New HT77XXA Product Release – Low Start-up Voltage DC/DC Converter Series

06/21/2007

The HT77XXA series of devices are a new range of high-efficiency Low Start-up Voltage DC/DC converters. The devices use PFM techniques for their output voltage control, and have the benefits of extremely low operating current and low noise characteristics. By using an integrated low impedance power transistor, the HT77XX series of devices only need to be connected to an external inductor, capacitor and diode to implement a complete DC/DC converter circuit, which can obtain high-efficiency ratings of up to 85%, providing related applications with a low cost and minimal area DC/DC solution.

With four fixed output voltage types of 2.7V, 3.0V, 3.3V and 5V, the devices possess the major advantage of being able to operate with input voltages as low as 0.7V. When this is added to their extremely low supply current of only 5uA, this new range of devices provide features which can extend battery life greatly, making them suitable for widespread use in single or multi-cell Alkaline, Lithium Ion or Ni-MH battery powered portable applications.

In the area of packaging, the devices are available in TO-92, SOT-89, SOT-23 and SOT-25 package types. The SOT-25 package type, in having an additional device enable pin, includes an internal power down function. If the device is placed into its power down mode, then the device will consume an even further reduced operating current of only 0.5uA.

Presently Holtek supplies two kinds of device categories within its DC/DC converter range, subdivided according to their current drive capabilities. This new range of HT77XXA devices can supply up to 200mA, while the other category, the HT77XX, can supply up to 100mA. Both categories are fully pin compatible and the user can determine which one is most suitable according to their application requirements.