LINEAR LTC3833 User Guide and Manual

October 2011 Volume 21 Number 3

Fast, Accurate Step-Down DC/DC

2-channel and 4-channel pin-selectable I2C multiplexer 11 Controller Converts 24V Directly to

high efficiency power 1.8V at 2MHz supply for Intel IMVP-

6/6+/6.5 CPUs 20 Bud Abesingha

3A linear regulator easily The continuous march in electronics toward lower supply voltages paralleled to spread power

and higher load currents puts tremendous pressure on point-of-

and heat 24

load DC/DC converters to maintain a fast pace of performance improvements. For instance, a lower supply voltage means a

LTspice IV update 36

regulator must support a higher step-down ratio from a 12V or 24V power rail while maintaining high efficiency. Regulation

frequency shifter for

accuracy also becomes more important as supply voltages

isolated PWM control 40

drop—and accuracy must be maintained in the presence of parasitic IR drops and dynamic load transients. EMI generated by switching converters is also of concern, especially in RF applications. Some applications require that their power supplies meet all of these strin- gent requirements: high power, high efficiency, high accuracy, high step- down ratio, fast transient performance and low EMI—and that they do it in a small footprint. The LTC®3833 is a high performance synchronous step-down DC/DC controller that steps up to the challenge. Figure 1 shows a typical application. The LTC3833 accepts an unregulated input volt- age between 4.5V and 38V (40V abs max) and downconverts it to 0.67% accurate output voltage between 0.6V and 5.5V (6V abs max).

It features a 20ns minimum on-time, enabling a high step-down ratio (high VIN to low VOUT) at high frequency (up to 2MHz), and its con- trol architecture is primed for fast transient performance. The LTC3833 is offered in 20-pin QFN (3mm × 4mm) and TSSOP pack-

Caption

ages with exposed pads for enhanced thermal performance.

(continued on page 4)Published September 2011 and now available. See page 2.

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