Hi, After spending some time with the TPS61195EVM we have the following questions/issues/observations:
1) Question: Can the TPS61195 work with SMBUS ONLY ? If yes, what is expected on the DPWM pin ? (High, Low, or does it need a pulse regardless)
2) Question: According to the doc, the Eval board can work with NO pulse on DPWM, is this confirmed ?
3) Observation: As mentioned above we are connecting the DPWM pin to VDDIO expecting “Full Brightness” but instead we get a “flickering” effect on the LEDs, they kind of blink very fast, but changing R4’s value did not change anything.
4) Question: We were under the impression that the FDIM pin was used to set the internal pwm frequency, can you please confirm ?
5) Setup: We have DPWM set to VDDIO, we set the SEL[2:1] pins in SMBUS mode and we adjust the brightness using the Eval Board’s USB bridge.
6) Issue: As mentioned above, the LEDs are blinking, and when set the brightness to 0, they stop blinking BUT they remain ON…
7) Issue: Moving the brightness from 0 to “any value other than 0” and back to 0, is NOT constant… Sometimes they DO shut off completely.
8) Setup: We are driving a string of LEDs between J6 pin 1 and J6 pin 10 = IFB2.
9) Issue: The Eval Board doc mentions that unused IFB pins should be tied to Ground… If we do this, our string never lights up.
10) Question: Is there a specific order on the Strings to be used ? i.e. Can we use String 2 alone ? or must we always start from String 1 ?
11) Observation: Even if we don’t get an overcurrent error during blinking, we did short the bottom end of the String into TWO IFBs as suggested in the TPS61195 spec to increase current drive, and we get the same results… Blinking.
12) Observation: When connected to 1 OR 2 IFBs, after dimming the brightness to 0 and increasing it back to above 0, sometimes trigger an overcurrent string error.
13) Please provide any directives and/or comments to help us better understand the situation.
Thank you.
Mike Lorenz
Senior Hardware Design Engineer
