SP6682
High Efficiency Charge Pump
Regulator for White LEDs
FEATURES
■
Ideal For White LED Driver
■
Low Profile, Inductorless Regulator
■
Output Current up to 200mA
■
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
■
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
V
OUT
C1P
V
IN
V
MODE
FB
1
2
3
4
5
10
C2P
C1N
GND
C2N
EN/PWM
SP6682
10 Pin DFN
9
8
7
6
Now Available in Lead Free Packaging
APPLICATIONS
■
Next Generation Mobile Phones
■
PDAs
■
3.3V to 5.0V Conversion
■
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 LEDs used in backlighting color displays or cell phone camera flash applications.
The charge pump automatically switches between X1.5 and X2 modes based on the program-
mable V
MODE
voltage, providing improved efficiency over traditional methods using charge pump
doubler followed by LDO. This input voltage threshold can be externally programmed by a resistor
divider network for optimized efficiency at specific output voltages and currents. The SP6682
operates with an internal 600kHz clock, which reduces switching noise and improves V
OUT
ripple.
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
LCD BACKLIGHT
APPLICATION
2.7 - 4.2V
C6
0.1µF
C2
2.2µF
®
Lithium-Ion
C1
2.2µF
C2P 10
SP6682
C1N 9
3
8
V
IN
GND
4
7
V
MODE
C2N
5
6
FB
EN/PWM
1 V
OUT
2 C1P
C4
2.2µF C5
2.2µF
White
LED
R6
20
R3
1M
20
20
20
ENABLE/PWM DIMMING
Date: 7/19/06 Rev
D
SP6682 High Efficiency Charge Pump Regulator for White LEDs
© 2006 Sipex Corporation
1
TYPICAL APPLICATION SCHEMATIC
Iout=200mA for 1W LED
CAMERA FLASH
APPLICATION
Vin: 3.0-4.2V
SP6682
1
Vout
2
C1P
3
Vin
GND
C1N
C2P
10
LEDA
9
8
C4
2.2uF
1W LED
4
Vmode
5
C2N
FB
EN/PWM
7
6
C1
2.2uF
R3
1.0M
C5
2.2uF
LEDK
VFB=300mV
Rfb
1.5 Ohm
ENABLE/PWM
ABSOLUTE MAXIMUM RATINGS
V
IN
, V
MODE
, V
OUT
and EN/PWM ................. -0.3V to 6V
V
IN
- V
OUT
........................................................... 0.7V
Output Current (I
OUT
) ...................................... 300mA
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
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: V
IN
=+2.7V to +5.0V, C1=C2=C4=C5=2.2µF (ceramic, ESR=0.03½), C3=0.1µF
(ceramic) and T
AMB
=-40°C to +85°C unless otherwise noted.
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
= 100µA
Shutdown Current
1.5
µA
EN/PWM = 0.0V, 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
Resistance
11
18
½½
FB = 0.0V, V
IN
= 3.6V,
I
OUT
= 20mA, V
MODE
= High
V
MODE
Threshold Voltage
1.15
1.25
1.35
V
V
IN
Falling @ 25°C
Hysteresis for Mode Transition
Voltage
30
mV
PP
V
IN
= 3.6V @ 25°C
V
MODE
Pin Current
0.01
0.5
µA
V
MODE
= 1.25
EN/PWM Logic Low
0.4
V
EN/PWM Logic High
EN/PWM Pin Current
FB Pin Current
1.6
0.01
175
V
0.5
0.5
µA
µA
V
EN/PWM
= 4.2V
V
FB
= 1V
V
OUT
Turn-On Time
500
µs
V
IN
= 3.6V, FB within 90% regulation
Date: 7/19/06 Rev
D
SP6682 High Efficiency Charge Pump Regulator for White LEDs
© 2006 Sipex Corporation
2
OPERATION
GENERAL OVERVIEW
The SP6682 is a current regulated charge
pump ideal for converting a Li-Ion battery
input for driving white LEDs used in back-
lighting color displays, Cell Phone Camera
Flash, PDAs, digital cameras and MP3 play-
ers. The SP6682ʼs proprietary AutoBoost
feature enables the IC to automatically trans-
ition 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 shutdown 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.
an input voltage to the mode comparator
which sets the logic state of the mode selec-
tion outputs to the X2 or X1.5 modes. V
MODE
is compared to a 1.25V bandgap voltage.
For example, if one makes a 158K½/100K½½
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.
During start-up, until the reference is estab-
lished, this block keeps the charge pump
inactive. During this period the output stays
floating, and 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 LEDs from experienc-
ing 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
feedback output voltage to control the V
OUT
needed for the application. Output current is
set by a bias resistor from FB pin to GND pin
chosen by the relationship:
I
= V
FB
OUT
THEORY OF OPERATION
The SP6682 regulated charge pump block
diagram consists of four main blocks
(Voltage Reference, Mode Control, Clock
Manager, Start-up and Charge-Pump
Switches) and two comparators (V
MODE
Comparator and V
OUT
Comparator).
1) Voltage Reference.
This block provides
the 306mV and 1.25V reference voltages
needed for the two comparators.
2) Mode Control.
An external voltage di-
vider connected to the V
MODE
pin will define
R
FB
where V
FB
= 306mV.
Date: 7/19/06 Rev
D
SP6682 High Efficiency Charge Pump Regulator for White LEDs
© 2006 Sipex Corporation
5
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