LM3354MMX-3.7 [NSC]
Regulated 90mA Buck-Boost Switched Capacitor DC/DC; 调节90毫安降压 - 升压型开关电容DC / DC
| 型号： | LM3354MMX-3.7 |
| 厂家： | 
National Semiconductor |
| 描述： | Regulated 90mA Buck-Boost Switched Capacitor DC/DC |
| 文件： | 总11页 (文件大小：355K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
November 2002
LM3354-3.7
Regulated 90mA Buck-Boost Switched Capacitor DC/DC
Converter
General Description
Features
n Regulated VOUT with 3% accuracy
n Standard output voltages of 1.8V, 3.3V, 4.1V, and 5.0V
also available
The LM3354 is a CMOS switched capacitor DC/DC con-
verter that produces a regulated output voltage by automati-
cally stepping up (boost) or stepping down (buck) the input
voltage. It accepts an input voltage between 2.5V and 5.5V.
The LM3354 is also available with standard output voltages
of 1.8V, 3.3V, 3.7V, 4.1V (ideal for white LED applications),
and 5.0V. If other output voltage options between 1.8V and
5.0V are desired, please contact your National Semiconduc-
tor representative.
n Custom output voltages available from 1.8V to 5.0V in
100 mV increments with volume order
n 2.5V to 5.5V input voltage range
n Up to 90mA output current
>
n
75% average efficiency
n Uses few, low-cost external components
n Very small solution size
The LM3354’s proprietary buck-boost architecture enables
up to 90mA of load current at an average efficiency greater
than 75%. Typical operating current is only 375 µA and the
typical shutdown current is only 2.3 µA.
n 375 µA typical operating current
n 2.3 µA typical shutdown current
n 1 MHz typical switching frequency
n Architecture and control methods provide high load
current and good efficiency
The LM3354 is available in a 10-pin MSOP package. This
package has a maximum height of only 1.1 mm.
The high efficiency of the LM3354, low operating and shut-
down currents, small package size, and the small size of the
overall solution make this device ideal for battery powered,
portable, and hand-held applications.
n MSOP-10 package
n Over-temperature protection
Applications
See the LM3352 for up to 200mA of output current or the
LM3355 for up to 50mA of output current.
n White LED display backlights
n 1-cell Lilon battery-operated equipment including PDAs,
hand-held PCs, cellular phones
n Flat panel displays
n Hand-held instruments
n Li-Ion, NiCd, NiMH, or alkaline battery powered systems
Typical Operating Circuit
20057301
© 2002 National Semiconductor Corporation
DS200573
www.national.com
Connection Diagram
20057302
Top View
MSOP-10 Pin Package
See NS Package Number MM
Ordering Information
Order Number
Package Type
MSOP-10
MSOP-10
NSC Package Drawing
Supplied As
3.5k Units, Tape and Reel
1k Units, Tape and Reel
LM3354MMX-3.7
LM3354MM-3.7
MUB10A
MUB10A
Pin Description
Pin Number
Name
VIN
Function
1
2
Input Supply Voltage
C1−
C1+
GND
GND
CFIL
SD
Negative Terminal for C1
Positive Terminal for C1
Ground
3
4
5
Ground
6
Filter Capacitor, a 1µF capacitor is recommended.
Shutdown, active low
7
8
VOUT
C2−
C2+
Regulated Output Voltage
9
Negative Terminal for C2
10
Positive Terminal for C2
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Rating (Note 3)
Human Body Model
Machine Model
1.5 kV
100V
All Pins
−0.5V to 5.6V
Operating Ratings
Power Dissipation (TA = 25˚C)
(Note 2)
Input Voltage (VIN
)
2.5V to 5.5V
1.8V to 5.0V
Internally Limited
150˚C
Output Voltage (VOUT
)
TJMAX (Note 2)
θJA (Note 2)
Ambient Temperature (TA) (Note 2)
−40˚C to +85˚C
−40˚C to +120˚C
250˚C/W
Junction Temperature (T ) (Note 2)
J
Storage Temperature
Lead Temperature (Soldering, 5
sec.)
−65˚C to +150˚C
260˚C
Electrical Characteristics
Limits in standard typeface are for TA = 25˚C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: C1 = C2 = 0.33 µF; CIN = 10 µF; COUT = 10 µF; CFIL = 1 µF; VIN = 3.5V.
Parameter
Conditions
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Units
LM3354-3.7
Output Voltage (V
VIN = (2.7, 5.5) V
IL = (1, 70) mA
VIN = (2.8, 4.0) V
IL = (1, 90) mA
VIN = (4.3, 5.5) V
IL = (1, 90) mA
ILOAD = 15 mA
3.589/3.552
3.589/3.552
3.589/3.552
3.7
3.7
3.7
3.811/3.848
3.811/3.848
3.811/3.848
OUT
)
V
Efficiency
75
70
%
I
LOAD= 70 mA
ILOAD = 50 mA
= 10 µF
Output Voltage
Ripple
C
75
mVP-P
OUT
(Peak-to-Peak)
ceramic
LM3354-ALL OUTPUT VOLTAGE VERSIONS
Operating Quiescent Measured at Pin
Current
VIN
I
;
375
2.3
1
475
5
µA
µA
MHz
V
= 0A (Note 6)
LOAD
Shutdown Quiescent SD Pin at 0V (Note
Current
7)
Switching
Frequency
0.6
1.4
<
<
SD Input Threshold 2.5V VIN 5.5V
0.2 VIN
Low
<
<
SD Input Threshold 2.5V VIN 5.5V
0.8 VIN
V
High
SD Input Current
Measured at SD
Pin;
0.3
µA
SD Pin = VIN = 5.5V
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is
intended to be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see “Electrical
Characteristics”.
Note 2: As long as T ≤ +85˚C, all electrical characteristics hold true and the junction temperature should remain below +120˚C except for the 5V output option.
A
The 5V option requires that T ≤ +60˚C.
A
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 4: Typical numbers are at 25˚C and represent the most likely norm.
Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are 100% tested
or guaranteed through statistical analysis. All limits at temperature extremes are guaranteed by correlation using standard Statistical Quality Control methods (SQC).
All limits are used to calculate Average Outgoing Quality Level (AOQL).
3
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Electrical Characteristics (Continued)
. This is to insure that the internal switches are off.
OUT
Note 6: The V
pin is forced to 200 mV above the typical V
OUT
Note 7: The output capacitor C
is fully discharged before measurement.
OUT
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4
Typical Performance Characteristics Unless otherwise specified TA = 25˚C.
VOUT vs. VIN
VOUT vs. VIN
20057341
20057342
Efficiency vs. VIN
Load Transient Response
20057314
20057320
Operating Quiescent
Current vs. VIN
Switching Frequency vs. VIN
20057324
20057323
5
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Typical Performance Characteristics Unless otherwise specified TA = 25˚C. (Continued)
Maximum VOUT Ripple vs. COUT
Maximum VOUT Ripple vs. COUT
20057332
20057330
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6
Applications Information
20057303
FIGURE 1. Block Diagram
Operating Principle
Charge Pump Capacitor Selection
The LM3354 is designed to provide a step-up/step-down
voltage regulation in battery powered systems. It combines
switched capacitor circuitry, reference, comparator, and
shutdown logic in a single 10-pin MSOP package. The
LM3354 can provide a regulated voltage between 1.8V and
5.0V from an input voltage between 2.5V and 5.5V. It can
supply a load current up to 90 mA (refer to Electrical Char-
acteristics).
A 0.33 µF ceramic capacitor is suggested for C1 and C2. To
ensure proper operation over temperature variations, an
X7R dielectric material is recommended.
Filter Capacitor Selection
a) CAPACITOR TECHNOLOGIES
The three major technologies of capacitors that can be used
as filter capacitors for LM3354 are: i) tantalum, ii) ceramic
and iii) polymer electrolytic technologies.
As shown in Figure 1, the LM3354 employs two feedback
loops to provide regulation in the most efficient manner
possible. The first loop is from VOUT through the comparator
COMP, the AND gate G1, the phase generator, and the
switch array. The comparator’s output is high when VOUT is
less than the reference VREF. Regulation is provided by
gating the clock to the switch array. In this manner, charge is
transferred to the output only when needed. The second
loop controls the gain configuration of the switch array. This
loop consists of the comparator, the digital control block, the
phase generator, and the switch array. The digital control
block computes the most efficient gain from a set of five
gains based on inputs from the A/D and the comparator. The
gain signal is sent to the phase generator which then sends
the appropriate timing and configuration signals to the switch
array. This dual loop provides regulation over a wide range of
loads efficiently.
i) Tantalum
Tantalum capacitors are widely used in switching regulators.
Tantalum capacitors have the highest CV rating of any tech-
nology; as a result, high values of capacitance can be ob-
tained in relatively small package sizes. It is also possible to
obtain high value tantalum capacitors in very low profile
<
(
1.2 mm) packages. This makes the tantalums attractive
for low-profile, small size applications. Tantalums also pos-
sess very good temperature stability; i.e., the change in the
capacitance value, and impedance over temperature is rela-
tively small. However, the tantalum capacitors have relatively
high ESR values which can lead to higher voltage ripple and
their frequency stability (variation over frequency) is not very
>
good, especially at high frequencies ( 1 MHz).
Since efficiency is automatically optimized, the curves for
VOUT vs. VIN and Efficiency vs. VIN in the Typical Perfor-
mance Characteristics section exhibit small variations. The
reason is that as input voltage or output load changes, the
digital control loops are making decisions on how to optimize
efficiency. As the switch array is reconfigured, small varia-
tions in output voltage and efficiency result. In all cases
where these small variations are observed, the part is oper-
ating correctly; minimizing output voltage changes and opti-
mizing efficiency.
ii) Ceramic
Ceramic capacitors have the lowest ESR of the three tech-
nologies and their frequency stability is exceptionally good.
These characteristics make the ceramics an attractive
choice for low ripple, high frequency applications. However,
the temperature stability of the ceramics is bad, except for
the X7R and X5R dielectric types. High capacitance values
>
(
1
µF) are achievable from companies such as
Taiyo-yuden which are suitable for use with regulators. Ce-
ramics are taller and larger than the tantalums of the same
capacitance value.
7
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the same size. Polymers offer good frequency stability (com-
parable to ceramics) and good temperature stability (compa-
rable to tantalums). The Aluminum Polymer Electrolytics
offered by Cornell-Dubilier and Panasonic, and the POS-
CAPs offered by Sanyo fall under this category.
Filter Capacitor Selection (Continued)
iii) Polymer Electrolytic
Polymer electrolytic is a third suitable technology. Polymer
capacitors provide some of the best features of both the
ceramic and the tantalum technologies. They provide very
low ESR values while still achieving high capacitance val-
ues. However, their ESR is still higher than the ceramics,
and their capacitance value is lower than the tantalums of
Table 1 compares the features of the three capacitor tech-
nologies.
TABLE 1. Comparison of Capacitor Technologies
Ceramic
Polymer
Electrolytic
Tantalum
ESR
Lowest
High
Low
<
Relative Height
Low for Small Values ( 10 µF); Taller for
Lowest
Low
Higher Values
Relative Footprint
Large
Small
Largest
Good
Good
Low
Temperature Stability
Frequency Stability
VOUT Ripple Magnitude
VOUT Ripple Magnitude
X7R/X5R-Acceptable
Good
Good
Low
Acceptable
High
<
>
@
@
50 mA
100 mA
Low
Slightly Higher
High
Low
@
dv/dt of VOUT Ripple All Loads
Lowest
Low
b) CAPACITOR SELECTION
low input and output ripple as well as size a 10 µF polymer
electrolytic or ceramic, or 15 µF tantalum capacitor is rec-
ommended. This will ensure low input ripple at 90 mA load
current. If lower currents will be used or higher input ripple
can be tolerated then a smaller capacitor may be used to
reduce the overall size of the circuit. The lower ESR ceram-
ics and polymer electrolytics achieve a lower VIN ripple than
the higher ESR tantalums of the same value. Tantalums
make a good choice for small size, very low profile applica-
tions. The ceramics and polymer electrolytics are a good
choice for low ripple, low noise applications where size is
less of a concern. The 10 µF polymer electrolytics are physi-
cally much larger than the 15 µF tantalums and 10 µF
ceramics.
i) Output Capacitor (COUT
)
The output capacitor COUT directly affects the magnitude of
the output ripple voltage so COUT should be carefully se-
lected. The graphs titled VOUT Ripple vs. COUT in the Typical
Performance Characteristics section show how the ripple
voltage magnitude is affected by the COUT value and the
capacitor technology. These graphs are taken at the gain at
which worst case ripple is observed. In general, the higher
the value of COUT, the lower the output ripple magnitude. At
lighter loads, the low ESR ceramics offer a much lower VOUT
ripple than the higher ESR tantalums of the same value. At
higher loads, the ceramics offer a slightly lower VOUT ripple
magnitude than the tantalums of the same value. However,
the dv/dt of the VOUT ripple with the ceramics and polymer
electrolytics is much lower than the tantalums under all load
conditions. The tantalums are suggested for very low profile,
small size applications. The ceramics and polymer electro-
lytics are a good choice for low ripple, low noise applications
where size is less of a concern.
iii) CFIL
A 1 µF, X7R ceramic capacitor should be connected to pin
CFIL. This capacitor provides the filtering needed for the
internal supply rail of the LM3354.
Of the different capacitor technologies, a sample of vendors
that have been verified as suitable for use with the LM3354
are shown in Table 2.
ii) Input Capacitor (CIN
)
The input capacitor CIN directly affects the magnitude of the
input ripple voltage, and to a lesser degree the VOUT ripple.
A higher value CIN will give a lower VIN ripple. To optimize
TABLE 2. Capacitor Vendor Information
Manufacturer
Taiyo-yuden
Tel
(408) 573-4150
(803) 448-9411
(207) 324-4140
Fax
(408) 573-4159
(803) 448-1943
(207) 324-7223
Website
www.t-yuden.com
www.avxcorp.com
www.vishay.com
Ceramic
AVX
Sprague/Vishay
Tantalum
Nichicon
(847) 843-7500
(847) 843-2798
(508) 996-3830
(619) 661-1055
www.nichicon.com
Polymer Electrolytic
Cornell-Dubilier (ESRD) (508) 996-8561
Sanyo (POSCAP) (619) 661-6322
www.cornell-dubilier.com
www.sanyovideo.com
www.national.com
8
Maximum Load Under Start-Up
Thermal Protection
Due to the LM3354’s unique start-up sequence, it is not able
to start up under all load conditions. Starting with 60 mA or
less will allow the part to start correctly under any tempera-
ture or input voltage conditions. After the output is in regu-
lation, any load up to the maximum as specified in the
Electrical Characteristics may be applied. Using a Power On
Reset circuit, such as the LP3470, is recommended if
greater start up loads are expected. Under certain conditions
the LM3354 can start up with greater load currents without
the use of a Power On Reset Circuit.
During output short circuit conditions, the LM3354 will draw
high currents causing a rise in the junction temperature.
On-chip thermal protection circuitry disables the charge
pump action once the junction temperature exceeds the
thermal trip point, and re-enables the charge pump when the
junction temperature falls back to a safe operating point.
Typical Application Circuits
20057333
FIGURE 2. Basic Buck/Boost Regulator
20057315
FIGURE 3. Low Output Noise and Ripple Buck/Boost Regulator
9
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Typical Application Circuits (Continued)
20057340
FIGURE 4. White LED Driver
mately equal to the maximum current multiplied by the duty
cycle. Using frequencies above 200Hz may cause less linear
results as the charge and discharge time of the output
capacitor becomes more significant.
Driving Light Emitting Diodes
The LM3354 can be used to drive LED’s of nearly any color.
The 4.1V option is ideal for driving the White LED’s required
for the backlight of small color displays. Figure 4 shows the
circuit used to power White LED’s. The LED current is set by
the resistors RB by using the equation ILED = (4.1V − VF)/RB
where VF is the typical forward voltage drop of the LED used.
Layout Considerations
Due to the 1 MHz typical switching frequency of the LM3354,
careful board layout is a must. It is important to place the
capacitors as close to the IC as possible and to keep the
traces between the capacitors and the IC short and direct.
Use of a ground plane is recommended. Figure 5 shows a
typical layout as used in the LM3354 evaluation board.
The brightness of the diodes may be controlled using the
shutdown pin. A PWM signal on the shutdown pin may be
used to adjust the brightness by varying the duty cycle. A
signal between 60Hz and 200Hz may be used for best
linearity. In this case the equivalent LED current is approxi-
20057316
FIGURE 5. Typical Layout, Top View (magnification 1.5X)
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10
Physical Dimensions inches (millimeters)
unless otherwise noted
MSOP-10 Pin Package (MM)
For Ordering, Refer to Ordering Information Table
NS Package Number MUB10A
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