33_OR_5_V_ANALOG_SWITCHES

Published:2009/7/14 2:33:00 Author:May | From:SeekIC

By adding a single component to a 3-V only or 5-V only board，you can operate conventional CMOS analog switches with Performance approaching that specified with ±15-V Supplies， This means fast switching，low ON resistance，CMOS /TTL compatibility, low power consumption，and a signal range （±Vcc） that exceeds the input supply range (Vcc to ground）．Simply add a charge-ump voltage converter：（IC1），which produces±2-Vcc outputs from a Vcc input .These unregulated voltages ensure reliable switch operation for Vcc levels as low as 3 V. Logic thresholds for the switch remain unaffected A Vcc of 3 V （for instance）produces，±6 v rails for the switch （IC2），resulting in ON resistance＜30Ω，switching times＜200 ns，leakage＜0.1 nA，and Vcc ourrent＜0.5mA Raising Vcc to 5 V produces±10-V rails，resulting in ON resistance＜20Ω，switching times＜150 ns，leakage＜0.4 nA，and Vcc current＜l.3 mA IC1 can easily power additional switches and／or low-power Op amps，but more than a few milliamperes of load current degrades Performance by lowering the unregulated supply rails．



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Switch_Control/33_OR_5_V_ANALOG_SWITCHES.html

Print this Page | Comments | Reading(3)