Diodes ZXSC300 User Manual

SINGLE OR MULTI CELL LED DRIVER SOLUTION

Q1

FMMT617

R1

0.33R

L1

100µH

V

BATT

LED1

WHITE LED

V

cc

Gnd

I

sense

V

drive

U1

ZXSC300

DESCRIPTION

The ZXSC300 is a single or multi cell LED driver
designed for applications where step-up voltage
conversion from very low input voltages is required.
These applications mainly operate from single 1.5V or

1.2V battery cells. The circuit generates constant
current pulses that are ideal for driving single or
multiple LED’s over a widerangeofoperating voltages.

The ZXSC300 is a PFM controller IC that drives an
external Zetex switching transistor with a very low
saturation resistance. These transistors are the best
switching devices available for this type of switching
conversion enabling high efficiency conversion with
input voltages below 1 volt. The drive output of the
ZXSC controller generates a dynamic drive signal for
the switching transistor.

The circuit can start up under full load and operates
down to an input voltage of 0.8 volts. The solution
configuration ensures optimum efficiency over a wide
range of load currents, several circuit configurations
are possible depending on battery life versus
brightness considerations.

The ZXSC300 is offered in the SOT23-5 package which,
when combined with a SOT23 switching transistor,
generates a high efficiency small size circuit solution.
The IC and discrete combination offers the ultimate
cost vs performance solution for single cell LEDdriving
applications.

ZXSC300

FEATURES

94% efficiency

•

Minimum operating input voltage 0.8V

•

•

Fixed output current

•

Low saturation voltage switching transistor

•

SOT23-5 package

TYPICAL APPLICATION CIRCUIT

APPLICATIONS

LED flashlights and torches

•

LED backlights

•

•

White LED driving

•

Multiple LED driving

•

Solar Equipment

ORDERING INFORMATION

DEVICE Reel Tapewidth Quantity

ZXSC300E5TA 7” 8mm 3,000

per reel

DEVICE MARKING C300

Package SOT23-5

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ZXSC300

ABSOLUTE MAXIMUM RATING

Supply Voltage -0.3 to 10V
Maximum Voltage Other Pins -0.3 to V
Power Dissipation 450mW

CC

+0.3V

Operating Temperature -40 to 85°C
Storage Temperature -55 to 150°C

ELECTRICAL CHARACTERISTICS: Test conditions unless otherwise stated: V

=1.5V, T

CC

AMB

=25°C

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNITS

η

V

CC

V

CC(min)

I

Q

I

VDRIVE

I

CC

V

VDRIVE(high)

V

VDRIVE(low)

V

ISENSE

(threshold)

T

CVISENSE

I

ISENSE

T

DRV

Efficiency

Recommended

(1)

0.8 8 V

supply voltage range

Minimum startup
and operating
voltage

Quiescent current

Base drive current V

Supply current

(3)

High level drive
voltage

Low level drive
voltage

Output current

(2)

I

DRIVE

I

DRIVE

T

AMB

DRIVE

V

DRIVE

V

ISENSE

V

ISENSE

=-600µA, V

=-600µA, V

(3)

=-10°C

=0.7V,V

=0.7V,V

=0V,I

=50mV,I

=0.7V

DRIVE

=0.7V,

DRIVE

=0V 1.5 3.6 mA

ISENSE

=0V 2 4 mA

ISENSE

=-0.5mA VCC-0.3 VCCV

VDRIVE

=5mA 0 0.2 V

VDRIVE

14 19 24 mV

reference voltage

I

SENSE

voltage temp co.

I

input current V

SENSE

2

=0V 0 -30 -65 µA

ISENSE

Discharge pulse width 1.2 1.7 3.2 µs

94 %

0.8

0.92 V

0.9

0.2 mA

0.4 %/°C

OPERATING CONDITIONS

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNITS

F

OSC

1

Application dependent, see reference designs.

2

These parameters guaranteed by design and characterisation

3

Total supply current =IQ+ I

4

Operating frequency is application circuit dependent. See applications section.

Recommended operating frequency

, see typical characteristics

VDRIVE

(4)

200 kHz

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ZXSC300

FMMT617

For the circuits described in the applications section, Zetex FMMT617 is the recommended pass transistor. The
following indicates outline data for the transistor, more detailed information can be found at
www.zetex.com/FMMT617

ELECTRICAL CHARACTERISTICS (at TA= 25°C unless otherwise stated).

PARAMETER SYMBOL MIN. TYP. MAX. UNIT CONDITIONS

Collector-Emitter
Saturation Voltage

Collector-Emitter
Breakdown Voltage

V

CE(sat)

V

(BR)CEO

15 18 V IC=10mA*

8

70

150

*Measured under pulsed conditions. Pulse width=300μs. Duty cycle ≤ 2%

ZHCS1000

For the circuits described in the applications section Zetex ZHCS1000 is the recommended Schottky diode. The
following indicates outline data for the diode, more detailed information is available at www.zetex.com

14
100
200

mV
mV
mV

IC=0.1A, IB=10mA*
I

=1A, IB=10mA*

C

I

=3A, IB=40mA*

C

ELECTRICAL CHARACTERISTICS (at T

PARAMETER SYMBOL MIN. TYP. MAX. UNIT CONDITIONS

Forward Voltage V

Reverse Current I

Reverse Recovery
Time

F

R

t

rr

= 25°C unless otherwise stated).

amb

400
500mVmV

50 100

12 ns Switched from IF= 500mA

μA

IF=500mA
I

=1A

F

VR=30V

to I

= 500mA. Measured

R

at I

=50mA

R

*Measured under pulsed conditions. Pulse width=300μs. Duty cycle ≤ 2%

ISSUE 4 - SEPTEMBER 2007

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ZXSC300

TYPICAL CHARACTERISTICS

ISSUE 4 - SEPTEMBER 2007

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