LM3352MTCX-2.5 [NSC]
Regulated 200 mA Buck-Boost Switched Capacitor DC/DC Converter; 监管200毫安降压 - 升压型开关电容DC / DC转换器
| 型号： | LM3352MTCX-2.5 |
| 厂家： | 
National Semiconductor |
| 描述： | Regulated 200 mA Buck-Boost Switched Capacitor DC/DC Converter |
| 文件： | 总11页 (文件大小：519K) |
| 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
n Custom output voltages available from 1.8V to 4.0V in
100 mV increments
n 2.5V to 5.5V input voltage
n Up to 200 mA output current
General Description
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
>
n
80% average efficiency
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 Na-
tional Semiconductor representative.
n Uses few, low-cost external components
n Very small solution size
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’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 TSSOP-16 package
The LM3352 is available in a 16-pin TSSOP package. This
package has a maximum height of only 1.1 mm.
n Over-temperature protection
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.
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
Features
±
n Regulated VOUT with 3% accuracy
n Standard output voltage options: 2.5V, 3.0V and 3.3V
Typical Operating Circuit
DS101037-1
© 1999 National Semiconductor Corporation
DS101037
www.national.com
Connection Diagram
DS101037-2
Top View
TSSOP-16 Pin Package
See NS Package Number MTC16
Ordering Information
Order Number
LM3352MTCX-2.5
LM3352MTC-2.5
LM3352MTCX-3.0
LM3352MTC-3.0
LM3352MTCX-3.3
LM3352MTC-3.3
Package Type
NSC Package Drawing
MTC16
Supplied As
2.5k Units, Tape and Reel
94 Units, Rail
TSSOP-16
TSSOP-16
TSSOP-16
TSSOP-16
TSSOP-16
TSSOP-16
MTC16
MTC16
2.5k Units, Tape and Reel
94 Units, Rail
MTC16
MTC16
2.5k Units, Tape and Reel
94 Units, Rail
MTC16
Pin Description
Pin Number
Name
GND
C3−
C3+
C2−
C2+
C1−
C1+
VOUT
GND
VIN
Function
*
Ground
1
2
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
3
4
5
6
7
8
*
Ground
9
10
11
12
13
14
15
16
Input Supply Voltage
NC
This pin must be left unconnected.
*
GND
SD
Ground
Active Low CMOS Logic-Level Shutdown Input
*
GND
CFIL
GND
Ground
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.
Lead Temperature (Soldering, 5 sec.)
260˚C
ESD Rating (Note 3)
human body model
machine model
2 kV
100V
VOUT Pin
−0.5V to 4.5V
−0.5V to 5.6V
Operating Ratings
All Other Pins
Input Voltage (VIN
)
2.5V to 5.5V
1.8V to 4.0V
Power Dissipation (TA = 25˚C)
(Note 2)
Output Voltage (VOUT
)
700 mW
150˚C
Ambient Temperature (TA ) (Note 2)
Junction Temperature (T J) (Note 2)
−40˚C to +85˚C
−40˚C to +125˚C
TJMAX (Note 2)
θJA (Note 2)
150˚C/W
Storage Temperature
−65˚C to +150˚C
Electrical Characteristics
=
Limits in standard typeface are for TJ 25˚C, and limits in boldface type apply over the full operating temperature range. Unless
=
=
=
=
=
=
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
Min
Typ
Max
Units
)
VIN = 3.5V; I
= 100 mA
LOAD
2.463
2.5
2.5
2.537
OUT
<
<
<
2.8V VIN 5.5V;
2.425/2.400
2.575/2.600
<
1 mA ILOAD 100 mA
V
<
<
3.6V VIN 4.9V;
2.425/2.400
2.425/2.400
2.5
2.5
2.575/2.600
2.575/2.600
<
<
1 mA ILOAD 200 mA
<
<
4.9V VIN 5.5V;
<
<
1 mA ILOAD 175 mA
Efficiency
ILOAD = 15 mA
85
75
%
ILOAD = 150 mA, VIN = 4.0V
ILOAD = 50 mA
Output Voltage Ripple
(Peak-to-Peak)
75
mVP-P
C
= 33 µF tantalum
OUT
LM3352-3.0
Output Voltage (V
OUT
)
VIN = 3.5V; I
= 100 mA
2.955
3.0
3.0
3.045
LOAD
<
<
2.5V VIN 5.5V;
2.910/2.880
3.090/3.120
<
<
1 mA ILOAD 100 mA
V
<
<
3.8V VIN 5.5V;
2.910/2.880
3.0
3.090/3.120
<
<
1 mA ILOAD 200 mA
Efficiency
ILOAD = 15 mA
80
75
%
ILOAD = 150 mA, VIN = 4.0V
ILOAD = 50 mA
Output Voltage Ripple
(Peak-to-Peak)
75
mVP-P
C
= 33 µF tantalum
OUT
LM3352-3.3
Output Voltage (V
OUT
)
VIN = 3.5V; I
= 100 mA
3.251
3.3
3.3
3.349
LOAD
<
<
2.5V VIN 5.5V;
3.201/3.168
3.399/3.432
<
<
1 mA ILOAD 100 mA
V
<
<
4.0V VIN 5.5V;
3.201/3.168
3.3
3.399/3.432
<
<
1 mA ILOAD 200 mA
Efficiency
ILOAD = 15 mA
90
80
%
ILOAD = 150 mA, VIN = 4.0V
ILOAD = 50 mA
Output Voltage Ripple
(Peak-to-Peak)
75
mVP-P
C
= 33 µF tantalum
OUT
LM3352-ALL OUTPUT VOLTAGE VERSIONS
Operating Quiescent Current
Measured at Pin VIN
;
400
500
µA
I
= 0A (Note 4)
LOAD
Shutdown Quiescent Current
Switching Frequency
SD Pin at 0V (Note 5)
2.5
1
5
µA
MHz
V
0.65
1.35
<
<
SD Input Threshold Low
SD Input Threshold High
2.5V VIN 5.5V
0.2 VIN
<
<
2.5V VIN 5.5V
0.8 VIN
V
3
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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
Conditions
Min
Typ
Max
Units
LM3352-ALL OUTPUT VOLTAGE VERSIONS
SD Input Current
Measured at SD Pin;
SD Pin = VIN = 5.5V
0.1
1.0
µA
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
≤
IN
A
=
>
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 at
IN
L
L
>
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 di-
rectly into each pin.
Note 4: The V
OUT
pin is forced to 200 mV above the typical V
. This is to insure that the internal switches are off.
is fully discharged before measurement.
OUT
Note 5: The output capacitor C
OUT
=
Typical Performance Characteristics Unless otherwise specified TA 25˚C.
VOUT vs. VIN
VOUT vs. VIN
DS101037-4
DS101037-5
VOUT vs. VIN
VOUT vs. VIN
DS101037-6
DS101037-7
www.national.com
4
=
Typical Performance Characteristics Unless otherwise specified TA 25˚C. (Continued)
VOUT vs. VIN
VOUT vs. VIN
VOUT vs. VIN
VOUT vs. VIN
DS101037-8
DS101037-10
DS101037-12
DS101037-9
VOUT vs. VIN
DS101037-11
Load Transient Response
DS101037-14
5
www.national.com
=
Typical Performance Characteristics Unless otherwise specified TA 25˚C. (Continued)
Efficiency vs. VIN
Efficiency vs. VIN
DS101037-20
DS101037-21
Efficiency vs. VIN
Switching Frequency vs. VIN
DS101037-23
DS101037-22
Operating Quiescent
Current vs. VIN
VOUT Ripple vs. COUT
DS101037-30
DS101037-24
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6
=
Typical Performance Characteristics Unless otherwise specified TA 25˚C. (Continued)
VOUT Ripple vs. COUT
VOUT Ripple vs. COUT
DS101037-31
DS101037-32
Applications Information
DS101037-3
FIGURE 1. Block Diagram
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.
Operating Principle
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 sup-
ply a load current up to 200 mA.
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.
As shown in Figure 1, the LM3352 employs two feedback
loops to provide regulation in the most efficient manner pos-
sible. 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 gat-
ing 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
Charge Pump Capacitor Selection
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.
7
www.national.com
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
Filter Capacitor Selection
a) CAPACITOR TECHNOLOGIES
>
(
1
µF) are achievable from companies such as
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.
Taiyo-yuden which are suitable for use with regulators. Ce-
ramics are taller and larger than the tantalums of the same
capacitance value.
i) Tantalum
iii) Polymer Electrolytic
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
Polymer electrolytic is a third suitable technology. Polymer
capacitors provide some of the best features of both the ce-
ramic and the tantalum technologies. They provide very low
ESR values while still achieving high capacitance values.
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 (compa-
rable to ceramics) and good temperature stability (compa-
rable to tantalums). The Aluminum Polymer Electrolytics of-
fered by Cornell-Dubilier and Panasonic, and the POSCAPs
offered by Sanyo fall under this category.
<
(
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
Table 1 compares the features of the three capacitor tech-
nologies.
>
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
TABLE 1. Comparison of Capacitor Technologies
Polymer
Ceramic
Tantalum
High
Electrolytic
ESR
Lowest
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
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
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 ce-
ramics 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 15 µF polymer electrolytics are physi-
cally much larger than the 33 µF tantalums and 22 µF ceram-
ics.
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 ca-
pacitor 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 electrolyt-
ics are a good choice for low ripple, low noise applications
where size is less of a concern.
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8
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.
Filter Capacitor Selection (Continued)
iii) CFIL
A 1 µF, XR7 ceramic capacitor should be connected to pin
CFIL. This capacitor provides the filtering needed for the in-
ternal supply rail of the LM3352.
TABLE 2. Capacitor Vendor Information
Manufacturer
Taiyo-yuden
AVX
Tel
Fax
Website
Ceramic
(408) 573-4150
(803) 448-9411
(207) 324-4140
(847) 843-7500
(508) 996-8561
(619) 661-6322
(408) 573-4159
(803) 448-1943
(207) 324-7223
(847) 843-2798
(508) 996-3830
(619) 661-1055
www.t-yuden.com
www.avxcorp.com
www.vishay.com
Tantalum
Sprague/Vishay
Nichicon
www.nichicon.com
www.cornell-dubilier.com
www.sanyovideo.com
Polymer Electrolytic
Cornell-Dubilier (ESRD)
Sanyo (POSCAP)
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 Regulated
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 cur-
rents while maintaining VOUT regulation. Refer to the Electri-
cal 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 regula-
tion, any load up to the maximum as specified in the Electri-
cal Characteristics may be applied. Using a Power On Reset
Typical Application Circuits
DS101037-33
FIGURE 2. Basic Buck/Boost Regulator
9
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Typical Application Circuits (Continued)
DS101037-15
FIGURE 3. Low Output Noise and Ripple Buck/Boost Regulator
between the capacitors and the IC short and direct. Use of a
ground plane is recommended. Figure 4 shows a typical lay-
out 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 ca-
pacitors as close to the IC as possible and to keep the traces
DS101037-16
FIGURE 4. Typical Layout, Top View (magnification 2.8X)
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10
Physical Dimensions inches (millimeters) unless otherwise noted
TSSOP-16 Pin Package
For Ordering, Refer to Ordering Information Table
NS Package Number MTC16
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systems which, (a) are intended for surgical implant
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accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
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can be reasonably expected to cause the failure of
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