73M1866B-IM/F Maxim Integrated Products, 73M1866B-IM/F Datasheet - Page 9

• Manufacturer Part Number: 73M1866B-IM/F
• Description: MICRODAA SGL PCM HIGHWAY 42-QFN
• Manufacturer: Maxim Integrated Products
• Series: MicroDAA™r

Specifications of 73M1866B-IM/F

• Includes: PCM Highway
• Function: Data Access Arrangement (DAA)
• Interface: PCM, Serial, SPI
• Number Of Circuits: 1
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 42-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Power (watts): -

AN_1x66B_003
Protection Circuitry
A thyristor (E1) across Tip and Ring rated at 275 V and 100 A (for the US) should follow the fuse. Besides
protecting the DAA circuitry from power cross faults, the thyristor is necessary to pass safety testing that will be
performed during certification. Many of the components in the DAA cannot tolerate the voltages and currents that
the DAA will be subjected to without this protection.
It is very important to provide adequate heat dissipation for the line voltage protection device E1. Some PTT
certification tests can be severe and require the voltage protection to operate for extended periods with a large
current (>2 A) without failure in order to pass power cross safety testing (refer to UL60950 NAC Fig. 2, Test M-3).
In this case, heat dissipation for the line voltage protection device (E1) should be provided by using 5 A-rated
(2.5 mm) circuit traces from the line connector to the thyristor.
9
over- voltage protection device
Add heat sink copper for
Line-Side Circuit
Figure 7: 73M1966B Reference PCB Top Copper Layer
Figure 6: 73M1966B Reference PCB Top View
Isolation Barrier
Add extra copper for
Q6 heat sink
73M1866B/73M1966B Schematic and Layout Guidelines
Capacitors crossing the
also mantain creepage
Host-Side Circuit
isolation barrier must
have a voltage rating
isolation voltage and
that exceeds the
distance
Rev. 3.5