Zetex (Now Diodes) ZXSC380FH Schematic [ru]

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ZXSC380

Single or multi cell LED driver solution

Description

The ZXSC380 is a highly integrated single or multi cell LED driver for applications where step-up voltage conversion from a very low input voltage is required. These applications mainly operate from 1.5V or 1.2V cells. The IC generates constant current pulses that are ideal for driving single or multiple LEDs over a wide range of operating voltages. The ZXSC380 provides a simple to use, low cost, space saving and easy to layout solutions.

The ZXSC380 uses a PFM control technique to drive an internal switching transistor which has a low saturation resistance. This ensures high efficiency, even for input voltages as low as 1V.

The IC can start up under full load and operates down to an input voltage of only 0.9V typical.

The ZXSC380 is offered in the space saving SOT23 package or in die form, offering an excellent cost vs performance solution for single cell LED driving applications.

SOT23

Features

Applications

80% efficiency

• LED flashlights and torches

• User adjustable output current

LED backlights

Single cell operation

White LED driver

Low saturation voltage switching transistor

Simple application circuit

Low external component count

SOT23 package

Available also in die form

Pin connections

 

Typical application circuit

 

 

 

 

VIN

 

VCC

1

 

L1

 

 

 

 

 

 

 

1

 

 

3

GND

VCC

 

 

2

 

 

 

 

 

 

 

 

ZXSC380 VOUT

 

VOUT

2

 

GND

 

 

3

LED1

 

 

 

 

Top view

 

GND

 

 

 

 

 

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ZXSC380

Absolute maximum ratings

Supply voltage (VCC)

-0.6V to 10V

Output voltage (VOUT)

-0.6V to 20V

Supply current

20mA

Output switch current

200mA

Power dissipation SOT23-3

450mW

Power dissipation die

1W

Operating temperature range

0°C to +85°C

Storage temperature range

-55°C to +150°C

Electrical characteristics

Measured at Tamb = 25°C, L = 100 H and VCC = 1.5V unless otherwise specified.

Parameter

Conditions

 

Limits

 

Units

 

 

 

 

 

 

 

 

Min.

Typ.

Max.

 

 

 

 

 

 

 

Supply voltage operating range

 

0.8

 

6

V

 

 

 

 

 

 

Minimum supply start-up voltage

 

 

0.9

1.0

V

 

 

 

 

 

 

Switch current

VOUT = 1.0V

65

80

95

mA

Switch saturation voltage

IVOUT = 50mA

 

0.3

0.5

V

Mean LED current

VLED = 3.5V

 

18

 

mA

Efficiency

VLED = 3.5V

 

75

 

%

Operating frequency

VLED = 3.5V

 

160

 

kHz

Discharge pulse width

 

1.4

2.2

3.0

s

 

 

 

 

 

 

Pin descriptions

 

 

 

 

 

 

 

VCC

1

 

 

 

 

 

 

 

 

 

 

 

 

 

3

GND

VOUT

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

Top view

 

 

Pin descriptions

 

 

 

 

 

 

 

 

 

Pin No.

 

Name

 

Description

 

 

 

 

 

 

 

1

 

 

VCC

 

Supply voltage, generally Alkaline, NiMH or NiCd single cell

2

 

 

VOUT

 

Switch output external inductor/LED

3

 

 

GND

 

Ground

 

 

 

 

 

 

 

Ordering information

Device

Package

Part Mark

 

ZXSC380FH

SOT23

380

 

 

 

 

 

 

 

 

 

Issue 3 - September 2007

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ZXSC380

Typical characteristics

LED Current vs Supply Voltage for L = 100uH

(mA)

80

 

 

 

 

 

70

 

 

 

 

 

60

 

 

 

 

 

ILed

 

 

 

 

 

50

 

 

 

 

 

 

 

 

 

 

 

Current,

40

 

 

 

 

 

30

 

 

 

 

 

20

 

 

 

 

 

LED

 

 

 

 

 

10

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

0.5

1

1.5

2

2.5

3

Supply Voltage Vvcc (V)

Efficiency vs Supply Voltgae for L = 100uH

 

100

 

 

 

 

 

 

90

 

 

 

 

 

(%)

80

 

 

 

 

 

70

 

 

 

 

 

60

 

 

 

 

 

Efficiency

 

 

 

 

 

50

 

 

 

 

 

40

 

 

 

 

 

30

 

 

 

 

 

20

 

 

 

 

 

 

 

 

 

 

 

 

10

 

 

 

 

 

 

0

 

 

 

 

 

 

0.5

1

1.5

2

2.5

3

Supply Voltage Vvcc (V)

Ivcc vs Supply Voltage for L = 100uH

 

100

 

 

 

 

 

 

90

 

 

 

 

 

 

80

 

 

 

 

 

(mA)

70

 

 

 

 

 

60

 

 

 

 

 

50

 

 

 

 

 

Ivcc

 

 

 

 

 

40

 

 

 

 

 

30

 

 

 

 

 

 

 

 

 

 

 

 

20

 

 

 

 

 

 

10

 

 

 

 

 

 

0

 

 

 

 

 

 

0.5

1

1.5

2

2.5

3

Supply Voltage Vvcc (V)

Operating Waveforms

Channel 1 (lower): LED current ILed. 50mA/div.

Channel 2 (upper): Voltage at Vout pin. 1V/div

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ZXSC380

Typical characteristics

 

 

 

LED Current vs Supply Voltage

 

 

 

 

 

for L = 22, 47, 68 & 100uH

 

 

 

20

 

 

 

 

 

 

18

 

 

 

 

 

(mA)

16

 

 

 

 

 

14

 

 

 

 

 

 

 

 

 

 

 

ILed

12

 

 

 

 

 

10

 

 

 

 

 

Current

 

 

 

 

 

8

 

 

 

 

 

 

 

 

 

 

 

LED

6

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

0

 

 

 

 

 

 

1

1.1

1.2

1.3

1.4

1.5

 

 

 

Supply Voltage Vvcc (V)

 

 

 

L = 100uH

 

L = 68uH

L = 47uH

 

L = 22uH

 

 

Frequency vs Supply Voltage

 

 

 

 

for L= 22, 47, 68 & 100uH

 

 

 

350

 

 

 

 

 

300

 

 

 

 

(kHz)

250

 

 

 

 

200

 

 

 

 

Frequency

 

 

 

 

150

 

 

 

 

100

 

 

 

 

 

 

 

 

 

 

50

 

 

 

 

 

0

 

 

 

 

 

1

1.5

2

2.5

3

 

 

Supply Voltage Vcc (V)

 

 

 

L = 100uH

L = 68uH

L = 47uH

 

L = 22uH

LED Current vs Supply Voltage for L= 22, 47, 68 & 100uH

 

80

 

 

 

 

 

70

 

 

 

 

(mA)

60

 

 

 

 

50

 

 

 

 

ILed

 

 

 

 

40

 

 

 

 

Current

 

 

 

 

30

 

 

 

 

LED

20

 

 

 

 

 

10

 

 

 

 

 

0

 

 

 

 

 

1

1.5

2

2.5

3

Supply Voltage Vvcc (V)

 

L = 100uH

L = 68uH

L = 47uH

 

L=22uH

 

 

Efficiency vs Supply Voltage

 

 

 

 

for L= 22, 47, 68 & 100uH

 

 

 

120

 

 

 

 

 

100

 

 

 

 

(%)

80

 

 

 

 

 

 

 

 

 

Efficiency

60

 

 

 

 

40

 

 

 

 

 

 

 

 

 

 

20

 

 

 

 

 

0

 

 

 

 

 

1

1.5

2

2.5

3

 

 

Supply Voltage Vvcc (V)

 

 

 

L = 100uH

L = 68uH

L = 47uH

 

L = 22uH

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