1
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
SP6682
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, 175S
1mA Quiescent Current
<1.5A 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
High Efficiency Charge Pump Regulator
for White LEDs
APPLICATIONS
Next Generation Mobile Phones
PDAs
3.3V to 5.0V Conversion
Digital Still Cameras
Digital Camcorders
Palmtop Computers
Color LCD Modules
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 1.5A current. The SP6682 is offered in a 10-pin MSOP
package, and a small 10-Pin DFN Package.
TYPICAL APPLICATION SCHEMATIC
SP6682
V
OUT
C1P
V
IN
V
MODE
FB
C2P
C1N
GND
C2N
EN/PWM
1
2
3
4
5
10
9
8
7
6
C2
2.2F
C4
2.2F C5
2.2F
R6
20
C1
2.2F
Lithium-Ion
ENABLE/PWM DIMMING
White
LED
C3
0.1F
R2
R1
R3
1M
20
20
20
2.7 - 4.2V
C6
0.1F
SP6682
10 Pin DFN
10
9
8
7
6
1
2
3
4
5
C2P
C1N
GND
C2N
EN/PWM
V
OUT
C1P
V
IN
V
MODE
FB
Now Available in Lead Free Packaging
2
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
PARAMETER
MIN
TYP
MAX
UNITS
CONDITIONS
Input Voltage
2.7
5.5
V
Quiescent Current
1.2
3
mA
V
IN
= 4.2V, V
OUT
= 3.6V, I
OUT
= 100A
Shutdown Current
1.5
A
EN/PWM = 0V, V
IN
= 5.5V
Oscillator Frequency
0.42
0.60
0.78
MHz
V
IN
= 3.6V
V
FB
Reference Voltage
0.275
0.306
0.337
V
Charge Pump Output
11
18
FB = 0V, V
IN
= 3.6V,
Resistance
I
OUT
= 20mA, V
MODE
= High
V
MODE
Threshold Voltage
1.15
1.25
1.35
V
V
IN
Falling @ 25C
Hysteresis for Mode Transition
30
mV
PP
V
IN
= 3.6V @ 25C
Voltage
V
MODE
Pin Current
0.01
0.5
A
V
MODE
= 1.25
EN/PWM Logic Low
0.4
V
EN/PWM Logic High
1.6
V
EN/PWM Pin Current
0.01
0.5
A
V
EN/PWM
= 4.2V
FB Pin Current
0.5
A
V
FB
= 1V
V
OUT
Turn-On Time
175
500
s
V
IN
= 3.6V, FB within 90% regulation
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: V
IN
=+2.7V to +5.0V, C1=C2=C4=C5=2.2F (ceramic, ESR=0.03), C3=0.1F
(ceramic) and T
AMB
=-40C to +85C unless otherwise noted.
V
IN
, V
MODE
, V
OUT
and EN/PWM ................. -0.3V to 6V
V
IN
- V
OUT
........................................................... 0.7V
Output Current (I
OUT
) ...................................... 120mA
Power Dissipation per Package - 10-pin MSOP
(derate 8.84mW/C above +70C) ................. 720mW
Junction Temperature .................................... +125C
Storage Temperature ...................... -65C to +150C
ESD Rating. ................................................ 2kV HBM
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.
ABSOLUTE MAXIMUM RATINGS
3
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
V
OUT
306m
EN/PW
1.25V
C2N
Start-up
and
Charge
Pump
Switches
V
MODE
C2P
C1P
FB
Mode Control
GND
V
IN
C1N
600 kHz
Clock
Manager
Voltage
Referenc
MODE
COMP
V
OUT
COMP
FUNCTIONAL DIAGRAM
PIN DESCRIPTION
PIN NUMBER
PIN NAME
DESCRIPTION
1
V
OUT
Regulated charge pump output.
2
C1P
Positive terminal to the charge pump flying capacitor C2.
3
V
IN
Input pin for the 2.7V to 5.5V supply voltage.
4
V
MODE
Charge pump mode program pin. When V
MODE
is greater than 1.25V,
X1.5 charge pump is used. Otherwise, charge pump switches to X2
mode. A voltage divider shown in typical application circuit programs
the V
IN
threshold for charge pump mode switching.
5
FB
This 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
OUT
from V
IN
and shutdown the SP6682.
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.
4
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
PERFORMANCE CHARACTERISTICS
Refer to the typical application circuit, T
AMB
= 25
C, I
O
= 60mA unless otherwise specified.
EN/PWM
V
OUT
5V/DIV
1V/DIV
V
IN
V
OUT
50mV/DIV
50mV/DIV
0
10
20
30
40
50
60
70
80
90
2.7
3
3.3
3.6
3.9
4.2
Input Voltage(V)
Efficiency (%)
0.26
0.27
0.28
0.29
0.3
0.31
0.32
0.33
0.34
2.7
3
3.3
3.6
3.9
4.2
V
IN
(V)
V
FB
(V)
V
OUT
50mV/DIV
50mV/DIV
V
IN
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
2.7
3
3.3
3.6
3.9
4.2
V
IN
(V)
I
SUPPL
Y
(mA)
Figure 1. Output voltage turn-on time
Figure 2. Power efficiency vs. input voltage
Figure 3. X2 mode voltage ripple when V
IN
= 2.7V
Figure 4. Feedback pin voltage vs. input voltage
Figure 5. X1.5 mode voltage ripple when V
IN
= 3.3V
Figure 6. Quiescent current vs. input voltage
5
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
0
1
2
3
4
5
6
2.7
3
3.3
3.6
3.9
4.2
Input Voltage (V)
Brightness (kcd/m2)
4 LED's @ 30mA
4 LED's @ 15mA
PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, T
AMB
= 25
C, I
O
= 60mA unless otherwise specified.
0
1
2
3
0
20
40
60
80
100
Duty Cycle,%
Brigtness, kCd/m2
100 Hz
500 Hz
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 cam-
eras and MP3 players. The SP6682's propri-
etary AutoBoost feature enables the IC to auto-
matically 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 oper-
ates with an internal 600kHz clock, enabling the
use of small external components. Other fea-
tures of SP6682 include PWM dimming control
as well as complete input/out disconnect in
shutdown. In shut down mode the IC draws less
than 1.5
A 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 dia-
gram consists of four main blocks (Voltage
Reference, Mode Control, Clock Manager, Start-
up and Charge-Pump Switches) and two com-
parators (V
MODE
Comparator and V
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
MODE
pin will define an input
voltage to the mode comparator which sets the
logic state of the mode selection outputs to the
X2 or X1.5 modes. V
MODE
is compared to a
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 comparator-
based 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. Dur-
ing start-up, until the reference is established,
this block keeps the charge pump inactive. Dur-
ing this period the output stays floating, by
consequence the charge pump drivers are now
referenced to V
OUT
. Charging of the output will
occur (e.g. when V
IN
is ramped up to 4.2V, V
OUT
ramps only up to about 3V), but not to the value
of V
IN
, protecting the White LED from experi-
Figure 7. Brightness vs. input voltage
Figure 8. Brightness vs duty cycle
OPERATION
6
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
encing high input voltages. Another important
operation of this block is the PWM/EN dim-
ming 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
OUT
Comparator and Output Control. A
306mV reference voltage is compared to feed-
1
8
5
Rb
SP6682
Rb
2.2uF
GND
FB
V
OUT
Figure 9. Driving discrete white LEDs as current source
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 R
B
. To set the operating
current, R
B
can be selected by:
R
B
= V
FB
I
LED
3-wire W-LED module
Anode
FB
GND
Fig 10. 3-wire white LED module
The current of the remaining white LEDs is set
according to the similarity of the white LEDs. 3-
wire white LED module with internal series
resistors as shown in figure 10 can also be driven
in this way.
GND
V
OUT
Anode
5
V
FB
Rb
SP6682
Cathode
8
2-wire W-LED module
1
Figure 11. Driving 2-wire white LED module as current
source
OPERATION: Continued
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:
I
OUT
= V
FB
R
FB
where V
FB
= 306mV.
In figure 11, SP6682 was used to drive a 2-wire
white LED module without internal series resis-
tors as a current source. The bias resistor R
B
is
selected to regulate the total current of the white
LED module instead of the current of single
LED as in figure 9.
APPLICATION INFORMATION
7
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
In this application, the bias resistor can be se-
lected by:
R
B
= V
FB
I
LED (TOTAL)
where I
LED(TOTAL)
is the total operating current
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
Anode
5
8
SP6682
Cathode
V
OUT
R6
1
R5
2.2uF
V
FB
2-wire W-LED
module
GND
Figure 12. Driving 2-wire white LED module as voltage
source
resistors and the feedback control voltage as
shown by:
V
OUT
= ( 1 +
R
5
) V
FB
R
6
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 volt-
age for mode change can be calculated by:
V
TH
= (V
F
+ 0.306 + m I
LED
R
OUT
)/1.5
Where V
F
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 R
1
and R
2
with V
MODE
= 1.25V is:
V
TH
= 1.25V (1+R
1
/R
2
)
which can be expressed as R1:
R
1
= (V
TH
/ 1.25 -1) R
2
For the typical SP6682 application, Using
V
F
=3.6V, m=4, I
LED
=15mA, R
OUT
=16
, the
V
TH
will be 3.24V. Select R
2
=100k
, then
R
1
=158k
.
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-
V
IN
V
IN
C2
GND
4
V
MODE
R1
SP6682
8
R2
3
Figure 13. Programming the Vmode Resistors
APPLICATION INFORMATION: Continued
8
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
tor leads to larger output resistance, thus de-
creasing 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
capacitors could further reduce the input and
output ripple.
Refer to Table 1 for some suggested low ESR
capacitors.
MANUFACTURERS/
PART NUMBER
CAPACITANCE/
CAPACITOR/
ESR
TELEPHONE#
VOLTAGE
SIZE/TYPE
AT 100kHz
TDK/847-803-6100
C2012X5R1A225K
2.2F/10V
0805/X5R
0.030
TDK/847-803-6100
C2012X5R0J475K
4.7F/6.3V
0805/X5R
0.020
MURATA/770-436-1300
GRM188R60J225KE01D
2.2F/6.3V
0603/X5R
0.030
MURATA/770-436-1300
GRM219R60J475KE01D
4.7F/6.3V
0805/X5R
0.020
Brightness Control Using PWM
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 tol-
erance, thus causing uneven brightness of the
white LEDs.
In figure 14, assume high-precision bias resis-
tors were used, the operating current ratio of two
different branches can be easily derived as shown
by:
I
1
= V
OUT
- V
F1
I
2
V
OUT
- V
F2
where I
1
I
2
are the operating current of the white
LEDs,V
F1
,V
F2
are the forward voltage of the
white LEDs.
Since the brightness of the white LED is propor-
tional to the operating current, for better bright-
ness matching, a higher output voltage could be
used. This could be done by using larger resis-
tor, 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.
Rb1
8
V
FB
D1
Rb
Dn
GND
VFn
VF1
V
OUT
1
Rb2
Rb
VF2
Rb
5
D2
SP6682
I
1
I
2
I
n
Figure 14. Increasing brightness matching
Table: 1
SUGGESTED LOW ESR CAPACITORS
Power Efficiency
The efficiency of driving the white LEDs can be
calculated by:
=
V
F
I
F
=
V
F
I
F
V
F
V
i
I
i
V
i
(n I
F
+ I
Q
)
V
i
n
APPLICATION INFORMATION
9
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
Where V
i
, I
i
are input voltage and current V
F
, I
F
are the forward voltage and operating current of
White LEDs I
Q
is quiescent current, which is
considered small compared with I
F
.
n is the boost ratio (X1.5 or X2)
SP6682 High Voltage White LED Driver
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
this application as well as actual data showing
efficiency of > 85%. By using an external induc-
tor, 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:
I
LED
=
V
FB
R
1
70
75
80
85
90
95
100
2.7
3.0
3.3
3.6
3.9
4.2
V
IN
(V)
Efficiency (%)
D11
X5R Ceramic
D3
SOT23
R2
15
25V
L1 LQH32CN4R7M11
4.7uH
D12
D8
DS SCHOTTKY MBR0530
D4
Q1
Ceramic
EN/PWM
R1
15
D6
C1
10uF
D9
D7
C3 X5R
2.2uF 25V
D10
D2
R3
1M
ILED = VFB/R1 = 20mA
SP6682
1
2
7
6
5
4
3
8
9
10
V
OUT
C1P
C2N
EN/PWM
FB
V
MODE
V
IN
GND
C1N
C2P
D1
SI1304
D5
Vin: 2.7-4.2V
Figure 15. Using SP6682 as a High Voltage White LED Driver
APPLICATION INFORMATION
PINOUTS
V
OUT
C1P
V
IN
V
MODE
FB
SP6682
10 Pin MSOP
1
2
3
4
5
10
9
8
7
6
C2P
C1N
GND
C2N
EN/PWM
SP6682
10 Pin DFN
10
9
8
7
6
1
2
3
4
5
C2P
C1N
GND
C2N
EN/PWM
V
OUT
C1P
V
IN
V
MODE
FB
10
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
PACKAGE: 10 PIN MSOP
(ALL DIMENSIONS IN MILLIMETERS)
0.07 - -
L1
L
R1
1
R
1
1
Seating Plane
1
E1
2
E/2
e1
e
E
D
Gauge Plane
L2
D
A2
A
A1
b
- - 1.1
0 - 0.15
Dimensions in (mm)
10-PIN MSOP
JEDEC MO-187
(BA) Variation
0.75 0.85 0.95
0.17 - 0.27
0.08 - 0.23
3.00 BSC
4.90 BSC
3.00 BSC
0.4 0.60 0.80
0.95
- 0.25 -
- 10 -
0.07 - -
0 8
A
A1
A2
b
c
D
E
E1
L
L1
L2
N
R
R1
0 - 15
1
MIN NOM MAX
e1
e
2.00 BSC
0.50 BSC
c
WITH PLATING
BASE METAL
(b)
-
-
Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)
11
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
PACKAGE: 10 PIN DFN
Top View
D/2
Bottom View
D
E
D2
E/2
E2
e
b
L
1
2
Pin 1 identifier to be located within this shaded area.
Terminal #1 Index Area (D/2 * E/2)
K
Side View
A
A1
A3
DIMENSIONS
in
(mm)
10 Pin DFN
(JEDEC MO-229,
VEED-5 VARIATION)
A
A1
A3
b
D
E2
E
e
D2
L
K
0.80 0.90 1.00
0.20 REF
2.20
-
2.70
3.00 BSC
1.40 -
1.75
0.30
0.40 0.50
0.20
0.18
0.25 0.30
3.00 BSC
0.50 PITCH
SYMBOL
MIN NOM MAX
0
0.02 0.05
-
-
10 PIN DFN
12
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
Corporation
ANALOG EXCELLENCE
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.
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
ORDERING INFORMATION
Part Number
Top Mark Operating Temperature Range
Package Type
SP6682EU ....................... SP6682EU....................................40C to +85C ............................. 10 Pin MSOP
SP6682EU/TR ................. SP6682EU....................................40C to +85C ............................. 10 Pin MSOP
SP6682ER ....................... SP6682EURYWW.........................40C to +85C ................................ 10 Pin DFN
SP6682ER/TR ................. SP6682ERYWW...........................40C to +85C ................................ 10 Pin DFN
/TR = Tape and Reel
Pack quantity is 2,500 for MSOP and 3,000 for DFN.
Available in lead free packaging. To order add "-L" suffix to part number.
Example: SP6682ER/TR = standard; SP6682ER-L/TR = lead free
PDF 
ZIP