AD8045 Exposed Paddle Connection

What do I have to connect the AD8045 exposed paddle to?

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  • 0
    •  Analog Employees 
    on Feb 16, 2011 2:35 PM over 10 years ago

    Hi

    Since expose paddle was mention here. We have had a lots on enquiry regarding this, not just specifically on the AD8045.

    Regarding ... how (best) in connecting the Expose paddle... “in General”.  The Expose Paddle otherwise, sometime Also Known As (AKA) expose pads. Thus I would like to add to this thread and summarize the followings.

    (a)   These are for thermal relief.

    (b)   These can be connected to a solder plane  or connected to the most negative(PCB) supply plane, (note. they can be in some cases, but not always you need to read the datasheet), see (d) below for more info.

    (c)   wrt multi layer PCB planes, (for best practice and performance). it is recommended that these ‘required’ planes on all layers under the paddle be stitched together with vias.

    (d)  Pending on the IC’s Voltages supply/supplies (Vs) and ground (Gnd, i.e. 0v) e.g. ( +Vs  and gnd),  (+/- Vs and gnd).  Connecting these expose pad is ... to the most negative supply plane of the respected IC in question. Connecting to ground is usually the best and easiest case, unless otherwise noted in the datasheet, such as the AD8045.

    Hence,

    (i)  if an IC has only  +Vs  and gnd, then the expose pad is connected to the gnd plane such as the AD8352, AD9776A,

    (ii) If an IC has +/-Vs  and gnd, then the expose pad is connected to the -Vs plane such as the AD8045,

                 N.B there are some update (exceptions) to this rule-of-thumb, please read threads further down.

    (e)   Majority of cases, the expose pads are describe well within the respected datasheet/device in question. We recommend user to consult this (as first hand info, from the datasheet). If this is not specified in the datasheet i.e. ADN8831 (rev.0). you can use the above as a general rule-of-thumb. More specifically if you are unsure and if it’s definitely not stated in the datasheet. We highly recommend that you contact us for clarification.

    In general the expose pad are internally connected... But not always (repeat not always) see AD7682 (rev.B),  if in this case then this can, either be connected to gnd plane or just to a solder plane which act as a heat sink.

    So, connecting the Expose paddle or (Expose pads)  ... The bottom line is, IC specific, pending on supply or supplies.

    More ref/info can be obtained via Analog website

    (1)    MT-093, Thermal Design Basics

    (2)    App note, AN-772,  A Design and Manufacturing Guide for the Lead Frame Chip Scale Package (LFCSP)

    Regards,

    Ching

Reply
  • 0
    •  Analog Employees 
    on Feb 16, 2011 2:35 PM over 10 years ago

    Hi

    Since expose paddle was mention here. We have had a lots on enquiry regarding this, not just specifically on the AD8045.

    Regarding ... how (best) in connecting the Expose paddle... “in General”.  The Expose Paddle otherwise, sometime Also Known As (AKA) expose pads. Thus I would like to add to this thread and summarize the followings.

    (a)   These are for thermal relief.

    (b)   These can be connected to a solder plane  or connected to the most negative(PCB) supply plane, (note. they can be in some cases, but not always you need to read the datasheet), see (d) below for more info.

    (c)   wrt multi layer PCB planes, (for best practice and performance). it is recommended that these ‘required’ planes on all layers under the paddle be stitched together with vias.

    (d)  Pending on the IC’s Voltages supply/supplies (Vs) and ground (Gnd, i.e. 0v) e.g. ( +Vs  and gnd),  (+/- Vs and gnd).  Connecting these expose pad is ... to the most negative supply plane of the respected IC in question. Connecting to ground is usually the best and easiest case, unless otherwise noted in the datasheet, such as the AD8045.

    Hence,

    (i)  if an IC has only  +Vs  and gnd, then the expose pad is connected to the gnd plane such as the AD8352, AD9776A,

    (ii) If an IC has +/-Vs  and gnd, then the expose pad is connected to the -Vs plane such as the AD8045,

                 N.B there are some update (exceptions) to this rule-of-thumb, please read threads further down.

    (e)   Majority of cases, the expose pads are describe well within the respected datasheet/device in question. We recommend user to consult this (as first hand info, from the datasheet). If this is not specified in the datasheet i.e. ADN8831 (rev.0). you can use the above as a general rule-of-thumb. More specifically if you are unsure and if it’s definitely not stated in the datasheet. We highly recommend that you contact us for clarification.

    In general the expose pad are internally connected... But not always (repeat not always) see AD7682 (rev.B),  if in this case then this can, either be connected to gnd plane or just to a solder plane which act as a heat sink.

    So, connecting the Expose paddle or (Expose pads)  ... The bottom line is, IC specific, pending on supply or supplies.

    More ref/info can be obtained via Analog website

    (1)    MT-093, Thermal Design Basics

    (2)    App note, AN-772,  A Design and Manufacturing Guide for the Lead Frame Chip Scale Package (LFCSP)

    Regards,

    Ching

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