Diodes ZXSC380 User Manual
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
• 80% efficiency
• User adjustable output current
• Single cell operation
Applications
• LED flashlights and torches
• LED backlights
• 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
V
V
V
CC
OUT
1
2
Top view
3
GND
GND
IN
ZXSC380
V
CC
V
GND
1
OUT
3
L1
2
LED1
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ZXSC380
V
CC
GND
V
OUT
Top view
1
2
3
Absolute maximum ratings
Supply voltage (VCC) -0.6V to 10V
Output voltage (V
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 T
Parameter Conditions Limits Units
Supply voltage operating range 0.8 6 V
Minimum supply start-up voltage 0.9 1.0 V
Switch current V
Switch saturation voltage IV
Mean LED current V
Efficiency V
Operating frequency V
Discharge pulse width 1.4 2.2 3.0 s
amb
) -0.6V to 20V
OUT
= 25°C, L = 100H and VCC = 1.5V unless otherwise specified.
Min. Typ. Max.
= 1.0V 65 80 95 mA
OUT
= 50mA 0.3 0.5 V
OUT
= 3.5V 18 mA
LED
= 3.5V 75 %
LED
= 3.5V 160 kHz
LED
Pin descriptions
Pin descriptions
Pin No. Name Description
1V
2V
CC
OUT
Supply voltage, generally Alkaline, NiMH or NiCd single cell
Switch output external inductor/LED
3 GND Ground
Ordering information
Device Package Part Mark
ZXSC380FH SOT23 380
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Typical characteristics
LED Current vs Supply Voltage for L = 100uH
0
10
20
30
40
50
60
70
80
0.511.522.53
Supply Voltage Vvcc (V)
LED Current, ILed (mA)
Ivcc vs Supply Voltage for L = 100uH
0
10
20
30
40
50
60
70
80
90
100
0.5 1 1.5 2 2.5 3
Supply Voltage Vvcc (V)
Ivcc (mA)
Efficiency vs Supply Voltgae for L = 100uH
0
10
20
30
40
50
60
70
80
90
100
0.5 1 1.5 2 2.5 3
Supply Voltage Vvcc (V)
Efficiency (%)
Operating Waveforms
Channel 1 (lower): LED current ILed. 50mA/div.
Channel 2 (upper): Voltage at Vout pin. 1V/div
ZXSC380
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© Zetex Semiconductors plc 2007
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