LINEAR TECHNOLOGY LTC3531, LTC3531-3.3, LTC3531-3 Technical data

FEATURES

■

Regulated Output with Input Above, Below or Equal

to the Output

■

Single Inductor

■

Up to 90% Effi ciency

■

VIN Range: 1.8V to 5.5V

■

200mA at 3.3V

■

125mA at 3V

■

Fixed V

■

Adjustable V

■

Burst Mode® Operation, No External Compensation

■

Ultra Low Quiescent Current: 16μA, Shutdown

Versions (TSOT, DFN): 3.3V, 3V

OUT

from 3.6V Input

OUT

from 2.5V Input

OUT

Version (DFN): 2V to 5V

OUT

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

■

Handheld Instruments

■

MP3 Players

■

Handheld computers

■

PDA/GPS

LTC3531/

LTC3531-3.3/LTC3531-3

200mA Buck-Boost

Synchronous DC/DC

Converters

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DESCRIPTIO

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 effi ciency over a wide range of
load currents.

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
ThinSOT
3mm DFN package for fi xed 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.

TM

package for fi xed voltage versions or a 3mm ×

TYPICAL APPLICATIO

10μH

2.2μF

SW1 SW2

V

IN

LTC3531-3.3

SHDN GND

ON OFF

V

3.1V TO

4.2V

Li-Ion

IN

+

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Effi ciency vs V

100

95

90

V

OUT

V

OUT

3.3V
160mA

10μF

3531 TA01a

85

80

75

EFFICIENCY (%)

70

65

60

1.5

BOOST

MODE

2

2.5
INPUT VOLTAGE (V)

3

4SW

MODE

3.5

3.3V

IN

4

BUCK

MODE

AT 100mA

OUT

4.5

5

3531 TA01b

5.5

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LTC3531/
LTC3531-3.3/LTC3531-3

WW

W

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ABSOLUTE AXI U RATI GS

(Note 1)

VIN, VOUT, SW1, SW2,

SW1, SW2 Voltage, <100ns Pulse ..................–0.3 to 7V

SHDN

Voltage ...........–0.3 to 6V

Storage Temperature Range ................... –65°C to 125°C

Lead Temperature (TS6, Soldering, 10 sec) .......... 300°C

Operating Temperature Range (Notes 2, 3) –40°C to 85°C

UUW

FOR ATIOPACKAGE/ORDER I

TOP VIEW

SW2 1

GND, PGND 2

V

3

OUT

6-LEAD PLASTIC TSOT-23

T

= 125°C, θJA = 102°C/W

JMAX

TOP VIEW

S6 PACKAGE

6 SW1

5 V

IN

4 SHDN

EXPOSED PAD IS GND (PIN 9), MUST BE SOLDERED TO PCB

1SW1

V

2

IN

GND

3

SHDN

4

8-LEAD (3mm × 3mm) PLASTIC DFN

T

JMAX

*NC FOR LTC3531-3.3V, LTC3531-3.0V.

9

DD PACKAGE

= 125°C, θJA = 43°C/W

ORDER PART NUMBER S6 PART MARKING ORDER PART NUMBER DD PART MARKING

8

PGND

SW2

7

V

6

OUT

FB*

5

LTC3531ES6-3.3
LTC3531ES6-3

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 specifi ed with wider operating temperature ranges.

The ● denotes the specifi cations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at TA = 25°C. VIN = 3.6V V

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

Minimum Startup Voltage ● 1.65 1.8 V

V

Regulation

OUT

Output Voltage (3.3V Version) No Load ● 3.25 3.32 3.39 V
Output Voltage (3V Version) No Load ● 2.95 3.02 3.09 V
FB Voltage (Adj Version) No Load ● 1.20 1.225 1.25 V
FB Input Current (Adj Version) VFB = 1.225V 1 50 nA

Operating Current

Quiescent Current in Sleep: VIN VIN = 5V, V
V

Shutdown Current VIN

Switch Performance

NMOS Switch Leakage Switches B and C 0.2 2 μA
PMOS Switch Leakage Switches A and D 0.2 2 μA
NMOS B, C R
PMOS A R

VIN = 5V 0.5 Ω

DSON

VIN = 5V 0.5 Ω

DSON

LTBWM
LTCBK

OUT

V

OUT

SHDN

LTC3531EDD
LTC3531EDD-3.3
LTC3531EDD-3

= 3.3V unless otherwise noted.

OUT

= 3.6V, FB = 1.3V 16 30 μA

OUT

= 3.6V 6 10 μA

= 0V, V

= 0V 1 μA

OUT

LBVC
LBWH
LCBV

3531fb

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LTC3531/

LTC3531-3.3/LTC3531-3

ELECTRICAL CHARACTERISTICS

The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

= 25°C. VIN = 3.6V V

A

= 3.3V unless otherwise noted.

OUT

PARAMETER CONDITIONS MIN TYP MAX UNITS

PMOS D R
PMOS D R

(3.3V Version or Adjustable Version set to 3.3V) V

DSON

(3V Version)

DSON

VOUT

= 3.1V 0.8 Ω

OUT

= 2.8V 0.9 Ω

Peak Current Limit L = 10μH, VIN = 5V 295 365 460 mA

SHDN

Input Threshold 0.4 1

SHDN

Hysteresis 60 mV

SHDN

Leakage Current V

SHDN

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

0.01 1 μA

SHDN

Continuous operation above the specifi ed maximum operating junction
temperature may result in device degradation or failure.

Note 3: The LTC3531 is guaranteed to meet performance specifi cations
from 0°C to 70°C. Specifi cations over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.

1.4

V

temperature will exceed 125°C when overtemperature protection is active.

UW

3531 G01

CE CHARACTERISTICSA

I

PEAK

450

L = 10μH

400

350

300

250

200

CURRENT (mA)

150

100

50

0

1.5

, I

VALLEY

TA = 25°C unless otherwise specifi ed.

, I

vs V

ZERO

I

2.52

3.53

VIN (V)

ZERO

I

VALLEY

IN

I

PEAK

4.54

5.55

3531 G02

Sleep Currents

20

18

16

14

12

10

8

CURRENT (μA)

6

4

2

0

1.5

I

VIN

23

2.5

3.5

VIN (V)

I

VOUT

5

4.5

4

5.5

3531 G03

TYPICAL PERFOR

Maximum I
(3.3V Version)

350

L = 10μH
V

OUT

300

250

(mA)

200

OUT

150

MAXIMUM I

100

50

0

1.5

= 3.3V

vs V

OUT

2.52 3.5 5.5

IN

VIN (V)

4.5 543

IIN Short Circuit vs V

180

160

140

120

100

(mA)

IN

80

I

60

40

20

0

1.5 2

2.5 3

3.5 4

VIN (V)

V

Ripple vs C

OUT

IN

4.5 5

5.5

3531 G04

(3.3V Version)

100

90

80

70

(mV)

60

50

40

30

RIPPLE PEAK-PEAK

V

20

10

0

1.5

23

2.5

OUT

3.5

VIN (V)

10μF

22μF

4

50mA LOAD

5

4.5

3531 G05

5.5

Load Regulation vs C
(3.3V Version)

3.40

3.35

3.30

(V)

V

OUT

3.25

3.20

3.15

VIN = 3.6V

0.1

22μF

1

LOAD CURRENT (mA)

10μF

47μF

10

OUT

100

1000

3521 G06

3531fb

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LTC3531/
LTC3531-3.3/LTC3531-3

UW

TYPICAL PERFOR A CE CHARACTERISTICS

TA = 25°C unless otherwise specifi ed.

Start-Up into Resistive Load
L = 10μH

30

28

26

24

22

(Ω)

20

MIN

R

18

16

14

12

10

1.5

23

2.5

3.5

4

V

(V)

IN

4.5

5

3531 G07

Switch On Resistances I

1000

V

= 5V

IN

= 3.3V

900

800

(mΩ)

700

DSON

R

600

500

400

–40

V

OUT

02040

–20

TEMPERATURE (°C)

D (PMOS)

A (PMOS)

B,C (NMOS)

60 80 100

3531 G10

5.5

Burst Frequency vs Load
(3.3V Version)

1000

L = 10μH
C

= 10μF

OUT

100

10mA

10

FREQUENCY (kHz)

1

0.1

1.5 3.53 4.54 5.55

400

350

300

250

200

150

CURRENT (mA)

100

50

0

–40

1mA

0.5mA

2.52

, I

PEAK

VALLEY

–20 0 40

5mA

V

(V)

IN

vs Temperature

I

PEAK

I

VALLEY

I

ZERO

20

TEMPERATURE (°C)

V

Regulation vs Temperature

OUT

(3.3V Version)

3.350

VIN = 3.6V

= 10mA

I

LOAD

(V)

OUT

V

3.325

3.300

3.275

3.250

–40

–20 0 20 40

TEMPERATURE (°C)

60 80 100

3531 G09

50mA

3531 G08

SHDN Pin Threshold and
Hysteresis

1

0.9

0.8

0.7

2.5V

IN

3.3V

OUT

10μH

80 100

60

3531 G11

VOLTAGE (V)

0.6

0.5
–40

SHUTDOWN

02040

–20

TEMPERATURE (°C)

OPERATING

60 80 100

3531 G12

4

3531fb

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TYPICAL PERFOR A CE CHARACTERISTICS

LTC3531/

LTC3531-3.3/LTC3531-3

TA = 25°C unless otherwise specifi ed.

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

200mA/DIV

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

200mA/DIV

Buck Mode at 5V

OUT

OUT

= 22μF

200mA

I

L

3.3V

L = 10μH
C

,

IN

5μs/DIV 5μs/DIV

Buck Mode Waveforms at 5VIN,

3.3V

I

L

OUT

20mA

Buck Mode at 5V

OUT

OUT

= 22μF

100mA

3.3V

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

I

L

200mA/DIV

3531 G13 3531 G14

L = 10μH
C

,

IN

4 Switch Mode Waveforms at

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

200mA/DIV

3.6VIN, 3.3V

I

L

OUT

200mA

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

200mA/DIV

L = 10μH

= 22μF

C

OUT

5μs/DIV 5μs/DIV

4 Switch Mode Waveforms at

3.6V

I

L

L = 10μH

= 22μF

C

OUT

, 3.3V

IN

100mA

OUT

5μs/DIV 5μs/DIV

3531 G15

L = 10μH

= 22μF

C

OUT

3531 G16

4 Switch Mode Waveforms at

, 3.3V

3.6V

IN

SW1

5V/DIV

SW2

5V/DIV

(AC)

V

OUT

50mV/DIV

I

L

200mA/DIV

3531 G17 3531 G18

L = 10μH
C

= 22μF

OUT

OUT

20mA

SW1

SW2

V

OUT

I

L

(AC)

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