A pilot conducting an RNAV Approach to a non-towered airport misread their chart and descended below a minimum altitude for a segment of the approach. ATC advised them to check their altitude.

Narrative

While on initial approach into ZZZ; I was cleared for the RNAV-XX via the ZZZZZ IAF. I was given the restriction to cross ZZZZZ at 4000 ft. I compiled with this restriction; then began my descent after crossing ZZZZZ for the next altitude. I selected 3;300 ft. on my altitude pre-select for the leg from ZZZZZ to ZZZZZ1. However; I didn't realize until crossing ZZZZZ1 that I selected the wrong altitude. On the Jeppesen charts; the altitude for the leg from ZZZZZ to ZZZZZ1 is in an inset; and the altitude for the leg is not prominent. While writing this report; I compared the NACO chart for the approach; and noticed that the altitude for this leg is presented in the same way as other legs. Just after noticing this error; Approach issued a 'check altitude' alert; but at that point; I had already crossed the ZZZZZ1 fix; and was at the appropriate altitude. Due to the fact that I was already at the appropriate altitude for this leg; there was no required corrective action. My initial training and check-ride was done using NACO charts; and I've only switched to Jepp charts in the last 2 years. In the future; I'll have to brief charts more carefully; and perhaps cross-reference against the NACO chart before beginning the approach; when workload is high.Contributing factors are high workload phase of flight; IMC conditions with continuous moderate turbulence; recent change in instrument charting provider and fatigue after 3 hour flight out of complex airspace