Datasheet SP4446 Datasheet (Sipex)

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Page 1

PRELIMINARY

SP4446

High Output Voltage Boost Regulator

LCD Bias Regulator

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

Now Available in Lead Free Packaging

SP4446

5 Pin SOT-23

123

GND

SHDN

■ 1Ω Switch (150mV at 150mA)

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

2 to 7V

SHDN

4.7µF

10µH

SP4446

GND

High Voltage Output

2.2 µF

Page 2

ABSOLUTE MAXIMUM RATINGS

VIN....................................................................... 15V

SW Voltage .............................................. -0.4 to 34V

Lead Temperature (Soldering, 10 sec) ............ 300°C

ESD Rating................................................. 2kV HBM

FB Voltage.......................................................... 2.5V

All other pins.................................. -0.3 to VCC + 0.3V

Current into FB ................................................. ±1mA

TJ Max ............................................................. 125°C

Operating Temperature Range ............ -40°C to 85°C

Peak Output Current < 10us SW .................... 500mA

Storage Temperature ...................... -65°C to +150°C

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.

Power Dissipation. ......................................... 200mW

ELECTRICAL CHARACTERISTICS

Specifications are at VIN = 3.3V, V temperature range, unless otherwise specified.

PARAMETER SYMBOL MIN TYP MAX UNITS CONDITIONS

Input voltage V

Supply Current I

Reference Voltage V FB Hysteresis HYST 8 mV VFB Input Bias Current I Line Regulation ∆Vo/∆V Switch Off Time T

Switch Saturation Voltage V

Switch Current Limit I SHDN Bias Current I SHDN High Threshold (on) V SHDN Low Threshold (off) V Switch Leakage Current I

= VIN, TA = 25°C, ♦ denotes the specifications which apply over the full operating

SHDN

1.0 8.0 V Switch Current Limit =

20 30 µA ♦ No Switching

150mA

0.01 1 µA SHDN = 0V

1.17 1.22 1.27 V ♦

OFF

CESAT

15 80 nA ♦ V

0.04 %/V 1.2 ≤ V 300 nS V

1200 nS V

50 mV ♦ ISW = 50mA

= 1.22V

> 1V

< 0.3V

150 mV ISW = 150mA

100 150 200 mA ♦

LIM

SHDN

SWLK

512µA ♦ V

0.9 V

0.25 V

25µA ♦ Switch Off, VSW = 5V

SHDN

= 5V

≤ 8V

PIN DESCRIPTION

PIN NUMBER PIN NAME DESCRIPTION

1SWSwitch input to the internal power switch. 2 GND Ground 3FBFeedback 4 SHDN Shutdown. Pull high (on) to enable. Pull low (off) for shutdown. 5VINInput Voltage. Bypass this pin with a capacitor as close to the device

as possible.

Page 3

(EXTERNAL)

FUNCTIONAL DIAGRAM

OUT

DISABLE SET

300ns

ONE-SHOT

CLEAR

DRIVER

52.5mV

TRANSISTOR

0.35

POWER

Shutdown

SHDN

Logic

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 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 150mA, comparator X2 clears the latch, which turns off the driver transistor 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.

GND

THEORY OF OPERATION

At the end of the 0.3µs 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 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. The SP4446 contains circuitry to provide protection during start-up and while in short-circuit conditions. When FB pin voltage is less than approximately 300mV, the switch off time is increased to about 1.2µs 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.

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APPLICATION INFORMAMTION

Inductor Selection

For SP4446, the internal switch will be turned off only after the inductor current reaches the typical dc current limit (I

=150mA). However, there is

LIM

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 = I

LIM

IN(MAX)

• 200nS

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 SP4446 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

MURATA LQH32CN100K21 0.44 300 770-436-1300 (10µH)

MURATA LQH32CN220K21 0.71 250 770-436-1300 (22µH)

TDK NLFC453232T-100K 847-803-6100 (10µH) 0.273 250

TDK NLC453232T-100K 0.9 370 847-803-6100 (22µH)

(Ω) Rating

(mA)

Capacitor Selection

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, 4.7µF input capacitor and 2.2µF 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 SP4446 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. PART CAP/ SIZE/

MURATA GRM32RR71E 2.2µF/25V 1210/X5R 770-436-1300 225KC01B

MURATA GRM31CR61A 4.7µF/10V 1206/X5R 770-436-1300 475KA01B

TDK C3225X7R1E 2.2µF/25V 1206/X7R 847-803-6100 225M

TDK C3216X5R1A 4.7µF/10V 1206/X5R 847-803-6100 475K

Output Voltage Program

NUMBER VOLTAGE TYPE

The SP4446 can be programmed as voltage source, the SP4446 requires 2 feedback resistors R1 & R to control the output voltage. As shown in Fig. 19.

VIN

VOUT

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,

SP4446

FBSHDN

1.22V

the reverse breakdown voltage of the schottky diode should be larger than the output voltage.

Figure 19. Using SP4446 as Voltage Source

Page 5

APPLICATION INFORMAMTION: Continued

The formula and table for the resistor selection are shown below:

OUT

- 1 ) • R

1.22

Table 3. Divider Resistor Selection

(V) R1 (Ω)R

OUT

(Ω)

12 1M 113K 15 1M 88.7K 18 1M 73.2K 20 1M 64.9K 30 1M 42.2K

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.

Load Disconnect in Shutdown

will be slightly sacrificed because of the saturation voltage and base current of the PNP transistor.

154K

5 V

10uH

SP4446

GND

1 SW

FBSHDN

4.7uF

1.22V

MMBT2907A

64.9K

C2 47pF

Fig. 20. Load Disconnect in Shutdown

PIN Diode Driver

The SP4446 can be used as PIN diode driver as shown in Fig. 21. Two Resistors (R1=1MΩ, R2=42.2KΩ) are used to program the output voltage to be 30V. When input voltage is 3.3V or 5V, it can supply a maximum current of 3mA and 5mA to the load.

Murata LQH32CN100K21

3.3V or 5V

Murata LQH32CN100K21

L1 10uH 0.3A

4.7uF

L1 10uH 0.3A

5 V

SP4446

SHDN

GND

MBR0530

47pF

R1 1M

FBSHDN

1.22V

1.22V R2

42.2K

2.2uF

30V

OUT

3 to 5 mA

OUT

20V

2.2uF

When SP4446 was shut down, the load is still connected to the input. In applications that require output isolation during shutdown, an external PNP transistor (for example MMBT2907A)

Fig. 21. Pin Diode Driver

can be added as shown in Figure 20. When the SP4446 is active, the voltage set at the emitter of the transistor exceeds the input voltage, forcing the transistor into the saturation region. When the SP4446 is shut down, the input voltage exceeds the emitter voltage, thus the transistor becomes inactive and provides high-impedance isolation between the input and load. Efficiency

Page 6

Refer to the typical application circuit, T

= 25°C, unless otherwise specified.

PERFORMANCE CHARACTERISTICS

AMB

Efficiency (%)

Vin=3.3V;Vout =12V Efficiency

0369121518

Iout (mA)

Figure 1. 12V Output Efficiency (V

Efficiency (%)

Vin=3.3V;Vout =15V Efficiency

=3.3V)

10 uH

22 uH

Efficiency (%)

051015 20 25 30

Vin=5.0V;Vout =12V Efficiency

Iout (mA)

Figure 2. 12V Output Efficiency (VIN=5V)

Efficiency (%)

Vin=5.0V;Vout =15V Efficiency

10 uH

22 uH

024681012

Iout (mA)

Figure 3. 15V Output Efficiency (VIN=3.3V)

Efficiency (%)

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Vin=3.3V; Vout = 18V Efficiency

10 uH

22 uH

Iout (mA)

Figure 5. 18V Output Efficiency (VIN=3.3V)

10 uH

22 uH

0369121518

Iout (mA)

Figure 4. 15V Output Efficiency (VIN=5V)

Efficiency (%)

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0

Vin=5.0V; Vout = 18V Efficiency

10 uH

22 uH

Iout (mA)

Figure 6. 18V Output Efficiency (VIN=5V)

10 uH

22 uH

Page 7

Refer to the typical application circuit, T

= 25°C, unless otherwise specified.

PERFORMANCE CHARACTERISTICS

AMB

Efficiency (%)

01234567

Vin=3.3V;Vout = 20V Efficiency

Iout (mA)

Figure 7. 20V Output Efficiency (VIN=3.3V)

Maximum Output Current (mA)

2.7 3 3.3 3.6 3.9 4.2 4.5 4.8 5.1

10uH

22uH

Input Voltage (V)

10 uH

22 uH

Efficiency (%)

024681012

Vin=5V;Vout = 20V Efficiency

Iout (mA)

Figure 8. 20V Output Efficiency (VIN=5V)

Maximum Output Current (mA)

10uH

22uH

2.7 3 3.3 3.6 3.9 4.2 4.5 4.8 5.1

Input Voltage (V)

10 uH

22 uH

Figure 9. Maximum Output Current vs. VIN (V

Quiescent Current (uA)

12345678

Input Voltage (V)

Figure 11. Quiescent Current IQ vs. V

Tamb=-40°C

Tamb=25°C

Tamb=85°C

OUT

=20V)

Figure 10. Maximum Output Current vs. VIN (V

Shutdown Pin Current (uA)

12345678

Figure 12. Shutdown Pin Current vs. V

Input Voltage (V)

OUT

=30V)

Page 8

Refer to the typical application circuit, T

= 25°C, unless otherwise specified.

PERFORMANCE CHARACTERISTICS

AMB

250

200

150

100

Ipk Current Limit (mA)

12345678

Input Voltage (V)

Figure 13. IPK Current Limit vs. V

Switch Saturation Voltage (mV)

1.25

1.24

1.23

1.22

1.21

Feedback Voltage (V)

1.20

1.19

1.18

-40 -15 10 35 60 85

Figure 14. Feedback Voltage vs. Temperature

OUT

Temperature (C)

(100mA/DIV)

OUT

=2mA)

=20V,

OUT

(5mA/DIV)

OUT

(AC)

OUT

=20V,

OUT

-40 -15 10 35 60 85

Figure 15. Switch Saturation Voltage V

Temperature (C)

CESAT

vs.

Temperature (ISW=50mA)

(0.1A/DIV)

(AC)

OUT

Figure 17. Typical Switching Waveforms (VIN=3.3V, V

OUT

=20V, I

OUT

=5mA)

Figure 16. Startup Waveform (VIN=3.3V, V I

Figure 18. Load Step Transient (VIN=3.3V, V 1O=100µA∼5mA)

Page 9

PACKAGE: 5 PIN SOT-23

E1/2

N/2 +1

N/22

5 Pin SOT-23 JEDEC MO-178 (AA) Variation

SYMBOL

MIN NOM MAX

A--1.45 A1 0 - 0.15 A2 0.9 1.15 1.3

b0.3-0.5

c0.08-0.22 D E

2.90 BSC

2.80 BSC

1.60 BSC

0.95 BSC

1.90 BSC

L0.30.45 0.6

L1 L2

0.60 REF

0.25 BSC Ø0º4º8º ø5º10º 15º

Note: Dimensions in (mm)

E/2

SEE VIEW C

VIEW A-A

Gauge Plane

Seating Plane

VIEW C

WITH PLATING

Seating Plane

SIDE VIEW

BASE METAL

SECTION B-B

Page 10

ORDERING INFORMATION

Part Number Operating Temperature Range Package Type

SP4446EK .................................................. -40°C to +85°C ........................................................ 5 Pin SOT-23

SP4446EK/TR ............................................ -40°C to +85°C ........................................................5 Pin SOT-23

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.

CLICK HERE TO ORDER SAMPLES

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.