SP6685
700mA Buck/Boost Charge Pump LED Driver
FEATURES
VIN 1
10 VOUT
■ Output Current up to 700mA
C1 2
■ Up to 94% Efficiency in Torch Mode
SP6685 9 PGND
■ Adjustable FLASH Mode Current
8 SGND
C2 3
10 Pin DFN
■ Minimum External Components: No Inductors
7 FB
FLASH 4
■ Automatic Buck/Boost Mode Switchover
6 RSET
EN 5
■ Wide VIN Range: 2.7V to 5.5V
■ High Frequency Operation: 2.4 MHz
Now Available in Lead Free Packaging
■ Low 50mV Reference for low Loss Sensing
■ IQ < 1μA in Shutdown
APPLICATIONS
■ PWM Dimming Control
■ White LED Torch/Flash for Cell
■ Automatic Soft Start Limits Inrush Current
Phones, DSCs, and Camcorders
■ Overvoltage Protection on Output
■ White LED Backlighting
■ Overcurrent/Temperature Protection
■ Generic Lighting/Flash/Strobe
Applications
■ Low Ripple and EMI
■ General Purpose High Current Boost
■ Ultra-low Dropout Voltage in Buck Mode
■ Space Saving 10-pin 3mm x 3mm DFN Package
DESCRIPTION
The SP6685 is a current-regulated charge pump ideal for powering high brightness LEDs for
camera flash applications. The charge pump can be set to regulate two current levels for
FLASH and TORCH modes. The SP6685 automatically switches modes between step-up
and step-down ensuring that LED current does not depend on the forward voltage. A low
current sense reference voltage (50mV) allows the use of small 0603 current sensing
resistors. The SP6685 is offered in the 10-pin DFN package.
TYPICAL APPLICATION CIRCUIT
VIN
(2.7 - 5.5V)
O
CIN
4.7μF
VIN
CFC
1μF
TORCH/FLASH
ENABLE
®
VOUT
C1
SP6685 PGND
C2
SGND
FLASH
FB
RSET
EN
COUT
1μF
RSET
88KΩ
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
1
WLED
RSENSE
0.22Ω
© 2006 Sipex Corporation
ABSOLUTE MAXIMUM RATINGS
VIN , VOUT ....................................................................... -0.3V to 6V
Output Current Pulse (Flash) ................................. 1A
Output Current Continuous (Torch) ..................... 0.4A
Storage Temperature ...................... -65°C to +150°C
Operating Temperature ..................... -40°C to +85°C
VEN ............................................................ 0.0V to 7V
3mmx3mm 10 DFN .............................OJA = 57.1°C/W
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
TA = -40°C to +85°C, VIN = 3.6V, CIN = 4.7μF, CFC = COUT = 1.0μF. VSHDN = VIN, typical values at 25°C. The ♦ denotes
the specifications which apply over the full operating temperature range unless otherwise noted.
PARAMETER
Operating Input Voltage
MIN.
TYP.
2.7
Quiescent Current
0.5
MAX.
UNITS
CONDITIONS
5.5
V
♦
3
mA
♦
2
Shutdown Current
FLASH = VIN, 2x mode
1
Oscillator Frequency
V IN = 2.7 - 5.5V FLASH = 0.0V,
ILOAD = 100μA
μA
2.4
V IN = 5.5V, VEN = 0.0V
MHz
Charge Pump Equivalent
Resistance (x2 mode)
5
V FB = 0.0V, VIN= 3.6V
Charge Pump Equivalent
Resistance (x1 mode)
0.6
0.8
V IN= 3.6V
FB Reference Voltage
138
150
162
mV
♦
FLASH = VIN R SET = 88.7K
FB Reference Voltage
45
50
55
mV
♦
FLASH = GND
FB Pin Current
0.5
μA
EN, FLASH Logic Low
0.4
V
♦
V
♦
0.5
μA
♦
500
μs
♦
EN, FLASH Logic High
1.3
EN, FLASH Pin Current
V OUT Turn-on Time
250
Thermal Shutdown
Temperature
145
Date: 7/6/06 Rev B
o
V FB = 0.3V
V IN = 3.6V, FB within 90% of
regulation
C
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
PIN DESCRIPTION
PIN NUMBER
PIN NAME
1
VIN
Input Voltage for the charge pump. Decouple with 4.7μF ceramic
capacitor close to the pins of the IC.
2
C1
Positive input for the external fly capacitor. Connect a ceramic 1μF
capacitor close to the pins of the IC.
3
C2
Negative input for the external fly capacitor. Connect a ceramic 1μF
capacitor close to the pins of the IC.
4
FLASH
Logic input to toggle operation between FLASH and TORCH mode.
In TORCH mode FB is regulated to the internal 50mV reference. In
FLASH mode FB reference voltage can be adjusted by changing the
resistor from RSET pin to ground. Choose the external current sense
resistor (RSENSE) based on desired current in TORCH mode.
5
EN
Shutdown control input. Connect to VIN for normal operation, connect
to ground for shutdown.
6
RSET
Connect a resistor from this pin to ground. When in FLASH mode
(FLASH = High) this resistor sets the current regulation point
according to the following: VFB = (1.26V/ RSET)*11.2KΩ.
7
FB
Feedback input for the current control loop. Connect directly to the
current sense resistor.
8
SGND
Internal ground pin. Control circuitry returns current to this pin.
9
PGND
Power ground pin. Fly capacitor current returns through this pin.
10
VOUT
Charge Pump Output Voltage. Decouple with an external capacitor.
At least 1μF is recommended. Higher capacitor values reduce output
ripple.
Date: 7/6/06 Rev B
DESCRIPTION
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, Typical Application Circuit, D1 = Luxeon LXCL-PWF1, TA = 25°C unless otherwise noted.
Torch Mode 200mA Iou
300
Flash Mode 700mA Io
900
800
Iout (mA)
Iout (mA)
700
200
Vf = 3.0V
Vf = 3.3V
Vf = 3.6V
100
600
500
Vf = 3.3V
400
Vf = 3.6V
300
Vf = 3.9V
Vf = 3.9V
Vf = 4.2V
200
100
0
3.0
0
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
3.0
Figure 1. Torch Mode Output Current
Efficiency (%)
Efficiency (%)
Vf
Vf
Vf
Vf
90
80
Vf
Vf
Vf
Vf
70
60
=
=
=
=
3.6
Vin (V
3.8
4.0
4.2
Flash Mode 700mA Efficie
100
90
3.0
3.3
3.6
3.9
50
40
3.0
3.4
Figure 2. Flash Mode Output Current
Torch Mode 200mA Efficie
100
3.2
80
=
=
=
=
3.3V
3.6V
3.9V
4.2V
70
60
50
40
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
3.0
Figure 3. Torch Mode Efficiency
Date: 7/6/06 Rev B
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
Figure 4. Flash Mode Efficiency
SP6685, 700mA Buck/BoostCharge Pump LED Driver
4
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, Typical Application Circuit, D1 = Luxeon LXCL-PWF1, TA = 25°C unless otherwise noted.
VIN
VIN
VOUT
VOUT
Figure 6. PWF1 Ripple 2X Flash 700mA Ch1 = VIN,
Ch2 = VOUT, VIN = 3.6V, CIN = 10μF, CFC = 1μF, COUT
= 4.7μF
Figure 5. PWF1 Ripple 1X Flash 700mA Ch1 = VIN,
Ch2 = VOUT, VIN = 4.2V, CIN = 10μF, CFC = 1μF, COUT
= 4.7μF
VIN
VIN
VOUT
VOUT
Figure 8. PWF1 Ripple 2X Torch 200mA VIN = 3.0V, CIN
= 10μF CFC = 1μF, COUT = 4.7μF
Figure 7. PWF1 Ripple 1X Torch 200mA VIN = 4.2V, CIN
= 10μF CFC = 1μF, COUT = 4.7μF
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, Typical Application Circuit, D1 = Luxeon LXCL-PWF1, TA = 25°C unless otherwise noted.
Flash 1X Input Ripple Vs Output
Flash 2X Input Ripple Vs Output
100
Vin Ripple (mVpp)
Vin Ripple (mVpp)
200
150
Cin = 4.7uF
100
Cin = 10uF
50
0
100
200
300
400
500
600
80
Cin = 4.7uF
Cin = 10uF
60
40
20
0
100
700
200
Output Current (m
Figure 9. COUT = 4.7μF
Flash 1X Vout Ripple Vs Output C
600
700
Flash 2X Vout Ripple Vs Output C
100
50
Cout = 1uF
Cout = 2.2uF
Cout = 4.7uF
300
400
500
600
150
100
50
0
200
700
Output Current (m
Cout = 1uF
Cout = 2.2uF
Cout = 4.7uF
300
400
500
600
700
Output Current (m
Figure 11. CIN = 10μF
Date: 7/6/06 Rev B
500
200
150
0
200
400
Figure 10. COUT = 4.7μF
Vout Ripple (mVpp)
Vout Ripple (mVpp)
200
300
Output Current (m
Figure 12. CIN = 10μF
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
D1 = Luxeon LXCL-PWFI LED, Rsense = 0.22ohms,
RSET = 88.7K, CIN = 4.7μF, CFC = 1.0μF, COUT = 1.0μF
D1 = AOT 3228HPW0303B LED, Rsense = 0.33ohms,
RSET = 162K, CIN = 4.7μF, CFC = 0.47μF, COUT = 1μF
Output Current Vs Supply Vol
900
400
800
350
300
600
500
Iout (mA)
Iout (mA)
700
Flash 700mA Vf = 3
400
Torch 200mA Vf = 3.
300
Flash 300mA Vf = 3.85
200
Torch 150mA Vf = 3.45
150
100
100
50
0
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
3.0
Figure 13.
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
Figure 16.
Efficiency Vs Supply Vol
100
100
90
90
Efficiency (%)
Efficiency (%)
250
200
0
3.0
80
Flash
700mA
3.45V
Torch
200mA
70
60
Mode
Vf =
Mode
Vf = 3.
80
Efficiency Vs Supply Vol
Flash 300m
Vf = 3.85V
Torch 150mA
Vf = 3.45V
70
60
50
50
40
3.0
3.2
3.4
3.6
Vin (V
3.8
4.0
40
3.0
4.2
Figure 14.
1800
Battery Current Vs Supply Vo
800
3.4
3.6
Vin (V
3.8
4.0
4.2
Battery Current Vs Supply Vo
700
1400
600
Iin (mA)
1200
1000
Flash 700mA Vf = 3.
800
Torch 200mA Vf = 3.
600
500
Flash 300mA Vf = 3.8
400
Torch 150mA Vf = 3.4
300
400
200
200
100
0
3.0
3.2
Figure 17.
1600
Iin (mA)
Output Current Vs Supply Vol
3.2
3.4
3.6
Vin (V
3.8
4.0
0
3.0
4.2
3.4
3.6
Vin (V
3.8
4.0
4.2
Figure 18.
Note: diode, resistor, and capacitor settings apply to
figures 16, 17, and 18.
Figure 15.
Note: diode, resistor, and capacitor settings apply to
figures 13, 14, and 15.
Date: 7/6/06 Rev B
3.2
SP6685, 700mA Buck/BoostCharge Pump LED Driver
7
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
D1 = AOT 2015HPW-1915B LED, Rsense = 0.22ohms,
RSET = 80.6K, CIN = 4.7μF, CFC = 1.0μF, COUT = 1.0μF
DI = AOT 6060HPW0305BD LED, Rsense = 0.33ohms,
RSET = 75K, CIN = 4.7μF, CFC = 1.0μF, COUT = 1.0μF
Output Current Vs Supply Vol
600
600
500
500
400
Flash 500mA Vf = 4
300
Torch 150mA Vf = 3
200
100
3.4
3.6
3.8
4.0
0
3.0
4.2
Vin (V
Efficiency Vs Supply Vol
100
3.4
3.6
Vin (V
3.8
4.0
4.2
Efficiency Vs Supply Vol
100
90
Efficiency (%)
90
Efficiency (%)
3.2
Figure 22.
Figure 19.
Flash 500mA
Vf = 4.1V
Torch 150mA
Vf = 3.5V
80
70
60
50
80
Flash 600mA Vf=3.8
70
Torch 200mA Vf = 3
60
50
40
3.0
3.2
3.4
3.6
3.8
4.0
40
4.2
3.0
Vin (V
Figure 20.
1400
3.2
3.4
3.6
Vin (V
3.8
4.0
4.2
4.0
4.2
Figure 23.
Battery Current Vs Supply Vo
1400
1200
1200
1000
1000
Iin (mA)
Iin (mA)
300
100
3.2
Flash 600mA
Vf=3.8V
Torch 200mA
Vf=3.2V
400
200
0
3.0
Output Current Vs Supply Vol
700
Iout (mA)
Iout (mA)
700
800
Flash 500mA Vf = 4
600
Torch 150mA Vf = 3
Flash 600mA Vf=3.
600
Torch 200mA Vf=3.
400
200
200
3.2
3.4
3.6
3.8
4.0
0
4.2
3.0
Vin (V
Figure 21.
3.2
3.4
3.6
Vin (V
3.8
Figure 24.
Note: diode, resistor, and capacitor settings apply to
figures 22, 23, and 24.
Note: diode, resistor, and capacitor settings apply to
figures 19, 20, and 21.
Date: 7/6/06 Rev B
Vs Supply V
800
400
0
3.0
Battery Current
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, Typical Application Circuit, D1 = Luxeon LXCL-PWF1, TA = 25°C unless otherwise noted.
Ch1 = EN
Ch1 = EN
Ch2 = VOUT
Ch4 = lin
Ch2 = VOUT
(0.5A/div)
Ch4 = lin
(0.5A/div)
Figure 25. Startup 200mA Torch,
VIN = 3.6V, VOUT = 3.2V
Figure 26. Startup 700mA Flash,
VIN = 3.6V, VOUT = 3.6V
Figure 27. Torch in 1X to Flash in 1X Mode VIN = 4.2V.
CH1 = FLASH, CH2 = VOUT, CH3 = VFB, CH4 = IOUT 1A/div.
Figure 28. Torch in 1X to Flash in 2X Mode VIN = 3.6V.
CH1 = FLASH, CH2 = VOUT, CH3 = VFB, CH4 = IOUT 1A/div.
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
9
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Application Circuit = Figure 31, TA = 25°C.
Efficiency
100
Output Current
900
Flash 600mA Vf=4.34V
Flash 600mA
Flash 400mA Vf=3.93V
700
Torch 150mA
600
Flash 500mA
Iout (mA)
Efficiency (%)
Flash 300mA Vf=3.72V
Torch 150mA Vf=3.33V
Flash 400mA
80
Flash 500mA Vf=4.13V
800
Flash 300mA
90
70
60
500
400
300
200
50
100
40
0
3.0
3.2
3.4
3.6
3.8
4.0
3.0
4.2
3.1
3.2
3.3
Vin (V)
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
Vin (V)
Figure 29. Efficiency vs. VIN.
Figure 30. Output Current vs. VIN.
APPLICATION INFORMATION
The SP6685 can be used with multiple LEDs in parallel as shown in figure 31. For best
performance, the LEDs should be in a single package, preferably from a single die to have
better matching for forward voltage Vf for a given forward current If. In practice, if the Vf of one
LED is higher than the others, it will consume a larger If, which will raise its temperature which
will then cause its Vf to reduce, correcting the imbalance. The overall current will be the sum
of the individual currents, for example Itotal = 4*ILED.
SP6685
Vin: 3.0-4.2V
1
Cin
10uF
1
2
CF
1uF
3
2
4
3
5
Vin
VOUT
C1
PGND
C2
SGND
FLASH
EN
IFB
ISET
10
9
Cout
4.7 uF
8
7
D1
Sharp LED
GM5BW05340AC
6
J2
Jumper
SW2
R EN
10K
R SET
139K
R FB VFB = 50mV Torch150mA
0.33 Ohm
100mV Flash 300mA
Push ON
Figure 31. MULTIPLE LED FLASH CIRCUIT.
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
10
© 2006 Sipex Corporation
FUNCTIONAL DIAGRAM
CLK
RSET BLOCK
RSET 6
+
RSET
{ }
1.26V
V= RSET
RSET REF
BG REF
+
- 1.26V
RESISTOR
TAPS
FB REF
1
MUX
2x1
50mV 0 s
+
-
FB 7
FB COMP
FB
COM P
SGN 8
SET
DOMINANT
S
0
ONE
SHOT
x11.2kohms
FLASH 4
FLASH=1, S=1, RSET REF
FLASH=0, S=0, 50mV
COUNTER
32 COUNT
CLR
R
EN 5
VIN 1
MODE SWITCH
0 =1X
1=2X
135C ON
THERMAL FAULT
OVER TEMP COMP
145C OFF
2.4MHZ
CLK
CHARGE
PUMP
SWITCHES
C1
C2
VOUT
CLK
PGND
THEORY OF OPERATION
The SP6685 is a charge pump regulator
designed for converting a Li-Ion battery
voltage of 2.7V to 4.2V to drive a white LED
used in digital still camera Flash and Torch
applications. The SP6685 has two modes
of operation which are pin selectable for
either Flash or Torch. Flash mode is usually
used with a pulse of about 200 to 300
milliseconds to generate a high intensity
Flash. Torch can be used continuously at a
lower output current than Flash and is often
used for several seconds in a digital still
camera “movie” mode.
The SP6685 also has two modes of operation to control the output current: the 1X
mode and 2X mode. Operation begins after
the enable pin EN receives a logic high, the
bandgap reference wakes up after 200μsec,
and then SP6685 goes through a soft-start
mode designed to reduce inrush current.
The SP6685 starts in the 1X mode, which
acts like a linear regulator to control the
output current by continuously monitoring
the feedback pin FB. In 1X mode, if the
Date: 7/6/06 Rev B
SP6685 auto detects a dropout condition,
which is when the FB pin is below the
regulation point for more than 32 cycles of
the internal clock, the SP6685 automatically switches to the 2X mode. The SP6685
remains in the 2X mode until one of four
things happens: 1) the enable pin EN has
been toggled, 2) the Flash pin has changed
from high to low, 3) VIN is cycled or, 4) a
thermal fault occurs.
The 2X mode is the charge pump mode
where the output can be pumped as high as
two times the input voltage, provided the
output does not exceed the maximum voltage for the SP6685, which is internally
limited to about 5.5V. In the 2X mode, as in
the 1X mode, the output current is regulated
by the voltage at the FB pin.
In the Torch mode, (Flash = GND) the Flash
pin is set to logic low and the SP6685 FB pin
regulates to 50mV output:
VFB = 50mV (Torch Mode)
SP6685, 700mA Buck/BoostCharge Pump LED Driver
11
© 2006 Sipex Corporation
THEORY OF OPERATION
When in Flash mode, (Flash = VIN), the FB
regulation voltage is set by the resistor RSET
connected between the RSET pin and SGND
and the equation:
off all of the output switches to prevent the
output voltage from rising further. When the
output decreases below 5.5V, the device
resumes normal operation.
VFB = (1.26V/ RSET)*11.2KΩ (Flash Mode)
___________________OVERCURRENT
PROTECTION
Where 1.26V is the internal bandgap reference voltage and 11.2KΩ is an internal
resistance used to scale the RSET current.
Typical values of RSET are 40KΩ to 180KΩ
for a range of VFB = 300mV to 75mV in Flash
mode.
The over current protection circuitry monitors the average current out of the VOUT =
50mV (Torch Mode) pin. If the average
output current exceeds approximately
1Amp, then the over current protection circuitry shuts off the output switches to protect the chip.
The output current is then set in either Flash
or Torch mode by the equation:
_____________________COMPONENT
SELECTION
IOUT = VFB / RSENSE
______________
OVERTEMPERATURE
PROTECTION
The SP6685 charge pump circuit requires 3
capacitors: 4.7μF input, 1μF output and 1μF
fly capacitor are typically recommended.
For the input capacitor, a larger value of
10μF will help reduce input voltage ripple for
applications sensitive to ripple on the battery
voltage. All the capacitors should be surface mount ceramic for low lead inductance
necessary at the 2.4MHz switching frequency
of the SP6685 and to obtain low ESR, which
improves bypassing on the input and output
and improves output voltage drive by reducing output resistance. Ceramic capacitors
with X5R or X7R temperature grade are
recommended for most applications. A selection of recommended capacitors is included in Table 1 below.
When the temperature of the SP6685 rises
above 145 degrees Celsius, the over temperature protection circuitry turns off the
output switches to prevent damage to the
device. If the temperature drops back down
below 135 degrees Celsius, the part automatically recovers and executes a soft start
cycle.
___________________
OVERVOLTAGE
PROTECTION
The SP6685 has over voltage protection. If
the output voltage rises above the 5.5V
threshold, the over voltage protection shuts
Manufacturers
Website
Part Number
Capacitance/
Voltage
Capacitor
Size/Type/Thickness
ESR at
100KHz
TDK/www.tdk.com
TDK/www.tdk.com
TDK/www.tdk.com
Murata/www.murata.com
Murata/www.murata.com
Murata/www.murata.com
C1005X5R0J105M
C1608X5R0J475K
C2012X5R0J106M
GRM155R60J105KE19B
GRM188R60J475KE19
GRM21BR60J106KE19L
1uF/6.3V
4.7uF/6.3V
10uF/6.3V
1uF/6.3V
4.7uF/6.3V
10uF/6.3V
0402/X5R/0.5mm
0603/X5R/0.9mm
0805/X5R/1.35mm
0402/X5R/0.55mm
0603/X5R/0.9mm
0805/X5R/1.35mm
0.03
0.02
0.02
0.03
0.02
0.02
Table 1: Recommended Capacitors
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
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© 2006 Sipex Corporation
COMPONENT SELECTION
The input and output capacitors should be
located as close to the VIN and VOUT pins as
possible to obtain best bypassing, and the
returns should be connected directly to the
PGND pin or to the thermal pad ground located
under the SP6685. The fly capacitor should
be located as close to the C1 and C2 pins as
possible. See typical circuit layout (page 13)
for details on the recommended layout.
for Torch mode, the VFB voltage can be
selected for Flash mode using the following
equation:
To obtain lower output ripple, the COUT value
can be increased from 1μF to 2.2μF or 4.7μF
with a corresponding decrease in output
ripple as shown in the Typical Performance
Characteristic curves. For output currents of
500mA to 700mA, the recommended CFC fly
capacitor value of 1μF should be used. Output currents in Flash of 100mA to 400mA
can use a 0.47μF CFC but a minimum 1μF
COUT is still needed.
_______________________
RESISTOR
SELECTION
RSET = (1.26V/ VFB)*11.2KΩ (Flash Mode)
VFB = IOUT * RSENSE (Flash Mode) where IOUT is
for Flash Mode.
Next, the RSET resistor can be selected for
Flash mode using the following equation:
The sense resistor RSENSE is determined by
the value needed in the Torch mode for the
desired output current by the equation:
RSENSE = VFB/ IOUT where VFB = 50mV (Torch
Mode)
Once the RSENSE resistor has been selected
Part Reference
RSET
RSET
RSET
RSET
RSET
RSET
RSET
RSET
RSET
RSET
RSENSE
RSENSE
RSENSE
RSENSE
RSENSE
Value
68k
75k
82k
91k
100k
110k
120k
130k
140k
For an example of 200mA Torch mode and
600mA Flash mode, the values RSENSE =
0.25Ω, VFB = 150mV (Flash Mode), and RSET
= 94KΩ are calculated. The power obtained
in the Flash mode would be:
PFLASH = VFB *IOUT = 150mV*600mA = 90mW.
The typical 0603 surface mount resistor is
rated 1/10 Watt continuous power and 1/5
Watt pulsed power, more than enough for
this application. For other applications, the
PFLASH power can be calculated and resistor
size selected. The RSENSE resistor is recommended to be size 0603 for most applications. The range of typical resistor values
and sizes are shown here in Table 2.
Tolerance
5%
Size
0402
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
0402
0402
0402
0402
0402
0402
0402
0402
0402
0603
0603
0603
0603
0603
150k
0.22
0.27
0.33
0.39
0.47
Manufacturers
any
any
any
any
any
any
any
any
any
any
Panasonic or
Panasonic or
Panasonic or
Panasonic or
Panasonic or
Vishay
Vishay
Vishay
Vishay
Vishay
Table 2: Resistor values and sizes
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
13
© 2006 Sipex Corporation
EVALUATION BOARD CIRCUIT LAYOUT
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
14
© 2006 Sipex Corporation
PACKAGE: 10 PIN DFN
D
D/2
ø
E/2
A
(A3)
E
A1
Seating Plane
SIDE VIEW
Pin1 Designator
to be within this
INDEX AREA
(D/2 x E/2)
TOP VIEW
D2
D2/2
1
2
3
4
5
INDEX AREA
(D/2 x E/2)
E2/2
E2
K
L
10
9
8
7
e
6
b
BOTTOM VIEW
3x3 10 Pin DFN
SYMBOL
JEDEC MO-229
Dimensions in Millimeters:
Controlling Dimension
NOM
0.90
0.02
0.20 REF
0.20
0º
b
0.18
0.25
D
3.00 BSC
D2
2.20
E
3.00 BSC
E2
1.40
e
0.50 BSC
L
0.30
0.40
SIPEX Pkg Signoff Date/Rev:
A
A1
A3
K
ø
Date: 7/6/06 Rev B
MIN
0.80
0.00
MAX
1.00
0.05
14º
0.30
2.70
1.75
0.50
VARIATION VEED-5
Dimensions in Inches
Conversion Factor:
1 Inch = 25.40 mm
MIN
NOM
MAX
0.032
0.036
0.039
0.000
0.001
0.002
0.008 REF
0.008
0º
14º
0.008
0.010
0.012
0.119 BSC
0.087
0.106
0.119 BSC
0.056
0.069
0.020 BSC
0.012
0.016
0.020
JL Aug09-05 / RevA
SP6685, 700mA Buck/BoostCharge Pump LED Driver
15
© 2006 Sipex Corporation
ORDERING INFORMATION
Part Number
Operating Temperature Range
Package Type
SP6685ER .................................................. -40°C to +85°C ........................................................... 10 Pin DFN
SP6685ER/TR ............................................ -40°C to +85°C .......................................................... 10 Pin DFN
Available in lead free packaging. To order add “-L” suffix to part number.
Example: SP6685ER/TR = standard; SP6685ER-L/TR = lead free
/TR = Tape and Reel
Pack quantity is 3,000 for DFN.
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.
Date: 7/6/06 Rev B
SP6685, 700mA Buck/BoostCharge Pump LED Driver
16
© 2006 Sipex Corporation