LTC3531ES6-3.3#TRPBF - Linear Technology

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

FEATURES DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

INPUT VOLTAGE (V)

1.5

EFFICIENCY (%)

5.5

3531 TA01b

60 2.5 3.5 4.5

2345

100

BOOST

MODE

4SW

MODE

3.3VOUT AT 100mA

BUCK

MODE

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, mini-

mizing 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 bat-

tery 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 ﬁ xed voltage versions or a 3mm ×

3mm DFN package for ﬁ xed and adjustable versions.

200mA Buck-Boost

Synchronous DC/DC

Converters

■ Regulated Output with Input Above, Below or Equal

to the Output

■ Single Inductor

■ Up to 90% Efﬁ ciency

■ V

IN 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

Efﬁ ciency vs VIN

■ Handheld Instruments

■ MP3 Players

■ Handheld computers

■ PDA/GPS

SW1 SW2

SHDN GND

VIN VOUT

LTC3531-3.3

2.2μF10μF

ON OFF

Li-Ion

10μH

VIN

3.1V TO

4.2V

VOUT

3.3V

160mA

3531 TA01a

, 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.

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

ABSOLUTE AXI U RATI GS

FOR ATIOPACKAGE/ORDER I

UUW

ELECTRICAL CHARACTERISTICS

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

temperature range, otherwise speciﬁ cations are at TA = 25°C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.

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

(Note 1)

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

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

VIN

Minimum Startup Voltage ● 1.65 1.8 V

VOUT Regulation

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 V

IN = 5V, VOUT = 3.6V, FB = 1.3V 16 30 μA

OUT V

OUT = 3.6V 6 10 μA

Shutdown Current VIN SHDN = 0V, VOUT = 0V 1 μA

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 RDSON V

IN = 5V 0.5 Ω

PMOS A RDSON V

IN = 5V 0.5 Ω

6 SW1

5 VIN

4 SHDN

SW2 1

TOP VIEW

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

GND, PGND 2

VOUT 3

TJMAX = 125°C, θJA = 102°C/W

TOP VIEW

DD PACKAGE

8-LEAD (3mm × 3mm) PLASTIC DFN

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

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

1SW1

VIN

GND

SHDN

PGND

SW2

VOUT

FB*

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

LTC3531ES6-3.3

LTC3531ES6-3

LTBWM

LTCBK

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 speciﬁ ed with wider operating temperature ranges.

TJMAX = 125°C, θJA = 43°C/W

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

TYPICAL PERFOR

CE CHARACTERISTICSA

TA = 25°C unless otherwise speciﬁ ed.

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.

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.

ELECTRICAL CHARACTERISTICS

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

temperature range, otherwise speciﬁ cations are at TA = 25°C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.

VIN (V)

1.5

MAXIMUM IOUT (mA)

200

250

300

4.5 543

3531 G01

150

100

2.52 3.5 5.5

350

VIN (V)

1.5

CURRENT (mA)

200

250

300

5.55

3531 G02

150

100

02.52 3.53 4.54

400

450

350

IPEAK

IVALLEY

IZERO

VIN (V)

1.5

CURRENT (μA)

2.5 3.5 4

3531 G03

23 4.5 55.5

IVIN

IVOUT

VIN (V)

1.5 2

IIN (mA)

100

120

5.5

3531 G04

02.5 3 3.5 4 4.5 5

160

180

140

VIN (V)

1.5

VRIPPLE PEAK-PEAK (mV)

100

2.5 3.5 4

3531 G05

23 4.5 55.5

10μF

22μF

LOAD CURRENT (mA)

0.1

VOUT (V)

3.25

3.30

1000

3521 G06

3.20

3.15 110 100

3.40

3.35

47μF

10μF

22μF

L = 10μH

VOUT = 3.3V

L = 10μH

50mA LOAD VIN = 3.6V

IIN Short Circuit vs VIN

VOUT Ripple vs COUT

(3.3V Version)

Load Regulation vs COUT

(3.3V Version)

Maximum IOUT vs VIN

(3.3V Version) IPEAK, IVALLEY

, IZERO vs VIN Sleep Currents

SHDN

PARAMETER CONDITIONS MIN TYP MAX UNITS

PMOS D RDSON (3.3V Version or Adjustable Version set to 3.3V) VOUT = 3.1V 0.8 Ω

PMOS D RDSON (3V Version)

VOUT = 2.8V 0.9 Ω

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

SHDN Input Threshold 0.4 1

1.4

SHDN Hysteresis 60 mV

SHDN Leakage Current VSHDN 0.01 1 μA

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

TA = 25°C unless otherwise speciﬁ ed.

TYPICAL PERFOR A CE CHARACTERISTICS

VIN (V)

FREQUENCY (kHz)

1000

1.5 3.53 4.54 5.55

3531 G08

0.1

2.52

100

0.5mA

1mA

5mA

10mA

50mA

TEMPERATURE (°C)

–40

3.250

VOUT (V)

3.275

3.300

3.325

3.350

–20 0 20 40

3531 G09

60 80 100

TEMPERATURE (°C)

–40

400

RDSON (mΩ)

500

600

700

800

1000

–20 02040

3531 G10

60 80 100

900

D (PMOS)

A (PMOS)

B,C (NMOS)

TEMPERATURE (°C)

–40

CURRENT (mA)

150

200

250

20 60

3531 G11

100

0–20 0 40

300

350

400

80 100

TEMPERATURE (°C)

–40

0.5

VOLTAGE (V)

0.6

0.7

0.8

0.9

–20 02040

3531 G12

60 80 100

L = 10μH

COUT = 10μF

VIN = 5V

VOUT = 3.3V

IZERO

IPEAK

IVALLEY

2.5VIN

3.3VOUT

10μH

SHUTDOWN

OPERATING

VIN (V)

1.5

RMIN (Ω)

2.5 3.5 4

3531 G07

23 4.5 55.5

VIN = 3.6V

ILOAD = 10mA

Start-Up into Resistive Load

L = 10μH

Burst Frequency vs Load

(3.3V Version)

VOUT Regulation vs Temperature

(3.3V Version)

Switch On Resistances IPEAK, IVALLEY vs Temperature

SHDN Pin Threshold and

Hysteresis

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

TA = 25°C unless otherwise speciﬁ ed.

Buck Mode at 5VIN,

3.3VOUT 200mA

Buck Mode at 5VIN,

3.3VOUT 100mA

Buck Mode Waveforms at 5VIN,

3.3VOUT 20mA

3531 G13 3531 G14

3531 G15

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

L = 10μH

COUT = 22μF

TYPICAL PERFOR A CE CHARACTERISTICS

4 Switch Mode Waveforms at

3.6VIN, 3.3VOUT 200mA

3531 G16

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

4 Switch Mode Waveforms at

3.6VIN, 3.3VOUT 100mA

4 Switch Mode Waveforms at

3.6VIN, 3.3VOUT 20mA

3531 G17 3531 G18

SW1

SW2

VOUT (AC)

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

L = 10μH

COUT = 22μF

5μs/DIV 5μs/DIV

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

TA = 25°C unless otherwise speciﬁ ed.

TYPICAL PERFOR A CE CHARACTERISTICS

Boost Mode Waveforms at

2.5VIN, 3.3VOUT 100mA

Boost Mode Waveforms at

2.5VIN, 3.3VOUT 20mA

Shorted Output

Start-Up into 50mA Load at

3.3 VOUT (Shows Start, Buck,

Then 4sw Modes)

3.6VIN, 3.3VOUT Load Step

200mA to 80mA

SW1 and SW2 Close-Up in Four

Switch Mode

3531 G22

3531 G23 3531 G24

3531 G19 3531 G20

3531 G21

VOUT

1V/DIV

200mA/DIV

SW1

2V/DIV

200mA/DIV

SW2

2V/DIV

20mA LOAD

100mA LOAD

20mA LOAD

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

SW1

5V/DIV

SW2

5V/DIV

VOUT (AC)

50mV/DIV

200mA/DIV

L = 10μH

COUT = 22μF

L = 10μH

COUT = 22μF

VIN = 5

VOUT (AC)

20mV/DIV

5μs/DIV 5μs/DIV

1μs/DIV 25μs/DIV

25μs/DIV 200ns/DIV

200mA/DIV

COUT = 22μF VIN = 3.6V

VOUT = 3.3V

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

PI FU CTIO S

UUU

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

efﬁ ciency 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

Rectiﬁ er. A ﬁ lter 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.

OUT =+

⎛

⎝

⎜⎞

⎠

⎟

12251 2

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.

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

BLOCK DIAGRA

3531 BD

GATE DRIVERS

AND

ANTICROSS

CONDUCTION

SHUTDOWN THERMAL

SHUTDOWN

STATE

MACHINE

AND

LOGIC

VBEST

AND

MODE DETECT

365mA

VIN

SHDN

PGND

VOUT

GND

VIN

VOUT

1.65V

PEAK

CURRENT

LIMIT

UVLO

VOUT

COMPARATOR

VBEST

BUCK, 4SW,

BOOST

IZERO/IVALLEY

DETECT

SW A

SW1 SW2

SW B SW C

SW D

1.225V VREF

NOT BONDED

FOR 3.3V AND

3V VERSIONS

INTERNAL

R1 AND R2

DISABLED

FOR ADJ VERSION

COMBINED

FOR TSOT

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

The LTC3531, LTC3531-3.3 and LTC3531-3 synchro-

nous buck-boost converters utilize a Burst Mode control

technique to achieve high efﬁ ciency 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 efﬁ ciency 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

occurs, C is turned off, D is turned on and current is deliv-

ered 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

ﬁ nal 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 volt-

age, 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 ﬁ nal 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.

OPERATIO

Figure 1. Voltage and Current Waveforms

VOUT

IMAX

BOOST MODE 4SW MODE BUCK MODE

IPEAK

IVALLEY

IZERO

VIN

tOFF tOFF

tOFF

AC AC AC AD AD ADADAD AD AD ACAC BD BDBD BD BD

3531 F01

VIN VOUT

SW1 SW2

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

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 sufﬁ cient mag-

netizing 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 induc-

tor) until an IVALLEY is detected. This AD then BD switch

sequence is repeated until the output is pumped above

its regulation voltage, a ﬁ nal 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 ﬂ ows 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

OPERATIO

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 rectiﬁ ers. 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 ap-

proximately 150°C, the part will go into thermal shut-

down 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 pack-

age. 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.

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

S I FOR ATIOAPPLICATIO

WUUU

Table 3. Capacitor Vendor Information

Supplier Series Phone Website

AVX X5R (803) 448-9411 www.avxcorp.com

Murata X5R USA: (814) 237-1431 www.murata.com

(800) 831-9172

Sanyo POSCAP (619) 661-6322 www.sanyovideo.com

Taiyo Yuden X5R (408) 573-4150 www.taiyo-yuden.com

TDK X5R (847) 803-6100 www.component.tdk.com

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

proﬁ le inductors and tiny external ceramic capacitors.

Inductor Selection

For best efﬁ ciency, 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-

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

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 capaci-

tor 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

Supplier Series Phone Website

COEV DN4835 (800) 227-7040 www.coev.net

Coilcraft MSS4020 (847) 639-6400 www.coilcraft.com

LPO3310

DS1608

Murata LQH43CN USA: (814) 237-1431 www.murata.com

LQH32CN (800) 831-9172

Sumida CDRH4D18 USA: (847) 956-0666 www.sumida.com

CDRH3D16/HP Japan: 81-3-3607-5111

Toko D312C (847) 297-0070 www.tokoam.com

D412C

DB320C

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

S I FOR ATIOAPPLICATIO

WUUU

5 – VIN

VOUT – 3

VIN

CIN VOUT

COUT

GND GND

GND – 2

SHUTDOWN

4 – SHDN

6 – SW1 SW2 – 1

SOT PIN-OUT

Recommended Layout (SOT Versions)

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

5V/Li-Ion to 3.3V with ThinSOT (3.3V Version)

2 AA Alkaline to 3V with ThinSOT (3V Version)

TYPICAL APPLICATIO

SW1 SW2

SHDN GND

VIN VOUT

LTC3531-3.3

–2.2μF10μF

5V/Li-Ion

ON OFF

10μH

VOUT

3.3V

160mA

VIN

3.1V TO

3531 TA02a

LOAD CURRENT (mA)

EFFICIENCY (%)

0.1 10 100 1000

3531 TA02b

4.4VIN

5VIN

3.6VIN

3.1VIN

POWER LOSS AT 3.6VIN

POWER LOSS (mW)

0.1

100

SW1 SW2

SHDN GND

VIN VOUT

LTC3531-3

–

2.2μF10μF

–

2 x AA

ALKALINE

ON OFF

10μH

3531 TA03a

VOUT

80mA

VIN

1.8V TO

3.2V

LOAD CURRENT (mA)

EFFICIENCY (%)

0.1 10 100 1000

3531 TA03b

2.5VIN

3.2VIN

POWER LOSS AT 3.2VIN

1.8VIN

POWER LOSS (mW)

0.1

100

SW1 SW2

SHDN GND

VIN VOUT

LTC3531

2.2μF10μF

324k

4.7μF

ON OFF

10μH

3531 TA04a

1Ω

VOUT

200mA

USB

4.35V TO

5.25V

LOAD CURRENT (mA)

EFFICIENCY (%)

POWER LOSS (mW)

0.1 10 100 1000

3531 TA04b

65 0.1

100

EFFICIENCY

POWER LOSS

USB to 5V with 3 × 3 DFN (Adjustable Version)

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

PACKAGE DESCRIPTIO

S6 Package

6-Lead Plastic TSOT-23

(Reference LTC DWG # 05-08-1636)

1.50 – 1.75

(NOTE 4)

2.80 BSC

0.30 – 0.45

6 PLCS (NOTE 3)

DATUM ‘A’

0.09 – 0.20

(NOTE 3) S6 TSOT-23 0302

2.90 BSC

(NOTE 4)

0.95 BSC

1.90 BSC

0.80 – 0.90

1.00 MAX 0.01 – 0.10

0.20 BSC

0.30 – 0.50 REF

PIN ONE ID

NOTE:

1. DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

3.85 MAX

0.62

MAX

0.95

REF

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

1.4 MIN

2.62 REF

1.22 REF

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

LTC3531/

LTC3531-3.3/LTC3531-3

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.

DD Package

8-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1698)

PACKAGE DESCRIPTIO

3.00 ±0.10

(4 SIDES)

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

0.38 ± 0.10

BOTTOM VIEW—EXPOSED PAD

1.65 ± 0.10

(2 SIDES)

0.75 ±0.05

R = 0.115

TYP

2.38 ±0.10

(2 SIDES)

PIN 1

TOP MARK

(NOTE 6)

0.200 REF

0.00 – 0.05

(DD) DFN 1203

0.25 ± 0.05

2.38 ±0.05

(2 SIDES)

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

1.65 ±0.05

(2 SIDES)2.15 ±0.05

0.50

BSC

0.675 ±0.05

3.5 ±0.05

PACKAGE

OUTLINE

0.25 ± 0.05

0.50 BSC

LTC3531/

LTC3531-3.3/LTC3531-3

3531fb

Linear Technolog

Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

LT 0807 REV B • PRINTED IN USA

TYPICAL APPLICATIO

SW1 SW2

SHDN

GND

VIN VOUT

LTC3531-3.3

10μF

22μF

10μH

3.1V TO 5.25V

3531 TA05

OTHER

DC/DC

100k

0.1μF

WALL NTC

OUT

CHRG

ACPR

VNTC

TIMER

CLPROG

PROG

IN1

IN2

HPWR

SUSP

BAT

GND

LTC4055

–Li-Ion

5V (NOM)

FROM USB

CABLE

SUSPEND

USB POWER

VOUT: USB OR BATTERY

C1, C2: TAIYO YUDEN JMK316BJ106ML

L1: MURATA LQH43CN100K03 (650mA 0.24Ω)

VOUT

3.3V

160mA

SHDN

Complete USB/Li-Ion Powered System

with 3.3VOUT and Linear Charger

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