highpowerZONE Products for the week of October 15, 2007

Intersil Says…

ISL6228: High Transient Response/Switching Efficiency for Notebook Peripherals
Dual-Output Buck Controller Offers Fast Transient Response Through a Hybrid Fixed/Variable frequency PWM and Wider Voltage Range Options (3.3 V to 25 V Input; +0.6 V to +5 V Output) for Flexibility

Intersil Corporation, a world leader in the design and manufacture of high-performance analog semiconductors, announced the release of the ISL6228 high-performance dual-output buck controller for notebook peripheral computing applications. Through Intersil’s patented R3 Technology this controller provides unmatched transient response, switching efficiency and design flexibility.

The ISL6228 is capable of operating over the industry’s widest input voltage range (3.3V to 25V) and has a highly flexible output voltage range from +0.6 to +5.0V. These broad voltage ranges, combined with dual independent switchers, make this controller the ideal choice for notebook peripheral applications, as well as a host of general purpose communications, storage, security and industrial automation applications.

Intersil’s R3 (Robust Ripple Regulator) Technology provides the dynamic response to input voltage and output load transients required by today’s faster, more powerful notebook processors. The R3 Technology represents a hybrid of fixed-frequency PWM control and variable-frequency hysteretic control to produce the industry’s fastest transient response.

EN-Genius Says…

When I first read that the ISL6228 had a PWM oscillator that changed frequency according to the load I thought I would be seeing a compromise solution for the two channels. But that is not the case; the two channels are completely duplicated.

Intersil is calling the technology R³ and is a hybrid of a fixed frequency control with a variable frequency hysteretic control, changing both the PWM switching frequency and the duty cycle, on the fly, according to the input voltage and the inductor load current; these produce a current drive through a transconductance amplifier for control. It is an extremely clever arrangement with a nominal frequency range from 200 kHz to 600 kHz, using a single external resistor and parallel capacitor. Additionally, at lower loads, the part switches from continuous-conduction mode to a diode-emulation mode.

The part has separate channel inductor overcurrent, soft crowbar overvoltage, and temperature protections together with undervoltage lock-out. An independent power good output is provided on each channel and there are separate soft-starts with sequencing possible between channels.

MOSFET drivers with shoot through protection (and bootstrap diode) are on-chip with dead times of 21 ms, both up and down. Efficiencies are very high, transients are very low. The output voltage is regulated to ±1% at each of the feedback pins. The input voltage range is 3.3 V to 25 V with an output range of 0.6 V to 5 V. Each channel of the part has its own reference. Each channel also has its own enable pin.

The complete separation, and control, of channels is a major plus for the ISL6228. The self-determining PWM frequency is a joy. This will be a huge winner in the market with applications all over the map.

The ISL6228 is in production in TQFN-28 priced at $2.20 in 1000-piece lots.