LTC3531/LTC3531-3.3/LTC3531-3 - 200mA Buck-Boost Synchronous DC/DC Converters

LTC3531/
LTC3531-3.3/LTC3531-3
200mA Buck-Boost
Synchronous DC/DC
Converters
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FEATURES
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DESCRIPTIO
Regulated Output with Input Above, Below or Equal
to the Output
Single Inductor
Up to 90% Efficiency
VIN Range: 1.8V to 5.5V
200mA at 3.3VOUT from 3.6V Input
125mA at 3VOUT from 2.5V Input
Fixed VOUT Versions (TSOT, DFN): 3.3V, 3V
Adjustable VOUT Version (DFN): 2V to 5V
Burst Mode® Operation, No External Compensation
Ultra Low Quiescent Current: 16μA, Shutdown
Current <1μA
Only 3 External Components Required
(Fixed Voltage Versions)
Short-Circuit Protection
Output Disconnect in Shutdown
Available in 6-Pin ThinSOT and 3mm × 3mm DFN
Packages
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APPLICATIO S
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The devices include two 0.5Ω N-channel MOSFET switches
and two P-channel switches (0.5Ω, 0.8Ω). Quiescent
current is typically 16μA, making the parts ideal for battery power applications. Other features include a <1μA
shutdown current, current limiting, thermal shutdown
and output disconnect. The parts are offered in a 6-pin
ThinSOTTM package for fixed voltage versions or a 3mm ×
3mm DFN package for fixed and adjustable versions.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6166527.
Handheld Instruments
MP3 Players
Handheld computers
PDA/GPS
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The LTC®3531/LTC3531-3.3/LTC3531-3 are synchronous
buck-boost DC/DC converters that operate from input
voltages above, below or equal to the output voltage. The
topology incorporated in the ICs provides a continuous
transfer through all operating modes, making the product
ideal for single cell Li-Ion and multicell alkaline or nickel
applications. The converters operate in Burst Mode, minimizing solution footprint and component count as well as
providing high conversion efficiency over a wide range of
load currents.
TYPICAL APPLICATIO
Efficiency vs VIN
100
10μH
95
Li-Ion
VIN
+
SW2
VOUT
LTC3531-3.3
2.2μF
VOUT
3.3V
160mA
10μF
SHDN
EFFICIENCY (%)
90
SW1
VIN
3.1V TO
4.2V
BOOST
MODE
85
BUCK
MODE
80
4SW
MODE
75
GND
70
3531 TA01a
65
ON OFF
60
1.5
3.3VOUT AT 100mA
2
2.5
3 3.5 4 4.5
INPUT VOLTAGE (V)
5
5.5
3531 TA01b
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LTC3531/
LTC3531-3.3/LTC3531-3
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ABSOLUTE
AXI U RATI GS
(Note 1)
VIN, VOUT, SW1, SW2, SHDN Voltage ...........–0.3 to 6V
SW1, SW2 Voltage, <100ns Pulse ..................–0.3 to 7V
Operating Temperature Range (Notes 2, 3) –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Lead Temperature (TS6, Soldering, 10 sec) .......... 300°C
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
TOP VIEW
SW2 1
GND, PGND 2
VOUT 3
6 SW1
5 VIN
4 SHDN
PGND
7
SW2
9
3
6
VOUT
SHDN 4
5
FB*
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 43°C/W
EXPOSED PAD IS GND (PIN 9), MUST BE SOLDERED TO PCB
*NC FOR LTC3531-3.3V, LTC3531-3.0V.
TJMAX = 125°C, θJA = 102°C/W
LTC3531ES6-3.3
LTC3531ES6-3
8
VIN 2
GND
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
ORDER PART NUMBER
SW1 1
S6 PART MARKING
ORDER PART NUMBER
LTBWM
LTCBK
DD PART MARKING
LTC3531EDD
LTC3531EDD-3.3
LTC3531EDD-3
LBVC
LBWH
LCBV
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.
PARAMETER
VIN
Minimum Startup Voltage
VOUT Regulation
Output Voltage (3.3V Version)
Output Voltage (3V Version)
FB Voltage (Adj Version)
FB Input Current (Adj Version)
Operating Current
Quiescent Current in Sleep:
Shutdown Current
Switch Performance
NMOS Switch Leakage
PMOS Switch Leakage
NMOS B, C RDSON
PMOS A RDSON
CONDITIONS
MIN
TYP
MAX
1.65
1.8
V
3.32
3.02
1.225
1
3.39
3.09
1.25
50
V
V
V
nA
VIN = 5V, VOUT = 3.6V, FB = 1.3V
VOUT = 3.6V
SHDN = 0V, VOUT = 0V
16
6
30
10
1
μA
μA
μA
Switches B and C
Switches A and D
VIN = 5V
VIN = 5V
0.2
0.2
0.5
0.5
2
2
μA
μA
Ω
Ω
●
No Load
No Load
No Load
VFB = 1.225V
VIN
VOUT
VIN
●
●
●
3.25
2.95
1.20
UNITS
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LTC3531/
LTC3531-3.3/LTC3531-3
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.
PARAMETER
PMOS D RDSON (3.3V Version or Adjustable Version set to 3.3V)
PMOS D RDSON (3V Version)
Peak Current Limit
CONDITIONS
VOUT = 3.1V
VOUT = 2.8V
L = 10μH, VIN = 5V
SHDN
SHDN Input Threshold
SHDN Hysteresis
SHDN Leakage Current
MIN
295
0.4
VSHDN
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TYPICAL PERFOR A CE CHARACTERISTICS
300
450
L = 10μH
VOUT = 3.3V
IPEAK, IVALLEY, IZERO vs VIN
CURRENT (mA)
MAXIMUM IOUT (mA)
150
100
2
2.5
3
3.5
4
4.5
5
14
250
200
IVALLEY
150
2
2.5
3
0
3.5
4
4.5
5.5
80
2.5
100
80
60
40
5
5.5
VIN (V)
3531 G04
5
5.5
3.35
70
60
50
22μF
40
3.30
22μF
3.25
47μF
30
3.20
50mA LOAD
0
4.5
4.5
10μF
10μF
10
4
3.5
4
VIN (V)
3.40
20
20
3
Load Regulation vs COUT
(3.3V Version)
VOUT (V)
VRIPPLE PEAK-PEAK (mV)
140
3.5
2
3531 G03
100
90
3
1.5
VOUT Ripple vs COUT
(3.3V Version)
120
IIN (mA)
5
3531 G02
160
2.5
IVOUT
VIN (V)
IIN Short Circuit vs VIN
2
8
2
IZERO
3531 G01
0
1.5
10
6
VIN (V)
180
12
4
0
1.5
5.5
IVIN
16
300
50
0
1.5
1
18
IPEAK
100
50
V
mV
μA
Sleep Currents
L = 10μH
350
200
1.4
460
20
400
250
1
60
0.01
UNITS
Ω
Ω
mA
TA = 25°C unless otherwise specified.
CURRENT (μA)
350
MAX
Continuous operation above the specified maximum operating junction
temperature may result in device degradation or failure.
Note 3: The LTC3531 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Maximum IOUT vs VIN
(3.3V Version)
TYP
0.8
0.9
365
1.5
2
2.5
3
3.5
4
VIN (V)
4.5
5
5.5
3531 G05
VIN = 3.6V
3.15
1
0.1
10
100
LOAD CURRENT (mA)
1000
3521 G06
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LTC3531/
LTC3531-3.3/LTC3531-3
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TYPICAL PERFOR A CE CHARACTERISTICS
Start-Up into Resistive Load
L = 10μH
TA = 25°C unless otherwise specified.
Burst Frequency vs Load
(3.3V Version)
30
1000
28
VOUT Regulation vs Temperature
(3.3V Version)
3.350
L = 10μH
COUT = 10μF
VIN = 3.6V
ILOAD = 10mA
26
100
RMIN (Ω)
22
20
18
16
3.325
50mA
10mA
10
VOUT (V)
FREQUENCY (kHz)
24
5mA
1mA
3.275
1
14
3.300
0.5mA
12
10
1.5
2
2.5
3
3.5
4
VIN (V)
4.5
5
0.1
1.5
5.5
2
3
2.5
3.5 4
VIN (V)
4.5
5
Switch On Resistances
VIN = 5V
VOUT = 3.3V
3.250
–40
–20
60
0
20
40
TEMPERATURE (°C)
80
3531 G08
3531 G07
1000
5.5
3531 G09
SHDN Pin Threshold and
Hysteresis
IPEAK, IVALLEY vs Temperature
1
400
D (PMOS)
100
IPEAK
350
900
0.9
700
A (PMOS)
600
250
IVALLEY
200
150
2.5VIN
3.3VOUT
10μH
100
500
400
–40
B,C (NMOS)
–20
60
0
20
40
TEMPERATURE (°C)
50
80
100
3531 G10
VOLTAGE (V)
800
CURRENT (mA)
RDSON (mΩ)
300
0
–40
0.8
OPERATING
0.7
SHUTDOWN
0.6
IZERO
–20
0
40
60
20
TEMPERATURE (°C)
80
100
3531 G11
0.5
– 40
– 20
60
0
20
40
TEMPERATURE (°C)
80
100
3531 G12
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LTC3531/
LTC3531-3.3/LTC3531-3
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TYPICAL PERFOR A CE CHARACTERISTICS
Buck Mode at 5VIN,
3.3VOUT 200mA
TA = 25°C unless otherwise specified.
Buck Mode at 5VIN,
3.3VOUT 100mA
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
L = 10μH
COUT = 22μF
5μs/DIV
3531 G13
L = 10μH
COUT = 22μF
5μs/DIV
3531 G14
4 Switch Mode Waveforms at
3.6VIN, 3.3VOUT 200mA
Buck Mode Waveforms at 5VIN,
3.3VOUT 20mA
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
L = 10μH
COUT = 22μF
5μs/DIV
3531 G15
L = 10μH
COUT = 22μF
4 Switch Mode Waveforms at
3.6VIN, 3.3VOUT 100mA
5μs/DIV
3531 G16
4 Switch Mode Waveforms at
3.6VIN, 3.3VOUT 20mA
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
L = 10μH
COUT = 22μF
5μs/DIV
3531 G17
SW1
SW2
VOUT (AC)
IL
L = 10μH
COUT = 22μF
5μs/DIV
3531 G18
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LTC3531/
LTC3531-3.3/LTC3531-3
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TYPICAL PERFOR A CE CHARACTERISTICS
TA = 25°C unless otherwise specified.
Boost Mode Waveforms at
2.5VIN, 3.3VOUT 100mA
Boost Mode Waveforms at
2.5VIN, 3.3VOUT 20mA
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
L = 10μH
COUT = 22μF
3531 G19
5μs/DIV
L = 10μH
COUT = 22μF
SW1
5V/DIV
SW2
5V/DIV
VOUT (AC)
50mV/DIV
IL
200mA/DIV
200mA/DIV
VOUT
1V/DIV
IL
200mA/DIV
3531 G21
1μs/DIV
25μs/DIV
3.6VIN, 3.3VOUT Load Step
200mA to 80mA
3531 G22
SW1 and SW2 Close-Up in Four
Switch Mode
100mA LOAD
20mA LOAD
3531 G20
Start-Up into 50mA Load at
3.3 VOUT (Shows Start, Buck,
Then 4sw Modes)
Shorted Output
L = 10μH
COUT = 22μF
VIN = 5
5μs/DIV
20mA LOAD
VOUT (AC)
20mV/DIV
SW1
2V/DIV
IL
200mA/DIV
SW2
2V/DIV
COUT = 22μF
25μs/DIV
3531 G23
VIN = 3.6V
VOUT = 3.3V
200ns/DIV
3531 G24
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LTC3531/
LTC3531-3.3/LTC3531-3
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PI FU CTIO S
ThinSOT/DFN Packages
SW2 (Pin 1/Pin 7): Buck-Boost Switch Pin Where Internal
Switches C and D are Connected. An optional Schottky
diode can be connected from SW2 to VOUT for a moderate
efficiency improvement. Minimize trace length to keep
EMI down.
GND (Pin 2/Pin 3): Signal Ground for the IC.
PGND (Pin 2/Pin 8): Power Ground for the IC. (Shared
on ThinSOT version)
VOUT (Pin 3/Pin 6): Output of the Buck-Boost Synchronous
Rectifier. A filter capacitor is placed from VOUT to GND.
A ceramic bypass capacitor is recommended as close to
the VOUT and GND pins as possible.
SHDN (Pin 4/Pin 4): External Shutdown Pin. An applied
voltage of < 0.4V shuts down the converter. A voltage
above >1.4V will enable the converter.
VIN (Pin 5/Pin 2): Input Supply Pin for the Buck-Boost
Converter. A minimum 2.2μF Ceramic Capacitor should
be placed between VIN and GND.
FB (NA/Pin 5): Feedback Pin for the Adjustable Version.
Connect the resistor divider tap here. The output voltage
can be adjusted from 2V to 5V.
⎛ R2 ⎞
VOUT = 1 . 225⎜ 1+ ⎟
⎝ R1 ⎠
SW1 (Pin 6/Pin 1): Buck-Boost Switch Pin Where Internal
Switches A and B are Connected. Connect the inductor
from SW1 to SW2.
Exposed Pad (Pin 9, DFN): Solder to PCB ground for
optimal thermal performance.
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LTC3531/
LTC3531-3.3/LTC3531-3
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BLOCK DIAGRA
SW1
SW2
SW A
SW D
VIN
VOUT
GATE DRIVERS
AND
ANTICROSS
CONDUCTION
SW B
365mA
SW C
VBEST
PEAK
CURRENT
LIMIT
BUCK, 4SW,
BOOST
VIN
VBEST
AND
MODE DETECT
STATE
MACHINE
AND
LOGIC
VIN
IZERO/IVALLEY
DETECT
VOUT
1.225V VREF
UVLO
R2
1.65V
VOUT
COMPARATOR
SHDN
SHUTDOWN
THERMAL
SHUTDOWN
PGND
GND
COMBINED
FOR TSOT
FB
NOT BONDED
FOR 3.3V AND
3V VERSIONS
R1
INTERNAL
R1 AND R2
DISABLED
FOR ADJ VERSION
3531 BD
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LTC3531/
LTC3531-3.3/LTC3531-3
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OPERATIO
The LTC3531, LTC3531-3.3 and LTC3531-3 synchronous buck-boost converters utilize a Burst Mode control
technique to achieve high efficiency over a wide dynamic
range of load currents. A 2% accurate comparator is
used to monitor the output voltage. If VOUT is above its
programmed reference threshold no switching occurs and
only quiescent current is drawn from the power source
(sleep mode). When VOUT drops below the reference
threshold the IC “wakes up”, switching commences, and
the output capacitor is charged. The value of the output
capacitor, the load current, and the comparator hysteresis
(~1%) determines the number of current pulses required
to pump-up the output capacitor before the part returns
to sleep.
In order to determine the best operating mode for the
converter, the LTC3531 contains a second comparator
that monitors the relative voltage difference between VIN
and VOUT. Input and output voltages in the various modes
as well as typical inductor currents are shown in Figure 1.
Regions of the current waveforms where switches A and
D are on provide the highest efficiency since energy is
transferred directly from the input source to the output.
Boost Mode
If VIN is ~400mV below VOUT, the LTC3531 operates in
boost or step-up mode. Referring to Figure 1 (left side)
when VOUT falls below its regulation voltage, switches A
and C are turned on (VIN is applied across the inductor)
and current is ramped until IPEAK is detected. When this
VIN
occurs, C is turned off, D is turned on and current is delivered to the output capacitor (VIN – VOUT is applied across
the inductor). Inductor current falls when D is on, until an
IVALLEY is detected. Terminating at IVALLEY, rather than IZERO,
results in an increased load current capability for a given
peak current. This AC then AD switch sequence is repeated
until the output is pumped above its regulation voltage, a
final IZERO is detected, and the part returns to sleep mode
(IVALLEY is ignored and IZERO is used in all modes once
VOUT is above its programmed value).
4-Switch Mode
If (VOUT – 400mV) < ~VIN < (VOUT + 800mV), the LTC3531
operates in 4-switch step-up/down mode. Returning to
Figure 1 (center) when VOUT falls below its regulation voltage, switches A and C are turned on and current is ramped
until IPEAK is detected. As with Boost Mode operation, C
is then turned off, D is turned on and current is delivered
to the output. When A and D are on, the inductor current
slope is dependant on the relationship between VIN, VOUT,
and the RDSON of the switches. In 4-switch mode, a tOFF
timer (approximately 3μs) is used to terminate the AD
pulse. Once the tOFF timer expires, switch A is turned off,
B is turned on and inductor current is ramped down (VOUT
is applied across the inductor) until IVALLEY is detected.
This sequence is repeated until the output is regulated,
BD switches are turned on, and a final IZERO is detected.
Anticross conduction circuitry in all modes ensures the
P-channel MOSFET and N-channel MOSFET switch pairs (A
and B or D and C) are never turned on simultaneously.
VOUT
VIN
VOUT
A
D
VIN
L
SW1
SW2
IMAX
B
C
IPEAK
tOFF
tOFF
tOFF
IVALLEY
IZERO
AC AD AC AD
BOOST MODE
AC AD BD AC AD
BD AC
4SW MODE
AD
BD
AD
BD AD BD
BUCK MODE
3531 F01
Figure 1. Voltage and Current Waveforms
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LTC3531/
LTC3531-3.3/LTC3531-3
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OPERATIO
Buck Mode
If VIN is ~800mV above VOUT, the LTC3531 operates in
buck or step-down mode. The higher offset between VIN
and VOUT (800mV) is required to ensure sufficient magnetizing voltage across the inductor when the RDSONS
are taken into account. At the beginning of a buck mode
cycle (Figure 1 right side) switches A and D are turned
on (VIN – VOUT is applied across the inductor), current
is delivered to the output and ramped up until IPEAK is
detected. When this occurs, A is turned off, B is turned
on and inductor current falls (–VOUT across the inductor) until an IVALLEY is detected. This AD then BD switch
sequence is repeated until the output is pumped above
its regulation voltage, a final IZERO is detected, and the
part returns to sleep mode.
Start-Up Mode
Before VOUT reaches approximately 1.6V, the D switch is
disabled and its body diode is used to transfer current to
the output capacitor. In start-up mode, the IVALLEY/IZERO
sense circuit is disabled and an alternate algorithm is used
to control inductor current. When the LTC3531 is brought
out of shutdown (assuming VOUT is discharged) switches
A and C are turned on until the inductor current reaches
IPEAK. The AC switches are then turned off and inductor
current flows to the output through the B switch and D
body diode. The period for the B switch/D body diode is
controlled by the tOFF timer to ~800nS. This sequence of
AC switch-on to IPEAK then B switch and D body diode for
~800ns is repeated until VOUT reaches ~1.6V. Once this
threshold is reached, the LTC3531 will transfer through the
required modes until VOUT is brought into regulation.
Due to propagation delays in the sense circuitry, the
magnitudes of the IPEAK, IVALLEY, and IZERO currents may
shift depending on VIN, VOUT and operating mode.
OTHER LTC3531 FEATURES
Shutdown: The part is shut down by pulling SHDN below
0.4V, and made active by pulling the pin up to VIN or VOUT.
Note that SHDN an be driven above VIN or VOUT, as long
as it is limited to less than 6V.
Output Disconnect and Inrush Limiting: The LTC3531
is designed to allow true output disconnect by opening
both P-channel MOSFET rectifiers. This allows VOUT to go
to zero volts during shutdown, drawing no current from
the input source. It also provides inrush current limiting
at turn-on, minimizing surge currents seen by the input
supply.
Thermal Shutdown: If the die temperature reaches approximately 150°C, the part will go into thermal shutdown and all switches will be turned off. The part will be
enabled again when the die temperature has dropped by
10°C (nominal). To deliver the power that the LTC3531
is capable of, it is imperative that a good thermal path be
provided to dissipate the heat generated within the package. It is recommended that multiple vias in the printed
circuit board be used to conduct heat away from the IC
and into a copper plane with as much area as possible.
Soldering the Exposed Pad to the GND plane (DFN version)
is recommended to improve thermal performance.
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LTC3531/
LTC3531-3.3/LTC3531-3
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APPLICATIO S I FOR ATIO
Component Selection
Only three power components are required to
complete the design of the buck-boost converter, VOUT
programming resistors are needed for the adjustable
version. The high operating frequency and low peak
currents of the LTC3531 allow the use of low value, low
profile inductors and tiny external ceramic capacitors.
ductor value with a >500mA current rating and <400mΩ
DCR is recommended. For applications where radiated
noise is a concern, a toroidal or shielded inductor can be
used. Table 2 contains a list of inductor manufacturers.
Capacitor Selection
For best efficiency, choose an inductor with high frequency
core material, such as ferrite, to reduce core loses. The
inductor should have low DCR (DC resistance) to reduce
the I2R losses, and must be able to handle the peak
inductor current without saturating. A 10μH to 22μH in-
The buck-boost convertor requires two capacitors. Ceramic
X5R types will minimize ESL and ESR while maintaining
capacitance at rated voltage over temperature. The VIN
capacitor should be at least 2.2μF. The VOUT capacitor
should be between 4.7μF and 22μF. A larger output capacitor should be used if lower peak to peak output voltage
ripple is desired. A larger output capacitor will also improve
load regulation on VOUT. See Table 3 for a list of capacitor
manufacturers for input and output capacitor selection.
Table 2. Inductor Vendor Information
Table 3. Capacitor Vendor Information
Inductor Selection
Supplier
COEV
Coilcraft
Murata
Sumida
Toko
Series
DN4835
MSS4020
LPO3310
DS1608
LQH43CN
LQH32CN
CDRH4D18
CDRH3D16/HP
D312C
D412C
DB320C
Phone
(800) 227-7040
(847) 639-6400
Website
www.coev.net
www.coilcraft.com
USA: (814) 237-1431
www.murata.com
(800) 831-9172
USA: (847) 956-0666
www.sumida.com
Japan: 81-3-3607-5111
(847) 297-0070
www.tokoam.com
Supplier
AVX
Murata
Series
X5R
X5R
Phone
(803) 448-9411
USA: (814) 237-1431
(800) 831-9172
Sanyo
POSCAP (619) 661-6322
Taiyo Yuden X5R
(408) 573-4150
TDK
X5R
(847) 803-6100
Website
www.avxcorp.com
www.murata.com
www.sanyovideo.com
www.taiyo-yuden.com
www.component.tdk.com
3531fb
11
LTC3531/
LTC3531-3.3/LTC3531-3
U
W
U
U
APPLICATIO S I FOR ATIO
SHUTDOWN
COUT
VIN
CIN
VOUT
L
GND
VOUT – 3
4 – SHDN
5 – VIN
GND – 2
6 – SW1
SW2 – 1
SOT PIN-OUT
GND
Recommended Layout (SOT Versions)
3531fb
12
LTC3531/
LTC3531-3.3/LTC3531-3
U
TYPICAL APPLICATIO
5V/Li-Ion to 3.3V with ThinSOT (3.3V Version)
95
100
4.4VIN
10μH
5VIN
5V/Li-Ion
VIN
VOUT
VOUT
3.3V
160mA
LTC3531-3.3
+
–
2.2μF
10μF
SHDN
GND
10
85
3.6VIN
80
3.1VIN
1
75
3531 TA02a
POWER LOSS (mW)
VIN
3.1V TO
5V
SW2
EFFICIENCY (%)
90
SW1
POWER LOSS AT 3.6VIN
70
ON OFF
65
0.1
1
10
100
LOAD CURRENT (mA)
0.1
1000
3531 TA02b
2 AA Alkaline to 3V with ThinSOT (3V Version)
90
100
10μH
2 x AA
ALKALINE
+
–
SW1
SW2
VIN
VOUT
VOUT
3V
80mA
LTC3531-3
2.2μF
+
–
10μF
SHDN
GND
80
10
2.5VIN
3.2VIN
75
1.8VIN
70
1
POWER LOSS (mW)
VIN
1.8V TO
3.2V
EFFICIENCY (%)
85
POWER LOSS AT 3.2VIN
3531 TA03a
65
ON OFF
60
0.1
1
10
100
LOAD CURRENT (mA)
0.1
1000
3531 TA03b
USB to 5V with 3 × 3 DFN (Adjustable Version)
95
100
10μH
4.7μF
SW1
SW2
VIN
VOUT
LTC3531
2.2μF
1Ω
R2
1M
10μF
FB
SHDN
GND
VOUT
5V
200mA
R1
324k
3531 TA04a
EFFICIENCY
10
85
80
POWER LOSS
1
75
POWER LOSS (mW)
USB
4.35V TO
5.25V
EFFICIENCY (%)
90
70
ON OFF
65
0.1
1
10
100
LOAD CURRENT (mA)
0.1
1000
3531 TA04b
3531fb
13
LTC3531/
LTC3531-3.3/LTC3531-3
U
PACKAGE DESCRIPTIO
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
0.62
MAX
2.90 BSC
(NOTE 4)
0.95
REF
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45
6 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
1.90 BSC
S6 TSOT-23 0302
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3531fb
14
LTC3531/
LTC3531-3.3/LTC3531-3
U
PACKAGE DESCRIPTIO
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 ±0.05
3.5 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
5
3.00 ±0.10
(4 SIDES)
0.38 ± 0.10
8
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
(DD) DFN 1203
0.200 REF
0.75 ±0.05
0.00 – 0.05
4
0.25 ± 0.05
1
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
3531fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However,
no responsibility is assumed for its use. Linear Technology Corporation makes no representation that
the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC3531/
LTC3531-3.3/LTC3531-3
U
TYPICAL APPLICATIO
Complete USB/Li-Ion Powered System
with 3.3VOUT and Linear Charger
5V (NOM)
FROM USB
CABLE
SUSPEND
USB POWER
+
Li-Ion
–
LTC4055
IN1
OUT
IN2
CHRG
HPWR
ACPR
SUSP
BAT
VOUT: USB OR BATTERY
OTHER
DC/DC
VNTC
3.1V TO 5.25V
TIMER
C1
22μF
100k
PROG
SHDN WALL NTC
SW1
SW2
VIN
VOUT
VOUT
3.3V
160mA
LTC3531-3.3
CLPROG
GND
L1
10μH
100k
0.1μF
C2
10μF
SHDN
GND
3531 TA05
C1, C2: TAIYO YUDEN JMK316BJ106ML
L1: MURATA LQH43CN100K03 (650mA 0.24Ω)
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1930/LT1930A
1A (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converter
VIN: 2.6V to 16V, VOUT(MAX) = 34V,
IQ = 4.2mA/5.5mA, ISD < 1μA, ThinSOT Package
LTC3400/LTC3400B
600mA (ISW), 1.2MHz Synchronous Step-Up DC/DC Converter
VIN: 0.85V to 5V, VOUT(MAX) = 5V,
IQ = 19μA/300μA, ISD < 1μA, ThinSOT Package
LTC3401/LTC3402
1A/2A (ISW), 3MHz Synchronous Step-Up DC/DC Converter
VIN: 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38μA,
ISD < 1μA, MS Package
LTC3405/LTC3405A
300mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter
VIN: 2.7V to 6V, VOUT(MIN) = 0.8V, IQ = 20μA,
ISD ≤ 1μA, MS10 Package
LTC3406/LTC3406B
600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter
VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20μA,
ISD ≤ 1μA, ThinSOT Package
LTC3421
3A (ISW), 3MHz Synchronous Step-Up DC/DC Converter
VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12μA,
ISD < 1μA, QFN Package
LTC3422
1.5A (ISW), 3MHz Synchronous Step-Up DC/DC Converter
VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25μA,
ISD < 1μA, 3mm × 3mm DFN Package
LTC3426
LTC3428
LTC3429
2A (ISW), 1.2MHz Step-Up DC/DC Converter in SOT-23
4A (ISW), 1.2MHz Step-Up DC/DC Converter
600mA (ISW), 500kHz Synchronous Step-Up DC/DC Converter
LTC3440
600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter
LTC3441
600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter
LTC3442
LTC3443
2MHz Synchronous Buck-Boost with Auto-Burst
1.2A (IOUT), 600kHz Synchronous Buck-Boost DC/DC Converter
LTC3458
LTC3458L
LTC3459
LTC3525/LTC3525-3.3/
LTC3525-5
1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter
1.7A, 1.5MHz Synchronous Step-Up DC/DC Converter
10V Micropower Synchronous Step-Up DC/DC Converter
400mA (ISW), Synchronous Step-Up DC/DC Converter
with Output Disconnect
VIN: 1.6V to 5V, VOUT up to 5.5V
VIN: 1.6V to 5V, VOUT up to 5.5V
VIN: 0.5V to 4.4V, VOUT(MIN) = 5V, IQ = 20μA,
ISD < 1μA, QFN Package
VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25μA,
ISD < 1μA, MS, DFN Packages
VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25μA,
ISD < 1μA, DFN Package
VIN: 2.4V to 5.5V, VOUT up to 5.25V
VIN: 2.4V to 5.5V, VOUT(MIN) = 5.25V, IQ = 28μA,
ISD < 1μA, MS Package
VIN: 1.5V to 6V, VOUT up to 7.5V
VIN: 1.5V to 6V, VOUT up to 6V
VIN: 1.5V to 5.5V, VOUT up to 10V
VIN: 0.5V to 4.5V, IQ = 7μA, ISD < 1μA,
2mm × 2mm SC70 Package
3531fb
16 Linear Technology Corporation
LT 0807 REV B • PRINTED IN USA
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