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Hello,
I'm testing the TPL5110 accuracy in order to decide to use it in my projects.
In the datasheet, the timer accuracy is reported to be 0.6%, but in my tests I get errors of 3-10% in the interval time in "EN" mode (timer).
I'm calculating the t_ip according to the Rext resistance measure with a multimeter.
I used several resistors and all gave me errors. The only case when I got a smaller error of 0.5-1% is with Rext=500ohm (for t_ip=100ms).
Questions concerning the accuracy in section 7.5 in the datasheet:
1. "Oscillator accuracy over supply voltage" - what is the base voltage to calculate from, 0V or 2.5V?
2. same question as #1 for "Time interval Setting Accuracy over supply voltage"
3. "Time interval Setting Accuracy" - does it already include the accuracy of #1 and #2? which errors does it include?
4. Concerning the quantization error - Equation 3 seems to give very big numbers. for example:
for Rext=8.215kohm (Tdesired=3.85sec), Tadc=INT[5.5]=6sec. Equation 3's result is 56% which is a strange big number.
Can you clarify how to use this equation to check my expected error?
Is it taken into account in the timer accuracy?
Thanks,
Avihai
Other questions please:
1. taking into account all those errors doesn't give me an error close to the actual number which I get in measurements:
for example, Vdd=4V, Rext=9.226kohm at 25 Celcius degrees gives 6.112s instead of 5.901sec (error of 3.6%)
what could also contribute to the error while it's a completely new chip and I get similar results in 4 other chips?
2.When using the timer with Vdd=1.8V, the actual minimal timer period is 200ms (instead of 100ms).
Is this a known or expected issue?
Also, at this voltage I don't get a square wave, but something more like a toothsaw.
Thanks again for your help.