5V/Adjustable, Negative-Output, Inverting, Current-Mode PWAf Regulators

The MAX735 and MAX755 are CMOS, inverting switch­ mode regulators with internal power MOSFETs. The MAX755 operates from a +2.7Vto +9V input and generates an adjustable negative output; 1W output power is guaran­ teed when powered from a +4.5V input. The MAX735 operates from a +4.0V to +6.2V output; 200mA output current is guaranteed for inputs greater than +4.5V. Quiescent supply current for the MAX735 is typically 1.6mA, and a shutdown mode reduces this to 10µA. These power­ conserving features, along with high efficiency and applications circuits that lend themselves to miniaturization, make the MAX735/MAX755 excel in a broad range of on-card and portable-equipment applications.

The MAX735/MAX755 employ a high-performance current­ mode pulse-width modulation (PWM) control scheme to provide tight output-voltage regulation and low subharmonic noise. The fixed-frequency oscillator is factory­ trimmed to 160kHz, allowing for easy noise filtering. The regulators are production tested in actual application circuits, and output accuracy is guaranteed to within ±5% over all specified conditions of line, load, and temperature.

The input-to-output differential of the MAX755 is limited to VIN + VOUT ≤ 11.7V.

For an adjustable-output device with a wider input voltage range, refer to the MAX759 data sheet. For a fixed -5V part with a wider input voltage range, refer to the MAX739 data sheet. For fixed -12V and -1SV versions, see the MAX736 and MAX737 data sheets. For lower-power applications, refer to the MAX635/636/637 data sheet.

APPLICATIONS

Board-Level DC-DC Conversion Battery-Powered Equipment Computer Peripherals

* Converts +2.7V to +9V Input to Adjustable Negative Output (MAX755)

* Converts +4.0V to +6.2V Input to -5V Output (MAX735)

* 1W Guaranteed Output Power (VIN ≥ 4.5V)

* 78% Typical Efficiency

* 1.6mA Quiescent Current (MAX735)

* 10µA Shutdown Mode

* 160kHz Fixed-Frequency Oscillator

* Current-Mode PWM - Low Noise and Jitter

* Soft-Start

* Simple Application Circuit