Zetex ZXSC300E5 Datasheet

SINGLE OR MULTI CELL LED DRIVER SOLUTION

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.
Theseapplicationsmainlyoperatefromsingle1.5Vor

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

FEATURES

• 94% efficiency

• Minimum operating input voltage 0.8V

• Fixed output current

• Low saturation voltage switching transistor

•

SOT23-5 package

the switching transistor.
The circuit can start up under full load and operates

down to an input voltage of 0.8 volts. The solution
configurationensuresoptimumefficiencyovera 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 LED driving applications.

ZXSC300

TYPICAL APPLICATION CIRCUIT

V

BATT

L1

100µH

U1

V

cc

V

drive

I

sense

Gnd

ZXSC300

ISSUE 1 - JUNE 2001

Q1

FMMT617

R1

0.33R

LED1

WHITE LED

ORDERING INFORMATION

DEVICE Package Partmarking

ZXSC300E5 SOT23-5 C300

1

ZXSC300

ABSOLUTE MAXIMUM RATING

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

ELECTRICAL CHARACTERISTICS:
Test conditions unless otherwise stated: V

CC

+0.3V

Operating Temperature -40 to 85°C
Storage Temperature -55 to 125°C

=1.5V, T

CC

AMB

=25°C

Symbol Parameter Conditions Min Typ Max Units

η

V

CC

Efficiency

Recommended
supply voltage

1

0.8 8 V

94 %

range

V

CC(min)

I

Q

I

VDRIVE

I

CC

V

VDRIVE(high)

V

VDRIVE(low)

V

ISENSE

(threshold)

T

CVISENSE

I

ISENSE

ELECTRICAL CHARACTERISTICS: AC PARAMETERS

Minimum startup
and operating
voltage

Quiescent current

2

Base drive current V

Supply current

3

High level drive
voltage

Low level drive
voltage

Output current
reference voltage

I

SENSE

voltage temp co.

I

input current V

SENSE

2

I

DRIVE

I

DRIVE

T

AMB

DRIVE

V

DRIVE

V

ISENSE

V

ISENSE

ISENSE

=-600µA, V

=-600µA, V

3

=-10°C

DRIVE

DRIVE

=0.7V

=0.7V,

0.8

0.9

0.92 V

0.2 mA

= 0.7V, V

= 0.7V, V

= 0V, I

= 50mV, I

VDRIVE

= 0V 1.5 3.6 mA

ISENSE

=0V 2 4 mA

ISENSE

=-0.5mA VCC-0.3 V

= 5mA 0 0.2 V

VDRIVE

CC

14 19 24 mV

0.4 %/°C

= 0V 0 -30 -65 µA

2

TEST CONDITIONS (Unless otherwise stated) )
V

=1.5V, T

CC

= 0 to 70°C

AMB

V

Symbol Parameter Conditions Min Typ Max Units

T

DRV

F

OSC

1

Application dependent, see reference designs.

2

These parameters guaranteed by Design

3

Total supply current =IQ+ I

4

Operating frequency is application circuit dependent. See applications section.

Discharge Pulse Width 1.2 1.7 3.2 µs
Recommended operating

frequency

4

, see typical characteristics

VDRIVE

200 kHz

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2

ZXSC300

FMMT617

For the circuits described in the applications section, ZetexFMMT617 is the recommended pass transistor. The
following indicates outline data for the transistor, more detailed information can be found in the Zetex surface
mount data book or at www.zetex.com

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

PARAMETER SYMBOL MIN. TYP. MAX. UNIT CONDITIONS.
Collector-Emitter

Saturation Voltage

V

CE(sat)

8

70

150

Collector-Emitter
Breakdown Voltage

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

V

(BR)CEO

15 18 V IC=10mA*

14
100
200

mV
mV
mV

I

=0.1A, IB=10mA*

C

I

=1A, IB=10mA*

C

I

=3A, IB=40mA*

C

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

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

µA

IF=500mA
I

VR=30V

12 ns Switched from IF= 500mA

to I
at I

=1A

F

= 500mA. Measured

R

=50mA

R

ISSUE 1 - JUNE 2001

3

3

ZXSC300

TYPICAL CHARACTERISTICS

300µ

200µ

100µ

Quiescent Current (A)

0

12345678

Input Voltage (V)

Quiescent Current v Input Voltage

30m

25m

20m

15m

10m

5m

Sense Voltage (V)

0

12345678

Input Voltage (V)

Sense Voltage v Input Voltage

4m

3m

2m

1m

Drive Current (A)

0

12345678

Input Voltage (V)

Drive Current v I nput Voltage

100

95

90

Efficiency (%)

85

1.0 1.5 2.0 2.5 3.0 3.5

Input Voltage (V)

Input Voltage v Efficiency

ISSUE 1 - JUNE 2001

4