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LED Drivers/LCD Bias
LED Drivers/LCD Bias Forum
TPS61160 CTRL pull down resistor
Currently trying to use the 61160 in EasyScale mode with the DM3725's HDQ/1-wire peripheral.
In the manual for the 61160, SLVS791C, on page 3 in the "Electrical Characteristics" table there is an entry for a "CTRL pull down resistor" R(ctrl).
What is this pull down resistor? Don't we want to pull CTRL high externally when using HDQ/1-wire mode? Or is this something internal to the 61160?
I agree with you, IMHO it is not clear from the datasheet wether the pulldown is internal or not.
I think that the pulldown is needed, for example, to avoid false operation during processor reset or sleep modes, or in any state where the pin connected to CTRL is in 3state (and could be seen as high by the device, thus enabling it).
The EVM datasheet clearly states that the pulldown is internal to the device:
"Installing this jumper ties the CTRL pin to VIN, and enables the device. Removing the jumper allows theinternal pulldown resistor to pull CTRL to ground, which disables the device. The jumper should beremoved if using an external signal to perform dimming." (page 3), http://www.ti.com/lit/ug/slvu221c/slvu221c.pdf
Hope this helps
Albert is correct. The pull down resistor is quite large is used to ensure that the CTRL pin is never floating.
Thanks for replying Albert and Jeff.
@Jeff: so to clarify, is the CTRL pulldown resistor mentioned in slvs791c an external one or is it already internal to the 61160?
Internal. It is R(CRTL) on page 3 of the datasheet.
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