View SP6682_36170.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

(R)
SP6682
High Efficiency Charge Pump Regulator for White LEDs
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
VOUT C1P VIN VMODE FB
1 2 3 4 5
10 C2P
SP6682
10 Pin DFN
9 C1N 8 GND 7 C2N 6 EN/PWM
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
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
C6 0.1F C4 2.2F C5 2.2F White LED
C2 2.2F 2.7 - 4.2V
(R)
Lithium-Ion
C1 2.2F
R1
C2P 10 SP6682 C1N 9 3 8 VIN GND 4 7 VMODE C2N 5 6 FB EN/PWM
1V OUT 2 C1P
R2
C3 0.1F
R6 20
20
20
20
ENABLE/PWM DIMMING
R3 1M
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
VIN, VMODE, VOUT and EN/PWM ................. -0.3V to 6V VIN - VOUT ........................................................... 0.7V Output Current (IOUT) ...................................... 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.
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: VIN =+2.7V to +5.0V, C1=C2=C4=C5=2.2F (ceramic, ESR=0.03), C3=0.1F (ceramic) and TAMB =-40C to +85C unless otherwise noted. PARAMETER Input Voltage Quiescent Current Shutdown Current Oscillator Frequency VFB Reference Voltage Charge Pump Output Resistance VMODE Threshold Voltage Hysteresis for Mode Transition Voltage VMODE Pin Current EN/PWM Logic Low EN/PWM Logic High EN/PWM Pin Current FB Pin Current VOUT Turn-On Time 175 1.6 0.01 0.5 0.5 500 1.15 0.42 0.275 0.60 0.306 11 1.25 30 0.01 0.5 0.4 MIN 2.7 1.2 TYP MAX 5.5 3 1.5 0.78 0.337 18 1.35 UNITS V mA A MHz V V mVPP A V V A A s VEN/PWM = 4.2V VFB = 1V VIN = 3.6V, FB within 90% regulation FB = 0V, VIN = 3.6V, IOUT = 20mA, VMODE = High VIN Falling @ 25C VIN = 3.6V @ 25C VMODE = 1.25 VIN = 4.2V, VOUT = 3.6V, IOUT = 100A EN/PWM = 0V, VIN = 5.5V VIN = 3.6V CONDITIONS
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER 1 2 3 4 PIN NAME VOUT C1P VIN VMODE DESCRIPTION Regulated charge pump output. Positive terminal to the charge pump flying capacitor C2. Input pin for the 2.7V to 5.5V supply voltage. Charge pump mode program pin. When VMODE 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 VIN threshold for charge pump mode switching. This is the feedback pin for output current or voltage regulation. The voltage of this pin is compared with an internal 306mV reference. Enable and PWM dimming control input. Pull this pin low to disconnect VOUT from VIN and shutdown the SP6682. Negative terminal to the charge pump flying capacitor, C4. Ground reference. Negative terminal to the charge pump flying capacitor, C2. Positive terminal to the charge pump flying capacitor C4.
5 6 7 8 9 10
FB EN/PWM C2N GND C1N C2P
FUNCTIONAL DIAGRAM
VIN EN/PW Voltage Referenc
1.25V
600 kHz Clock Manager
C1P Start-up and Charge Pump Switches C1N C2P C2N VOUT
VMODE
MODE COMP
Mode Control
306m
FB
VOUT COMP
GND
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
3
PERFORMANCE CHARACTERISTICS Refer to the typical application circuit, TAMB = 25C, IO = 60mA unless otherwise specified.
EN/PWM
5V/DIV 1V/DIV VOUT
90 80 70
Efficiency (%)
60 50 40 30 20 10 0 2.7 3 3.3 3.6 3.9 4.2
Input Voltage(V)
Figure 1. Output voltage turn-on time
Figure 2. Power efficiency vs. input voltage
VIN
50mV/DIV
0.34 0.33 0.32
VFB (V)
0.31 0.3 0.29
VOUT
50mV/DIV
0.28 0.27 0.26 2.7 3 3.3 VIN (V) 3.6 3.9 4.2
Figure 3. X2 mode voltage ripple when VIN = 2.7V
Figure 4. Feedback pin voltage vs. input voltage
VIN
50mV/DIV
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 2.7 3 3.3 VIN (V) 3.6 3.9 4.2
VOUT
50mV/DIV
Figure 5. X1.5 mode voltage ripple when VIN = 3.3V
Figure 6. Quiescent current vs. input voltage
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
ISUPPLY (mA)
(c) Copyright 2004 Sipex Corporation
4
PERFORMANCE CHARACTERISTICS: Continued Refer to the typical application circuit, TAMB = 25C, IO = 60mA unless otherwise specified.
6 5 Brightness (kcd/m2)
3 100 Hz
Brigtness, kCd/m2
4 3 2 1 0 2.7
500 Hz 2
1
0
3 3.3 3.6 3.9 4.2
0
20
40
60
80
100
Input Voltage (V) 4 LED's @ 30mA 4 LED's @ 15mA
Duty Cycle,%
Figure 7. Brightness vs. input voltage
Figure 8. Brightness vs duty cycle
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 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 1.5A 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
parators (VMODE Comparator and VOUT 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 divider connected to the VMODE 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. VMODE 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 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 VOUT. Charging of the output will occur (e.g. when VIN is ramped up to 4.2V, VOUT ramps only up to about 3V), but not to the value of VIN, protecting the White LED from experi-
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-
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
5
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) VOUT Comparator and Output Control. A 306mV reference voltage is compared to feedback 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 = VFB
OUT
RFB where VFB = 306mV. APPLICATION INFORMATION
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 = VFB ILED
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
FB
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.
1
VOUT Anode 1
VOUT SP6682 FB
5
Rb Rb
SP6682
2-wire W-LED module
VFB GND
8
5
Cathode
Rb
GND 8
2.2uF
Figure 9. Driving discrete white LEDs as current source
Date: 5/5/04
Figure 11. Driving 2-wire white LED module as current source
(c) Copyright 2004 Sipex Corporation
SP6682 High Efficiency Charge Pump Regulator for White LEDs
6
APPLICATION INFORMATION: Continued In this application, the bias resistor can be selected by: R = VFB
B
Programming the Operating Mode
ILED (TOTAL) where ILED(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
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: VTH = (VF + 0.306 + m * ILED * ROUT)/1.5 Where VF and m are the forward voltage and number of the white LEDs, Rout is the output resistance of the SP6682.
VOUT
1
Anode
R5
SP6682 VFB 5
2.2uF
R6
GND 8
2-wire W-LED module Cathode
The equation for the voltage divider R1 and R2 with VMODE = 1.25V is: VTH = 1.25V * (1+R1/R2)
Figure 12. Driving 2-wire white LED module as voltage source
which can be expressed as R1: R1 = (VTH / 1.25 -1) * R2 For the typical SP6682 application, Using VF=3.6V, m=4, ILED=15mA, ROUT=16, the VTH will be 3.24V. Select R2=100k, then R1=158k.
Capacitor Selection
resistors and the feedback control voltage as shown by: VOUT = ( 1 + R5 ) * VFB R6
VIN
3 VIN
R1
4
R2
SP6682 VMODE
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(c) Copyright 2004 Sipex Corporation
C2
GND 8
Figure 13. Programming the Vmode Resistors
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
7
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/ TELEPHONE# TDK/847-803-6100 TDK/847-803-6100 MURATA/770-436-1300 MURATA/770-436-1300 PART NUMBER C2012X5R1A225K C2012X5R0J475K GRM188R60J225KE01D GRM219R60J475KE01D CAPACITANCE/ VOLTAGE 2.2F/10V 4.7F/6.3V 2.2F/6.3V 4.7F/6.3V CAPACITOR/ SIZE/TYPE 0805/X5R 0805/X5R 0603/X5R 0805/X5R ESR AT 100kHz 0.030 0.020 0.030 0.020
capacitors could further reduce the input and output ripple. Refer to Table 1 for some suggested low ESR capacitors.
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
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.
VOUT
1
I1
D1
I2
D2
In
Dn
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: I1 I2 = VOUT - VF1 VOUT - VF2
VF1
VF2
VFn
SP6682
Rb1
5 VFB GND 8
Rb
Rb2
Rb
Rb
Figure 14. Increasing brightness matching
Power Efficiency
The efficiency of driving the white LEDs can be calculated by:
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 proporDate: 5/5/04
VF * IF VF = VF * IF = Vi * Ii Vi * (n * IF + IQ) Vi * n
(c) Copyright 2004 Sipex Corporation
SP6682 High Efficiency Charge Pump Regulator for White LEDs
8
APPLICATION INFORMATION Where Vi, Ii are input voltage and current VF, IF 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
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: ILED = VFB R1
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
DS SCHOTTKY MBR0530
ILED = VFB/R1 = 20mA
D1 D2 D7 D8
100 95
SP6682
1 2 VOUT C1P VIN VMODE FB C2P C1N GND C2N EN/PWM 10 9 8 7 6 Q1 SI1304 SOT23 25V 2.2uF 25V C3 X5R Ceramic
Efficiency (%)
D3
D9
Vin: 2.7-4.2V
90 85 80 75
3 4
D4
D10
C1
5 R3 1M
10uF X5R Ceramic
D5 D6
D11 D12
EN/PWM
R1 15
R2 15
70 2.7 3.0 3.3 3.6 3.9 4.2 VIN (V)
Figure 15. Using SP6682 as a High Voltage White LED Driver
PINOUTS
VOUT C1P VIN VMODE FB
1 2 3 4 5
10 C2P
VOUT 1 C1P 2 VIN 3 VMODE 4 FB 5
10 C2P
SP6682
10 Pin DFN
9 C1N 8 GND 7 C2N 6 EN/PWM
SP6682
10 Pin MSOP
9 C1N 8 GND 7 C2N 6 EN/PWM
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
9
PACKAGE: 10 PIN MSOP
(ALL DIMENSIONS IN MILLIMETERS)
D e1
O1
E/2
R1 R Gauge Plane L2 Seating Plane
1 2
E
E1
O1
L L1
O
e Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)
Dimensions in (mm)
10-PIN MSOP JEDEC MO-187 (BA) Variation MIN NOM MAX 0 0.75 0.17 0.08 0.85 3.00 BSC 4.90 BSC 3.00 BSC 0.50 BSC 2.00 BSC 0.4 0.07 0.07 0 0 0.60 0.95 0.25 10 0.80 8 15 1.1 0.15 0.95 0.27 0.23
A A1 A2 b c D E E1 e e1 L L1 L2 N R R1 O O1
(b)
WITH PLATING
c
BASE METAL
D A2 b A1 A
1
Date: 5/5/04 SP6682 High Efficiency Charge Pump Regulator for White LEDs (c) Copyright 2004 Sipex Corporation
10
PACKAGE: 10 PIN DFN
Top View D
Bottom View
e b
D/2 1 2
E/2
E K L
E2
Pin 1 identifier to be located within this shaded area. Terminal #1 Index Area (D/2 * E/2)
D2
10 Pin DFN
(JEDEC MO-229, VEED-5 VARIATION)
DIMENSIONS in (mm)
SYMBOL A A1 A3 b D D2 e E E2 K L
MIN NOM MAX
0.80 0.90 1.00 A A1 A3
0
0.02 0.05
0.20 REF
0.18 0.25 0.30 3.00 BSC 2.20 2.70 0.50 PITCH 3.00 BSC 1.40 1.75 0.20 0.30 0.40 0.50
Side View
10 PIN DFN
Date: 5/5/04 SP6682 High Efficiency Charge Pump Regulator for White LEDs (c) Copyright 2004 Sipex Corporation
11
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 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.
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.
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs
(c) Copyright 2004 Sipex Corporation
12

▲Up To Search▲

Price & Availability of SP6682

	To Download SP6682 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .