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SP6686
400mA Buck/Boost Charge Pump LED Driver
FEATURES Output Current up to 480mA 10 VOUT VIN 1 Up to 94% Efficiency in Torch Mode C1 2 SP6686 9 PGND Automatic Softstart limits inrush current 8 SGND C2 3 Adjustable FLASH mode 10 Pin DFN 7I FLASH 4 FB x1 and x2 Automatic Modes for High Efficiency 6I EN 5 SET Minimum External Components: No Inductors High Frequency Operation: 2.4 MHz Now Available in Lead Free Packaging Low 50mV reference for low loss sensing 1A shutdown current PWM Dimming Control APPLICATIONS Automatic switchover between buck/boost White LED Torch/Flash for Cell Over voltage protection on output Phones, DSCs, and Camcorders Over current/temerature protection Generic Lighting/Flash/Strobe Low Ripple and EMI Applications Space Saving 10-pin 3mm x 3mm DFN White LED Backlighting Package DESCRIPTION The SP6686 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 SP6686 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 SP6686 is offered in 10-pin DFN package. TYPICAL APPLICATION CIRCUIT
VIN (2.7 - 5.5V) VIN CFC 0.47F TORCH/FLASH ENABLE C1 C2 FLASH EN VOUT 400mA FLASH COUT 1F WLED
(R)
CIN 2.2F
SP6686 PGND SGND FB RSET
RSET 106K
RSENSE 0.33
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
VIN , VOUT ...................................................................... -0.3V to 6V Output Current Pulse (Flash) .......................... 500mA Output Current Continuous (Torch) ................. 200mA Storage Temperature ...................... -65C to +150C Operating Temperature ..................... -40C to +85C VEN ......................................................... ZeroV to 7V 3x3 10 DFN .........................................OJA = 57.1C/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 = -40C to +85C, VIN = 3.6, CIN = 2.2F, CFC = 0.47F, COUT = 1.0F. VSHDN = VIN, typical values at 25C. The denotes the specifications which apply over the full operating range unless otherwise noted.
PARAMETER Operating Input Voltage Quiescent Current
MIN. 2.7
TYP.
MAX. 5.5
UNITS V mA
CONDITIONS
0.5 2
3
V IN = 2.7 - 5.5V FLASH = 0Volts, Iload = 100A FLASH = VIN, 2x mode
Shutdown Current Oscillator Frequency Charge Pump Equivalent Resistance (x2 mode) Charge Pump Equivalent Resistance (x1 mode) FB Reference Voltage FB Reference Voltage FB Pin Current EN, FLASH Logic Low EN, FLASH Logic High EN, FLASH Pin Current V OUT Turn-on Time Thermal Shutdown Temperature 250 145 1.3 138 45 2.4 5 0.6 150 50
1
A MHz
V IN = 5.5V, VEN = 0Volts
V FB = 0Volts, VIN= 3.6V V IN= 3.6V FLASH = VIN R SET = 106K FLASH = GND V FB = 0.3V V IN = 3.6V, FB within 90% of regulation
0.8 162 55 0.5 0.4
mV mV A V V
0.5 500
A s C
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER 1 2 3 4 PIN NAME VIN C1 C2 FLASH DESCRIPTION Input Voltage for the charge pump. Decouple with 2.2F ceramic capacitor close to the pins of the IC. Positive input for the external fly capacitor. Connect a ceramic 0.47F capacitor close to the pins of the IC. Negative input for the external fly capacitor. Connect a ceramic 0.47F capacitor close to the pins of the IC. 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. Shutdown control input. Connect to VIN for normal operation, connect to ground for shutdown. 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)*11.2K. Feedback input for the current control loop. Connect directly to the current sense resistor. Internal ground pin. Control circuitry returns current to this pin. Power ground pin. Fly capacitor current returns through this pin. Charge Pump Output Voltage. Decouple with an external capacitor. At least 1uF is recommended. Higher capacitor values reduce output ripple.
5 6
EN RSET
7 8 9 10
FB SGND PGND VOUT
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
3
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6, Typical Application, TA = 25C unless otherwise noted. D1 = AOT 2015HPW-1915B LED.
250 200
Torch Mode 150mA Iout
600 500 400
Flash Mode 400mA Iout
(mA)
150 100 50 0 3.0
IOUT (mA)
Iout
Vf = 3.5V Vf = 3.3V Vf = 3.1V Vf = 3.0V
3.2 3.4 3.6 Vin (V) 3.8 4.0 4.2
300 200 100 0 3.0
Vf = 4.1V Vf = 3.8V Vf = 3.5V Vf = 3.2V
3.2 3.4 3.6 VIN (V) 3.8 4.0 4.2
Figure 1. Output Current vs. Supply Voltage (CIN = 2.2F, CFC = 0.47F, COUT = 1.0F
Figure 2. Output Current vs. Supply Voltage (CIN = 2.2F, CFC = 0.47F, COUT = 1.0F
Torch Mode 150mA Efficiency 100 90
100 90
Flash Mode 400mA Efficiency
Vf = 4.1V Vf = 3.8V Vf = 3.5V Vf = 3.2V
70 60 50 40
Efficiency (%)
Efficiency (%)
80
80
Vf = 3.5V
70 60 50 40 3.0 3.2 3.4 3.6 Vin (V) 3.8 4.0 4.2
Vf = 3.3V Vf = 3.1V Vf = 3.0V
3.0
3.2
3.4
3.6 Vin (V)
3.8
4.0
4.2
Figure 3. Efficiency vs. Supply Voltage (CIN = 2.2F, CFC = 0.47F, COUT = 1.0F)
Figure 4. Efficiency vs. Supply Voltage (CIN = 2.2F, CFC = 0.47F, COUT = 1.0F)
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
4
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6, Typical Application, TA = 25C unless otherwise noted. D1 = AOT 2015HPW-1915B LED.
Figure 5. Ripple 1X Flash 400mA CH1=Vin, CH2=Vout, Vin=4.2V, Cin=4.7F, CFC=0.47F, Cout=2.2F
Figure 6. Ripple 2X Flash 400mA CH1=Vin, CH2=Vout, Vin=3.6V, Cin=4.7F, CFC=0.47F, Cout=2.2F
Figure 7. Ripple 1X Torch 150mA CH1=Vin, CH2=Vout, Vin=4.2V, Cin=4.7F, CFC=0.47F, Cout=2.2F
Figure 8. Ripple 2X Torch 150mA CH1=Vin, CH2=Vout, Vin=3.0V, Cin=4.7F, CFC=0.47F, Cout=2.2F
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
5
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6, Typical Application, TA = 25C unless otherwise noted.
D1 = AOT2015HPW-1915B LED, Rsense = 0.33, Rset = 106K, Cin = 2.2F, Cfc = 0.47F, Cout = 1F.
Output Current Vs Supply Voltage
D1 = AOT 3228HPW0303B LED, Rsense = 0.33, Rset = 140K, Cin = 2.2F, Cfc = 0.47F, Cout = 1F.
500
400 350
Output Current Vs Supply Voltage
400
300 250 200 150 100
Iout (mA)
200
Flash 400mA Vf = 3.5V Torch 150mA Vf = 3.1V
Iout (mA)
300
Flash 300mA Vf = 3.85V Torch 150mA Vf = 3.45V
100
50 0
0 3.0
3.2
3.4
3.6 Vin (V)
3.8
4.0
4.2
3.0
3.2
3.4
3.6
3.8
4.0
4.2
Vin (V)
Figure 9
Figure 12
100 90
Efficiency Vs Supply Voltage
100 90
Efficiency Vs Supply Voltage
Efficiency (%)
70 60 50 40 3.0
Flash 400mA Vf = 3.5V Torch 150mA Vf = 3.1V
Efficiency (%)
80
80 70 60 50 40 3.0
Flash 300mA Vf = 3.85V Torch 150mA Vf = 3.45V
3.2
3.4
3.6 Vin (V)
3.8
4.0
4.2
3.2
3.4
3.6
3.8
4.0
4.2
Vin (V)
Figure 10
Figure 13
1000 800
Battery Current Vs Supply Voltage
Battery Current Vs Supply Voltage
800 700 600
Iout (mA)
600
400 200 0 3.0
Flash 400mA Vf = 3.5V Torch 150mA Vf = 3.1V
Iout (mA)
500 400 300 200 100
Flash 300mA Vf = 3.85V Torch 150mA Vf = 3.45V
3.2
3.4
3.6 Vin (V)
3.8
4.0
4.2
0 3.0 3.2 3.4 3.6 3.8 4.0 4.2
Vin (V)
Figure 11
Note: Diode, resistor and capacitor settings apply to figures 9, 10 & 11.
Figure 14
Note: Diode, resistor and capacitor settings apply to figures 12, 13 & 14.
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
6
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6, Typical Application, D1 = AOT2015HPW-1915B LED,TA = 25C unless otherwise noted.
ENABLE ENABLE VOUT
VOUT IIN (0.5A/div) Figure 15. Startup Torch, Vin=3.6V, Vout=3.1V Cin=4.7F,CFC=0.47F, Cout=2.2F
IIN (0.5A/div)
Figure 16. Startup Flash, Vin=3.6V, Vout=3.5V Cin=4.7F,CFC=0.47F, Cout=2.2F
Flash VOUT
Flash VOUT
VFB IOUT (0.5A/div) Figure 17. Torch in 1X to Flash 1X Mode, Vin=4.2V, Cin=4.7F,CFC=0.47F, Cout=2.2F
VFB IOUT (0.5A/div)
Figure 18. Torch in 1X to Flash 2X Mode, Vin=3.6V, Cin=4.7F,CFC=0.47F, Cout=2.2F
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
7
FUNCTIONAL DIAGRAM
RSET BLOCK RSET 6 RSET
1.26V V= RSET
CLK RSET REF BG REF + - 1.26V
RESISTOR TAPS
+ -
MUX 2x1 50mV 0 s
1
FB REF + FB 7 SGN 8 FB COM P
COUNTER 32 COUNT
FB COMP
CLR
SET DOMINANT S 0 R
{ }x11.
2kohms
ONE SHOT
FLASH 4 FLASH=1, S=1, RSET REF FLASH=0, S=0, 50mV
EN 5 VIN 1 MODE SWITCH 0 =1X 1=2X
135C ON 145C OFF
THERMAL FAULT OVER TEMP COMP
CHARGE PUMP SWITCHES
C1 C2 VOUT
2.4MHZ CLK
CLK
PGND
THEORY OF OPERATION The SP6686 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 SP6686 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 SP6686 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 200sec, and then SP6686 goes through a soft-start mode designed to reduce inrush current. The SP6686 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 SP6686 auto detects a dropout condition, which is when the FB pin is below the
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
8
THEORY OF OPERATION regulation point for more than 32 cycles of the internal clock, the SP6686 automatically switches to the 2X mode. The SP6686 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 SP6686, 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 SP6686 FB pin regulates to 50mV output: VFB = 50mV (Torch Mode) 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: VFB = (1.26V/ RSET)*11.2K (Flash Mode) Where 1.26V is the internal bandgap reference voltage and 11.2K is an internal resistance used to scale the RSET current. Typical values of RSET are 40K to 180K for a range of VFB = 300mV to 75mV in Flash mode. The output current is then set in either Flash or Torch mode by the equation: IOUT = VFB / RSENSE
_______________OVERTEMPERATURE PROTECTION When the temperature of the SP6686 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 SP6686 has over voltage protection. If the output voltage rises above the 5.5V threshold, the over voltage protection shuts 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 ____________________OVERCURRENT PROTECTION 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.
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
9
COMPONENT SELECTION The SP6686 charge pump circuit requires 3 capacitors: 4.7F input, 1F output and 0.47F fly capacitor are typically recommended. For the input capacitor, a larger value of 10F will help reduce input voltage ripple for applications sensitive to ripple on the battery voltage. All the capacitors should be ceramic to obtain low ESR, which improves bypassing on the input and output and improves output voltage drive by reducing output resistance. X5R or X7R Ceramic capacitors are recommended for most applications. A selection of recommended capacitors is included in Table 1. The input and output capacitors should be located as close to the VIN and VOUTpins 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 SP6686. The fly capacitor should be located as close to the C1 and C2 pins as possible. 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 for Torch mode, the VFB voltage can be selected for Flash mode using the following equation: 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: RSET = (1.26V/ VFB)*11.2K (Flash Mode) For an example of 150mA Torch mode and 400mA Flash mode, the values RSENSE = 0.33, VFB = 135mV (Flash Mode), and RSET = 106K are calculated. The power obtained in the Flash mode would be: PFLASH = VFB *IOUT = 133mV*400mA = 53mW. The typical 0603 surface mount resistor is rated at 1/10 Watt continuous power and 1/5 Watt pulsed power, more than enough for this application. For other applications, the PFLASH can be calculated from the resistor size selected. The RSENSE resistor is recommended to be size 0603 for most applications.
Manufacturers/ Website TDK/www.tdk.com TDK/www.tdk.com TDK/www.tdk.com TDK/www.tdk.com Murata/www.murata.com Murata/www.murata.com Murata/www.murata.com Murata/www.murata.com
Part Number C1005X5R0J474K C1005X5R0J105K C1608X5R0J225K C1608X5R0J475K GRM155R60J474KE19D GRM155R60J105KE19D GRM188R60J225KE19D GRM188R60J475KE19D
Capacitance/ Voltage 0.47uF/6.3V 1uF/6.3V 2.2uF/6.3V 4.7uF/6.3V 0.47uF/6.3V 1uF/6.3V 2.2uF/6.3V 4.7uF/6.3V
Capacitor Size/Type/Thickness 0402/X5R/0.55mm 0402/X5R/0.55mm 0603/X5R/0.9mm 0603/X5R/0.9mm 0402/X5R/0.55mm 0402/X5R/0.55mm 0603/X5R/0.8mm 0603/X5R/0.8mm
ESR at 100KHz 0.03 0.03 0.03 0.02 0.03 0.03 0.03 0.02
Table 1: Recommended Capacitors
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
10
COMPONENT SELECTION
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 150k 0.22 0.27 0.33 0.39 0.47 Tolerance 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% Size 0402 0402 0402 0402 0402 0402 0402 0402 0402 0402 0603 0603 0603 0603 0603 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
EVALUATION BOARD LAYOUT
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
11
PACKAGE: 10 PIN DFN
D D/2 o E/2
A
E
(A3)
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
L
10 9 8 7 6
K e b
BOTTOM VIEW
3x3 10 Pin DFN SYMBOL
JEDEC MO-229
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 0 14 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
Dimensions in Millimeters: Controlling Dimension MIN 0.80 0.00 MAX 1.00 0.05 14 0.30 2.70 1.75 0.50
A A1 A3 K o
NOM 0.90 0.02 0.20 REF 0.20 0 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:
Date: 03/10/06
SP6686 400mA, Buck/Boost Charge Pump LED Driver
(c) Copyright 2006 Sipex Corporation
12
ORDERING INFORMATION
Part Number Operating Temperature Range Package Type
SP6686ER .................................................. -40C to +85C ........................................................... 10 Pin DFN SP6686ER/TR ............................................ -40C to +85C .......................................................... 10 Pin DFN Available in lead free packaging. To order add "-L" suffix to part number. Example: SP6686ER/TR = standard; SP6686ER-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
Solved By SipexTM
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: 03/10/06 SP6686 400mA, Buck/Boost Charge Pump LED Driver (c) Copyright 2006 Sipex Corporation
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