ZETEX ZXSC300 Technical data
ZXSC300
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.
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 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 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 LED driving applications.
FEATURES |
APPLICATIONS |
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94% efficiency |
• LED flashlights and torches |
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• Minimum operating input voltage 0.8V |
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LED backlights |
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Fixed output current |
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White LED driving |
• Low saturation voltage switching transistor |
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Multiple LED driving |
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SOT23-5 package |
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Solar Equipment |
TYPICAL APPLICATION CIRCUIT |
ORDERING INFORMATION |
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L1 |
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DEVICE |
Reel |
Tapewidth |
Quantity |
VBATT |
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per reel |
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100µH |
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ZXSC300E5TA |
7” |
8mm |
3,000 |
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U1 |
Q1 |
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Vcc |
FMMT617 |
DEVICE MARKING C300 |
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LED1 |
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Vdrive |
Package SOT23-5 |
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WHITE LED |
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Isense |
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Gnd |
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ZXSC300 |
R1 |
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0.33R |
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ISSUE 2 - FEBRUARY 2004
1 |
SEMICONDUCTORS |
ZXSC300
ABSOLUTE MAXIMUM RATING
Supply Voltage |
-0.3 to 10V |
Operating Temperature |
-40 to 85°C |
Maximum Voltage Other Pins -0.3 to VCC+0.3V |
Storage Temperature |
-55 to 150°C |
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Power Dissipation |
450mW |
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ELECTRICAL CHARACTERISTICS: Test conditions unless otherwise stated: VCC=1.5V, TAMB=25°C
SYMBOL |
PARAMETER |
CONDITIONS |
MIN. |
TYP. |
MAX. |
UNITS |
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η |
Efficiency1 |
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94 |
% |
VCC |
Recommended |
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0.8 |
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8 |
V |
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supply voltage range |
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VCC(min) |
Minimum startup |
IDRIVE=-600µA, VDRIVE=0.7V |
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0.8 |
0.92 |
V |
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and operating |
IDRIVE=-600µA, VDRIVE=0.7V, |
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0.9 |
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voltage |
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TAMB=-10°C3 |
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IQ |
Quiescent current2 |
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0.2 |
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mA |
IVDRIVE |
Base drive current |
VDRIVE = 0.7V, VISENSE = 0V |
1.5 |
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3.6 |
mA |
ICC |
Supply current3 |
VDRIVE = 0.7V, VISENSE = 0V |
2 |
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4 |
mA |
VVDRIVE(high) |
High level drive |
VISENSE = 0V, IVDRIVE =-0.5mA |
VCC-0.3 |
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VCC |
V |
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voltage |
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VVDRIVE(low) |
Low level drive |
VISENSE = 50mV, IVDRIVE = 5mA |
0 |
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0.2 |
V |
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voltage |
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VISENSE |
Output current |
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14 |
19 |
24 |
mV |
(threshold) |
reference voltage |
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TCVISENSE |
ISENSE |
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0.4 |
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%/°C |
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voltage temp co.2 |
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IISENSE |
ISENSE input current |
VISENSE = 0V |
0 |
-30 |
-65 |
µA |
TDRV |
Discharge pulse width |
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1.2 |
1.7 |
3.2 |
µs |
OPERATING CONDITIONS
SYMBOL |
PARAMETER |
CONDITIONS |
MIN. |
TYP. |
MAX. |
UNITS |
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FOSC |
Recommended operating frequency4 |
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200 |
kHz |
1Application dependent, see reference designs.
2These parameters guaranteed by design and characterisation
3Total supply current =IQ + IVDRIVE, see typical characteristics
4Operating frequency is application circuit dependent. See applications section.
ISSUE 2 - FEBRUARY 2004
SEMICONDUCTORS |
2 |
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 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 |
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Collector-Emitter |
VCE(sat) |
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8 |
14 |
mV |
IC=0.1A, IB=10mA* |
Saturation Voltage |
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70 |
100 |
mV |
IC=1A, IB=10mA* |
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150 |
200 |
mV |
IC=3A, IB=40mA* |
Collector-Emitter |
V(BR)CEO |
15 |
18 |
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V |
IC=10mA* |
Breakdown Voltage |
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*Measured under pulsed conditions. Pulse width=300 s. 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
ELECTRICAL CHARACTERISTICS (at Tamb = 25°C unless otherwise stated).
PARAMETER |
SYMBOL |
MIN. |
TYP. |
MAX. |
UNIT |
CONDITIONS |
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Forward Voltage |
VF |
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400 |
mV |
IF=500mA |
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500 |
mV |
IF=1A |
Reverse Current |
IR |
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50 |
100 |
A |
VR=30V |
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Reverse Recovery |
trr |
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12 |
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ns |
Switched from IF = 500mA |
Time |
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to IR = 500mA. Measured at |
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IR=50mA |
*Measured under pulsed conditions. Pulse width=300 s. Duty cycle ≤ 2%
ISSUE 2 - FEBRUARY 2004
3 |
SEMICONDUCTORS |
ZXSC300
TYPICAL CHARACTERISTICS
ISSUE 2 - FEBRUARY 2004
SEMICONDUCTORS |
4 |
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