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(R)
SP6691
Micro Power Boost Regulator Series White LED Driver
FEATURES Drives up to 6 LED's @ 25mA Drives up to 8 LED's @ 20mA High Output Voltage: Up to 34V Optimized for Single Supply, 2.7V - 4.2V Applications Operates Down to 1V High Efficiency: Greater Than 75% Low Quiescent Current: 20A Ultra Low Shutdown Current: 10nA Single Battery Cell Operation Programmable Output Voltage 1 switch (350mV at 350mA) Available in 8 Pin DFN, 5 Pin TSOT or 5 Pin SOT23
NC FB NC SW
1 2 3 4
8 GND
SP6691
8 Pin DFN
7 VIN 6 VEN 5 NC
Now Available in Lead Free Packaging
APPLICATIONS White LED Driver High Voltage Bias Digital Cameras Cell Phone Battery Backup Handheld Computers
DESCRIPTION The SP6691 is a micro power boost regulator that is specifically designed for powering series configuration white LED. The part utilizes fixed off time architecture and consumes only 10nA quiescent current in shutdown. Low voltage operation, down to 1V, fully utilizes maximal battery life. The SP6691 is offered in a 8 Pin DFN, 5-pin SOT-23 or 5 Pin TSOT package and enables the construction of a complete regulator occupying < 0.2 in2 board space. TYPICAL APPLICATION CIRCUIT
10H 2.7 to 4.2V L1
D1 SW
(R)
VIN
SP6691 SHDN 4.7F GND C1 FB
C2
2.2 F
Rb
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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ABSOLUTE MAXIMUM RATINGS
VIN ....................................................................... 15V SW Voltage .............................................. -0.4 to 34V FB Voltage ......................................................... 2.5V All other pins ................................... -0.3 to VIN + 0.3V Current into FB ................................................. 1mA TJ Max ............................................................. 125C Operating Temperature Range ............ -40C to 85C Peak Output Current < 10us SW .................... 500mA Storage Temperature ...................... -65C to +150C Power Dissipation. ......................................... 200mW Lead Temperature (Soldering, 10 sec) ............ 300C 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
Specifications are at TA=25C, VIN =3.3, VSHDN =VIN, denotes the specifications which apply over the full operating temperature range, unless otherwise specified. PARAMETER Input Voltage Supply Current SYMBOL VIN IQ MIN 1.0 20 0.01 Reference Voltage FB Hysteresis VFB Input Bias Current Line Regulation Switch Off Time Switch Saturation Voltage Switch Current Limit SHDN Bias Current SHDN High Threshold (on) SHDN Low Threshold (off) Switch Leakage Current VFB HYST IFB Vo/VI TOFF VCESAT ILIM ISHDN VIH VIL ISWLK 0.01 0.9 0.25 5 325 1.17 1.22 8 15 0.1 250 170 450 5 450 575 12 80 0.3 TYP MAX 13.5 30 1 1.27 UNITS V A A V mV nA %/V nS mV mA A V V A

CONDITIONS
No Switching SHDN = 0V (off)
VFB = 1.22V 1.2 VIN 13.5V

ISW = 325mA
VSHDN = 3.3V
Switch Off, VSW = 5V
PIN DESCRIPTION
PIN NUMBER 1 2 3 4 5 PIN NAME SW GND FB SHDN VIN DESCRIPTION Switch input to the internal power switch. Ground Feedback Shutdown. Pull high (on) to enable. Pull low (off) for shutdown. Input Voltage. Bypass this pin with a capacitor as close to the device as possible.
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation
2
FUNCTIONAL DIAGRAM
5
VIN
SW
1
R1
R2 X1 + DISABLE SET 250ns ONE-SHOT R3 CLEAR X2 DRIVER + R4 POWER TRANSISTOR
Q1 FB 3
Q2
GND SHDN 4 Shutdown Logic 2
THEORY OF OPERATION
General Overview:
Operation can be best understood by referring to the functional diagram above and the typical application circuit in the front page. Q1 and Q2 along with R3 and R4 form a band gap reference. The input to this circuit completes a feedback path from the high voltage output through a voltage divider, and is used as the regulation control input. When the voltage at the FB pin is slightly above 1.22V, comparator X1 disables most of the internal circuitry. Current is then provided by capacitor C2, which slowly discharges until the voltage at the FB pin drops below the lower hysteresis point of X1, about 6mV. X1 then enables the internal circuitry, turns on chip power, and the current in the inductor begins to ramp up. When the current through the driver transistor reaches about 450mA, comparator X2 clears the latch, which turns off the driver transistor for a preset 250nS. At the instant of shutoff, inductor current is diverted to the output through diode D1. During this 250nS time limit, inductor current decreases while its energy charges C2.
Date: 5/25/04
At the end of the 250ns time period, driver transistor is again allowed to turn on which ramps the current back up to the 450mA level. Comparator X2 clears the latch, it's output turns off the driver transistor, and this allows delivery of L1's stored kinetic energy to C2. This switching action continues until the output capacitor voltage is charged to the point where FB is at band gap (1.22V). When this condition is reached, X1 turns off the internal circuitry and the cycle repeats.
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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PERFORMANCE CHARACTERISTICS
Refer to the typical application circuit, TAMB = 25C, unless otherwise specified.
Vout = 12V Efficiency
90 80 70 60 50 0 20 40 60 80 Iout (mA) 100 120 140 160 Vin = 5.0V Vin = 4.2V Vin = 3 3V
13.0 12.5
Vout (V)
Vout = 12V Load Regulation
Vin = 5.0V Vin = 4.2V Vin = 3 3V
Efficiency (%)
12.0 11.5 11.0 0 20 40 60 80 100 120 140 160 Iout (mA)
Figure 1. 12V Output Efficiency
Figure 2. 12V Output Load Regulation
90
Vout = 15V Efficiency
Vin = 5.0V Vin = 4.2V Vin = 3.3V Vi
16.0
Vout = 15V Load Regulation
Vin = 5.0V Vin = 4.2V 15.5 Vin = 3.3V Vin = 2.7V 15.0
Efficiency (%)
80
70
60
Vout (V)
14.5
50 0 20 40 60 80 100 120
14.0 0 20 40 60 80 100 120
Iout (mA)
Iout (mA)
Figure 3. 15V Output Efficiency
Figure 4. 15V Output Load Regulation
Vout = 18V Efficiency
90 Vin = 5.0V Vin = 4.2V Vin = 3 3V
Vout = 18V Load Regulation
19.0 Vin = 5.0V Vin = 4.2V Vin = 3 3V
Efficiency (%)
80
18.5 Vout (V)
70
18.0
60
17.5
50 0 20 40 60 Iout (mA) 80 100
17.0 0 20 40 60 Iout (mA) 80 100
Figure 5. 18V Output Efficiency
Figure 6. 18V Output Load Regulation
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation
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PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, TAMB = 25C, unless otherwise specified.
Vout = 21V Efficiency
90 Vin = 5.0V Vin = 4.2V Vin = 3 3V
Vout = 21V Load Regulation
22.0 Vin = 5.0V Vin = 4.2V Vin = 3 3V
Efficiency (%)
80
21.5
70
Vout (V)
21.0
60
20.5
50 0 10 20 30 40 Iout (mA) 50 60 70
20.0 0 10 20 30 40 Iout (mA) 50 60 70
Figure 7. 21V Output Efficiency
Figure 8. 21V Output Load Regulation
Vout = 24V Efficiency 90
Efficiency (%)
Vin = 5.0V Vin = 4.2V Vin = 3 3V
25.0
Vout = 24V Load Regulation
Vin = 5.0V Vin = 4.2V Vin = 3 3V
80 70 60 50 0 10 20 30 Iout (mA) 40 50 60
24.5
Vout (V)
24.0
23.5
23.0 0 10 20 30 Iout (mA) 40 50 60
Figure 9. 24V Output Efficiency
Figure 10. 24V Output Load Regulation
Vout = 30V Efficiency
90 80 Vin = 5.0V Vin = 4.2V Vin = 3 3V
31.0 30.5 Vout (V) 30.0 29.5
Vout = 30V Load Regulation
Vin = 5.0V Vin = 4.2V Vin = 3 3V
Efficiency (%)
70 60 50 40 0 5 10 15 Iout (mA) 20 25 30
29.0 0 5 10 15 Iout (mA) 20 25 30
Figure 11. 30V Output Efficiency
Figure 12. 30V Output Load Regulation
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, TAMB = 25C, unless otherwise specified.
25
Shutdown Pin Current (uA)
10 8 6 4 2 0
Quiescent Current (uA)
20 15 10 5 0 1.2 1.8 2.4 3 3.6 4.2 4.8 5.4 Input Voltage (V) Tamb=-25C Tamb=25C Tamb=85C
1.2
1.8
2.4
3
3.6
4.2
4.8
5.4
Input Voltage (V)
Figure 13. Quiescent Current IQ vs. VIN
Figure 14. Shutdown Pin Current vs. VIN
600
Switch Saturation Voltage (mV)
400 350 300 250 200 150 100 50 0 -30 -10 10 30
Temperature (C)
500
Current Limit (mA)
400 300 200 100 0 1.2 1.8 2.4 3 3.6 4.2 4.8 5.4 Input Voltage (V)
50
70
90
Figure 15. IPK Current Limit vs. VIN
Figure 16. Switch Saturation Voltage VCESAT vs. Temperature (ISW = 450mA)
20 16
Iout/Idc (%)
1.25
Feedback Voltage (V)
1.24 1.23 1.22 1.21
12 8
4
1.20 -30 -10 10 30
Temperature (C)
50
70
90
0 0 20 40 60 80 100 PWM Duty Cycle (%)
Figure 17. Feedback Voltage vs. Temperature
Figure 18. Average IO vs. SHDN Duty Cycle (VIN=3.3V, Standard 4x20mA WLED Evaluation Board, PWM Frequency 100Hz
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation
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PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, TAMB = 25C, unless otherwise specified.
EN
VSW
VOUT VOUT (AC) IIN (0.5A/Div) IL (0.5A/Div)
Figure 19. Startup Waveform (VIN=3.3V, VOUT=15V, IOUT=20mA)
Figure 20. Typical Switching Waveforms (VIN=3V, VOUT=15V, IOUT=20mA)
IOUT (100mA/Div) VOUT (AC)
IL (0.5A/Div)
Figure 21. Load Step Transient (VIN=3V, VOUT=21V, 115mA Load Step
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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APPLICATION INFORMAMTION
Inductor Selection Capacitor Selection
For SP6691, the internal switch will be turned off only after the inductor current reaches the typical dc current limit (ILIM=450mA). However, there is typically propagation delay of 200nS between the time when the current limit is reached and when the switch is actually turned off. During this 200nS delay, the peak inductor current will increase, exceeding the current limit by a small amount. The peak inductor current can be estimated by: IPK = ILIM + VIN(MAX) L * 200nS
Ceramic capacitors are recommended for their inherently low ESR, which will help produce low peak to peak output ripple, and reduce high frequency spikes. For the typical application, 4.7F input capacitor and 2.2F output capacitor are sufficient. The input and output ripple could be further reduced by increasing the value of the input and output capacitors. Place all the capacitors as close to the SP6691 as possible for layout. For use as a voltage source, to reduce the output ripple, a small feedforward (47pF) across the top feedback resistor can be used to provide sufficient overdrive for the error comparator, thus reduce the output ripple. Refer to Table 2 for some suggested low ESR capacitors. Table 2. Suggested Low ESR Capacitor
MANUF. MURATA 770-436-1300 MURATA 770-436-1300 PART NUMBER GRM32RR71E 225KC01B GRM31CR61A 475KA01B C3225X7R1E 225M C3216X5R1A 475K CAP SIZE /VOLTAGE /TYPE 2.2F /25V 4.7F /10V 2.2F /25V 4.7F /10V 1210 /X5R 1206 /X5R 1210 /X7R 1206 /X5R
The larger the input voltage and the lower the inductor value, the greater the peak current. In selecting an inductor, the saturation current specified for the inductor needs to be greater than the SP6691 peak current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. Choosing an inductor with low DCR decreases power losses and increase efficiency. Refer to Table 1 for some suggested low ESR inductors. Table 1. Suggested Low ESR inductor
MANUF. PART NUMBER DCR () Current Rating (mA) 450
TDK 847-803-6100 TDK 847-803-6100
MURATA 770-436-1300 TDK 847-803-6100
LQH32CN100K11 (10H) NLC453232T-100K (10H)
0.3
0.55
500
LED Current Program
Diode Selection
A schottky diode with a low forward drop and fast switching speed is ideally used here to achieve high efficiency. In selecting a Schottky diode, the current rating of the schottky diode should be larger than the peak inductor current. Moreover, the reverse breakdown voltage of the schottky diode should be larger than the output voltage.
Date: 5/25/04
In the white LEDs application, the SP6691 is generally programmed as a current source. The bias resistor Rb, as shown in the typical application circuit is used to set the operating current of the white LED using the equation: Rb = VFB IF
where VFB is the feedback pin voltage (1.22V), IF is the operating current of the White LEDs. In order to achieve accurate LED current, 1%
(c) Copyright 2004 Sipex Corporation
SP6691 Micro Power Boost Regualtor, Series White LED Driver
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APPLICATION INFORMAMTION: Continued precision resistors are recommended. Table 3 below shows the Rb selection for different white LED currents. For example, to set the operating current to be 20mA, Rb is selected as 60.4 , as shown in the schematic. Table 3. Bias Resistor Selection IF (mA) 5 10 12 15 20
Output Voltage Program
Table 4. Divider Resistor Selection VOUT (V) 12 15 18 21 30
Brightness Control
R1 () 1M 1M 1M 1M 1M
R2 () 113K 88.7K 73.2K 61.9K 42.2K
Rb () 243 121 102 80.6 60.4
The SP6691 can be programmed as either a voltage source or a current source. To program the SP6691 as voltage source, the SP6691 requires 2 feedback resistors R1 & R2 to control the output voltage. As shown in Figure 22.
VIN
L1
D1
Dimming control can be achieved by applying a PWM control signal to the SHDN pin. The brightness of the white LEDs is controlled by increasing and decreasing the duty cycle of the PWM signal. A 0% duty cycle corresponds to zero LED current and a 100% duty cycle corresponds to full load current. 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. The magnitude of the PWM signal should be higher than the minimum SHDN voltage high.
Open Circuit Protection
VOUT
C2 C1 U1
5 VI N 4 1 SW
R1
SP6691
SHDN G ND FB
3
1.22V
R2
2
Figure 22. Using SP6691 as Voltage Source
When any white LED inside the white LED module fails or the LED module is disconnected from the circuit, the output and the feedback control will be open, thus resulting in a high output voltage, which may cause the SW pin voltage to exceed it maximum rating. In this case, a zener diode can be used at the output to limit the voltage on the SW pin and protect the part. The zener voltage should be larger than the maximum forward voltage of the White LED module.
The formula and table for the resistor selection are shown below: VOUT 1.22 - 1 ) * R2
R1 =(
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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APPLICATION INFORMAMTION: Continued
Layout Consideration
Both the input capacitor and the output capacitor should be placed as close as possible to the IC. This can reduce the copper trace resistance which directly effects the input and output ripples. The feedback resistor network should be kept close to the FB pin to minimize copper trace connections that can inject noise into the system. The ground connection for the feedback resistor network should connect directly to the GND pin or to an analog ground plane that is tied directly to the GND pin. The inductor and the schottky diode should be placed as close as possible to the switch pin to minimize the noise coupling to the other circuits, especially the feedback network.
Power Efficiency
VIN
2.7-4.2V
Murata LQH32CN100K11 L1 10uH 0.45A
DS
MBR0530
C1 4.7uF
C2 2.2uF
5 V 4
R1 150Kohm
U1
IN
1 SW D1 FB 3
WLED MODULE
SP6691
SHDN GND 2
0.7V 1.22V
DIODE
Rb 34.8ohm
Figure 23. Improve Efficiency with Diode in Feedback Loop
For the typical application circuit, the output efficiency of the circuit is expressed by = VOUT * IOUT VIN * IIN
To further improve the efficiency and reduce the effects of the ambient temperature on the diode D1 used in method 1, an op amp circuit can be used as shown in Figure 24. The gain of the op amp circuit can be calculated by: Av = R1 + R 2 R1 If the voltage across the bias resistor is set to be 0.1V the current through R1 and R2 to be around 100A, R1 and R2 can be selected as 1K and 11.2K respectively. LMV341 can be used because of its small supply current, offset voltage and minimum supply voltage. By using this method, the efficiency can be increased around 7%.
Vbattery
Where VIN , IIN, VOUT, IOUT are the input and output voltage and current respectively. While the white LED efficiency is expressed by (VOUT - 1.22) * IOUT VIN * IIN
=
This equation indicates that the white LED efficiency will be much smaller than the output efficiency of the circuit when VOUT is not very large, compared to the feedback voltage (1.22V). The other power is consumed by the bias resistor. To reduce this power loss, two circuits can be used, as shown in Figure 23 and Figure 24. In Figure 23, a general-purpose diode (for example, 1N4148) is used to bring the voltage across the bias resistor to be around 0.7V. R1 is used to create a loop that provides around 100A operating current for the diode. 3% efficiency improvement can be achieved by using this method.
2.7-4.2V
Murata LQH32CN100K11 L1 10uH 0.45A
DS
MBR0530
Vbattery
C1 4.7uF
5 V 4
U1 SP6691
IN
1 SW 3
C2 2.2uF 5 6
+ LMV341 1
WLED MODULE
0.1V
3
SHDN GND 2
FB
4
OUT
1.22V
R2
2
-
Rb 11.2K R1 1K 5.1
Figure 24. Improve Efficiency with Op Amp in Feedback Loop
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation
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PACKAGE: PINOUTS
VIN
SHDN
VIN
SHDN
5
4
5
4
SP6691
5 Pin SOT-23
1
SW
SP6691
5 Pin TSOT
3
FB
2
GND
1
SW
2
GND
3
FB
NC FB NC SW
1 2 3 4
8 GND
SP6691
8 Pin DFN
7 VIN 6 VEN 5 NC
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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PACKAGE: 8 PIN DFN
Top View
D D/2 1
Bottom View
D2 2
E/2
E
E2
K L b
Pin 1 identifier to be located within this shaded area. Terminal #1 Index Area (D/2 * E/2)
e
Side View
2x3 8 Pin DFN JEDEC mo-229C (VCED-2) Variation Symbol A
Dimensions in (mm) MIN 0.80 0 0.18
NOM 0.90 0.02 0.20 0.25 2.00 BSC
MAX 1.00 0.05 0.30
A
A1 A3
A1 A3 b D D2 e E E2 K L
1.50 1.60 0.20 0.30
0.50 3.00 BSC 0.40
1.75 1.90 0.50
2x3 8 Pin DFN
Date: 5/25/04 SP6691 Micro Power Boost Regualtor, Series White LED Driver (c) Copyright 2004 Sipex Corporation
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PACKAGE: 5 PIN SOT-23
D e1
N
N/2 +1 E/2
H B
E
E1/2 E1
B
SEE VIEW C
1 e
2
N/2
O1
b
Gauge Plane
5 PIN SOT-23 JEDEC MO-178 (AA) Variation A A1 A2 b c D e e1 E E1 L L1 L2 O O1
Dimensions in (mm) MIN 0 0.90 0.30 0.08 NOM MAX 1.15 2.90 BSC 0.95 BSC 1.90 BSC 2.80 BSC 1.60 BSC 0.30 0.45 0.60 REF 0.25 BSC 0 5 4 10 8 15 0.60 1.45 0.15 1.30 0.50 0.22
Seating Plane
4X O1
L L1
O
L2
VIEW C
A
A2
A1
SIDE VIEW
b
WITH PLATING
c
BASE METAL
5 PIN SOT-23
Date: 5/25/04 SP6691 Micro Power Boost Regualtor, Series White LED Driver (c) Copyright 2004 Sipex Corporation5
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PACKAGE: 5 PIN TSOT
D e1
N
N/2 +1 E/2
H B
E
E1/2 E1
B
SEE VIEW C
INDEX AREA (D/2 X E1/2)
1 e
2
N/2
O1
Detais of the pin1 identifier are optional, but must be located within the zone indicated.
b
Dimensions in (mm)
5 PIN TSOT JEDEC MO-193 (AB) Variation MIN NOM MAX 0 0.70 0.30 0.30 0.08 0.08 0.90 0.40 0.13 2.90 BSC 0.95 BSC 1.90 BSC 2.80 BSC 1.60 BSC 0.30 0.45 0.60 REF 0.25 BSC 0 4 4 10 8 12 0.60 1.10 0.10 1.00 0.50 0.45 0.20 0.16
Gauge Plane Seating Plane
4X o1
L L1
o
L2
A A1 A2 b b1 c c1 D e e1 E E1 L L1 L2 O O1
VIEW C
A
A2
SEATING PLANE
C
A1
SIDE VIEW
WITH PLATING
b b1
c
c1
BASE METAL
5 PIN TSOT
Date: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation
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ORDERING INFORMATION
Part Number
SP6691EK SP6691EK/TR SP6691EK1 SP6691EK1/TR SP6691ER SP6691ER/TR
Operating Temperature Range
-40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Type
5 PIN SOT-23 5 PIN SOT-23 5 PIN TSOT 5 PIN TSOT 8 PIN DFN 8 PIN DFN
Available in lead free packaging. To order add "-L" suffix to part number. Example: SP6134EU/TR = standard; SP6134EU-L/TR = lead free /TR = Tape and Reel Pack quantity is 2,500 for TSOT or SOT-23 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: 5/25/04
SP6691 Micro Power Boost Regualtor, Series White LED Driver
(c) Copyright 2004 Sipex Corporation5
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