Product category:
Power Supply ICs and Controllers
News Release from: Semtech | Subject: SC4601
Edited by the Electronicstalk Editorial
Team on 29 May 2003
High efficiency for buck controller
The SC4601 is a highly efficient low-voltage controller for building synchronous step-down switch-mode regulators.
The SC4601 is a highly efficient low-voltage controller for building synchronous step-down ("buck") switch-mode regulators The highly integrated, BiCMOS-based device is designed to drive two external, complementary power mosfets
This article was originally published on Electronicstalk on 16 Jul 2001 at 8.00am (UK)
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Among the SC4601's many competitive features are its efficient, accurate, low-voltage operation; low-current sleep mode; lossless overcurrent protection; programmable switching frequency to 700kHz; soft-start operation; 0 to 100% duty cycle; and a small surface-mount package.
By packing all this capability into the outline of a 10-lead MSOP, the SC4601 reduces the size and cost of building low-voltage power sources.
And by reducing the parts count, the SC4601 streamlines component procurement and end-equipment manufacturing.
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Geared for the latest low-voltage designs, the SC4601 supplies 5 to 0.8V from a 2.7 to 6V source.
Some specific applications for the SC4601 include distributed (point-of-load) power architectures; servers and workstations; microprocessor-core, DSP and I/O power supplies; and battery-powered, telecommunications and datacommunications equipment.
"The SC4601 expands Semtech's portfolio of networking and industrial switching controllers with a highly integrated, high efficiency, low-voltage, small footprint, synchronous buck device", notes George Georgalis, Semtech's Director of Networking/Industrial Power Management.
"System and power-supply designers who compare it with competitive parts will find the SC4601 hard or impossible to beat, given its broad array of features and benefits".
The SC4601 drives two external complementary power mosfets: a P-channel mosfet on the high side and, on the low side, its N-channel counterpart.
Having a high-side P-channel mosfet kills the need for an external charge pump and simplifies the high-side gate-drive circuit.
In addition, built-in nonoverlap protection prevents both mosfets from conducting simultaneously and causing current to shoot through both of them.
Also, during conduction, the SC4601 senses the voltage drop across the P-channel mosfet to impose lossless current limiting in the event of a short circuit.
For enhanced power efficiency, the SC4601 can drop into a sleep mode, which typically draws only 10uA.
Moreover, the SC4601's switching frequency can be synchronised to an external oscillator of up to 700kHz.
Also, soft-start operation, spread over a 5ms period, prevents output voltage spikes during startup.
Still other key features include a duty cycle that is programmable from 0 to 100%.
This feature, and in particular the ability to set the duty cycle to 100%, allows the SC4601, in the event of a low battery, to operate as a low-dropout (LDO) voltage regulator.
Voltage accuracy is maintained by the SC4601's built in typically +/-1%-accurate 0.8V reference.
Production volumes of the SC4601 controller are available now through Semtech's authorised network of sales representatives and distributors.
The product comes in an MSOP-10 package and operates over a -40 to +85C temperature range.
Pricing starts at $0.81 each in 10,000-piece quantities.
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