LINEAR TECHNOLOGY LTC3215 Technical data

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FEATURES

■

High Efficiency Operation: 1x, 1.5x or 2x Boost
Modes with Automatic Mode Switching

■

Ultralow Dropout I

■

Output Current up to 700mA

■

Low Noise Constant Frequency Operation*

■

Wide VIN Range: 2.9V to 4.4V

■

Open/Shorted LED Protection

■

LED Disconnect in Shutdown

■

Low Shutdown Current: 2.5µA

■

4% LED Current Programming Accuracy

■

Automatic Soft-Start Limits Inrush Current

■

No Inductors

■

Tiny Application Circuit (All Components <1mm

Current Control

LED

Profile)

■

3mm × 3mm 10-Lead DFN Package

U

APPLICATIO S

■

LED Torch/Camera Light Supply for Cell Phones,
PDAs and Digital Cameras

■

General Lighting and/or Flash/Strobe Applications

LTC3215

700mA Low Noise High

Current LED Charge Pump

U

DESCRIPTIO

The LTC®3215 is a low noise, high current charge pump
DC/DC converter designed to power high current LEDs.
The part includes an accurate programmable current
source capable of driving loads up to 700mA from a 2.9V
to 4.4V input. Low external parts count (two flying capaci­tors, one programming resistor and two bypass capaci­tors) makes the LTC3215 ideally suited for small, battery­powered applications.

Built-in soft-start circuitry prevents excessive inrush cur­rent during start-up. High switching frequency enables the
use of small external capacitors. LED current is pro­grammed with an external resistor. The LED is discon­nected from V

An ultralow dropout current source maintains accurate
LED current at very low I
switching optimizes efficiency by monitoring the voltage
across the LED current source and switching modes only
when I

LED

a low profile 3mm × 3mm 10-Lead DFN package.

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

*Protected by U.S. Patent 6411531.

during shutdown.

IN

voltages. Automatic mode

LED

dropout is detected. The LTC3215 is available in

TYPICAL APPLICATIO

2.9V TO 4.4V

2.2µF

C1

2.2µF

+C1–C2+C2–

C1

V

C

IN

IN

ENDISABLE ENABLE

I

SET

LED1: AOT2015 HPW 1751B

C2

2.2µF

LTC3215

20k
1%

CPO

I

LED

U

3215 TA01a

LED1

I

LED

200mA

C

CPO

4.7µF

100

90

80

70

) (%)

IN

/P

60

LED

50

40

30

EFFICIENCY (P

20

LED = AOT2015 HPW 1751B

10

= 3V TYP AT 200mA

V

F

0

2.8

3.0 3.4

3.2

Efficiency vs V

I

LED

3.6

3.8

VIN (V)

IN

= 200mA

4.0

4.2

3215 TA01b

4.4

3215f

1

LTC3215

WW

W

ABSOLUTE AXI U RATI GS

U

UUW

PACKAGE/ORDER I FOR ATIO

(Note 1)

VIN to GND ............................................... –0.3V to 5.5V

CPO to GND ............................................. –0.3V to 5.5V

EN ................................................... – 0.3V to V

I

, I

CPO

(Note 2) ........................................... 1000mA

ILED

+ 0.3V

IN

CPO Short-Circuit Duration ............................ Indefinite

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

Operating Temperature Range (Note 3) .. – 40°C to 85°C

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. V

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Power Supply

VIN Operating Voltage ● 2.9 4.4 V

I

Operating Current I

VIN

I

Shutdown Current EN = LOW 2.5 7 µA

VIN

LED Current

LED Current Ratio (I

I

Dropout Voltage Mode Switch Threshold, I

LED

Mode Switching Delay (LED Warmup Time) 2.5 ms

LED Current On Time EN to LED Current On 130 µs

Charge Pump (CPO)

1x Mode Output Voltage I

1.5x Mode Output Voltage I

2x Mode Output Voltage I

1x Mode Output Impedance 0.25 Ω

1.5x Mode Output Impedance V

2x Mode Output Impedance V

CLK Frequency ● 0.6 0.9 1.2 MHz

EN

High Level Input Voltage (VIH) ● 1.4 V

Low Level Input Voltage (VIL) ● 0.4 V

Input Current (IIH) ● –1 1 µA

Input Current (IIL) ● –1 1 µA

)I

LED/ISET

The ● denotes the specifications which apply over the full operating

= 3.6V, CIN = C1 = C2 = 2.2µF, C

IN

= 0mA, 1x Mode 300 µA

CPO

= 0mA, 1.5x 7 mA

I

CPO

I

= 0mA, 2x Mode 9.2 mA

CPO

= 200mA to 600mA ● 3139 3270 3400 mA/mA

LED

= 0mA V

CPO

= 0mA 4.6 V

CPO

= 0mA 5.1 V

CPO

= 3.4V, V

IN

= 3.2V, V

IN

CPO

CPO

C2

C1

CPO

I

LED

I

SET

10-LEAD (3mm × 3mm) PLASTIC DFN

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

< 4.6V, C1 = C2 = 2.2µF 1.5 Ω

< 5.1V, C1 = C2 = 2.2µF 1.7 Ω

TOP VIEW

+

1

+

2

11

3

4

5

DD PACKAGE

T

= 125°C, θJA = 43°C/W

JMAX

EXPOSED PIN (PIN 11) IS GND

MUST BE SOLDERED TO PCB

= 200mA 120 mV

LED

10

9

8

7

6

–

C1

GND

–

C2

V

IN

EN

= 4.7µF.

CPO

ORDER PART

NUMBER

LTC3215EDD

DD PART

MARKING

LBPX

IN

V

2

3215f

LTC3215

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. V

The ● denotes the specifications which apply over the full operating

= 3.6V, CIN = C1 = C2 = 2.2µF, C

IN

CPO

= 4.7µF.

PARAMETER CONDITIONS MIN TYP MAX UNITS

I

SET

V

ISET

I

ISET

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

Note 2: Based on long-term current density limitations. Assumes an
operating duty cycle of ≤ 10% under absolute maximum conditions for

I

= 50µA ● 1.195 1.22 1.245 V

SET

● 225 µA

Note 3: The LTC3215E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C ambient
operating temperature range are assured by design, characterization and
correlation with statistical process controls.

durations less than 10 seconds. Max current for continuous operation is
350mA.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

I

Dropout Voltage

LED

vs LED Current

0.8
VIN = 3.6V

0.7

0.6

0.5

0.4

0.3

DROPOUT VOLTAGE (V)

0.2

0.1

0

0 200

LED CURRENT (mA)

400 800600

3216 G01

I

Pin Current

LED

vs I

Pin Voltage

LED

600

500

400

300

PIN CURRENT (mA)

200

LED

I

100

0

0

0.2 0.4 0.6 0.8
I

PIN VOLTAGE (V)

LED

(TA = 25°C unless otherwise specified)

I

vs R

LED

1000

I

= 500mA

LED

800

400mA

300mA

200mA

100mA

1.0

3216 G02

600

(mA)

LED

I

400

200

0

0

515

SET

35

(kΩ)

30

25

40

1573 G06

10

20

R

SET

1x Mode Charge Pump Open-Loop
Output Resistance vs Temperature

0.31
I

= 200mA

CPO

OUTPUT RESISTANCE (Ω)

0.29

0.27

0.25

0.23

0.21

0.19

0.17

0.15

VIN = 3.6V

–15 10 60

–40

VIN = 3.3V

35

TEMPERATURE (°C)

VIN = 3.9V

3216 G07

1.5x Mode Charge Pump
Open-Loop Output Resistance
(1.5VIN – V

1.8

1.6

1.4

1.2

1.0

0.8

0.6

OUTPUT RESISTANCE (Ω)

VIN = 3V

0.4

0.2

85

V

CPO

= C1 = C2 = 2.2µF

C

IN

C

CPO

0

–40

= 4.2V

= 4.7µF

–15 35

)/I

CPO

TEMPERATURE (°C)

vs Temperature

CPO

10

85

60

3216 G05

2x Mode Charge Pump
Open-Loop Output Resistance

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

OUTPUT RESISTANCE (Ω)

0.4

0.2

(2VIN – V

VIN = 3V
V

CPO

= C1 = C2 = 2.2µF

C

IN

C

CPO

0

–40

)/I

CPO

CPO

= 4.8V

= 4.7µF

–15 35

10

TEMPERATURE (°C)

vs Temperature

85

60

3216 G06

3215f

3

LTC3215

UW

TYPICAL PERFOR A CE CHARACTERISTICS

(TA = 25°C unless otherwise specified)

Input Shutdown Current
vs Input Voltage

4.0

3.5

3.0

2.5

2.0

1.5

1.0

INPUT SHUTDOWN CURRENT (µA)

0.5

TA = 85°C

0

2.9 4.5

TA = 25°C

3.3

3.7

INPUT VOLTAGE (V)

TA = –40°C

4.13.1 3.5 3.9

Efficiency vs V

100

90

80

70

) (%)

IN

/P

60

LED

50

40

100mA

30

EFFICIENCY (P

200mA

20

400mA

AOT2015 HPW 1751B

10

= 3V TYP AT 100mA

V

F

0

2.8

3.0 3.4

3.2

4.3

3216 G04

IN

3.6

VIN (V)

930

920

910

900

890

880

870

FREQUENCY (kHz)

860

850

840

4.0

3.8

Oscillator Frequency
vs Supply Voltage

TA = 25°C

TA = –40°C

TA = 85°C

3.1 3.5 3.9

2.9 4.5

3.3

3.7

SUPPLY VOLTAGE (V)

4.1

4.3

3216 G03

I

SET/ILED

vs I

3400

3350

3300

3250

3200

CURRENT RATIO

3150

3100

4.2

4.4

3215 G15

0

Current Ratio

Current

LED

85°C

200 400

I

LED

Efficiency vs V

100

90

80

70

) (%)

IN

/P

60

LED

50

40

30

EFFICIENCY (P

20

LED = LXCL-PWF1 LUMILED

10

= 3V TYP AT 200mA

V

F

0

2.8

3.0 3.4

25°C

–40°C

CURRENT (mA)

200mA

3.2

600

IN

VIN (V)

3215 G16

3.6

800

400mA

3.8

600mA

4.0

4.2

4.4

3216 G11

V

CPO

50mV/DIV

A/C COUPLED

4

1.5x Mode CPO Output Ripple

I

IN

CPO

= 3.6V

= 200mA

500ns/DIVV

3216 G12

V

CPO

20mV/DIV

A/C COUPLED

2x Mode CPO Output Ripple

IN

I

CPO

= 3.6V

= 400mA

500ns/DIVV

3216 G13

Charge Pump Mode Switching
and Input Current (I

V

CPO

1V/DIV

I

VIN

500mA/

DIV

EN2

5V/DIV

= 3V 1ms/DIV

V

IN

= 400mA)

LED

3215 G14

3215f