LM3352MTCX-2.5/NOPB [TI]
SWITCHED CAPACITOR REGULATOR, 1350 kHz SWITCHING FREQ-MAX, PDSO16;
| 型号： | LM3352MTCX-2.5/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | SWITCHED CAPACITOR REGULATOR, 1350 kHz SWITCHING FREQ-MAX, PDSO16 开关 光电二极管 |
| 文件： | 总12页 (文件大小：543K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
September 1999
LM3352
Regulated 200 mA Buck-Boost Switched Capacitor
DC/DC Converter
General Description
Features
n Regulated VOUT with 3% accuracy
n Standard output voltage options: 2.5V, 3.0V and 3.3V
n Custom output voltages available from 1.8V to 4.0V in
100 mV increments
The LM3352 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 LM3352 is available in three standard output voltage
versions: 2.5V, 3.0V and 3.3V. If other output voltage options
between 1.8V and 4.0V are desired, please contact your
National Semiconductor representative.
n 2.5V to 5.5V input voltage
n Up to 200 mA output current
>
n
80% average efficiency
n Uses few, low-cost external components
n Very small solution size
The LM3352’s proprietary buck-boost architecture enables
up to 200 mA of load current at an average efficiency greater
than 80%. Typical operating current is only 400 µA and the
typical shutdown current is only 2.5 µA.
n 400 µA typical operating current
n 2.5 µA typical shutdown current
n 1 MHz switching frequency (typical)
n Architecture and control methods provide high load
current and good efficiency
The LM3352 is available in a 16-pin TSSOP package. This
package has a maximum height of only 1.1 mm.
The high efficiency of the LM3352, 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 TSSOP-16 package
n Over-temperature protection
Applications
n 1-cell Lilon battery-operated equipment including PDAs,
hand-held PCs, cellular phones
n Flat panel displays
n Hand-held instruments
n NiCd, NiMH, or alkaline battery powered systems
n 3.3V to 2.5V and 5.0V to 3.3V conversion
Typical Operating Circuit
10103701
© 2004 National Semiconductor Corporation
DS101037
www.national.com
Connection Diagram
10103702
Top View
TSSOP-16 Pin Package
See NS Package Number MTC16
Ordering Information
Order Number
Package Type
TSSOP-16
TSSOP-16
NSC Package Drawing
Supplied As
2.5k Units, Tape and Reel
94 Units, Rail
LM3352MTCX-2.5
LM3352MTC-2.5
LM3352MTCX-3.0
LM3352MTC-3.0
LM3352MTCX-3.3
LM3352MTC-3.3
MTC16
MTC16
MTC16
MTC16
MTC16
MTC16
TSSOP-16
TSSOP-16
TSSOP-16
TSSOP-16
2.5k Units, Tape and Reel
94 Units, Rail
2.5k Units, Tape and Reel
94 Units, Rail
Pin Description
Pin Number
Name
GND
C3−
C3+
C2−
C2+
C1−
C1+
VOUT
GND
VIN
Function
1
2
Ground*
Negative Terminal for C3
Positive Terminal for C3
Negative Terminal for C2
Positive Terminal for C2
Negative Terminal for C1
Positive Terminal for C1
Regulated Output Voltage
Ground*
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Input Supply Voltage
NC
This pin must be left unconnected.
Ground*
GND
SD
Active Low CMOS Logic-Level Shutdown Input
Ground*
GND
CFIL
GND
Filter Capacitor; A 1 µF ceramic capacitor is suggested.
Ground*
*All GND pins of the LM3352 must be connected to the same ground.
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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.
Operating Ratings
Input Voltage (VIN
)
2.5V to 5.5V
1.8V to 4.0V
Output Voltage (VOUT
)
Ambient Temperature (TA) (Note 2)
−40˚C to +85˚C
−40˚C to +125˚C
VOUT Pin
−0.5V to 4.5V
−0.5V to 5.6V
Junction Temperature (T ) (Note 2)
J
All Other Pins
Power Dissipation (TA = 25˚C)
(Note 2)
700 mW
150˚C
TJMAX (Note 2)
θJA (Note 2)
150˚C/W
Storage Temperature
Lead Temperature (Soldering, 5
sec.)
−65˚C to +150˚C
260˚C
ESD Rating (Note 3)
human body model
machine model
2 kV
100V
Electrical Characteristics
Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: C1 = C2 = C3 = 0.33 µF; CIN = 15 µF; COUT = 33 µF; VIN = 3.5V.
Parameter
LM3352-2.5
Output Voltage (V
Conditions
VIN = 3.5V; I
Min
Typ
2.5
2.5
Max
2.537
Units
=
LOAD
2.463
OUT
)
100 mA
<
<
2.8V VIN 5.5V;
<
<
1 mA ILOAD
2.425/2.400
2.575/2.600
100 mA
<
<
V
3.6V VIN 4.9V;
<
<
1 mA ILOAD
2.425/2.400
2.425/2.400
2.5
2.5
2.575/2.600
2.575/2.600
200 mA
<
<
4.9V VIN 5.5V;
<
<
1 mA ILOAD
175 mA
Efficiency
ILOAD = 15 mA
85
75
%
ILOAD = 150 mA, VIN
= 4.0V
Output Voltage
Ripple
ILOAD = 50 mA
C
= 33 µF
75
mVP-P
OUT
(Peak-to-Peak)
LM3352-3.0
tantalum
Output Voltage (V
VIN = 3.5V; I
100 mA
=
LOAD
2.955
3.0
3.0
3.045
OUT
)
<
<
2.5V VIN 5.5V;
<
<
1 mA ILOAD
2.910/2.880
3.090/3.120
V
100 mA
<
<
3.8V VIN 5.5V;
<
<
1 mA ILOAD
2.910/2.880
3.0
3.090/3.120
200 mA
Efficiency
ILOAD = 15 mA
80
75
%
ILOAD = 150 mA, VIN
= 4.0V
Output Voltage
Ripple
ILOAD = 50 mA
C
= 33 µF
75
mVP-P
OUT
(Peak-to-Peak)
tantalum
3
www.national.com
Electrical Characteristics (Continued)
Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: C1 = C2 = C3 = 0.33 µF; CIN = 15 µF; COUT = 33 µF; VIN = 3.5V.
Parameter
LM3352-3.3
Output Voltage (V
Conditions
VIN = 3.5V; I
Min
3.251
Typ
3.3
3.3
Max
3.349
Units
=
LOAD
OUT
)
100 mA
<
<
2.5V VIN 5.5V;
<
<
1 mA ILOAD
3.201/3.168
3.399/3.432
V
100 mA
<
<
4.0V VIN 5.5V;
<
<
1 mA ILOAD
3.201/3.168
3.3
3.399/3.432
200 mA
Efficiency
ILOAD = 15 mA
90
80
%
ILOAD = 150 mA, VIN
= 4.0V
Output Voltage
Ripple
ILOAD = 50 mA
C
= 33 µF
75
mVP-P
OUT
(Peak-to-Peak)
tantalum
LM3352-ALL OUTPUT VOLTAGE VERSIONS
Operating Quiescent Measured at Pin
Current
VIN
I
;
400
2.5
1
500
5
µA
µA
MHz
V
= 0A (Note 4)
LOAD
Shutdown Quiescent SD Pin at 0V (Note
Current
5)
Switching
Frequency
0.65
1.35
0.2 VIN
<
<
SD Input Threshold 2.5V VIN 5.5V
Low
<
<
SD Input Threshold 2.5V VIN 5.5V
0.8 VIN
V
High
SD Input Current
Measured at SD
Pin;
0.1
1.0
µA
SD Pin = VIN = 5.5V
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
beyond its rated operating conditions.
Note 2: As long as T ≤ +85˚C, all electrical characteristics hold true for the 3.0V and 3.3V options at all current loads and the 2.5V option at all loads when V
A
IN
>
≤ 5V. For V
5V with the 2.5V option, the junction temperature rise above ambient is: ∆T = 540I −23 where I is in amps. The output current must be derated
IN
L
L
>
at higher ambient temperatures to make sure T does not exceed 150˚C when operating the 2.5V option at V
5V.
J
IN
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: The V
pin is forced to 200 mV above the typical V
. This is to insure that the internal switches are off.
OUT
OUT
Note 5: 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
VOUT vs. VIN
VOUT vs. VIN
10103704
10103705
10103707
10103709
VOUT vs. VIN
10103706
VOUT vs. VIN
10103708
5
www.national.com
Typical Performance Characteristics Unless otherwise specified TA = 25˚C. (Continued)
VOUT vs. VIN
VOUT vs. VIN
10103710
10103711
VOUT vs. VIN
Load Transient Response
10103712
10103714
Efficiency vs. VIN
Efficiency vs. VIN
10103720
10103721
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6
Typical Performance Characteristics Unless otherwise specified TA = 25˚C. (Continued)
Efficiency vs. VIN
Switching Frequency vs. VIN
10103723
10103722
Operating Quiescent
Current vs. VIN
VOUT Ripple vs. COUT
10103724
10103730
VOUT Ripple vs. COUT
VOUT Ripple vs. COUT
10103731
10103732
7
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Applications Information
10103703
FIGURE 1. Block Diagram
Operating Principle
Charge Pump Capacitor Selection
The LM3352 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 16-pin TSSOP package. The
LM3352 can provide a regulated voltage between 1.8V and
4V from an input voltage between 2.5V and 5.5V. It can
supply a load current up to 200 mA.
A 0.33 µF ceramic capacitor is suggested for C1, C2 and C3.
To ensure proper operation over temperature variations, an
X7R dielectric material is recommended.
Filter Capacitor Selection
a) CAPACITOR TECHNOLOGIES
As shown in Figure 1, the LM3352 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 seven
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.
The three major technologies of capacitors that can be used
as filter capacitors for LM3352 are: i) tantalum, ii) ceramic
and iii) polymer electrolytic technologies.
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
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.
>
good, especially at high frequencies ( 1 MHz).
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-
www.national.com
8
ues. However, their ESR is still higher than the ceramics,
and their capacitance value is lower than the tantalums of
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)
yuden which are suitable for use with regulators. Ceramics
are taller and larger than the tantalums of the same capaci-
tance value.
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-
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
A higher value CIN will give a lower VIN ripple. To optimize
low input and output ripple as well as size a 15 µF polymer
electrolytic, 22 µF ceramic, or 33 µF tantalum capacitor is
recommended. This will ensure low input ripple at 200 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
ceramics 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 applications. The ceramics and polymer electrolytics
are a good choice for low ripple, low noise applications
where size is less of a concern. The 15 µF polymer electro-
lytics are physically much larger than the 33 µF tantalums
and 22 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, XR7 ceramic capacitor should be connected to pin
CFIL. This capacitor provides the filtering needed for the
internal supply rail of the LM3352.
Of the different capacitor technologies, a sample of vendors
that have been verified as suitable for use with the LM3352
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.
TABLE 2. Capacitor Vendor Information
Manufacturer
Taiyo-yuden
Tel
(408) 573-4150
(803) 448-9411
(207) 324-4140
(847) 843-7500
Fax
(408) 573-4159
(803) 448-1943
(207) 324-7223
(847) 843-2798
(508) 996-3830
(619) 661-1055
Website
www.t-yuden.com
www.avxcorp.com
www.vishay.com
Ceramic
AVX
Tantalum
Sprague/Vishay
Nichicon
www.nichicon.com
www.cornell-dubilier.com
www.sanyovideo.com
Polymer Electrolytic
Cornell-Dubilier (ESRD) (508) 996-8561
Sanyo (POSCAP) (619) 661-6322
9
www.national.com
Reset circuit, such as the LP3470, is recommended if
greater start up loads are expected. Under certain conditions
the LM3352 can start up with greater load currents without
the use of a Power On Reset Circuit (See application note
AN-1144: Maximizing Startup Loads with the LM3352 Regu-
lated Buck/Boost Switched Capacitor Converter).
Maximum Available Output Current
The LM3352 cannot provide 200 mA under all VIN and VOUT
conditions. The VOUT vs VIN graphs in the Typical Perfor-
mance Characteristics section show the minimum VIN at
which the LM3352 is capable of providing different load
currents while maintaining VOUT regulation. Refer to the
Electrical Characteristics for guaranteed conditions.
Thermal Protection
During output short circuit conditions, the LM3352 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.
Maximum Load Under Start-Up
Due to the LM3352’s unique start-up sequence, it is not able
to start up under all load conditions. Starting with 45 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
Typical Application Circuits
10103733
FIGURE 2. Basic Buck/Boost Regulator
10103715
FIGURE 3. Low Output Noise and Ripple Buck/Boost Regulator
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10
traces between the capacitors and the IC short and direct.
Use of a ground plane is recommended. Figure 4 shows a
typical layout as used in the LM3352 evaluation board.
Layout Considerations
Due to the 1 MHz typical switching frequency of the LM3352,
careful board layout is a must. It is important to place the
capacitors as close to the IC as possible and to keep the
10103716
FIGURE 4. Typical Layout, Top View (magnification 2.8X)
11
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Physical Dimensions inches (millimeters) unless otherwise noted
TSSOP-16 Pin Package
For Ordering, Refer to Ordering Information Table
NS Package Number MTC16
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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