A new family of current-mode adjustable-frequency step-up convertors with internal 2A/40V switches can be adapted in a
Semtech Corp has released the SC4501, SC4502 and SC4502H, a family of current-mode, adjustable frequency step-up (boost) convertors with internal 2A/40V switches. Each convertor can be adapted in a variety of topologies such as boost, sepic and flyback for generating high output voltage from multicell alkaline, NiCd, NiMH or single-cell Li-ion batteries. The boost convertors operate from input voltages as low as 1.4V to generate outputs to 40V at efficiencies over 90%.

Switching frequency can be programmed using a single resistor to select the desired value between 250kHz and 2MHz.

A high frequency of operation enables the system designer to minimise external component size and avoid interference with noise sensitive frequency bands in the system.

A small inductor and ceramic capacitors keep the total solution footprint compact while minimising total solution cost.

The SC4501, with a low-saturation-voltage (220mV) switch, delivers up to 2A at 32V.

The SC4502 and SC4502H feature 210 and 250mV saturation-voltage switches, respectively, to supply up to 1.4A at 32V for the SC4502 and 1.4A at 40V for the SC4502H.

The boost convertor family is ideal for driving up to 10 white LEDs in series configuration for backlighting in cellphones, PDAs and automotive displays.

The high current internal switches also make them well suited for generating bias voltages in LCD panels and for system voltages in battery operated systems such as portable DVDs, digital video cameras, portable medical equipment and many other consumer portables.

The SC4502 and SC4502H include most of the features of the SC4501 and are further optimised for high efficiencies at light loads.

Equipped with a smaller 1.4A switch, they have a low shutdown supply current of 10uA.

In battery-operated appliances where battery conservation is crucial, the SC4502 and SC4502H are highly attractive choices.

The device family includes additional features such as programmable soft start and programmable undervoltage lockout (UVLO) which help eliminate inrush currents during startup and protect the system from line voltage transients, thereby ensuring reliable system performance.

‘Semtech has traditionally dominated the white LED driver market with its charge pump convertor products’, says Ven Shan, VP of Marketing for Semtech’s Power Management Products.

‘The SC4501, SC4502 and SC4502H are inductor-based convertors that complement and extend Semtech’s portfolio of white LED drivers’.

‘They provide performance and efficiency advantages for driving up to 10 white LEDs in series-connected LCD backlight applications, yet are flexible enough to address a much broader range of applications’.

The SC4501 is available in a 3 x 3mm, 10-pin MLPD and in an 8-pin MSOP package.

The SC4502 and SC4502H are offered in the 3 x 3mm 10-pin MLPD package only.

Both packages incorporate a special thermal design for high-power applications.

The lead-free design of the devices meets worldwide environmental and regulatory requirements including the European Union’s RoHS Directive.

All products are available immediately in production quantities.

The SC4501 is priced at $0.89 each in 1000-piece lots with ordering code SC4501MLTRT (MLPD package) and SC4501MSETRT (MSOP package).

The SC4502 is priced at $1.05 each in 1000-piece lots with ordering code SC4502MLTRT (MLPD package).

And, the SC4502H is priced at $1.05 each in 1000-piece lots using ordering code SC4502HMLTRT (MLPD package).