500kHz, 36V Output, SOT23, PWM Step-Up DC-DC Converters

The MAX5025–MAX5028 constant-frequency, pulse-width modulating (PWM), low-noise boost converters are intended for low-voltage systems that often need a locally generated high voltage. These devices are capable of generating low-noise, high output voltages required for varactor diode biasing in TV tuners, set-top boxes, and PCI cable modems. The MAX5025–MAX5028 operate from as low as 3V and switch at 500kHz.

The constant-frequency, current-mode PWM architecture provides for low output noise that is easy to filter. A 40V lateral DMOS device is used as the internal power switch, making the devices ideal for boost converters up to 36V. The MAX5025/MAX5026 adjustable versions require the use of external feedback resistors to set the output voltage. The MAX5027/MAX5028 offer a fixed 30V output. These devices are available in a small, 6-pin SOT23 package.

Applications

* Avalanche Photodiode Biasing * LCD Power Supply * Low-Noise Varactor Diode Biasing * PCI Cable Modem * Set-Top Box Tuner Power Supply * TV Tuner Power Supply * Voice-Over-Cable

* Input Voltage Range:

* 3V to 11V (MAX5026/MAX5028)

* 4.5V to 11V (MAX5025/MAX5027)

* Wide Output Voltage Range: VCC to 36V

* Output Power: 120mW (max)

* User-Adjustable Output Voltage with MAX5025/MAX5026 Using External Feedback Resistors

* Fixed 30V Output Voltage: MAX5027/MAX5028

* Internal 1.3Ω (typ), 40V Switch

* Constant PWM Frequency Provides Easy Filtering in Low-Noise Applications

* 500kHz (typ) Switching Frequency

* 1µA (max) Shutdown Current

* Small, 6-Pin SOT23 Package