Part Number: TPL1401
How do I use the TPL1401 as a voltage input to devices with adjustable current limits?
If you are using a device that has an input for an adjustable output-current limit, the TPL1401 is a very compact way to provide that analog input. In addition, the integrated nonvolatile memory (NVM) makes sure the settings are retained even after power cycling, allowing the device to work without a processor after initial programming.
The datasheet of the device with the programmable current limit will provide the voltage ranges required to set the limit. Find the DPOT code needed to set the TPL1401 to output that voltage using the transfer function:
The available gain options for the TPL1401 are 1.5x, 2x, 3x, 4x in order to scale the 1.21V internal reference voltage to better fit the voltage range given by the current limited device. Alternatively, VDD can be used as an external reference (1.8V to 5.5V).
For details on how to write this code to the TPL1401 DPOT_POSITION register and save to the NVM, see [FAQ] How to generate a DC setpoint or bias using the TPL1401
The above solution could also be done with a standard digipot as well, such as the 8-bit TPL0501 or TP0102.
The TPL0501 is shown here. As you can see, there is no NVM and no precision reference. Although the TPL0501 comes in a slightly smaller package than the TPL1401, the addition of the precision reference and external buffer would increase the price and overall size of this solution.
The TPL0102 show here does integrate the NVM, but again there is no precision reference or wiper buffer.
It is clear that the TPL1401 is the lowest cost, most precise, and most integrated solution.
The TPL1401 can be found in many common applications:
Exit and emergency lighting
Cordless vacuum cleaners
Robotic lawn mowers
Laser distance meter
You can find some additional information about the TPL1401 here:
You can find more information about precision DACs here:
Precision DAC Learning Center
TI Precision Labs - DACs
Data Converter Circuit Cookbook
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