Holtek HT77xxS Synchronous PFM DC/DC Step-up Converters
Following the successful release of Holtek’s high efficiency step-up DC/DC converter devices, namely the HT77xx series, Holtek is now delighted to announce a new range of synchronous step-up DC/DC converter, the HT77xxS series. The “S” suffix in the part number indicates synchronous operation.
HT77xxS devices, manufactured using trimmed CMOS technology, have a low
start-up voltage of only 0.7V and a standby current of 4uA. These features are
especially suitable for use in applications which are powered using a single
Alkaline, Ni-MH, Ni-Cd or Lithium-ion cell. Because of their PFM synchronous
rectifier design structure, the devices can achieve DC/DC conversion
efficiencies of up to 93%, an important feature in their ability to extend
battery life in power sensitive battery powered applications. In addition, with
their low noise characteristic, the
devices can also extend their usage into RF module applications.
With regard to external component requirements, as the
series is a synchronous step-up DC/DC converter device range, the external
Schottky diode which is a requirement of the
series is no longer required for this new device range. As a result, the devices
only require three external components, a 10uF ceramic multilayer input
capacitor, a 10uF ceramic multilayer output capacitor, and a 10uH wire wound or
a newer type multilayer inductor.
HT77xxS can supply output an current over 100mA, with fixed output voltages
of 1.8V, 2.2V, 2.7V, 3.0V, 3.3V, 3.7V and 5.0V. As for packaging, the devices
are available in SOT23, SOT23-5, SOT89 and TO92 package types whose pin
assignments are the same as the previously released
series. These low package profiles and other features combine to provide an
excellent DC/DC converter choice for a huge range of portable and other