SP4446 SIPEX | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 10
Technical content
Rev. 7/14/03 SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator © Copyright 2003 Sipex Corporation SP4446
FEATURES
■ High Output Voltage: Up to 30V ■ High Efficiency ■ Low Quiescent Current: ~20uA ■ Miniature Package: (5-lead SOT-23) ■ Single Battery Cell Operation ■ Programmable Output Voltage ■ 1Ω Switch (150mV at 150mA) High Output Voltage Boost Regulator LCD Bias Regulator
APPLICATIONS
■ LCD Bias ■ Tuner Pin Voltage ■ White LED Driver ■ High Voltage Bias ■ Digital Cameras ■ Cell Phone ■ Battery Backup ■ Handheld Computers
DESCRIPTION
The SP4446 is a micro power Boost Regualtor in a 5-lead SOT-23 package. It is a current limited, fixed off time regulator configured for use in boost mode applications. The operating voltage can be less than 3V and is capable of generating voltages as high as 30 Volts. The SP4446 is to be supplied in a SOT-23-5 and permits the construction of complete regulators that occupy < 0.2 square inches of board space. TYPICAL APPLICATION SCHEMATIC PRELIMINARY 12 3 SP4446 VIN SHDN SW GND FB
5 Pin SOT-23
Now Available in Lead Free Packaging VIN SW GNDSHDN FB 10µH D1L1 2.2 µF High Voltage Output VIN 4.7µF 2 to 7V SP4446
Rev. 7/14/03 SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator © Copyright 2003 Sipex Corporation PIN DESCRIPTION PARAMETER SYMBOL MIN TYP MAX UNITS CONDITIONS Input voltage V IN 1.0 8.0 V Switch Current Limit = 150mA Supply Current I Q 20 30 µA ♦ No Switching 0.01 1 µA SHDN = 0V Reference Voltage V FB 1.17 1.22 1.27 V ♦ FB Hysteresis HYST 8 mV VFB Input Bias Current I FB 15 80 nA ♦ VFB = 1.22V Line Regulation ∆Vo/∆VI 0.04 %/V 1.2 ≤ VIN ≤ 8V Switch Off Time T OFF 300 nS V FB > 1V 1200 nS V FB < 0.3V Switch Saturation Voltage V CESAT 50 mV ♦ ISW = 50mA 150 mV I SW = 150mA Switch Current Limit I LIM 100 150 200 mA ♦ SHDN Bias Current I SHDN 51 2 µA ♦ VSHDN = 5V SHDN High Threshold (on) V IH 0.9 V SHDN Low Threshold (off) V IL 0.25 V Switch Leakage Current I SWLK 25 µA ♦ Switch Off, VSW = 5V
ELECTRICAL CHARACTERISTICS
Specifications are at V IN = 3.3V, VSHDN = VIN, TA = 25°C, ♦ denotes the specifications which apply over the full operating temperature range, unless otherwise specified. ABSOLUTE MAXIMUM RATINGS 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. PIN NUMBER PIN NAME DESCRIPTION 1S W Switch input to the internal power switch.
2 GND Ground
4 SHDN Shutdown. Pull high (on) to enable. Pull low (off) for shutdown. 5V IN Input Voltage. Bypass this pin with a capacitor as close to the device as possible.
Rev. 7/14/03 SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator © Copyright 2003 Sipex Corporation FUNCTIONAL DIAGRAM VI (EXTERNAL) (EXTERNAL) SHDN 4 Q1 Q2 R6R5 Shutdown Logic 300ns ONE-SHOT CLEAR X2 + SET DRIVER 52.5mV 0.35 GND SW C2 D1 VOUT POWER TRANSISTOR DISABLE VIN FB General Overview: Operation can be best understood by referring to the above block diagram. 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 di- vider, 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 150mA, comparator X2 clears the latch, which turns off the driver tran- sistor for a preset 0.3µs. At the instant of shutoff, inductor current is diverted to the output through diode D1. During this 0.3µs time limit, inductor current decreases while its energy charges C2. THEORY OF OPERATION At the end of the 0.3 µs time period, driver transistor is again allowed to turn on which ramps the current back up to the 150mA 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 switch- ing 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. The SP4446 contains circuitry to provide protection during start-up and while in short-circuit conditions. When FB pin volt- age is less than approximately 300mV, the switch off time is increased to about 1.2 µs and the current limit is reduced to about 70% of its normal value. While in this mode, the average inductor current is reduced and helps minimize power dissipation in the SP4446, the external inductor and diode.
parator, thus reduce the output ripple. Table 2. Suggested Low ESR Capacitor inductor value, the greater the peak current. and could damage the inductor. power losses and increase efficiency. Table 1. Suggested Low ESR inductor diode should be larger than the output voltage. to control the output voltage. As shown in Fig. 19. Figure 19. Using SP4446 as Voltage Source
Table 3. Divider Resistor Selection should be placed as close as possible to the IC. ground plane that is tied directly to the GND pin. especially the feedback network. tion voltage and base current of the PNP transistor.
Rev. 7/14/03 SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator © Copyright 2003 Sipex Corporation PACKAGE: 5 PIN SOT-23 A A2 A1 SIDE VIEW D E E/2 N/221 b e E1/2 N N/2 L Seating Plane Gauge Plane VIEW C SEE VIEW C B B c WITH PLATING BASE METAL b Ø1 Ø - - 1.45 0 - 0.15 Dimensions in (mm)5 PIN SOT-23 JEDEC MO-178 (AA) Variation 0.90 1.15 1.30 0.30 - 0.50 0.08 - 0.22
2.90 BSC
2.80 BSC
1.60 BSC
0.30 0.45 0.60
0.60 REF
0º 4º 8º A b c D E L Ø 5º 10º 15ºØ1 MIN NOM MAX
0.25 BSC
e e1 1.90 BSC
0.95 BSC
Rev. 7/14/03 SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator © Copyright 2003 Sipex Corporation Corporation ANALOG EXCELLENCE Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability aris ing out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor t he rights of others. Sipex Corporation Headquarters and Sales Office
233 South Hillview Drive
Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600
ORDERING INFORMATION
Part Number Operating Temperature Range Package Type Available in lead free packaging. To order add "-L" suffix to part number. Example: SP4446EK/TR = standard; SP4446EK-L/TR = lead free /TR = Tape and Reel Pack quantity is 2,500 for SOT-23.