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TLC59116EVM-390: TLC59116EVM-390 Voltage Regulator Choice

Part Number: TLC59116EVM-390
Other Parts Discussed in Thread: TLC59116

To Whom it May Concern,

Why is such a capable voltage regulator, the fast-transient response, 1.5A rated, TPS7A4533KTT used on the eval board?  The LEDs are driven by Vin and I do not see a mechanism to switch them over to the TPS7A4533KTT.  The datasheet stipulates a TLC59116PW current draw (Icc) of 37mA at 5.5V with all channels on and almost full LED sink current (Iout).  Was the design originally capable of/designed to support the LEDs from the voltage regulator?  Or is this supporting protection circuits setup against the output channels and/or LED surge currents. 

Thanks,

Steve

  • Hi Steve,

    This board is too old to find the original designer so I do not sure why TPS7A4533KTT is chosen.

    In my understanding, LDO is used to switch VIN range 5V-17V to a power line 3V-5.5V for VCC of TLC59116. Output current of TLC59116 can support up to 120mA and output pin can stand with max 17V, which means a string LEDs like 5~6 pcs can be driven. VLED for the LED string is achieved to 17V so VIN for EVM board should be up to 17V. But VCC of TLC59116 is only 3V-5.5V. In order to supply EVM board with only one power, an level switch device is considered to supply TLC59116. As for 1.5A rated, I guess that when choosing the LDO, engineer just find an device can do it but not most efficiency for it.

  • Thanks for the quick response Hardy.

    To confirm, you also do not see any need for such a highly rated regulator based on accomplished design.  Per-channel 120mA is sunk to ground, not supplied.  So if 3.3V regulator only supports TLC59116 chips could be rated at few hundred mA versus 1.5A.

    Take Care,

    Steve 

  • Hi Steve,

    Yes I think so for this board. All 120mA output channels are supplied from power supply and TLC59116 are supplied from the LDO.