LTC3525ISC6-3.3#TRPBF - LINEAR TECHNOLOGY

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

LOAD (mA)

0.01 0.1

EFFICIENCY (%)

100

POWER LOSS (mW)

100

0.1

0.01

1 10 1000100

LT3525 • TA02

EFFICIENCY

POWER LOSS

VIN = 3V

VIN = 2.4V

VIN = 1.2V

400mA Micropower

Synchronous Step-Up DC/DC

Converter with Output Disconnect

The LTC

3525-3/LTC3525-3.3/LTC3525-5 are high efficiency

synchronous step-up DC/DC converters with output discon-

nect that can start up with an input as low as 0.85V. They

offer a compact, high efficiency alternative to charge pumps

in single cell or dual cell alkaline or Li-Ion applications. Only

three small external components are required. The LTC3525

is offered in fixed output voltages of 3V, 3.3V or 5V.

The device includes a 0.5Ω N-channel MOSFET switch and

a 0.8Ω P-channel synchronous rectifier. Peak switch current

ranges from 150mA to 400mA, depending on load, providing

enhanced efficiency. Quiescent current is an ultralow 7µA,

maximizing battery life in portable applications.

Other features include <1µA shutdown current, anti-

ringing control and thermal shutdown. The LTC3525 is

available in a tiny 6-Lead SC70 package.

List of LTC3525 Options

PART NAME INPUT START-UP

VOLTAGE

OUTPUT

VOLTAGE

VOUT STATUS IN

SHUTDOWN MODE

LTC3525-3 0.85V 3V Output Disconnect

LTC3525-3.3 0.85V 3.3V Output Disconnect

LTC3525-5 0.85V 5V Output Disconnect

LTC3525D-3.3 0.85V 3.3V Pass Through Mode

LTC3525L-3 0.7V 3V Output Disconnect

n MP3 Players

n Portable Instruments

n Glucose Meters

n Digital Cameras

n Up to 95% Efficiency

n Output Disconnect and Inrush Current Limit

n Fixed Output Voltages of 3V, 3.3V or 5V

n Delivers 65mA at 3V from a 1V Input

n Delivers 60mA at 3.3V from a 1V Input,

or 140mA at 3.3V from a 1.8V Input

n Delivers 175mA at 5V from a 3V Input

n Burst Mode

Operation: IQ = 7µA

n Only Three External Components

n VIN > VOUT Operation

n <1µA Shutdown Current

n Antiringing Control

n Short-Circuit and Overtemperature Protection

n Very Low Profile of 1mm

n Tiny 6-Lead SC70 Package

LTC3525-3.3 Efficiency and Power

Loss vs Load Current

L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks

and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners. Patents pending.

Typical applicaTion

FeaTures DescripTion

applicaTions

L1*

10µH

3525 TA01

LTC3525-3.3

*MURATA LQH32CN100K53

VOUT

3.3V

60mA

VOUT

GND

SHDN

GND

VIN

1V TO 1.6V

10µF

1µF

OFF ON

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

VIN, VOUT Voltage ........................................ – 0.3V to 6V

SW Voltage ................................................. – 0.3V to 6V

SW Voltage < 100ns .................................... –0.3V to 7V

SHDN Voltage ............................................. –0.3V to 6V

Operating Junction Temperature Range

(Notes 2, 5) ............................................ –40°C to 125°C

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

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

(Note 1)

pin conFiguraTionabsoluTe MaxiMuM raTings

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC3525ESC6-3#PBF LTC3525ESC6-3#TRPBF LCDR 6-Lead Plastic SC70 –40°C to 85°C

LTC3525ISC6-3#PBF LTC3525ISC6-3#TRPBF LCDR 6-Lead Plastic SC70 –40°C to 125°C

LTC3525ESC6-3.3#PBF LTC3525ESC6-3.3#TRPBF LBTG 6-Lead Plastic SC70 –40°C to 85°C

LTC3525ISC6-3.3#PBF LTC3525ISC6-3.3#TRPBF LBTG 6-Lead Plastic SC70 –40°C to 125°C

LTC3525ESC6-5#PBF LTC3525ESC6-5#TRPBF LBWT 6-Lead Plastic SC70 –40°C to 85°C

LTC3525ISC6-5#PBF LTC3525ISC6-5#TRPBF LBWT 6-Lead Plastic SC70 –40°C to 125°C

Consult LTC Marketing for parts specified with wider operating temperature ranges.

Consult LTC Marketing for information on non-standard lead based finish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/

SHDN 1

GND 2

VIN 3

6 SW

5 GND

4 VOUT

TOP VIEW

SC6 PACKAGE

6-LEAD PLASTIC SC70

TJMAX = 125°C

θJA = 256°C/W IN FREE AIR, θJA = 150°C/W ON BOARD OVER GROUND PLANE

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at

TA = 25°C. VIN = 1.2V, VSHDN = 1.2V, VOUT = 3V unless otherwise noted. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Start-Up Voltage 0.85 1 V

Output Voltage (Note 6) l2.91 3.00 3.09 V

Quiescent Current, VOUT SHDN = VIN (Note 4) 7 15 µA

Quiescent Current, VIN SHDN = VIN (Note 4) 0.5 3 µA

Quiescent Current, VIN – Shutdown SHDN = 0V, VOUT = 0V

Not Including Switch Leakage

0.1 1 µA

NMOS Switch Leakage Current VIN = VOUT = VSW = 5V, SHDN = 0V 0.1 1 µA

PMOS Switch Leakage Current VIN = VSW = 5V, VOUT = 0V, SHDN = 0V 0.1 3 µA

NMOS Switch On-Resistance (Note 3) 0.6 Ω

PMOS Switch On-Resistance (Note 3) 0.9 Ω

Peak Current Limit 0.4 0.45 A

SHDN Threshold Voltage 0.4 0.6 1 V

SHDN Input Current VSHDN = VIN or VOUT 0.01 1 µA

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Start-Up Voltage 0.85 1 V

Output Voltage (Note 6) l3.20 3.30 3.40 V

Quiescent Current, VOUT SHDN = VIN (Note 4) 7 15 µA

Quiescent Current, VIN SHDN = VIN (Note 4) 0.5 3 µA

Quiescent Current, VIN – Shutdown SHDN = 0V, VOUT = 0V

Not Including Switch Leakage

0.1 1 µA

NMOS Switch Leakage Current VIN = VOUT = VSW = 5V, SHDN = 0V 0.1 1 µA

PMOS Switch Leakage Current VIN = VSW = 5V, VOUT = 0V, SHDN = 0V 0.1 3 µA

NMOS Switch On-Resistance (Note 3) 0.5 Ω

PMOS Switch On-Resistance (Note 3) 0.8 Ω

Peak Current Limit 0.4 0.45 A

SHDN Threshold Voltage 0.4 0.6 1 V

SHDN Input Current VSHDN = VIN or VOUT 0.01 1 µA

elecTrical characTerisTics

(LTC3525-3)

The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at

TA = 25°C. VIN = 1.2V, VSHDN = 1.2V, VOUT = 3.3V unless otherwise noted. (Note 2)

elecTrical characTerisTics

(LTC3525-3.3)

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

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: The LTC3525 is tested under pulsed load conditions such that

TJ ≈ TA. The LTC3525E is guaranteed to meet performance specifications

from 0°C to 85°C. Specifications over the –40°C to 85°C operating

junction temperature range are assured by design, characterization and

correlation with statistical process controls. The LTC3525I is guaranteed

over the –40°C to 125°C operating junction temperature range. Note that

the maximum ambient temperature consistent with these specifications

is determined by specific operating conditions in conjunction with board

layout, the rated package thermal impedance and other environmental

(LTC3525-5)

The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at

TA = 25°C. VIN = 2.4V, VSHDN = 2.4V, VOUT = 5V unless otherwise noted. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Start-Up Voltage 0.85 1 V

Output Voltage (Note 6) l4.85 5.00 5.15 V

Quiescent Current, VOUT SHDN = VIN (Note 4) 8 18 µA

Quiescent Current, VIN SHDN = VIN (Note 4) 1.5 5 µA

Quiescent Current, VIN – Shutdown SHDN = 0V, VOUT = 0V

Not Including Switch Leakage

0.1 1 µA

NMOS Switch Leakage Current VIN = VOUT = VSW = 5V, SHDN = 0V 0.1 1 µA

PMOS Switch Leakage Current VIN = VSW = 5V, VOUT = 0V, SHDN = 0V 0.1 3 µA

NMOS Switch On-Resistance (Note 3) 0.4 Ω

PMOS Switch On-Resistance (Note 3) 0.7 Ω

Peak Current Limit 0.4 0.5 A

SHDN Threshold Voltage 0.4 0.6 1 V

SHDN Input Current VSHDN = VIN or VOUT 0.01 1 µA

factors. TJ is calculated from the ambient temperature TA and power

dissipation PD according to the following formula:

TJ = TA + (PD • 150°C/W)

Note 3: Specification is guaranteed by design and not 100% tested in

production.

Note 4: Current Measurements are performed when the LTC3525 is not

switching.

Note 5: 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 specified maximum operating junction

temperature may impair device reliability.

Note 6: Consult LTC Marketing for other output voltage options.

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

Typical perForMance characTerisTics

Maximum Output Current vs VIN

(for VOUT to Drop 2.5%)

Maximum Startup Load vs VIN

(Resistive Load)

No-Load Input Current vs VIN

LTC3525-3 Efficiency and Power

Loss vs Load

LTC3525-5 Efficiency and Power

Loss vs Load

LTC3525-3.3 Load Regulation

LTC3525-5 Load Regulation

TA = 25°C unless otherwise noted.

LTC3525-3.3 Efficiency and Power

Loss vs Load

VIN (V)

0.5 1.0

OUT

(mA)

300

250

200

150

100

02.5 3.5

3525 G01

1.5 2.0 3.0 4.0 4.5

LTC3525-5

LTC3525-3.3

LTC3525-3

3525 G02

250

200

150

100

LOAD (mA)

VIN (V)

0.5 1.0 1.5 2.0 2.5 3.0

LTC3525-3.3

LTC3525-5

3525 G03

VIN (V)

1.0 2.5 3.51.5 2.0 3.0 4.0 4.5

IIN (µA)

LTC3525-5

LTC3525-3.3

LTC3525-3

LOAD (mA)

0.01 0.1

EFFICIENCY (%)

100

POWER LOSS (mW)

100

0.1

0.01

1 10 1000100

3525 G24

EFFICIENCY

POWER LOSS

VIN = 2.4V

VIN = 1.2V

LOAD (mA)

0.01 0.1

EFFICIENCY (%)

100

POWER LOSS (mW)

100

0.1

0.01

1 10 1000100

3525 G04

EFFICIENCY

POWER LOSS

VIN = 3V

VIN = 2.4V

VIN = 1.2V

LOAD (mA)

0.01 0.1

EFFICIENCY (%)

100

POWER LOSS (mW)

1000

100

0.1

0.01

1 10 1000100

3525 G05

EFFICIENCY

POWER LOSS

VIN = 3.6V

VIN = 2.4V

VIN = 1.2V

3525 G06

LOAD (mA)

0 40 602010 30 50 70 80

CHANGE IN VOUT (%)

2.5

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

COUT = 22µF

COUT = 10µF

VIN = 1.2V

3525 G07

LOAD (mA)

0 140 16012010020 40 60 80 180

CHANGE IN VOUT (%)

2.5

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

COUT = 22µF

COUT = 10µF

VIN = 2.4V

3525 G08

LOAD (mA)

0 402010 30 50 60

CHANGE IN VOUT (%)

2.5

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

COUT = 22µF

COUT = 10µF

VIN = 1.2V

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

LTC3525-5 Load Regulation

Switching Frequency vs VIN

Light Load Burst Frequency

vs Load

VOUT Variation vs Temperature

(Normalized to 25°C)

Startup Delay Coming Out of

Shutdown

LTC3525-3.3 Input Current and

VOUT at Start-Up LTC3525-3.3 Output Voltage

Ripple

LTC3525-5 Load Regulation

Typical perForMance characTerisTics

TA = 25°C unless otherwise noted.

3525 G09

LOAD (mA)

0 12010020 40 60 80 140

CHANGE IN VOUT (%)

2.5

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

COUT = 22µF

COUT = 10µF

VIN = 2.4V

3525 G10

LOAD (mA)

0 15050 200100

CHANGE IN VOUT (%)

2.5

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

COUT = 22µF

COUT = 10µF

VIN = 3.6V

3525 G11

VIN (V)

1.0 2.5 3.51.5 2.0 3.0 4.0 4.5

FREQUENCY (kHz)

1200

1100

1000

900

800

700

600

500

400

300

LTC3525-5

LTC3525-3.3

L = 10µH

3525 G12

LOAD (mA)

0.1

BURST FREQUENCY (kHz)

01 10

COUT = 10µF

COUT = 22µF

TEMPERATURE (

–50

–25

100

125

–0.40

–0.30

–0.20

–0.10

–0.00

0.10

0.20

0.30

0.40

CHANGE IN V

OUT

(%)

3525 G13

1.0 2.5 3.51.5 2.0 3.0 4.0 4.5

3525 G14

120

100

SWITCHING DELAY (µs)

VIN (V)

3525 G15

INPUT

CURRENT

100mA/DIV

VOUT

1V/DIV

500µs/DIV

VIN = 1.2V

3525 G16

50mV/DIV

IOUT

80mA

IOUT

40mA

IOUT

5mA

50µs/DIV

VIN = 1.2V

COUT = 10µF

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

LTC3525-3.3 Output Voltage

Ripple

LTC3525-5 Output Voltage Ripple

LTC3525-3.3 50mA Load Step

Response

LTC3525-3.3 100mA Load Step

Response

LTC3525-5 100mA Load Step

Response

LTC3525-3.3 Output Voltage

Ripple

Typical perForMance characTerisTics

TA = 25°C unless otherwise noted.

3525 G17

IOUT

80mA

IOUT

40mA

IOUT

5mA

50µs/DIV

VIN = 1.2V

COUT = 22µF

50mV/DIV

3525 G18

IOUT

190mA

IOUT

100mA

IOUT

5mA

50µs/DIV

VIN = 2.4V

COUT = 22µF

50mV/DIV

3525 G19

IOUT

150mA

IOUT

50mA

VIN = 2.4V

COUT = 22µF

IOUT

5mA

50µs/DIV

50mV/DIV

3525 G20

IOUT

200mA

IOUT

100mA

VIN = 3.6V

COUT = 22µF

OUT

20mA

50µs/DIV

50mV/DIV

3525 G21

OUTPUT

RIPPLE

50mV/DIV

LOAD

CURRENT

20mA/DIV

VIN = 1.2V

COUT = 22µF

500µs/DIV 3525 G22

OUTPUT

RIPPLE

50mV/DIV

LOAD

CURRENT

50mA/DIV

VIN = 2.4V

COUT = 22µF

500µs/DIV 3525 G23

OUTPUT

RIPPLE

50mV/DIV

LOAD

CURRENT

50mA/DIV

VIN = 3.6V

COUT = 22µF

500µs/DIV

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

SHDN (Pin 1): Logic-Controlled Shutdown Input. Con-

nect to a voltage >1V to enable the LTC3525. Connect to

a voltage <0.4V to disable the LTC3525.

GND (Pins 2, 5): Ground.

VIN (Pin 3): Input Voltage. The LTC3525 is powered from

VIN until VOUT exceeds VIN. Once VOUT is greater than (VIN

+ 0.2V typical), it is powered from VOUT. Place a ceramic

bypass capacitor from VIN to GND. A minimum value of

1µF is recommended.

VOUT (Pin 4): Output Voltage Sense and the Output of the

Synchronous Rectifier. Connect the output filter capacitor

from VOUT to GND, close to the IC. A minimum value of

10µF ceramic is recommended. Use 22µF for reduced

output ripple. The output disconnect feature disconnects

VOUT from VIN when SHDN is <0.4V.

SW (Pin 6): Switch Pin. Connect an inductor from this

pin to VIN. An internal antiringing resistor is connected

across SW and VIN after the inductor current has dropped

to zero to minimize EMI.

pin FuncTions

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

block DiagraM

–

VREF

IPK

COMPARATOR

IVALLEY

COMPARATOR

SLEEP

COMPARATOR

INTEGRATOR

WAKETSD

IVAL

VOUT

SHDN

IPK

ADJUST

GND

OFFSET

ADJUST

OFFSET

ADJUST

LOGIC

GATE DRIVERS

AND

ANTI-CROSS

CONDUCTION

WELL

SWITCH

VBEST

VREF

UVLO

THERMAL

SHUTDOWN

START-UP

UVLO

SHUTDOWN

VREF

VSEL

VOUT

3525 BD

–

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

The LTC3525 is a high performance Burst Mode operation

only, synchronous boost converter requiring only three

small external components. Its simplicity and small size

make it a high efficiency alternative to charge pump designs.

It is designed to start up from a single alkaline or nickel

cell, with input voltages as low as 1V, or from two or three

cells (or a Li-Ion battery), with voltages as high as 4.5V.

Once started, VIN can be as low as 0.5V (depending on

load current) and maintain regulation. The output voltage

is preset internally to either 3V, 3.3V or 5V. Peak switch

current is 400mA minimum, providing regulation with load

currents up to 150mA, depending on input voltage.

Synchronous rectification provides high efficiency opera-

tion while eliminating the need for an external Schottky

diode. True output disconnect eliminates inrush current

at start-up, and allows VOUT to be disconnected from VIN,

for zero shutdown current.

The output disconnect feature also allows the LTC3525 to

maintain regulation with an input voltage equal to or greater

than VOUT. Note, however, that the synchronous rectifier

is not enabled in this mode resulting in lower efficiency

and reduced output current capability.

The operating quiescent current is only 7µA typical, allow-

ing the converter to maintain high efficiency at extremely

light loads.

Shutdown

The LTC3525 is shut down by pulling SHDN below 0.4V,

and made active by raising it above 1V. Although SHDN can

be driven above VIN or VOUT (up to the absolute maximum

rating) without damage, the LTC3525 has a proprietary test

mode that may be engaged if SHDN is held in the range

of 0.5V to 1V higher than the greater of VIN or VOUT. If

the test mode is engaged, normal PWM switching action

is interrupted, which can cause undesirable operation

in some applications. Therefore, in applications where

SHDN may be driven above VIN, a resistor divider or other

means must be employed to keep the SHDN voltage below

(VIN + 0.4V) to prevent the possibility of the test mode

being engaged. Please refer to Figure 1 for two possible

implementations.

After the SHDN pin rises, there is a short delay before

switching starts. The delay is 20µs to 120µs, depending

on input voltage (see Typical Performance Characteristics

curve).

Start-Up

A start-up oscillator allows the LTC3525 to start with input

voltages as low as 1V. It remains in start-up mode until

two conditions are met. VOUT must exceed VIN by at least

0.2V typical and either VIN or VOUT must be greater than

1.8V typical.

During start-up, the synchronous rectifier is not enabled,

and the internal P-channel synchronous rectifier acts as

a follower, causing the peak voltage on SW to reach (VIN

+ 1V) typical. This limits inrush current by maintaining

control of the inductor current when VOUT is less than VIN.

To reduce power dissipation in the P-channel synchronous

rectifier when the output is shorted, a foldback feature is

incorporated that reduces the peak inductor current when

VIN is more than 1.7V greater than VOUT.

Normal Operation

Once VOUT has increased more than 0.2V typical above

VIN, and either voltage is above 1.8V, normal operation

begins, with synchronous rectification enabled. In this

mode, the internal N-channel MOSFET connected be-

tween SW and GND stays on until the inductor current

reaches a maximum peak value, after which it is turned

off and the P-channel synchronous rectifier is turned

on. It stays on, delivering current to the output, until the

inductor current has dropped below a minimum value at

operaTion

LTC3525

VCNTRL

VIN

VCNTRL

SHDN

LTC3525

3525 F01

ZETEX ZC2811E

R > (VCNTRL/(VIN + 0.4) – 1) MΩ

SHDN

Figure 1

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

which point it turns off and the cycle repeats. When the

output voltage reaches its regulated value both switches

are turned off and the LTC3525 goes to sleep, during

which time the output capacitor supplies current to the

load. Once the output voltage drops approximately 9mV

below the regulation value the IC leaves sleep mode and

switching is resumed.

The LTC3525 has been designed for low output voltage

ripple. The output voltage ripple is typically only 20mV

peak-to-peak at light load and 60mV peak-to-peak at

full load using the minimum recommended 10µF output

capacitor for the LTC3525-3.3 and a 22µF capacitor for

the LTC3525-5 (due to the capacitor’s DC bias effect). An

antiring circuit damps any oscillation at the switch node

when the inductor current falls to zero.

Power Adjust Feature

The LTC3525 incorporates a feature that maximizes

efficiency at light load while providing increased power

capability at heavy load by adjusting the peak and valley

of the inductor current as a function of load. Lowering the

peak inductor current to 150mA at light load optimizes

efficiency by reducing conduction losses in the internal

MOSFET switches. As the load increases, the peak inductor

current is automatically increased to a maximum of 400mA.

At intermediate loads, the peak inductor current may vary

from 150mA to 400mA. Figure 2 shows an example of

how the inductor current changes as the load increases.

Please note that output capacitor values greater than 47µF

will result in higher peak currents than necessary at light

load. This will lower the light load efficiency.

The valley of the inductor current is automatically adjusted

as well, to maintain a relatively constant inductor ripple

current. This keeps the switching frequency relatively

constant.

The maximum average load current that can be supported

is given by:

VAmps

OMAX IN

()

03.• •η

where η is the efficiency (see Typical Performance Char-

acteristics).

The “burst” frequency (how often the LTC3525 delivers

a burst of current pulses to the load) is determined by

the internal hysteresis (output voltage ripple), the load

current and the amount of output capacitance. All Burst

Mode operation or hysteretic converters will enter the

audible frequency range when the load is light enough.

However, due to the low peak inductor current at light

load, circuits using the LTC3525 do not typically generate

any audible noise.

Figure 2. Inductor Current Changing as a Function of Load

operaTion

3525 F02

INDUCTOR

CURRENT

100mA/DIV

LOAD

CURRENT

50mA/DIV

10µs/DIV

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

Component Selection

Inductor values between 4.7µH and 15µH are recom-

mended. In most applications 10µH will yield the best

compromise between size and efficiency. The inductor

should be a low loss ferrite design and must be rated for

peak currents of at least 400mA without saturating. Induc-

tors with lower DC resistance will improve efficiency. Note

that the inductor value does not have a significant effect

on ripple current, so while lower values will increase the

operating frequency, they do not reduce output voltage

ripple.

Some recommended inductor examples are Murata

LQH32C and Coilcraft LPO4812, LPO3310, DO3314,

DS1608 and MSS4020.

A ceramic input bypass capacitor should be located as

close as possible to the VIN and GND pins of the IC. A

minimum value of 1µF is recommended. If the battery is

more than a few inches away, a bulk tantalum decoupling

cap of at least 10µF is recommended on VIN.

The output capacitor should also be a ceramic, located close

to the VOUT and GND pins. A minimum value of 10µF is

recommended. Increasing the value of the output capacitor

to 22µF will result in lower output ripple. Higher capacitor

values will only offer a small reduction in output ripple,

while reducing light load efficiency by causing the peak

inductor current to increase above its minimum value of

150mA. The input and output capacitors should be X5R

or X7R types, not Y5V.

Figure 3. Recommended Component Placement

Table 2. Capacitor Vendor Information

SUPPLIER PHONE FAX WEBSITE

Murata USA: (814) 237-1431 USA: (814) 238-0490 www.murata.com

Taiyo Yuden (408) 573-4150 (408) 573-4159 www.t-yuden.com

TDK (847) 803-6100 (847) 803-6296 www.component.tdk.com

AVX (803) 448-9411 (803) 448-1943 www.avxcorp.com

SHDN

GND

VIN

GND

VOUT

LTC3525

SHDN

VIN

3525 F03

VOUT

operaTion

Table 1. Inductor Vendor Information

SUPPLIER PHONE FAX WEBSITE

Murata USA: (814) 237-1431 USA: (814) 238-0490 www.murata.com

Coilcraft (847) 639-6400 (847) 639-1469 www.coilcraft.com

Sumida USA: (847) 956-0666 USA: (847) 956-0702 www.sumida.com

Taiyo Yuden (408) 573-4150 (408) 573-4159 www.t-yuden.com

TOKO (847) 297-0070 (847)699-7864 www.toko.co.jp/products/en

TDK (847)699-2299 (847)803-6296 www.tdk.com

Würth (605)886-4385 (605)886-4486 www.we-online.com

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

Single Alkaline or NiMH to 3.3V Converter with 1mm Profile

2-Alkaline or NiMH to 3.3V Li-Ion to 5V

Single Cell to 3V Converter Using 1mm High Monolithic Inductor

Typical applicaTions

6.8µH*

3525 TA03

LTC3525-3

*COILCRAFT XPL2010-682ML

VOUT

65mA

2 5

VOUT

GND

SHDN

GND

VIN

1V TO 1.6V

10µF

1µF

10µH*

3525 TA05

LTC3525-3.3

*TOKO DFE322512C 1277AS-H-100M

VOUT

3.3V

140mA

2 5

VOUT

GND

SHDN

GND

VIN

1.8V TO 3.2V

10µF

1µF

6.8µH*

3525 TA04

LTC3525-3.3

*COILCRAFT LPO3310-682MXD

**MURATA GRM219R60J106KE191D

VOUT

3.3V

60mA

2 5

VOUT

GND

SHDN

GND

VIN

1V TO 1.6V

10µF**

6.3V

1µF

10µH*

3525 TA06

LTC3525-5

*TAIYO YUDEN NRH3012T100MN

VOUT

175mA

Li-Ion 5

VOUT

GND

SHDN

GND

VIN

3V TO 4.2V

10µF

1µF

OFF ON

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

SC6 Package

6-Lead Plastic SC70

(Reference LTC DWG # 05-08-1638 Rev B)

package DescripTion

1.15 – 1.35

(NOTE 4)

1.80 – 2.40

0.15 – 0.30

6 PLCS (NOTE 3)

SC6 SC70 1205 REV B

1.80 – 2.20

(NOTE 4)

0.65 BSC

PIN 1

0.80 – 1.00

1.00 MAX

0.00 – 0.10

REF

NOTE:

1. DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

5. MOLD FLASH SHALL NOT EXCEED 0.254mm

6. DETAILS OF THE PIN 1 IDENTIFIER ARE OPTIONAL,

BUT MUST BE LOCATED WITHIN THE INDEX AREA

7. EIAJ PACKAGE REFERENCE IS EIAJ SC-70

8. JEDEC PACKAGE REFERENCE IS MO-203 VARIATION AB

2.8 BSC

0.47

MAX

0.65

REF

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

1.8 REF

1.00 REF

INDEX AREA

(NOTE 6)

0.10 – 0.18

(NOTE 3)

0.26 – 0.46

GAUGE PLANE

0.15 BSC

0.10 – 0.40

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

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 representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

revision hisTory

REV DATE DESCRIPTION PAGE NUMBER

B 09/10 Updated “Shutdown” section 8

C 04/15 Changed input starting voltage from 1V to 0.85V

Added table to reference other LTC3525 family parts

Changed Operating Temperature Range to Operating Junction Temperature Range and changed the Operating

Junction Temperature Range from 85°C to 125°C in the Absolute Maximum Ratings section

Updated Order Information table

Changed Operating Temperature Range to Operating Junction Temperature Range and added Note 2 to the Electrical

Characteristics section

Updated Note 2 for addition of I Grade

Updated VOUT Variation vs Temperature curve

Updated Inductor Vendor Information in Table 1

Updated Inductor Information

Updated title and inductor vendor in the Typical Application section

Modified Related Parts table

3, 4

(Revision history begins at Rev B)

LTC3525-3/

LTC3525-3.3/LTC3525-5

3525fc

For more information www.linear.com/LTC3525

 LINEAR TECHNOLOGY CORPORATION 2005

LT 0415 REV C • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC3525

3.3V TO 5V Converter with 1.2mm Profile

PART NUMBER DESCRIPTION COMMENTS

LTC1751-3.3/

LTC1751-5

100mA, 800kHz, Micropower, Regulated Charge Pump

DC/DC Converters

VIN: 2.5V to 5.5V, VOUT(MAX) = 3.3V/5V, IQ = 20µA,

ISD < 1µA, MS8 Package

LTC3200-5 100mA, 2MHz, Regulated 5V Charge Pump VIN: 2.7V to 4.5V, VOUT(MAX) = 5V, IQ = 2mA,

ISD < 1µA, ThinSOT Package

LTC3400/LTC3400B 600mA (ISW), 1.2MHz, Synchronous Step-Up DC/DC Converter 92% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5V,

IQ = 19µA/300µA, ISD < 1µA, ThinSOT Package

LTC3401 1A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V,

IQ = 38µA, ISD < 1µA, MS Package

LTC3402 2A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V,

IQ = 38µA, ISD < 1µA, MS Package

LTC3421 3A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter

with Output Disconnect

95% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V,

IQ = 12µA, ISD < 1µA, QFN-24 Package

LTC3425 5A (ISW), 8MHz, 4-Phase Synchronous Step-Up DC/DC Converter

with Output Disconnect

95% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V,

IQ = 12µA, ISD < 1µA, QFN-32 Package

LTC3429/LTC3429B 600mA, 500kHz Single/Dual Cell Micropower Synchronous

Boost Converter with Output Disconnect

95% Efficiency, VIN: 1V to 4.5V, VOUT(MAX) = 5V,

IQ = 20µA, ISD < 1µA, SC70 Package

LTC3458 1.4A (ISW), 1.5MHz, Synchronous Step-Up DC/DC Converter

with Output Disconnect

VIN: 1.5V to 6V, VOUT(MAX) = 7.5V, ISD < 1µA,

3mm × 4mm DFN Package

LTC3458L 1.7A (ISW), 1.5MHz, Synchronous Step-Up DC/DC Converter

with Output Disconnect

VIN: 1.5V to 6V, VOUT(MAX) = 6V, ISD < 1µA,

3mm × 4mm DFN Package

LTC3459 60mA, 10V Micropower Synchronous Boost Converter 95% Efficiency, VIN: 1.5V to 6V, VOUT(MAX) = 10V, IQ = 10µA, ISD

< 1µA, ThinSOT Package

LT3464 85mA (ISW), High Efficiency Step-Up DC/DC Converter

with Integrated Schottky and PNP Disconnect

VIN: 2.3V to 10V, VOUT(MAX) = 34V, IQ = 25µA,

ISD < 1µA, ThinSOT Package

LTC3528/LTC3528B 1A, 1MHz Synchronous Step-Up DC/DC Converter with Output

Disconnect

94% Efficiency, VIN Start-Up Voltage: 700mV, VOUT(MAX) = 5.25V,

IQ = 12 µA, ISD < 1µA, 2mm × 3mm DFN Package

LTC3529 1.5A, 1.5MHz, Synchronous Step-Up DC/DC Converter 95% Efficiency, VIN: 1.8V to 5.25V, VOUT(MAX) = 5.15V,

ISD < 1µA, 2mm × 3mm DFN Package

LTC3539/LTC3539-2 2A, 1MHz/2MHz Synchronous Step-Up DC/DC Converter 94% Efficiency, VIN Start-Up Voltage: 700mV, VOUT(MAX) = 5.25V,

IQ = 12µA, ISD < 1µA, 2mm × 3mm DFN Package

Typical applicaTion

10µH*

3525 TA07

LTC3525-5

*SUMIDA 252012CDMCQDS-100MC

**MURATA GRM21BR60J226ME39L

VOUT

200mA

2 5

VOUT

GND

SHDN

GND

VIN

3.3V

22µF**

6.3V

1µF

relaTeD parTs