73M1866B-IM/F Maxim Integrated Products, 73M1866B-IM/F Datasheet - Page 10

• 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): -

73M1866B/73M1966B Schematic and Layout Guidelines
Special Layout Considerations for the 73M1866B
The 73M1866B is intended for use in applications that require the smallest possible footprint at the expense of the
greatest possible high voltage isolation. If isolation over 4.5 kV is required, the 73M1966B should be used instead.
The minimum separation between the circuits on the line side and host side are on the bottom of the package. This
minimum 73M1866 contact spacing is more than 2.5 mm; therefore it exceeds the IEC 60950 requirements for
clearance and creepage. It is important that the PCB connections do not compromise the clearance by having less
than 2.5 mm between the PCB mounting pads nearest the barrier separation. This also applies to the backside
contact pads on the bottom of the 73M1866B package. It is also important that the assembly and attachment of
the parts do not compromise the separation as well. The soldering process often leaves debris under the package,
such as solder and flux, and this can degrade the isolation performance of the device even though the PCB layout
provides adequate separation. Because the device package lies flat against the circuit board, it can be difficult to
thoroughly clean in between them. Excessive solder is particularly difficult to remove after assembly, so great care
needs to be taken during the soldering process. Many solder fluxes can be conductive to some degree, so
washing needs to be thorough to get the best isolation voltage performance. Needless to say, the components on
the host and line side also need to maintain the same 2.5 mm clearance as the 73M1866 package in order to not
violate the IEC 60950 requirement.
See the following documents for additional information:
•
•
It should be noted that the 73M1866B package is not symmetrical where the corners separations for isolation are
located. Do not infringe on the gap between the host and line-side connections when laying out the circuit traces.
This can reduce the separations to less than the minimum 2.5 mm that is required by IEC 60950. Because of the
asymmetry it may appear to be maintaining the spacing when it is not.
10
Amkor document Board Level Assembly and Reliability Considerations for QFN Type Packages
(http://solder.net/PDFs/QFN_Assembly_Reliability.pdf).
Design for QFN Devices (http://circuitsource.blogspot.com/2008/06/design-with-qfn-devices.html).
Line-side circuits
Figure 8: 73M1966B Reference PCB Bottom Copper Layer
Heat sink for Q6
Host-side circuits
AN_1x66B_003
Rev. 3.5