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lmz10500 and it's susceptibility to light

Calum Mackinnon
Genius 4155 points
Other Parts Discussed in Thread: LMZ10501
Hi
 
In the datasheet http://www.ti.com/lit/ds/snvs723a/snvs723a.pdf there is a paragraph that states
 
"The nano module package includes an LTCC inductor on the bottom and a micro SMD die mounted on top. The die has exposed edges and can be sensitive to ambient light. For applications with direct high intensity ambient red, infrared, LED, or natural light it is recommended to have the device shielded from the light source to avoid abnormal behavior."
 
Can you expand on this - what intensity of light, how long it has to be exposed to have an effect, etc.
  • 0
    TI__Mastermind 19891 points

    Hello Calum, 

    This paragraph is a typical note for devices which have exposed die edges (i.e. micro SMD package devices, LMZ10501, etc.). It is known that "light" can affect the operation of a semiconductor device. As you noted, it depends on the light wavelength, intensity, angle, etc. Because there are so many variables, it is difficult to quantify what may get affected and what parameters could shift if a particular light is shone on the device.The suggestion is always to "cover" the device in order to guarantee the specs and performance. 

    That said, at least I can share the tests I have done and the changes observed. I have looked at the device output regulation, power dissipation, and shutdown current while exposing it to white LED light, IR light, and UV light. For the light sources I used the following devices:

    White LED: Array of 7 Seoul Semiconductor LEDs (part number XP42180) LEDs mounted on a board, operated at 1A, placed 4cm from the top of the LMZ10501 device.

    IR LED: Array of 7 850nm OSRAM High Power Infrared Emitter LED (part number SFH 4232) mounted on a board, operated at 1A, placed 4cm from the top of the LMZ10501 device.

    UV LED: Array of 7 400nm lTT Electronics Metal Can UV LEDs (part number OUE8A400Y1) mounted on a board, placed 4cm from the top of the LMZ10501 device.

    During these tests I observed slight shift in output voltage (i.e. less than 5mV on 1.8V output), slight shift of shutdown input current (i.e. +3uA), and very minor increase in power dissipation (i.e 30mW at 1A load). No device failure or abnormal behavior were observed in the described tests and conditions. No other tests were performed and no other performance parameters were monitored.

    Again, to guarantee any specifications or performance in long term and over temperature, the LMZ10501 should be shielded from the light source when the application exposes the device to ambient light.

    I hope this helps.

    Best Regards, 
    Denislav