摘要 :Data access arrangement (DAA) interface protection prevents other components in the line-side circuitry from being damaged by voltages and currents in excess of their rated limits. Most safety-regulatory agencies require protection that is activated when voltages > 275V occur between the tip and ring connections to the public switched-telephone network (PSTN). This minimum voltage-trip level prevents conducting under worst-case ringing and battery-voltage conditions. However, there are also cases when there are requirements to safeguard the DAA interface against voltages that fall under the high voltage-protection threshold. This article provides guidance on these cases, and highlights the Teridian 73M1866B/73M1966B and 73M1822/73M1922 low-voltage, transient protection, MicroDAA® solutions.