1
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
1 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
5
4
1
2
3
SP4446
VIN
SHDN
SW
GND
FB
5 Pin SOT-23
Now Available in Lead Free Packaging
V
IN
SW
GND
SHDN
FB
10H
D1
L1
R1
R2
C2
2.2 F
High
Voltage Output
V
IN
4.7F
C1
2 to 7V
SP4446
2
Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
PIN DESCRIPTION
V
IN
....................................................................... 15V
SW Voltage .............................................. -0.4 to 34V
FB Voltage .......................................................... 2.5V
All other pins .................................. -0.3 to V
CC
+ 0.3V
Current into FB ................................................. 1mA
T
J
Max ............................................................. 125C
Operating Temperature Range ............ -40C to 85C
Peak Output Current < 10us SW .................... 500mA
Storage Temperature ...................... -65C to +150C
Power Dissipation. ......................................... 200mW
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
A
No Switching
0.01
1
A
SHDN = 0V
Reference Voltage
V
FB
1.17
1.22
1.27
V
FB Hysteresis
HYST
8
mV
V
FB
Input Bias Current
I
FB
15
80
nA
V
FB
= 1.22V
Line Regulation
V
o
/V
I
0.04
%/V
1.2 V
IN
8V
Switch Off Time
T
OFF
300
nS
V
FB
> 1V
1200
nS
V
FB
< 0.3V
Switch Saturation Voltage
V
CESAT
50
mV
I
SW
= 50mA
150
mV
I
SW
= 150mA
Switch Current Limit
I
LIM
100
150
200
mA
SHDN Bias Current
I
SHDN
5
12
A
V
SHDN
= 5V
SHDN High Threshold (on)
V
IH
0.9
V
SHDN Low Threshold (off)
V
IL
0.25
V
Switch Leakage Current
I
SWLK
2
5
A
Switch Off, V
SW
= 5V
ELECTRICAL CHARACTERISTICS
Specifications are at V
IN
= 3.3V, V
SHDN
= V
IN
, T
A
= 25
C, denotes the specifications which apply over the full operating
temperature range, unless otherwise specified.
ABSOLUTE MAXIMUM RATINGS
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.
PIN NUMBER
PIN NAME
DESCRIPTION
1
SW
Switch input to the internal power switch.
2
GND
Ground
3
FB
Feedback
4
SHDN
Shutdown. Pull high (on) to enable. Pull low (off) for shutdown.
5
V
IN
Input Voltage. Bypass this pin with a capacitor as close to the device
as possible.
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Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
FUNCTIONAL DIAGRAM
+
-
VI
(EXTERNAL)
(EXTERNAL)
R1
R2
C1
SHDN
4
Q1
Q2
R3
R4
R6
R5
X1
Shutdown
Logic
300ns
ONE-SHOT
CLEAR
X2
+
-
SET
DRIVER
52.5mV
0.35
GND
2
1
5
3
L1
SW
C2
D1
V
OUT
POWER
TRANSISTOR
DISABLE
V
IN
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 0.3
s. At the instant of shutoff,
inductor current is diverted to the output through
diode D1. During this 0.3
s time limit, inductor
current decreases while its energy charges C2.
THEORY OF OPERATION
At the end of the 0.3
s 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
s 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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Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
Capacitor Selection
Ceramic capacitors are recommended for their
inherently low ESR, which will help produce low
peak to peak output ripple, and reduce high fre-
quency spikes.
For the typical application, 4.7
F input capacitor
and 2.2
F output capacitor are sufficient. The
input and output ripple could be further reduced by
increasing the value of the input and output capaci-
tors. 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 com-
parator, 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/
NUMBER
VOLTAGE
TYPE
MURATA
GRM32RR71E
2.2
F/25V
1210/X5R
770-436-1300
225KC01B
MURATA
GRM31CR61A
4.7
F/10V
1206/X5R
770-436-1300
475KA01B
TDK
C3225X7R1E
2.2
F/25V
1206/X7R
847-803-6100
225M
TDK
C3216X5R1A
4.7
F/10V
1206/X5R
847-803-6100
475K
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
LIM
=150mA). 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:
I
PK
=
I
LIM
+
V
IN(MAX)
200nS
L
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
(
)
Rating
(mA)
MURATA
LQH32CN100K21
0.44
300
770-436-1300
(10
H)
MURATA
LQH32CN220K21
0.71
250
770-436-1300
(22
H)
TDK
NLFC453232T-100K
847-803-6100
(10
H)
0.273
250
TDK
NLC453232T-100K
0.9
370
847-803-6100
(22
H)
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.
Output Voltage Program
The SP4446 can be programmed as voltage source,
the SP4446 requires 2 feedback resistors R
1
& R
2
to control the output voltage. As shown in Fig. 19.
L1
1.22V
R2
D1
C1
C2
R1
VOUT
U1
SP4446
1
2
3
4
5
SW
G ND
FB
SHDN
V
I N
VIN
Figure 19. Using SP4446 as Voltage Source
5
Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
APPLICATION INFORMAMTION: Continued
The formula and table for the resistor selection
are shown below:
R
1
=
(
V
OUT
- 1
)
R
2
1.22
Table 3. Divider Resistor Selection
V
OUT
(V)
R
1
(
)
R
2
(
)
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.
3.3V or 5V
R1
1M
C1
4.7uF
30V
R2
42.2K
U1
SP4446
1
2
3
4
5
SHDN
Murata LQH32CN100K21
3 to 5 mA
DS
MBR0530
C2
47pF
1.22V
L1 10uH 0.3A
C3
2.2uF
3.3V or 5V
R1
1M
C1
4.7uF
30V
R2
42.2K
U1
SP4446
1
2
3
4
SW
GND
FB
SHDN
V
IN
Murata LQH32CN100K21
V
IN
3 to 5 mA
DS
MBR0530
V
OUT
C2
47pF
1.22V
L1 10uH 0.3A
C3
2.2uF
V
IN
DS
C1
4.7uF
Q1
MMBT2907A
R1
1M
R3
154K
20V
1.22V
C2
47pF
R2
64.9K
U1
SP4446
1
2
3
4
5
SW
GND
FB
SHDN
V
IN
V
OUT
L1
10uH
C3
2.2uF
Load Disconnect in Shutdown
When SP4446 was shut down, the load is still
connected to the input. In applications that re-
quire output isolation during shutdown, an ex-
ternal PNP transistor (for example MMBT2907A)
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
will be slightly sacrificed because of the satura-
tion voltage and base current of the PNP transistor.
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 (R
1
=1M
,
R
2
=42.2K
) are used to program the output volt-
age to be 30V. When input voltage is 3.3V or 5V,
it can supply a maximum current of 3mA and 5mA
to the load.
Fig. 21. Pin Diode Driver
6
Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
Figure 5. 18V Output Efficiency (V
IN
=3.3V)
Figure 6. 18V Output Efficiency (V
IN
=5V)
Figure 3. 15V Output Efficiency (V
IN
=3.3V)
Figure 4. 15V Output Efficiency (V
IN
=5V)
Vin=3.3V; Vout = 18V Efficiency
40
45
50
55
60
65
70
75
80
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Iout (mA)
Efficiency (%)
10 uH
22 uH
Vin=5.0V; Vout = 18V Efficiency
40
45
50
55
60
65
70
75
80
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
Iout (mA)
Efficiency (%)
10 uH
22 uH
PERFORMANCE CHARACTERISTICS
Refer to the typical application circuit, T
AMB
= 25
C, unless otherwise specified.
Figure 1. 12V Output Efficiency (V
IN
=3.3V)
Figure 2. 12V Output Efficiency (V
IN
=5V)
Vin=3.3V;Vout =12V Efficiency
50
55
60
65
70
75
80
85
0
3
6
9
12
15
18
Iout (mA)
Efficiency (%)
10 uH
22 uH
Vin=5.0V;Vout =12V Efficiency
50
55
60
65
70
75
80
85
0
5
10
15
20
25
30
Iout (mA)
Efficiency (%)
10 uH
22 uH
Vin=3.3V;Vout =15V Efficiency
50
55
60
65
70
75
80
0
2
4
6
8
10
12
Iout (mA)
Efficiency (%)
10 uH
22 uH
Vin=5.0V;Vout =15V Efficiency
50
55
60
65
70
75
80
0
3
6
9
12
15
18
Iout (mA)
Efficiency (%)
10 uH
22 uH
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Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
Vin=3.3V;Vout = 20V Efficiency
30
35
40
45
50
55
60
65
70
75
0
1
2
3
4
5
6
7
Iout (mA)
Efficiency (%)
10 uH
22 uH
Vin=5V;Vout = 20V Efficiency
35
40
45
50
55
60
65
70
75
0
2
4
6
8
10
12
Iout (mA)
Efficiency (%)
10 uH
22 uH
PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, T
AMB
= 25
C, unless otherwise specified.
Figure 7. 20V Output Efficiency (V
IN
=3.3V)
Figure 8. 20V Output Efficiency (V
IN
=5V)
Figure 9. Maximum Output Current vs. V
IN
(V
OUT
=20V)
Figure 10. Maximum Output Current vs. V
IN
(V
OUT
=30V)
0
2
4
6
8
10
12
2.7
3
3.3
3.6
3.9
4.2
4.5
4.8
5.1
Input Voltage (V)
Maximum Output Current (mA)
10uH
22uH
0
1
2
3
4
5
6
2.7
3
3.3
3.6
3.9
4.2
4.5
4.8
5.1
Input Voltage (V)
Maximum Output Current (mA)
10uH
22uH
0
5
10
15
20
25
30
1
2
3
4
5
6
7
8
Input Voltage (V)
Quiescent Current (uA)
Tamb=-40C
Tamb=25C
Tamb=85C
0
2
4
6
8
10
1
2
3
4
5
6
7
8
Input Voltage (V)
Shutdown Pin Current (uA)
Figure 11. Quiescent Current I
Q
vs. V
IN
Figure 12. Shutdown Pin Current vs. V
IN
8
Rev. 7/14/03
SP4446 High Output Voltage Boost Regualtor, LCD Bias Regulator Copyright 2003 Sipex Corporation
V
OUT
(AC)
I
OUT
(5mA/DIV)
V
SW
V
OUT
(AC)
I
L
(0.1A/DIV)
V
SW
V
IN
V
OUT
I
IN
(100mA/DIV)
Figure 16. Startup Waveform (V
IN
=3.3V, V
OUT
=20V,
I
OUT
=2mA)
Figure 17. Typical Switching Waveforms (V
IN
=3.3V,
V
OUT
=20V, I
OUT
=5mA)
Figure 18. Load Step Transient (V
IN
=3.3V, V
OUT
=20V,
1
O
=100
A5mA)
Figure 13. I
PK
Current Limit vs. V
IN
Figure 14. Feedback Voltage vs. Temperature
0
50
100
150
200
250
1
2
3
4
5
6
7
8
Input Voltage (V)
Ipk Current Limit (mA)
1.18
1.19
1.20
1.21
1.22
1.23
1.24
1.25
-40
-15
10
35
60
85
Temperature (C)
Feedback V
oltage (V)
PERFORMANCE CHARACTERISTICS: Continued
Refer to the typical application circuit, T
AMB
= 25
C, unless otherwise specified.
Figure 15. Switch Saturation Voltage V
CESAT
vs.
Temperature (I
SW
=50mA)
0
10
20
30
40
50
60
-40
-15
10
35
60
85
Temperature (C)
Switch Saturation V
oltage (mV)
9
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
e1
N/2
2
1
b
e
E1
E1/2
N
N/2
+1
L1
L
L2
1
Seating Plane
Gauge Plane
VIEW C
SEE VIEW C
B
B
c
WITH PLATING
BASE METAL
b
1
- - 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
0 4 8
A
A1
A2
b
c
D
E
E1
L
L1
L2
5 10 15
1
MIN NOM MAX
0.25 BSC
e
e1
1.90 BSC
0.95 BSC
SECTION B-B
Seating Plane
VIEW A-A
5 PIN SOT-23
10
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 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.
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
SP4446EK .................................................. -40C to +85C ........................................................ 5 Pin SOT-23
SP4446EK/TR ............................................ -40C to +85C ........................................................ 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.
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