LM3661

The LM3661 step-down DC-DC converter is optimized for powering ultra-low voltage circuits from a single Lithium-Ion cell. The device provides two pin-selectable output voltages. See ordering information for a list of voltage options available . This allows adjustment for DSP or CPU voltage options, as well as dynamic output voltage switching for reduced power consumption. Internal synchronous rectification provides high efficiency (92% typ. at 1.35V_OUT).

The LM3661 offers superior features and performance for mobile phones and similar portable applications. Pin-selectable PWM and Linear modes provide improved system control for maximizing battery life. During full-load, fixed frequency PWM operation reduces interference in RF and data acquisition applications by minimizing noise harmonics at sensitive IF and sampling frequencies. The SYNC/MODE input allows synchronization of the switching frequency in a range of below 500 kHz to 750 kHz to prevent noise from intermodulation with system frequencies. Linear operation reduces quiescent current to 29 µA (typ.) during system standby for extended battery life, while supplying up to 15 mA. Shutdown turns the device off and reduces battery consumption to 0.5 µA (typ.). This device offers a selectable over Current Limit to protect a variety of inductors.

The LM3661 is available in a 10 pin micro SMD package. This packaging uses National's chip-scale micro SMD technology and offers the smallest possible size. A high (600 kHz) switching frequency allows use of tiny surface-mount components; only three are required-an inductor and two ceramic capacitors.

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