73M1866B-IFX Maxim Integrated Products, 73M1866B-IFX Datasheet - Page 6

• Manufacturer Part Number: 73M1866B-IFX
• Description: KIT EVALUATION FOR 73M1866B
• Manufacturer: Maxim Integrated Products

Specifications of 73M1866B-IFX

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

73M1866B/73M1966B Schematic and Layout Guidelines
Reference Schematics and Layout Examples
The following figures contain the reference schematics and layouts that are used with the 73M1866B and
73M1966B Demo Boards. Some components are optional and may or may not be needed for a particular
application.
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R69 can be used if it is necessary to speed up the discharge of the internal circuitry after going on hook. In
some applications it may be desirable to be able read the battery open circuit voltage soon after the 73M1x66
has gone on hook, so the value of R69 can be chosen to get the best settling time with the least impact on the
overall operation of the circuits. Approximately 100 K is a good starting value and speeds up settling by 5X.
C24 can be used to improve the radiated EMI, but is not needed in most applications. Generally the normal
product shielding for other circuitry will be adequate for the FXO circuits as well. The power supply bypassing
can also be adjusted to optimize the EMI performance verses parts count. This is highly dependent on the
overall circuit layout, the use of power planes and circuit routing.
For conditions where a highly inductive network connection is present, Zener diode D1 may be needed to limit
the inductive kick-back that can lead to excessive voltages on the DAA circuit. This diode prevents voltages
across the internal DAA circuits from exceeding 25 V. If current limiting is enabled, the Zener voltage rating
should be increased to allow for the open circuit battery voltage.
AN_1x66B_003
Rev. 3.5