TB62731FU Ver la hoja de datos (PDF) - Marktech Optoelectronics
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TB62731FU Datasheet PDF : 9 Pages
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TOSHIBA
TB62731FU
Operational Description
TB62731FU is a pulse-skipping converter that uses a combined control scheme of voltage feedback
loop and current limited feedback loop to operate constant LED driving current. Operation can be easily
understood by referring to the Block Diagram and Switching Waveforms.
The internal MOSFET is turned on when amplifier A senses that the average voltage at R_sens is lower
than REF level. The N-channel MOSFET stays “turned on” until either the switching current peak
reaches 220mA(typ), or the oscillator automatically turns it off at its maximum on-duty (83.3%). Once
turned off, the MOSFET keeps off during the off-time. Subsequently, if the R_sens voltage is still lower
than reference level, another switching cycle is started. Otherwise, the internal MOSFET remains turned
off as long as the average R_sens voltage is higher than reference level.
[Shutdown Mode]
The TB62731FU falls into shutdown mode, when SHDN=”L”. In shutdown mode, the reference, control
circuitry, oscillator and internal switching MOSFET are stopped and current consumption is reduced
below 0.5uA. Connect SHDN to “VCC” for normal operation.
Switching Waveforms Illustration
V(A)
Inductor
current
I(A)
220 mA
LED
current
Average
Current
OSC
Fs=360 kHz
on-duty(max)=83.3%
Preset LED current level
Available from:
Marktech Optoelectronics
120 Broadway • Menands, NY 12203
800.984.5337 FAX: 518.432.7454
Website: www.marktechopto.com
Email: info@marktechopto.com
The information contained herein is subject to change without notice.
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