Linear Technology LTC3401EMS Datasheet

FEATURES

LTC3401

1A, 3MHz Micropower

Synchronous Boost Converter

U

DESCRIPTIO

■

Synchronous Rectification: Up to 97% Efficiency

■

1A Switch Current Rating

■

Fixed Frequency Operation Up to 3MHz

■

Wide Input Range: 0.5V to 5.5V (Operating)

■

Very Low Quiescent Current: 38µA (Burst Mode
Operation)

■

2.6V to 5.5V Adjustable Output Voltage

■

0.85V (Typ) Start-Up Voltage

■

No External Schottky Diode Required (V

■

Synchronizable Switching Frequency

■

Burst Mode Enable Control

■

Antiringing Control Reduces Switching Noise

■

PGOOD Output

■

OPTI-LOOP® Compensation

■

Very Low Shutdown Current: <1µA

■

Small 10-Pin MSOP Package

OUT

< 4.3V)

U

APPLICATIO S

■

Pagers

■

Handheld Instruments

■

Cordless Phones

■

Wireless Handsets

■

GPS Receivers

■

Battery Backup

■

CCFL Backlights

The LTC®3401 is a high efficiency, fixed frequency, step­up DC/DC converter that operates from an input voltage
below 1V. The device includes a 0.16Ω N-channel MOSFET
switch and a 0.18Ω 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 38µA 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 1µA shutdown, antiringing control,
open-drain power good output, thermal shutdown and
current limit. The LTC3401 is available in the 10-lead
thermally enhanced MSOP package. Higher current appli­cations should use the 2A rated LTC3402 synchronous
boost converter. Applications that require V

OUT

< 2.6V

should use the LTC3423.

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

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

TYPICAL APPLICATION

All-Ceramic-Capacitor 2-Cell to 3.3V at 500mA Step-Up Converter

VIN = 1.8V to 3V

+

2
CELLS

C1

4.7µF

0 = FIXED FREQUENCY

1 = Burst Mode OPERATION

3

V

10

SHDN

2

MODE/SYNC

6

PGOOD

1

R

R

t

30.1k

IN

t

L1

4.7µH

LTC3401

SW

V

OUT

FB

V

C

GND

C1: TAIYO YUDEN JMK212BJ475MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: SUMIDA CD43-4R7M

U

V

OUT

3.3V
500mA

4

7

8

9

C3
470pF

5

R5
82k

909k

C4

4.7pF

R2

C2
22µF

R1
549k

3404 TA01

100

Burst Mode

90

OPERATION
80
70
60
50
40

EFFICIENCY (%)

30
20
10

VIN = 2.4V WITH SCHOTTKY

0

0.1

Efficiency

1MHz
FIXED
FREQUENCY

1000

110

I

OUT

3401fa

100

(mA)

3401 TA02

1

LTC3401

PACKAGE/ORDER I FOR ATIO

UU

W

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

VIN, V

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

VC, Rt Voltages ......................... –0.5V to (V

PGOOD, SHDN, FB, MODE Voltages ........... –0.5V to 6V

Operating Temperature Range (Note 2) .. –40°C to 85°C

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

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

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

OUT

OUT

+ 0.3V)

ORDER PART

TOP VIEW

10

1

R

t

MODE

2

V

3

IN

SW

4

GND

5

MS PACKAGE

10-LEAD PLASTIC MSOP

T

= 125°C

JMAX

= 130°C/W 1 LAYER BOARD

θ

JA

= 100°C/W 4 LAYER BOARD

θ

JA

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

9
8
7
6

SHDN
V

C

FB
V

OUT

PGOOD

NUMBER

LTC3401EMS

MS PART MARKING

LTPG

ELECTRICAL CHARACTERISTICS

The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VIN = 1.2V, V

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Start-Up Voltage I
Minimum Operating Voltage (Note 4) ● 0.5 V
Output Voltage Adjust Range ● 2.6 5.5 V
Feedback Voltage ● 1.22 1.25 1.28 V
Feedback Input Current VFB = 1.25V 1 50 nA
Quiescent Current—Burst Mode Operation VC = 0V, MODE/SYNC = 3.3V (Note 3) 38 65 µA
Quiescent Current—SHDN SHDN = 0V, Not Including Switch Leakage 0.1 1 µA
Quiescent Current—Active VC = 0V, MODE/SYNC = 0V, Rt = 300k (Note 3) 440 800 µA
NMOS Switch Leakage 0.1 5 µA
PMOS Switch Leakage 0.1 10 µA
NMOS Switch On Resistance 0.16 Ω
PMOS Switch On Resistance 0.18 Ω
NMOS Current Limit ● 1 1.6 A
NMOS Burst Current Limit 0.66 A
Maximum Duty Cycle Rt = 15k ● 80 85 %
Minimum Duty Cycle ● 0%
Frequency Accuracy Rt = 15k ● 1.6 2 2.4 MHz
MODE/SYNC Input High 1.4 V
MODE/SYNC Input Low 0.4 V
MODE/SYNC Input Current V
Error Amp Transconductance ∆I = –5µA to 5µA, VC = V
PGOOD Threshold Referenced to Feedback Voltage –6 –9 – 12 %

= 3.3V unless otherwise noted.

OUT

< 1mA 0.85 1.0 V

LOAD

MODE/SYNC

= 5.5V 0.01 1 µA

FB

85 µmhos

2

3401fa

LTC3401

ELECTRICAL CHARACTERISTICS

The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VIN = 1.2V, V

PARAMETER CONDITIONS MIN TYP MAX UNITS

PGOOD Low Voltage I

PGOOD Leakage V
SHDN Input High V
SHDN Input Low 0.4 V
SHDN Input Current V
Thermal Shutdown 170 °C

= 3.3V unless otherwise noted.

OUT

= 1mA 0.1 0.2 V

PGOOD

= 1V, I

V

OUT

= 5.5V 0.01 1 µA

PGOOD

= VIN = V

SHDN

= 5.5V 0.01 1 µA

SHDN

= 20µA 0.1 0.4 V

PGOOD

OUT

1V

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

Note 2: The LTC3401 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

Note 3: Current is measured into V
bootstrapped to the V
supply by (V

Note 4: Once the output is started, the IC is not dependant upon the V
supply.

with statistical process controls.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

SW Pin and Inductor Current (IC)
in Discontinuous Mode. Ringing
Control Circuitry Eliminates High

Switching Waveform on SW Pin

50mA/DIV

SW

1V/DIV

Frequency Ringing Transient Response 5mA to 50mA

I

L

0A

SW

1V/DIV

0V

since the supply current is

V

OUT

50mA

5mA

OUT

pin and in the application will reflect to the input

OUT

) • Efficiency. The outputs are not switching.

OUT/VIN

100mV/DIV

I

OUT

IN

50ns/DIV

3401 G01

200ns/DIV

3401 G02

C

= 22µF 200µs/DIV 3401 G03

OUT

L = 3.3µH

= 1MHz

f

OSC

3401fa

3

LTC3401

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Transient Response 50mA to 500mA

V

OUT

200mV/DIV

550mA

I

OUT

50mA

C

= 22µF 200µs/DIV 3401 G04

OUT

L = 3.3µH

= 1MHz

f

OSC

Converter Efficiency 1.2V to 3.3V

100

90

Burst Mode

80

OPERATION

70
60
50
40

EFFICIENCY (%)

30
20
10

0

0.1 10 100 1000

300kHz

1MHz

1
OUTPUT CURRENT (mA)

3MHz

3401 G07

Burst Mode Operation

V

OUT

AC

100mV/DIV

SW

1V/DIV

= 1.2V 5ms/DIV 3401 G05

V

IN

V

= 3.3V

OUT

= 100µF

C

OUT

= 250µA

I

OUT

MODE/SYNC PIN = HIGH

Converter Efficiency 2.4V to 3.3V

100

Burst Mode

90

OPERATION

80
70

300kHz

60
50
40

EFFICIENCY (%)

30
20
10

0

0.1 10 100 1000

1
OUTPUT CURRENT (mA)

3MHz

1MHz

3401 G08

Burst Mode Operation

V

OUT

AC

100mV/DIV

SW

1V/DIV

VIN = 1.2V 200µs/DIV 3401 G06
V

= 3.3V

OUT

= 100µF

C

OUT

= 20mA

I

OUT

MODE/SYNC PIN = HIGH

Converter Efficiency 3.6V to 5V

100

Burst Mode OPERATION

90
80
70
60
50
40

EFFICIENCY (%)

30
20

10

0

0.1

1MHz
FIXED
FREQUENCY

110

LOAD CURRENT (mA)

100

1000

3401 G10

Start-Up Voltage
vs I

OUT

500

TA = 25°C

400

300

200

OUTPUT CURRENT (mA)

100

0

0.8

0.9

4

1

1.1 1.2

VIN (V)

1.3

3401 G09

1.4

Efficiency Loss Without Schottky
vs Frequency

14

T

= 25°C

A

12

10

8

6

4

EFFICIENCY LOSS (%)

2

0

0.2

0.6 1.0
FREQUENCY (MHz)

1.8 2.6 3.0

1.4 2.2

3401 G11

Current Limit

1.80

1.75

1.70

1.65

1.60

1.55

CURRENT (A)

1.50

1.45

1.40
–15 25 105

–55

TEMPERATURE (°C)

3401fa

65

125

3401 G12

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC3401

EA FB Voltage

1.28

1.27

1.26

1.25

VOLTAGE (V)

1.24

1.23

1.22
–55

PMOS R

0.30
V

OUT

0.25

0.20

0.15

RESISTANCE (Ω)

0.10

0.05

–55

–15 25 105

TEMPERATURE (°C)

65

DS(ON)

= 3.3V

–15 25 105

TEMPERATURE (°C)

65

3401 G13

3401 G16

125

125

Oscillator Frequency Accuracy

2.10
Rt = 15k

2.05

2.00

FREQUENCY (MHz)

1.95

1.90
–15 25 105

–55

TEMPERATURE (°C)

Start-Up Voltage

1.1

1.0

0.9

0.8

VOLTAGE (V)

0.7

0.6
–15 25 105

–55

TEMPERATURE (°C)

NMOS R

0.30

0.25

0.20

0.15

RESISTANCE (Ω)

0.10

65

125

3401 G14

0.05
–55

DS(ON)

V

= 3.3V

OUT

–15 25 105

TEMPERATURE (°C)

65

125

3401 G22

Shutdown Threshold

1.10

1.05

1.00

0.95

0.90

0.85

0.80

VOLTAGE (V)

0.75

0.70

0.65

65

125

3401 G17

0.60
–15 25 105

–55

TEMPERATURE (°C)

65

125

3401 G18

PGOOD Threshold

–7.0
–7.5
–8.0
–8.5

(%)

FB

–9.0

–9.5
–10.0
–10.5

PERCENT FROM V

–11.0
–11.5
–12.0

–55

–15 25 105

TEMPERATURE (°C)

65

3401 G19

125

Burst Mode Operation Current

44

42

40

38

36

CURRENT (µA)

34

32

30

–15 25 105

–55

TEMPERATURE (°C)

V

Turn-Off Voltage

OUT

2.50

2.45

2.40

2.35

2.30

2.25

2.20

VOLTAGE (V)

2.15

2.10

2.05

65

125

3401 G20

2.00
–15 25 105

–55

TEMPERATURE (°C)

3401fa

65

125

3401 G21

5