent Current 1.2 3 mA V

Shutdown Current 1.5 µA EN/PWM = 0V, VIN = 5.5V

Oscillator Frequency 0.42 0.60 0.78 MHz VIN = 3.6V

Reference Voltage 0.275 0.306 0.337 V

Charge Pump Output 11 18 Ω FB = 0V, VIN = 3.6V, Resistance I

Threshold Voltage 1.15 1.25 1.35 V VIN Falling @ 25°C

MODE

Hysteresis for Mode Transition 30 mVPPVIN = 3.6V @ 25°C Voltage

Pin Current 0.01 0.5 µAV

MODE

EN/PWM Logic Low 0.4 V

EN/PWM Logic High 1.6 V

EN/PWM Pin Current 0.01 0.5 µAV

FB Pin Current 0.5 µAVFB = 1V

Turn-On Time 175 500 µsVIN = 3.6V, FB within 90% regulation

OUT

=-40°C to +85°C unless otherwise noted.

AMB

= 4.2V, V

= 20mA, V

OUT

= 1.25

MODE

EN/PWM

OUT

= 4.2V

= 3.6V, I

= High

MODE

= 100µA

OUT

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PIN DESCRIPTION

PIN NUMBER PIN NAME DESCRIPTION

OUT

Regulated charge pump output.

2 C1P Positive terminal to the charge pump flying capacitor C2.

3VINInput pin for the 2.7V to 5.5V supply voltage.

MODE

Charge pump mode program pin. When V

is greater than 1.25V,

MODE

X1.5 charge pump is used. Otherwise, charge pump switches to X2 mode. A voltage divider shown in typical application circuit programs the VIN threshold for charge pump mode switching.

5FBThis is the feedback pin for output current or voltage regulation. The

voltage of this pin is compared with an internal 306mV reference.

6 EN/PWM Enable and PWM dimming control input. Pull this pin low to discon-

nect V

from VIN and shutdown the SP6682.

OUT

7 C2N Negative terminal to the charge pump flying capacitor, C4.

8 GND Ground reference.

9 C1N Negative terminal to the charge pump flying capacitor, C2.

10 C2P Positive terminal to the charge pump flying capacitor C4.

FUNCTIONAL DIAGRAM

C1P

C1N

C2P

C2N

OUT

COMP

600 kHz

Clock

Manager

Mode Control

GND

Start-up

and

Charge

Pump

Switches

MODE COMP

Voltage

Referenc

306m

EN/PW

1.25V

MODE

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Refer to the typical application circuit, T

PERFORMANCE CHARACTERISTICS

= 25°C, IO = 60mA unless otherwise specified.

AMB

EN/PWM

OUT

Figure 1. Output voltage turn-on time

OUT

5V/DIV

1V/DIV

50mV/DIV

Efficiency (%)

2.7 3 3.3 3.6 3.9 4.2

Input Voltage(V)

Figure 2. Power efficiency vs. input voltage

0.34

0.33

0.32

0.31

(V)

0.3

0.29

0.28

0.27

0.26

2.7 3 3.3 3.6 3.9 4.2

(V)

Figure 3. X2 mode voltage ripple when VIN = 2.7V

OUT

50mV/DIV

Figure 4. Feedback pin voltage vs. input voltage

0.9

0.8

0.7

0.6

(mA)

0.5

0.4

SUPPLY

0.3

0.2

0.1

2.7 3 3.3 3.6 3.9 4.2

(V)

Figure 5. X1.5 mode voltage ripple when VIN = 3.3V Figure 6. Quiescent current vs. input voltage

Page 5

Refer to the typical application circuit, T

PERFORMANCE CHARACTERISTICS: Continued

= 25°C, IO = 60mA unless otherwise specified.

AMB

Brightness (kcd/m2)

2.7 3 3.3 3.6 3.9 4.2

Figure 7. Brightness vs. input voltage

Input Voltage (V)

4 LED's @ 30mA 4 LED's @ 15mA

General Overview

The SP6682 is a current regulated charge pump ideal for converting a Li-Ion battery input for driving white LEDs used in backlighting color displays in cellular phones, PDAs, digital cameras and MP3 players. The SP6682’s proprietary AutoBoost feature enables the IC to automatically transition from X1.5 boost mode to X2 boost mode based on battery input voltage for optimal efficiency and performance. The SP6682 is able to efficiently drive up to six 20mA white LEDs in parallel and maintain a constant brightness over a very wide operating voltage range (2.7V to 5.5V). The SP6682 operates with an internal 600kHz clock, enabling the use of small external components. Other features of SP6682 include PWM dimming control as well as complete input/out disconnect in shutdown. In shut down mode the IC draws less than 1.5µA current. The output regulation is achieved by sensing the voltage at the feedback pin and modulating the switcher between the charge pump and output capacitor.

Theory of Operation

The SP6682 regulated charge pump block diagram consists of four main blocks (Voltage Reference, Mode Control, Clock Manager, Startup and Charge-Pump Switches) and two com-

100 Hz

500 Hz

Brigtness, kCd/m2

020406080100

Figure 8. Brightness vs duty cycle

Duty Cycle,%

OPERATION

parators (V

Comparator and V

MODE

OUT

Com-

parator).

1) Voltage Reference. This block provides the 306mV and 1.25V reference voltages needed for the two comparators.

2) Mode Control. An external voltage divider connected to the V

pin will define an input

MODE

voltage to the mode comparator which sets the logic state of the mode selection outputs to the X2 or X1.5 modes. V

is compared to a

MODE

1.25V bandgap voltage. For example, if one makes a 158K/100K divider, the mode will change at 2.58 x 1.25 V =3.23V. A comparatorbased cycle by cycle regulation ensures that no mode change occurs during cycles.

3) Clock Manager. An internal 600 kHz clock is generated in this block. Depending on the mode control, the appropriate clock phasing is generated here and sent to the start-up and charge-pump switches block.

4) Start-up and Charge Pump Switches. During start-up, until the reference is established, this block keeps the charge pump inactive. During this period the output stays floating, by consequence the charge pump drivers are now referenced to V occur (e.g. when VIN is ramped up to 4.2V, V

. Charging of the output will

OUT

ramps only up to about 3V), but not to the value of VIN, protecting the White LED from experi-

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OPERATION: Continued

encing high input voltages. Another important operation of this block is the PWM/EN dimming control, which is implemented in the delay of each pump driver, so that the enable high pulse width is proportional to the delay of the individual pump switches.

5) V

Comparator and Output Control. A

OUT

306mV reference voltage is compared to feed-

Configuring the SP6682 as Voltage or Current Source

The white LED load configuration used by customers can be discrete white LEDs or a white LED module. Inside the white LED module, there may or may not be resistors in series with the white LEDs. According to the different application requirements, the SP6682 can be configured as either a voltage source or a current source to provide solutions for these different applications, as shown in figure 9~12. Figure 9 shows using the SP6682 to drive discrete white LEDs as a current source.

The current in one white LED current is set by the ratio of the feedback pin voltage (306mV) and the bias resistor RB. To set the operating current, RB can be selected by:

RB = I

LED

back output voltage to control the Vout needed for the application. Output current is set by a bias resistor from FB pin to GND pin chosen by the relationship:

OUT

where VFB = 306mV.

APPLICATION INFORMATION

The current of the remaining white LEDs is set according to the similarity of the white LEDs. 3wire white LED module with internal series resistors as shown in figure 10 can also be driven in this way.

Anode

3-wire W-LED module

GND

Fig 10. 3-wire white LED module

In figure 11, SP6682 was used to drive a 2-wire white LED module without internal series resistors as a current source. The bias resistor RB is selected to regulate the total current of the white LED module instead of the current of single LED as in figure 9.

OUT

SP6682

GND

Figure 9. Driving discrete white LEDs as current source

2.2uF

Figure 11. Driving 2-wire white LED module as current source

SP6682

GND

OUT

Anode

2-wire W-LED module

Cathode

Page 7

In this application, the bias resistor can be selected by:

LED (TOTAL)

is the total operating current

where I

RB = I

LED(TOTAL)

of all the white LEDs.

To use SP6682 as a voltage source for fixed voltage applications, a voltage divider is need to program the ouput voltage, as shown in figure 12.

The output voltage is set by the ratio of the two

APPLICATION INFORMATION: Continued

Programming the Operating Mode

SP6682 can automatically change from X1.5 mode to X2 mode for highest efficiency. To use this feature, divider resistors should be chosen according to the specific application, as shown in figure 13.

The guideline for divider resistor selections is as follows. For high input voltage, the SP6682 will work in X1.5 mode. When the input voltage drops to Vth threshold voltage, it will switch to X2 mode automatically. The Vth threshold voltage for mode change can be calculated by:

OUT

SP6682

GND

Figure 12. Driving 2-wire white LED module as voltage source

2.2uF

Anode

2-wire W-LED module

Cathode

resistors and the feedback control voltage as shown by:

SP6682

MODE

) • V

GND

= ( 1 +

OUT

Figure 13. Programming the Vmode Resistors

VTH = (VF + 0.306 + m • I

LED

• R

OUT

)/1.5

Where VF and m are the forward voltage and number of the white LEDs, Rout is the output resistance of the SP6682.

The equation for the voltage divider R1 and R with V

MODE

= 1.25V is:

VTH = 1.25V • (1+R1/R2)

which can be expressed as R1:

R1 = (V

/ 1.25 -1) • R

For the typical SP6682 application, Using VF=3.6V, m=4, I

=15mA, R

LED

=16Ω, the

OUT

VTH will be 3.24V. Select R2=100kΩ, then R1=158kΩ.

Capacitor Selection

Ceramic capacitors are recommended for their inherently low ESR, which will help produce low peak to peak output ripple, and reduce high frequency spikes.

The fly capacitor controls the strength of the charge pump. Selection of the fly capacitor is a trade-off between the output voltage ripple and the output current capability. Decreasing the fly capacitor will reduce the output voltage ripple because less charge will be delivered to the output capacitor. However, smaller fly capaci-

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APPLICATION INFORMATION

tor leads to larger output resistance, thus decreasing the output current capability and the circuit efficiency. Place all the capacitors as close to the SP6682 as possible for layout. Increasing the value of the input and output

Table: 1

SUGGESTED LOW ESR CAPACITORS

MANUFACTURERS/ PART NUMBER CAPACITANCE/ CAPACITOR/ ESR TELEPHONE# VOLTAGE SIZE/TYPE AT 100kHz

TDK/847-803-6100 C2012X5R1A225K 2.2µF/10V 0805/X5R 0.030Ω

TDK/847-803-6100 C2012X5R0J475K 4.7µF/6.3V 0805/X5R 0.020Ω

MURATA/770-436-1300 GRM188R60J225KE01D 2.2µF/6.3V 0603/X5R 0.030Ω

MURATA/770-436-1300 GRM219R60J475KE01D 4.7µF/6.3V 0805/X5R 0.020Ω

Brightness Control Using PWM

capacitors could further reduce the input and output ripple.

Refer to Table 1 for some suggested low ESR capacitors.

Dimming control can be achieved by applying a PWM control signal to the EN/PWM pin. The brightness of the white LEDs is controlled by increasing and decreasing the duty cycle of the PWM signal. While the operating frequency range of the PWM control is from 60Hz to 700Hz, the recommended maximum brightness frequency range of the PWM signal is from 60Hz to 200Hz. A repetition rate of at least 60Hz is required to prevent flicker.

Brightness Matching

For white LEDs, the forward voltage drop is a function of the operating current. However, for a given current, the forward voltage drops do not always match due to normal manufacturing tolerance, thus causing uneven brightness of the white LEDs.

In figure 14, assume high-precision bias resistors were used, the operating current ratio of two different branches can be easily derived as shown by:

- V

OUT

I2 V

OUT

- V

where I1 I2 are the operating current of the white LEDs,VF1,VF2 are the forward voltage of the white LEDs.

Since the brightness of the white LED is propor-

tional to the operating current, for better brightness matching, a higher output voltage could be used. This could be done by using larger resistor, as shown in figure 14. Rb2 is used to bias the operating current of the white LED, Rb1 is use to increase the output voltage. Better brightness matching was achived at the cost of the power wasted on the bias resistor.

OUT

SP6682

GND

Figure 14. Increasing brightness matching

Power Efficiency

Rb1

Rb2

VF2

VFnVF1

The efficiency of driving the white LEDs can be calculated by:

VF • IF

Vi •Ii

VF • IF

≈

Vi • (n • IF + IQ)Vi • n

Page 9

Where Vi, Ii are input voltage and current VF, I are the forward voltage and operating current of White LEDs IQ is quiescent current, which is considered small compared with IF.

n is the boost ratio (X1.5 or X2)

SP6682 High Voltage White LED Driver

APPLICATION INFORMATION

this application as well as actual data showing efficiency of > 85%. By using an external inductor, MOSFET and diode, high output voltage can be generated to drive 12 white LEDs (2 branches, each branch has 6 white LEDs in series). The current through the white LEDs is determined by:

The SP6682 can also be configured as a high voltage boost converter to drive more than 10 white LEDs. Figure 15 shows the schematic of

L1 LQH32CN4R7M11

4.7uH

SP6682

OUT

Vin: 2.7-4.2V

10uF

X5R Ceramic

EN/PWM

C1P

3 8

VINGND

MODE

R3 1M

Figure 15. Using SP6682 as a High Voltage White LED Driver

C2P

C1N

C2N

EN/PWMFB

DS SCHOTTKY MBR0530

Q1 Ceramic

SI1304

SOT23

25V

ILED = VFB/R1 = 20mA

2.2uF 25V C3 X5R

R1 15

D10

D11

D12

R2 15

LED

100

Efficiency (%)

2.7 3.0 3.3 3.6 3.9 4.2

(V)

PINOUTS

OUT

C1P

SP6682

MODE

10 Pin DFN

C2P

C1N

GND

C2N

EN/PWM

MODE

OUT

C1P

SP6682

10 Pin MSOP

C2P

C1N

GND

C2N

Page 10

PACKAGE: 10 PIN MSOP

Ø1

E/2

Seating Plane

Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)

10 Pin MSOP JEDEC MO-187 (BA) Variation

SYMBOL

MIN NOM MAX

A--1.1 A1 0 - 0.15 A2 0.75 0.85 0.95

b 0.17 - 0.27

c 0.08 - 0.23

E E1

e e1

3.00 BSC

4.90 BSC

3.00 BSC

0.50 BSC

2.00 BSC

L 0.4 0.6 0.8 L1 L2

0.95 REF

0.25 BSC N-10R 0.07 - -

R1 0.07 - -

ø0º-8º

ø1 0º - 15º

Note: Dimensions in (mm)

Ø1

WITH PLATING

Gauge Plane

BASE METAL

Section B-B

Page 11

Top View

D/2

PACKAGE: 10 PIN DFN

E/2

Side View

3x3 10 Pin DFN JEDEC MO-229 (VEED-5)

VARIATION

SYMBOL

MIN NOM MAX

A 0.8 0.9 1 A1 0 0.02 0.05 A2 0.55 0.65 0.8 A3

0.20 REF

b 0.18 0.25 0.3

3.00 BSC

D2 2.2 2.7

0.5 PITCH

3.00 BSC

E2 1.4 - 1.75

K 0.2 - -

L 0.3 0.4 0.5

Note: Dimensions in (mm)

Bottom View

Page 12

ORDERING INFORMATION

Part Number Top Mark Operating Temperature Range Package Type

SP6682EU .......................SP6682EU....................................-40°C to +85°C ............................ 10 Pin MSOP

SP6682EU/TR .................SP6682EU....................................-40°C to +85°C ............................ 10 Pin MSOP

SP6682ER ...................... SP6682EURYWW.........................-40°C to +85°C ............................... 10 Pin DFN

SP6682ER/TR ................. SP6682ERYWW...........................-40°C to +85°C ............................... 10 Pin DFN

Available in lead free packaging. To order add "-L" suffix to part number.

Example: SP6682ER/TR = standard; SP6682ER-L/TR = lead free

/TR = Tape and Reel

Pack quantity is 2,500 for MSOP and 3,000 for DFN.

CLICK HERE TO ORDER SAMPLES

Corporation

ANALOG EXCELLENCE

Sipex Corporation

Headquarters and Sales Office

233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600

Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.