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TE
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T6309B
Micropower Step-up DC/DC Converter
FEATURES
• Matched LED Current with Overvoltage
Protection
• Drives LEDs in series
• Up to 85% Efficiency
• Low 400mV Feedback Reference,
Optional 1.19V Feedback Reference
• Internal Current Limit 250mA
• Under Voltage Lock Out Circuits
• 0.1uA Low Shutdown Supply Current
• 6-pin SOT-23 Package
• ESD Human Body Mode Over 5KV
GRNERAL DESCRIPTION
The T6309B is a step-up DC/DC converter
that drives LED with a constant current. The
device can driver up to 3 series LEDs from a
single-cell Li-Ion battery. Series connection of
the LEDs provides constant LED current that
results in uniform brightness.
The T6309B features a minimum off-time
current-limited PFM control scheme. The
LED current is set with an external sense
resistor (Rs) and is regulated by the feedback
pin (FB) that regulates the voltage across the
sense resistor to 400mV (typ). The low
400mV feedback reference voltage reduces
power loss and improves efficiency for LED
driver applications. Optional 1.19V feedback
reference is available for normal output
voltage applications like LCD bias. Output
overvoltage protection (OVP) is integrated to
prevent damage in case of output open circuit
condition (e.g. faulty LED). The OVP pin can
monitor the output voltage and turn off the
converter in the event of overvoltage
condition. The T6309B is available in SOT-
23-6 packages.
APPLICATIONS
• Cellular Phones
• Portable Communication Devices
• Handheld Electronics
• PDAs
• LED/Display Back Light Driver
PART NUMBER EXAMPLES
Part no.
T6309B-AX
T6309B-BX
Feedback Referemce
Voltage
400mV
1.19V
TM Technology Inc. reserves the right
to change products or specifications without notice.
P. 1
Publication Date: SEP. 2005
Revision: A
TMT [ TAIWAN MEMORY TECHNOLOGY ]
