Linear Technology LTC3400BES6, LTC3400ES6 Datasheet

FEATURES

■

Up to 92% Efficiency

■

Generates 3.3V at 100mA from a Single AA Cell

■

Low Start-Up Voltage: 0.85V

■

1.2MHz Fixed Frequency Switching

■

Internal Synchronous Rectifier

■

2.5V to 5V Output Range

■

Automatic Burst Mode® Operation (LTC3400)

■

Continuous Switching at Light Loads (LTC3400B)

■

Logic Controlled Shutdown (<1µA)

■

Antiringing Control Minimizes EMI

■

Tiny External Components

■

Low Profile (1mm) ThinSOTTM Package

U

APPLICATIO S

■

Pagers

■

MP3 Players

■

Digital Cameras

■

LCD Bias Supplies

■

Handheld Instruments

■

Wireless Handsets

■

GPS Receivers

LTC3400/LTC3400B

600mA, 1.2MHz Micropower

Synchronous Boost Converter

in ThinSOT

U

DESCRIPTIO

The LTC®3400/LTC3400B are synchronous, fixed fre­quency, step-up DC/DC converters delivering high effi­ciency in a 6-lead ThinSOT package. Capable of supplying

3.3V at 100mA from a single AA cell input, the devices
contain an internal NMOS switch and PMOS synchronous
rectifier.

A switching frequency of 1.2MHz minimizes solution
footprint by allowing the use of tiny, low profile inductors
and ceramic capacitors. The current mode PWM design is
internally compensated, reducing external parts count.
The LTC3400 features automatic shifting to power saving
Burst Mode operation at light loads, while the LTC3400B
features continuous switching at light loads. Antiringing
control circuitry reduces EMI concerns by damping the
inductor in discontinuous mode, and the devices feature
low shutdown current of under 1µA.

Both devices are available in the low profile (1mm) ThinSOT
package.

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

ThinSOT is a trademark of Linear Technology Corporation.

TYPICAL APPLICATIO

L1

4.7µH

+

SINGLE
AA CELL

C1, C2: TAIYO-YUDEN X5R EMK316BJ475ML
L1: COILCRAFT DO160C-472

Figure 1. Single Cell to 3.3V Synchronous Boost Converter

C1

4.7µF

OFF

ON

6

4

V

IN

LTC3400

SHDN

SW

GND

U

Efficiency

100

1

V

C2

4.7µF

3400 F01

OUT

3.3V
100mA

5

V

OUT

2

R1

1.02M
1%

3

FB

R2
604k
1%

90

80

70

EFFICIENCY (%)

60

FIGURE 1 CIRCUIT

50

WITH OPTIONAL SCHOTTKY DIODE
(SEE APPLICATIONS INFORMATION)

40

0.1 10 100 1000

VIN = 2.4V

VIN = 1.5V

1

LOAD CURRENT (mA)

3400 F01a

3400f

1

LTC3400/LTC3400B

PACKAGE/ORDER I FOR ATIO

UU

W

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

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

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

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

V

........................................................... –0.3V to 6V

OUT

Operating Temperature Range (Note 2) .. – 30°C to 85°C

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

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

ORDER PART

TOP VIEW

SW 1

GND 2

FB 3

S6 PACKAGE

6-LEAD PLASTIC SOT-23

T

= 125°C, θJA = 256°C/W

JMAX

6 V

IN

5 V

OUT

4 SHDN

NUMBER

LTC3400ES6
LTC3400BES6

S6 PART MARKING

LTWK
LTUN

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

ELECTRICAL CHARACTERISTICS

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 SHDN = VIN (Note 4) 0.5 0.65 V
Output Voltage Adjust Range 2.5 5 V
Feedback Voltage ● 1.192 1.23 1.268 V
Feedback Input Current VFB = 1.25V (Note 3) 1 nA
Quiescent Current (Burst Mode Operation) VFB = 1.4V (Note 5), LTC3400 Only 19 30 µA
Quiescent Current (Shutdown) V
Quiescent Current (Active) Measured On V
NMOS Switch Leakage VSW = 5V 0.1 5 µA
PMOS Switch Leakage VSW = 0V 0.1 5 µA
NMOS Switch On Resistance V

PMOS Switch On Resistance V

NMOS Current Limit 600 850 mA
Burst Mode Operation Current Threshold LTC3400 Only (Note 3) 3 mA
Current Limit Delay to Output (Note 3) 40 ns
Max Duty Cycle VFB = 1.15V ● 80 87 %
Switching Frequency 0.95 1.2 1.5 MHz

SHDN Input High 1V
SHDN Input Low 0.35 V
SHDN Input Current V

LOAD

SHDN

OUT

V

OUT

OUT

V

OUT

SHDN

The ● denotes the specifications which apply over the full operating

= 3.3V, unless otherwise specified.

OUT

= 1mA 0.85 1 V

= 0V, Not Including Switch Leakage 0.01 1 µA

OUT

= 3.3V 0.35 Ω
= 5V 0.20 Ω

= 3.3V 0.45 Ω
= 5V 0.30 Ω

● 0.85 1.2 1.5 MHz

= 5.5V 0.01 1 µA

300 500 µA

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

Note 2: The LTC3400E/LTC3400BE are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –30°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.

2

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

Note 4: Minimum V
battery’s ability to provide the necessary power as it enters a deeply
discharged state.

Note 5: Burst Mode operation I
by V

to get the equivalent input (battery) current.

OUT/VIN

operation after start-up is only limited by the

IN

is measured at V

Q

. Multiply this value

OUT

3400f

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC3400/LTC3400B

Output Load Burst Mode Threshold
vs V

IN

L = 4.7µH

= 25°C

T

A

20

V

= 3.3V V

OUT

10

OUTPUT CURRENT (mA)

0

0.9

1.5 2.1 2.7 3.3

OUT

VIN (V)

= 5V

No Load Battery Current vs V

1000

V

= 3.3V

OUT

= 25°C

T

A

100

3.9 4.5

3400 G01

BATT

V

vs Temperature

OUT

3.36
FIGURE 1 CIRCUIT

I

= 10mA

O

3.34

3.32

(V)

3.30

OUT

V

3.28

3.26

3.24

–60

03060

–30

TEMPERATURE (°C)

Normalized Oscillator Frequency
vs Temperature

1.01

1.00

0.99

0.98

90 120

3400 G02

Minimum Start-Up Voltage
vs Load Current

1.4
TA = 25°C

1.3

1.2

1.1

1.0

START-UP VOLTAGE (V)

0.9

0.8

0.1

1 10 100

I

(mA) CURRENT SOURCE LOAD

OUT

SW Pin Antiringing Operation

V

SW

1V/DIV

3400 G03

BATTERY CURRENT (µA)

10

0.9

1.2

1.8

BATTERY VOLTAGE (V)

SW Pin Fixed Frequency,
Continuous Inductor Current
Operation

V

SW

1V/DIV

0V

= 1.3V 100ns/DIV 3400 G07

V

IN

V

= 3.3V

OUT

= 50mA

I

OUT

L = 6.8µH
C

= 4.7µF

OUT

2.1 2.4 2.7

3400 G04

3.01.5

0.97

NORMALIZED FREQUENCY

0.96

0.95
–50

–30 –10

Fixed Frequency and Burst Mode
Operation V

V

OUT(AC)

100mV/DIV

60mA

I

OUT

10µA

V

= 1.3V 10ms/DIV 3400 G08

IN

V

= 3.3V

OUT

= 60mA TO 10µA

I

OUT

L = 6.8µH
C

= 4.7µF

OUT

30 70 90

10 50

TEMPERATURE (°C)

3400 G05

0V

V

OUT(AC)

100mV/DIV

100mA

I

OUT

40mA

= 1.3V 100ns/DIV 3400 G06

V

IN

V

= 3.3V

OUT

I

= 10mA

OUT

L = 6.8µH

= 4.7µF

C

OUT

Transient Response

OUT

V

= 1.3V 100µs/DIV 3400 G09

IN

V

= 3.3V

OUT

= 40mA TO 100mA

I

OUT

L = 6.8µH
C

= 4.7µF

OUT

3400f

3

LTC3400/LTC3400B

U

UU

PI FU CTIO S

SW (Pin 1): Switch Pin. Connect inductor between SW
and VIN. Optional Schottky diode is connected between
SW and V
wide as possible to reduce EMI and voltage overshoot. If
the inductor current falls to zero, or SHDN is low, an
internal 100Ω antiringing switch is connected from SW to
VIN to minimize EMI.

GND (Pin 2): Signal and Power Ground. Provide a short
direct PCB path between GND and the (–) side of the output
capacitor(s).

FB (Pin 3): Feedback Input to the gm Error Amplifier.
Connect resistor divider tap to this pin. The output voltage
can be adjusted from 2.5V to 5V by:

V

OUT

SHDN (Pin 4): Logic Controlled Shutdown Input.

SHDN = High: Normal free running operation, 1.2MHz
typical operating frequency.

. Keep these PCB trace lengths as short and

OUT

= 1.23V • [1 + (R1/R2)]

SHDN = Low: Shutdown, quiescent current <1µA.
100Ω connected between SW and VIN.

Typically, SHDN should be connected to VIN through a 1M
pull-up resistor.

V

(Pin 5): Output Voltage Sense Input and Drain of the

OUT

Internal Synchronous Rectifier MOSFET. Bias is derived
from V
capacitor(s) should be as short and wide as possible. V

. PCB trace length from V

OUT

to the output filter

OUT

OUT

is held at VIN – 0.6V in shutdown due to the body diode of
the internal PMOS.

VIN (Pin 6): Battery Input Voltage. The device gets its
start-up bias from VIN. Once V
comes from V

. Thus, once started, operation is com-

OUT

exceeds VIN, bias

OUT

pletely independent from VIN. Operation is only limited by
the output power level and the battery’s internal series
resistance.

BLOCK DIAGRA

SINGLE

+

RAMP

GEN

1.2MHz

CELL
INPUT

V

6

IN

COMPARATOR

START-UP

PWM

SLEEP

OSC

W

CONTROL

SLOPE

+
–
–

Burst Mode

OPERATION

CONTROL

PWM

COMP

C
1µF

L1

4.7µH

IN

+

V

OUT

GOOD

–

A/B

A

MUX

B

SYNC

DRIVE

CONTROL

Σ

R

C

80k

C

C

150pF

C

P2

2.5pF

2.3V

SW

1

0.35Ω

CURRENT
SENSE

0.45Ω

g

m

ERROR

AMP

OPTIONAL

SCHOTTKY

–

+

FB

3

1.23V
REF

3.3V

OUTPUT

R1

1.02M
1%
(EXTERNAL)

R2
604k
1%
(EXTERNAL)

C

OUT

4.7µF

V

OUT

5

4

SHDN

4

SHUTDOWN

CONTROL

SHUTDOWN

2

GND

3400 BD

3400f