PULSE PE-64995NL

The S interface is a standardized four-wire digital telephone access point defined by the CCITT I-series ISDN recommendations. This "Basic Rate Access" accommodates two 64 Kbps "B channels" for information transfer, one 16 Kbps "D channel" for signaling and control, and 48 Kbps for framing and other purposes, for a total bit rate of 192 Kbps. The CCITT physical layer recommendation specifies transformer coupling for the user-network interface. The transformer provides isolation between the line card or terminal and the line, and also serves as a means of supplying phantom power to terminals via the S bus. Both ends require a transmit transformer and a receive transformer. In certain applications, chokes are used to reduce common-mode noise. The transformers described in this datasheet are matched to transceivers offered by the major IC manufacturers listed. Using the transformer-chip pair ensures that all CCITT I.430 requirements for pulse waveform masks, impedance, and longitudinal balance are met. In addition, the transformers provide the isolation voltage required by regulatory agencies and are capable of passing surge voltage tests. The transformer plays a critical role in achieving the required balance. Through a well-configured AC-balanced winding arrangement, capacitive coupling between the primary and secondary windings is evenly distributed, while the two halves of the line-side winding are also well balanced. The transformers meet the following Longitudinal Conversion Loss (LCL) specifications: a minimum of 60 dB from 10 kHz to 300 kHz; the minimum value rolls off at a rate of 20 dB per decade from 300 kHz to 1 MHz. The minimum impedance requirements for NT and TE transmitters and receivers in the inactive and power-down states are represented by impedance masks. At the low-frequency end of 1 MHz, it is reasonable to assume that the impedance seen from the line is purely capacitive. The maximum capacitance budget derived from the mask differs slightly between NT and TE. The contributing factors to total capacitance include chip output, protection circuits, transformer, common-mode choke, and any other components that may be present.

• Pulse waveform mask compliant with CCITT I.430 (when paired with recommended transformer and chip)
• Excellent longitudinal balance
• 2kVrms isolation voltage
• Available in tape-and-reel, tray, or tube packaging
• UL certified