DC/DC regulators for single Li+ cell applications

Intersil has introduced a trio of dual-output FET buck regulators that provide up to 95 per cent power conversion efficiency and are said to offer designers greater flexibility.

The ISL8022, ISL8033/A and ISL8036/A have quiescent currents as low as 40uA and support an input voltage range of 2.85 to 6V, making them suitable for single Li+ cell, three NiMH cell or 3/5V DC input voltage applications.

The ISL8033/A and ISL8036/A are dual-output step-down DC/DC regulators that can deliver up to 3A continuous output current per channel.

The ISL8022 provides similar functionality for lower-current applications, delivering up to 2/1.7A continuous output current on its two channels.

All three ranges of devices feature a peak-current mode, fixed-frequency control architecture that enables ultra-low duty-cycle operation, loop stability and fast load transient response.

The fast load transient response reduces required output capacitance and enables a smaller total solution size compared with traditional voltage mode control architectures.

The two channels in the ISL8033/A, ISL8036/A and ISL8022 switch 180deg out-of-phase, reducing the input ripple current and filter requirements.

Internal loop compensation further reduces the external component count and cost.

The ISL8033 and ISL8036 offer a fixed switching frequency of 1MHz, while the ISL8033A and ISL8036A switch at 2.5MHz to significantly reduce the overall DC/DC converter size.

The ISL8033 and ISL8036 can also be synchronised to an external clock of up to 6MHz, further reducing the overall solution size and eliminating beat frequencies in multi-switcher designs.

Independent enable and PGOOD pins for both channels provide complete start-up control and inherent output monitoring, eliminating the need for discrete sequencers and voltage monitors.

In addition to sourcing 3A independently, both channels in the ISL8036/A can be paralleled to create a single 6A output in current sharing mode for higher power applications.

The ISL8033/A provides the user the flexibility to program the over-current trip threshold for each channel, thereby allowing the IC to be configured in either a 3A/2A or 2A/2A configuration to support various load profiles.

The internal power MOSFETs are optimised to support output voltages as low as 0.8V while providing high efficiency.

The ISL8022 offers selectable forced-PWM mode or automatic PWM/PFM mode to optimise battery life in portable and handheld applications.

The 40uA quiescent current makes the ISL8022 suitable for battery-powered and other 'green power' applications.

The ISL8022 operates at a fixed switching frequency of 2.25MHz, offering designers the ability to use small, cost-effective inductors and capacitors.

Similar to the ISL8033/36, the ISL8022 can also be synchronised to an external clock up to 8MHz, further reducing the overall solution size and eliminating beat frequencies in multi-switcher designs.

The internal power MOSFETs are optimised to support output voltages as low as 0.6V while providing high efficiency.

The ISL8022 is available in a space-saving 12-lead 4 x 3mm DFN package, while the ISL8033/A and ISL8036/A are available in 24-lead 4 x 4mm QFN packages.

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