LTC3402

3402fa

2A, 3MHz Micropower

Synchronous Boost Converter

The LTC

3402 is a high efficiency, fixed frequency, step-

up DC/DC converter that operates from an input voltage
below 1V. The device includes a 0.16

N-channel MOSFET

switch and a 0.18

P-channel synchronous rectifier.

Switching frequencies up to 3MHz are programmed with
an external timing resistor and the oscillator can be
synchronized to an external clock. An external Schottky
diode is optional but will slightly improve efficiency.

Quiescent current is only 38

A in Burst Mode operation,

maximizing battery life in portable applications. Burst
Mode operation is user controlled and can be enabled by
driving the MODE/SYNC pin high. If the MODE/SYNC pin
has either a clock or is driven low, then fixed frequency
switching is enabled.

Other features include a 1

A shutdown, antiringing con-

trol, open-drain power good output, thermal shutdown
and current limit. The LTC3402 is available in the 10-lead
thermally enhanced MSOP package. Lower current appli-
cations should use the 1A rated LTC3401 synchronous
boost converter. Applications that require V

OUT

< 2.6V

should use the LTC3424.

All Ceramic Capacitor 2-Cell to 3.3V at 1A Step-Up Converter

Cellular Telephones

Handheld Computers

MP3 Players

2-Way Pagers

GPS Receivers

Battery Backup Supplies

CCFL Backlights

Synchronous Rectification: Up to 97% Efficiency

2A Switch Current Rating

Fixed Frequency Operation Up to 3MHz

Wide Input Range: 0.5V to 5V

Very Low Quiescent Current: 38

A (Burst Mode

Operation)

2.6V to 5.5V Adjustable Output Voltage

0.85V (Typ) Start-Up Voltage

No External Schottky Diode Required (V

OUT

< 4.3V)

Synchronizable Switching Frequency

Burst Mode Enable Control

Antiringing Control Reduces Switching Noise

PGOOD Output

OPTI-LOOP

Compensation

Very Low Shutdown Current: < 1

Small 10-Pin MSOP Package

, LTC and LT are registered trademarks of Linear Technology Corporation.

Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.

OUT

(mA)

0.1

EFFICIENCY (%)

100

3402 TA02

100

1000

Burst Mode

OPERATION

1MHz
CONSTANT
FREQUENCY

= 2.4V WITH SCHOTTKY

Efficiency

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

3402 TA01

LTC3402

SHDN

MODE/SYNC

PGOOD

OUT

GND

C3
470pF

C4
4.7pF

2
CELLS

R5
82k

30.1k

909k

R1
549k

OUT

3.3V
1A

2.2

C2
44

C1: TAIYO YUDEN JMK212BJ106MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: COILCRAFT: D03316P-222

= 1.8V to 3V

0 = FIXED FREQ

1 = Burst Mode OPERATION

LTC3402

3402fa

(Note 1)

, V

OUT

Voltages ...................................... 0.5V to 6V

SW Voltage ................................................. 0.5V to 6V
V

, R

Voltages ......................... 0.5V to (V

OUT

+ 0.3V)

PGOOD, SHDN, FB, MODE Voltages ........... 0.5V to 6V
Operating Temperature Range (Note 2) .. 40

C to 85

Storage Temperature Range ................. 65

C to 125

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

JMAX

= 125

= 130

C/ W 1 LAYER BOARD

= 100

C/ W 4 LAYER BOARD

MS PART MARKING

ORDER PART

NUMBER

LTC3402EMS

LTSK

The

denotes specifications that apply over the full operating temperature range, otherwise specifications are at T

= 25

= 1.2V, V

OUT

= 3.3V unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Minimum Start-Up Voltage

LOAD

= <1mA

0.85

1.0

Minimum Operating Voltage

(Note 4)

0.5

Output Voltage Adjust Range

2.6

5.5

Feedback Voltage

1.22

1.25

1.28

Feedback Input Current

= 1.25V

Quiescent Current--Burst Mode Operation

= 0V, MODE/SYNC = 3.3V (Note 3)

Quiescent Current--SHDN

SHDN = 0V, Not Including Switch Leakage

0.1

Quiescent Current--Active

= 0V, MODE/SYNC = 0V, R

= 300k (Note 3)

440

800

NMOS Switch Leakage

0.1

PMOS Switch Leakage

0.1

NMOS Switch On Resistance

0.16

PMOS Switch On Resistance

0.18

NMOS Current Limit

2.5

NMOS Burst Current Limit

0.66

Maximum Duty Cycle

= 15k

Minimum Duty Cycle

Switching Frequency

= 15k

1.6

2.4

MHz

MODE/SYNC Input High

1.4

MODE/SYNC Input Low

0.4

MODE/SYNC Input Current

MODE/SYNC

= 5.5V

0.01

Error Amp Transconductance

I = 5

A to 5

A, V

= V

mhos

PGOOD Threshold

Referenced to Feedback Voltage

ABSOLUTE AXI U RATI GS

PACKAGE/ORDER I FOR ATIO

ELECTRICAL CHARACTERISTICS

1
2
3
4
5

MODE

GND

10
9
8
7
6

SHDN
V

FB
V

OUT

PGOOD

TOP VIEW

MS PACKAGE

10-LEAD PLASTIC MSOP

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

LTC3402

3402fa

The

denotes specifications that apply over the full operating temperature range, otherwise specifications are at T

= 25

= 1.2V, V

OUT

= 3.3V unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

PGOOD Low Voltage

PGOOD

= 1mA

0.1

0.2

OUT

= 1V, I

PGOOD

= 20

0.1

0.4

PGOOD Leakage

PGOOD

= 5.5V

0.01

SHDN Input High

= V

SHDN

SHDN Input Low

0.4

SHDN Input Current

SHDN

= 5.5V

0.01

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: The LTC3402E 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 3: Current is measured into the V

OUT

pin since the supply current is

bootstrapped to the output pin and in the application will reflect to the
input supply by (V

OUT

) · Efficiency. The outputs are not switching.

Note 4: Once the output is started, the IC is not dependent upon the V

supply.

TYPICAL PERFOR A CE CHARACTERISTICS

Switching Waveform on SW Pin

SW Pin and Inductor Current (I

)

in Discontinuous Mode. Ringing
Control Circuitry Eliminates High
Frequency Ringing

Transient Response 5mA to 50mA

1V/DIV

50ns/DIV

3402 G01

1V/DIV

200ns/DIV

3402 G02

50mA/DIV

OUT

= 22

200

s/DIV

3402 G03

L = 3.3

OSC

= 1MHz

OUT

100mV/DIV

50mA

5mA

= 25

C unless otherwise noted)

Transient Response 50mA to 500mA

Burst Mode Operation

OUT

200mV/DIV

550mA

50mA

OUT

= 22

200

s/DIV

3402 G04

L = 3.3

OSC

= 1MHz

OUT

100mV/DIV

= 1.2V

5ms/DIV

3402 G05

OUT

= 3.3V

OUT

= 100

OUT

= 250

MODE/SYNC PIN = HIGH

1V/DIV

OUT

100mV/DIV

= 1.2V

200

s/DIV

3402 G06

OUT

= 3.3V

OUT

= 100

OUT

= 20mA

MODE/SYNC PIN = HIGH

1V/DIV

LTC3402

3402fa

TYPICAL PERFOR A CE CHARACTERISTICS

Converter Efficiency 1.2V to 3.3V

OUTPUT CURRENT (mA)

EFFICIENCY (%)

100

0.1

100

1000

3402 G07

300kHz

3MHz

1MHz

Burst Mode

OPERATION

OUTPUT CURRENT (mA)

EFFICIENCY (%)

100

0.1

100

1000

3402 G08

300kHz

3MHz

1MHz

Burst Mode

OPERATION

(V)

0.8

OUTPUT CURRENT (mA)

100

200

300

0.9

1.1

1.2

3402 G09

1.3

400

500

1.4

= 25

Converter Efficiency 2.4V to 3.3V

Start-Up Voltage
vs I

OUT

Converter Efficiency 3.6V to 5V

LOAD CURRENT (mA)

0.1

EFFICIENCY (%)

100

3402 G10

100

1000

1MHz
FIXED
FREQUENCY

Burst Mode OPERATION

= 3.6V

Efficiency Loss Without Schottky
vs Frequency

FREQUENCY (MHz)

0.2

1.4

2.2

3402 G11

0.6

1.0

1.8

2.6

3.0

EFFICIENCY LOSS (%)

= 25

Current Limit

TEMPERATURE (

CURRENT (A)

2.6

2.8

3.0

125

3402 G12

2.4

2.2

2.0

105

3.2

3.4

= 25

C unless otherwise noted)

EA FB Voltage

Oscillator Frequency Accuracy

TEMPERATURE (

VOLTAGE (V)

1.23

1.24

1.25

125

3402 G13

1.22

105

1.26

1.27

1.28

TEMPERATURE (

FREQUENCY (MHz)

2.00

125

3402 G14

1.95

1.90

105

2.05

2.10

= 15k

NMOS R

DS(ON)

TEMPERATURE (

RESISTANCE (

)

0.15

125

3402 G22

0.10

0.05

105

0.20

0.25

0.30

OUT

= 3.3V

LTC3402

3402fa

TYPICAL PERFOR A CE CHARACTERISTICS

PMOS R

DS(ON)

Start-Up Voltage

Shutdown Threshold

PGOOD Threshold

Burst Mode Operation Current

OUT

Turn-Off Voltage

TEMPERATURE (

RESISTANCE (

)

0.15

125

3402 G16

0.10

0.05

105

0.20

0.25

0.30

OUT

= 3.3V

TEMPERATURE (

VOLTAGE (V)

0.8

125

3402 G17

0.7

0.6

105

0.9

1.0

1.1

TEMPERATURE (

VOLTAGE (V)

0.70

125

3402 G18

0.60

105

0.80

0.90

1.00

0.65

1.05

1.10

0.75

0.85

0.95

TEMPERATURE (

PERCENT FROM V

(%)

10.0

125

3402 G19

11.0

12.0

105

9.0

8.0

7.0

10.5

11.5

9.5

8.5

7.5

TEMPERATURE (

CURRENT (

125

3402 G20

105

TEMPERATURE (

VOLTAGE (V) 2.20

125

3402 G21

2.10

2.00

105

2.30

2.40

2.50

2.15

2.05

2.25

2.35

2.45

= 25

C unless otherwise noted)

LTC3402

3402fa

(Pin 1): Timing Resistor to Program the Oscillator

Frequency.

OSC

3 10

MODE/SYNC (Pin 2): Burst Mode Select and Oscillator
Synchronization.

MODE/SYNC = High. Enable Burst Mode operation. The
inductor peak inductor current will be 1/3 the current
limit value and return to zero current on each cycle.
During Burst Mode operation the operation is variable
frequency, providing a significant efficiency improve-
ment at light loads. It is recommended the Burst Mode
operation only be entered once the part has started up.

MODE/SYNC = Low. Disable Burst Mode operation and
maintain low noise, constant frequency operation.

MODE/SYNC = External CLK. Synchronization of the
internal oscillator and Burst Mode operation disable. A
clock pulse width of 100ns to 2

s is required to

synchronize.

(Pin 3): Input Supply Pin.

SW (Pin 4): Switch Pin. Connect inductor and Schottky
diode here. For applications with output voltages over
4.3V, a Schottky diode is required to ensure that the SW
pin voltage does not exceed its absolute maximum
rating. Minimize trace length to keep EMI and high
ringing down. For discontinuous inductor current, a
controlled impedance is placed from SW to V

from the

PI FU CTIO S

IC to eliminate high frequency ringing due to the resonant
tank of the inductor and SW node capacitance, therefore
reducing EMI radiation.

GND (Pin 5): Signal and Power Ground for the IC.

PGOOD (Pin 6): Power Good Comparator Output. This
open-drain output is low when V

< 9% from its

regulation voltage.

OUT

(Pin 7): Output of the Synchronous Rectifier and

Bootstrapped Power Source for the IC. A ceramic capaci-
tor of at least 1

F is required and should be located as

close to the V

OUT

and GND pins as possible (Pins 7 and 5).

FB (Pin 8): Feedback Pin. Connect resistor divider tap
here. The output voltage can be adjusted from 2.6V to 5V.
The feedback reference voltage is typically 1.25V.

(Pin 9): Error Amp Output. A frequency compensation

network is connected to this pin to compensate the loop.
See the section "Compensating the Feedback Loop" for
guidelines.

SHDN (Pin 10): Shutdown. Grounding this pin shuts down
the IC. Tie to >1V to enable (V

or digital gate output). To

operate with input voltages below 1V once the converter
has started, a 1M resistor from SHDN to V

and a 5M

resistor from SHDN to V

OUT

will provide sufficient hyster-

esis. During shutdown, the output voltage will hold up to
V

minus a diode drop due to the body diode of the PMOS

synchronous switch. If the application requires a com-
plete disconnect during shutdown, refer to the section
"Output Disconnect Circuits."

LTC3402

3402fa

APPLICATIO S I FOR ATIO

DETAILED DESCRIPTION

The LTC3402 provides high efficiency, low noise power
for applications such as portable instrumentation. The
current mode architecture with adaptive slope compensa-
tion provides ease of loop compensation with excellent
transient load response. The low R

DS(ON)

, low gate charge

synchronous switches provide the pulse width modula-
tion control at high efficiency.

The Schottky diode across the synchronous PMOS switch
provides a lower drop during the break-before-make time
(typically 20ns) of the NMOS to PMOS transition. The
addition of the Schottky diode will improve efficiency (see
graph "Efficiency Loss Without Schottky vs Frequency").
While the IC's quiescent current is a low 38

A, high

efficiency is achieved at light loads when Burst Mode
operation is entered.

Low Voltage Start-Up

The LTC3402 is designed to start up at input voltages of
typically 0.85V. The device can start up under some load,
(see graph Start-Up vs Input Voltage). Once the output
voltage exceeds a threshold of 2.3V, then the IC powers
itself from V

OUT

instead of V

. At this point, the internal

circuitry has no dependency on the input voltage, eliminat-
ing the requirement for a large input capacitor. The input
voltage can drop below 0.5V without affecting the opera-
tion, but the limiting factor for the application becomes the
availability of the power source to supply sufficient energy
to the output at the low voltages.

Low Noise Fixed Frequency Operation

Oscillator. The frequency of operation is set through a
resistor from the R

pin to ground where f = 3 · 10

. An

internally trimmed timing capacitor resides inside the IC.
The oscillator can be synchronized with an external clock
inserted on the MODE/SYNC pin. When synchronizing the
oscillator, the free running frequency must be set to
approximately 30% lower than the desired synchronized
frequency. Keeping the sync pulse width below 2

s will

ensure that Burst Mode operation is disabled.

Current Sensing. Lossless current sensing converts the
peak current signal to a voltage to sum in with the internal
slope compensation. This summed signal is compared to

the error amplifier output to provide a peak current control
command for the PWM. The slope compensation in the IC
is adaptive to the input and output voltage. Therefore, the
converter provides the proper amount of slope compensa-
tion to ensure stability and not an excess causing a loss of
phase margin in the converter.

Error Amp. The error amplifier is a transconductance
amplifier with g

= 0.1ms. A simple compensation net-

work is placed from the V

pin to ground.

Current Limit. The current limit amplifier will shut the
NMOS switch off once the current exceeds its threshold.
The current amplifier delay to output is typically 50ns.

Zero Current Amp. The zero current amplifier monitors the
inductor current to the output and shuts off the synchro-
nous rectifier once the current is below 50mA, preventing
negative inductor current.

Antiringing Control. The anitringing control will place an
impedance across the inductor to damp the ringing on the
SW pin during discontinuous mode operation. The LC

ringing (L = inductor, C

= capacitance on the switch pin)

is low energy, but can cause EMI radiation.

Burst Mode Operation

Burst Mode operation is when the IC delivers energy to the
output until it is regulated and then goes into a sleep mode
where the outputs are off and the IC is consuming only
38

A. In this mode, the output ripple has a variable

frequency component with load current and the steady
state ripple will be typically below 3%.

During the period where the device is delivering energy to
the output, the peak current will be equal to 1/6 the current
limit value and the inductor current will terminate at zero
current for each cycle. In this mode the maximum output
current is given by:

Amps

OUT MAXBURST

OUT

(

)

Burst Mode operation is user controlled by driving the
MODE/SYNC pin high to enable and low to disable. It is
recommended that Burst Mode operation be entered after
the part has started up.

LTC3402

3402fa

APPLICATIO S I FOR ATIO

COMPONENT SELECTION

Inductor Selection

The high frequency operation of the LTC3402 allows the
use of small surface mount inductors. The minimum
inductance value is proportional to the operating fre-
quency and is limited by the following constraints:

H and L

f Ripple V

IN MIN

OUT MAX

IN MIN

OUT MAX

> µ

(

)

(

)

(

)

(

)

(

)

where

f = Operating Frequency (Hz)

Ripple = Allowable Inductor Current Ripple (A)

IN(MIN)

= Minimum Input Voltage (V)

OUT(MAX)

= Maximum Output Voltage (V)

The inductor current ripple is typically set to 20% to 40%
of the maximum inductor current.

Figure 1. Recommended Component Placement. Traces
Carrying High Current Are Direct. Trace Area FB and V

Pins

Are Kept Low. Lead Length to Battery Should be Kept Short

Output Capacitor Selection

The output voltage ripple has several components. The
bulk value of the capacitor is set to reduce the ripple due
to charge into the capacitor each cycle. The max ripple due
to charge is given by:

BULK

OUT

where

= Peak Inductor Current

The ESR can be a significant factor for ripple in most
power converters. The ripple due to capacitor ESR is
simply given by:

CESR

= I

· R

ESR

where

ESR

= Capacitor Series Resistance

Low ESR capacitors should be used to minimize output
voltage ripple. For surface mount applications, AVX TPS
series tantalum capacitors and Sanyo POSCAP or Taiyo-
Yuden ceramic X5R or X7R type capacitors are recom-
mended. For through-hole applications Sanyo OS-CON
capacitors offer low ESR in a small package size. See Table
2 for a list of component suppliers. In some layouts it may
be required to place a 1

F low ESR capacitor as close to the

OUT

and GND pins as possible.

OUT

3402 F01

MODE
V

SW
GND

SHDN

OUT

POK

Table 1. Inductor Vendor Information

SUPPLIER

PHONE

FAX

WEBSITE

Coilcraft

(847) 639-6400

(847) 639-1469

www.coilcraft.com

Coiltronics

(516) 241-7876

(516) 241-9339

www.coiltronics.com

Murata

(814) 237-1431

(814) 238-0490

www.murata.com

(800) 831-9172

Sumida

USA: (847) 956-0666

(847) 956-0702

www.japanlink.com

Japan: 81-3-3607-5111 81-3-3607-5144

sumida

Table 2. Capacitor Vendor Information

SUPPLIER

PHONE

FAX

WEBSITE

AVX

(803) 448-9411

(803) 448-1943

www.avxcorp.com

Sanyo

(619) 661-6322

(619) 661-1055

www.sanyovideo.com

Taiyo Yuden

(408) 573-4150

(408) 573-4159

www.t-yuden.com

For high efficiency, choose an inductor with a high fre-
quency core material, such as ferrite, to reduce core
losses. The inductor should have low ESR (equivalent
series resistance) to reduce the I

R losses and must be

able to handle the peak inductor current without saturat-
ing. Molded chokes or chip inductors usually do not have
enough core to support the peak inductor currents in the
1A to 2A region. To minimize radiated noise, use a toroid,
pot core or shielded bobbin inductor. See Table 1 for
suggested components and Table 1 for a list of component
suppliers.

LTC3402

3402fa

Input Capacitor Selection

The input filter capacitor reduces peak currents drawn from
the input source and reduces input switching noise. Since
the IC can operate at voltages below 0.5V once the output
is regulated, then demand on the input capacitor is much
less and in most applications a 4.7

F is recommended.

Output Diode

For applications with output voltages over 4.3V, a Schottky
diode is required to ensure that the SW pin voltage does
not exceed its absolute maximum rating. The Schottky
diode across the synchronous PMOS switch provides a
lower drop during the break-before-make time (typically
20ns) of the NMOS to PMOS transition. The Schottky
diode improves peak efficiency (see graph "Efficiency
Loss Without Schottky vs Frequency). Use of a Schottky
diode such as a MBR0520L, 1N5817 or equivalent. Since
slow recovery times will compromise efficiency, do not
use ordinary rectifier diodes.

Operating Frequency Selection

There are several considerations in selecting the operating
frequency of the converter. The first is determining the
sensitive frequency bands that cannot tolerate any spec-
tral noise. For example, in products incorporating RF
communications, the 455kHz IF frequency is sensitive to
any noise, therefore switching above 600kHz is desired.
Some communications have sensitivity to 1.1MHz. In this
case, a 2MHz converter frequency may be employed.

The second consideration is the physical size of the
converter. As the operating frequency goes up, the induc-
tor and filter caps go down in value and size. The trade off
is in efficiency since the switching losses due to gate
charge are going up proportional with frequency. For
example in Figure 2, for a 2.4V to 3.3V converter, the
efficiency at 100mA is 5% less at 2MHz compared to
300kHz.

Another operating frequency consideration is whether the
application can allow "pulse skipping." In this mode, the
minimum on time of the converter cannot support the duty
cycle, so the converter ripple will go up and there will be
a low frequency component of the output ripple. In many

APPLICATIO S I FOR ATIO

applications where physical size is the main criterion then
running the converter in this mode is acceptable. In
applications where it is preferred not to enter this mode,
then the maximum operating frequency is given by:

MAX NOSKIP

OUT

ON MIN

(

)

where t

ON(MIN)

= minimum on time = 120ns.

Figure 2. Converter Efficiency 2.4V to 3.3V

OUTPUT CURRENT (mA)

EFFICIENCY (%)

100

0.1

100

1000

3402 G08

300kHz

3MHz

1MHz

Burst Mode

OPERATION

Reducing Output Capacitance with a Load Feed
Forward Signal

In many applications the output filter capacitance can be
reduced for the desired transient response by having the
device commanding the change in load current, (i.e.
system microcontroller), inform the power converter of
the changes as they occur. Specifically, a "load feed
forward" signal coupled into the V

pin gives the inner

current loop a head start in providing the change in output
current. The transconductance of the LTC3402 converter
at the V

pin with respect to the inductor current is typically

170mA/100mV, so the amount of signal injected is pro-
portional to the anticipated change of inductor current
with load. The outer voltage loop performs the remainder
of the correction, but because of the load feed forward
signal, the range over which it must slew is greatly
reduced. This results in an improved transient response.
A logic level feed forward signal, V

, is coupled through

components C5 and R6. The amount of feed forward

LTC3402

3402fa

signal is attenuated with resistor R6 and is given by the
following relationship:

OUT

1 5

· .

where

OUT

= load current change.

APPLICATIO S I FOR ATIO

Closing the Feedback Loop

The LTC3402 used current mode control with internal
adaptive slope compensation. Current mode control elimi-
nates the 2nd order filter due to the inductor and output
capacitor exhibited in voltage mode controllers, and sim-
plifies it to a single-pole filter response. The product of the
modulator control to output DC gain plus the error amp
open-loop gain equals the DC gain of the system.

= G

CONTROLOUTPUT

· G

CONTROL

OUT

2 ·

, G

2000

The output filter pole is given by:

FILTERPOLE

OUT

where C

OUT

is the output filter capacitor.

3402 F03

LTC3402

SHDN

MODE/SYNC

PGOOD

OUT

GND

LOAD FEED

FORWARD

SIGNAL

3.3nF

OUT

Figure 3

The output filter zero is given by:

FILTERZERO

ESR

OUT

2 ·

where R

ESR

is the capacitor equivalent series resistance.

A troublesome feature of the boost regulator topology is
the right half plane zero (RHP) and is given by:

V R

RHPZ

At heavy loads this gain increase with phase lag can occur
at a relatively low frequency. The loop gain is typically
rolled off before the RHP zero frequency.

The typical error amp compensation is shown in Figure 4.
The equations for the loop dynamics are as follows:

which is extremelyclose to DC

POLE

ZERO

POLE

20 10

Refer to AN76 for more closed-loop examples.

1.25V

ERROR

AMP

OUT

3402 F04

Figure 4

LTC3402

3402fa

3404 TA05a

LTC3402

SHDN

MODE/SYNC

PGOOD

OUT

GND

C3
470pF

C4
20pF

1
CELL

3.3

R5
39k

866k

R1
619k

OUT

3V
500mA

2.2

C2
10

C1: TAIYO YUDEN JMK212BJ335MG
C2: TAIYO YUDEN JMK325BJ106MM
D1: ON SEMICONDUCTOR MBRM120T3
L1: COILCRAFT DO1608-222

= 0.9V TO 1.5V

0 = FIXED FREQUENCY

1 = Burst Mode OPERATION

10k

5.1M

TYPICAL APPLICATIO S

Single Cell to 3V at 500mA, All Ceramic Capacitor, 3MHz Step-Up Converter

Efficiency

OUTPUT CURRENT (mA)

EFFICIENCY (%)

0.1

100

1000

3402 TA05b

Burst Mode

OPERATION

3MHz FIXED
FREQUENCY

Li-Ion to 5V at 300mA, 1MHz Step-Up Converter

Efficiency

3402 TA07a

LTC3402

SHDN

MODE/SYNC

PGOOD

OUT

GND

C3
470pF

C4
4.7pF

Li-Ion

4.7

R5
82k

30.1k

1.65M

R1
549k

D1*

OUT

5V
600mA

C2*
22

*LOCATE COMPONENTS AS CLOSE TO
IC AS POSSIBLE
C1: TAIYO YUDEN JMK212BJ475MG
C2: TAIYO YUDEN JMK325BJ226MM
D1: ON SEMICONDUCTOR MBRM120T3
L1: SUMIDA CDH53-100

= 2.5V TO 4.2V

0 = FIXED FREQUENCY

1 = Burst Mode OPERATION

LOAD CURRENT (mA)

0.1

EFFICIENCY (%)

100

3402 G10

100

1000

1MHz
FIXED
FREQUENCY

Burst Mode OPERATION

= 3.6V

LTC3402

3402fa

PACKAGE DESCRIPTIO

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

MS Package

10-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1661)

MSOP (MS) 0402

0.53

0.01

(.021

.006)

SEATING

PLANE

0.18

(.007)

1.10

(.043)

MAX

0.17 0.27

(.007 .011)

0.13

0.05

(.005

.002)

0.86

(.034)

REF

0.50

(.0197)

TYP

1 2 3 4 5

4.88

0.10

(.192

.004)

0.497

0.076

(.0196

.003)

REF

7 6

3.00

0.102

(.118

.004)

(NOTE 3)

3.00

0.102

(.118

.004)

NOTE 4

NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

0.254

(.010)

TYP

DETAIL "A"

GAUGE PLANE

5.23

(.206)

MIN

3.2 3.45

(.126 .136)

0.889

0.127

(.035

.005)

RECOMMENDED SOLDER PAD LAYOUT

0.305

0.038

(.0120

.0015)

TYP

0.50

(.0197)

BSC

LTC3402

3402fa

LT/TP 0502 1.5K REV A · PRINTED IN USA

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

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OUT

to 34V

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LT1615

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= 20

A, 1

A Shutdown Current, V

As Low As 1V

LT1619

High Efficiency Boost DC/DC Controller

1A Gate Drive, 1.1V to 20V Input, Separate V

for Gate Drive

LTC1872

SOT-23 Boost DC/DC Controller

550kHz, 2.5V to 9.8V Input

LT1930/LT1930A

1.2MHz/2.2MHz DC/DC Converters in SOT-23

= 2.6V to 16V, 5V at 450mA from 3.3V Input

LT1949

600kHz, 1A Switch PWM DC/DC Converter

1A, 0.5

, 30V Internal Switch, V

As Low As 1.5V,

Low-Battery Detect Active in Shutdown

LTC3400

Single Cell, High Current (600mA), Micropower,

= 0.85V to 5.5V, Up to 92% Efficiency Synchronizable

Synchronous 1.2MHz Step-Up DC/DC Converter

Oscillator from 100kHz to 1.2MHz, ThinSOT Package

LTC3401

Single Cell, High Current (1A), Micropower,

= 0.5V to 5V, Up to 97% Efficiency Synchronizable

Synchronous 3MHz Step-Up DC/DC Converter

Oscillator from 100kHz to 3MHz, 10-Lead MSOP Package

LTC3424

Single Cell, High Current (2A), Micropower,

OUT

= 1.5V, Up to 97% Efficiency Synchronizable

Synchronous 3MHz Step-Up DC/DC Converter

Oscillator from 100kHz to 3MHz, 10-Lead MSOP Package

LINEAR TECHNOLOGY CORPORATION 2000

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

FAX: (408) 434-0507

www.linear.com

Triple Output Converter

TYPICAL APPLICATIO

549k

3402 TA08

909k

C1: TAIYO YUDEN JMK212BJ475MG
C2: TAIYO YUDEN JMK325BJ226MM
D1: ON SEMICONDUCTOR MBRM120T3
D2 TO D7: ZETEX FMND7000 DUAL DIODE
L1: SUMIDA CD43-2R2M

C2
22

C3
470pF

C4
4.7pF

4.7

0.1

2.5V
1mA

OUT

3.3V
500mA

0.1

4.7

8V
2mA

LTC3402

SHDN

MODE/SYNC

PGOOD

OUT

GND

L1 2.2

30.1k

R5
82k

0 = FIXED FREQ

1 = Burst Mode OPERATION

2
CELLS

=1.8V TO 3V

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LTC3402

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LTC3402