Low-noise power supplies for varactor diode biasing

Maxim Integrated Products introduces the MAX5026/MAX5028 SOT23 step-up DC-DC converters targeted at low-noise varactor diode biasing in TV RF tuners, set-top boxes, satellite receivers, PCI cable modems and voice-over-cable modems. These devices operate from 3 to 11 VDC input and boost the output to 36 VDC (depending on version). As much as 12 mA output current is possible, depending on input and output voltage. The devices are designed to operate in discontinuous mode, which reduces switching noise and voltage spikes. In addition, the slew rate at the switch/inductor pin is controlled to further reduce noise. Both devices operate at constant PWM frequency, allowing high-frequency switching ripple of less than 1 mV peak-to-peak at the output of the power supply. Both devices operate at 500 kHz switching frequency, which allows the use of a surface-mount 47 microfarads inductor and a 1 microfarads ceramic output capacitor. Both are available in a 6-pin SOT23 package and are rated for operation from -40 to +85°.
Maxim
www.maxim-ic.com

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Specifications at a glance:

• 3 to 11 VDC input voltage
• Up to 36 VDC output voltage
• <1mV PP ripple at the output
• -40 to +85° C operating temp.

LDO with low quiescent current

Micro Analog Systems introduces a 50 mA low quiescent current LDO regulator, MAS9164, that features low dropout voltage and noise performance. The device is designed for real-time clocks (RTC) and SRAMs in cellular phones and other portable applications due to its quiescent current of only 10 µA and dropout voltage of 150 mV. The device is encapsulated into a true CSP package, as well as an SOT23 package. The regulator is available in a 1.8 VDC output voltage version. Other versions will follow.
Micro Analog Systems
www.mas-oy.com
info@mas-oy.com