No the max reverse leakage current of the ZLS500 is 50 times less than the CUS. It's very importan for that diode have a very low leakage otherwise the BOOST capacitor may discharge and the internal switch may never turn on or only turn on for a short time.
ok, so giving this summary tab (from DS):
| Diodo | Package | VRRM max | V IR | IR (typ) |
|---|---|---|---|---|
| CMPSH1‑4 | SOT‑23F | 40 V | 30 V reverse | ~5 µA |
| CUS10S30 | SOD‑323 | 20 V (30 V peak) | 30 V reverse | ≤ 500 µA (0,5 mA) max |
| ZLLS500 | SOT‑23‑6 | 40 V | 30 V reverse | ~10 µA |
My CUS has about 3 to 8 times more leakage than the standard evaluation design(CMPSH1‑4) due to the different package it would be difficult to test it 
but i will try..
I will try to measure with DSO TC3 the catode..
looks more like 100 times
You should always look at the max values, not the typical when you do a design
Got it!
Could an SS14 diode be a great substitute (I saw online in some other design) as D4 and most important I have on my desk!
I'm looking something reachable form amazon or Aliexpress in order to test (hope is the only problem). the ZLLS500 seams to be tight for my rated current 1000mA, but the CMPSH is obsolete part, unfoundable for me...
What about 1N4148WS (same pakage of CUS).
Another, maybe unrelated thing I saw.
Why is Vreg going to the ATTiny25, and especially the 320k/TL431 part.
A TL431 needs a lot more current to reach it's 2.5V operating voltage.
The second page was never realized. My initial idea was to use an ATtiny to implement a real Perturb and Observe algorithm in order to reach the exact MPP. In the end, I felt the design was too complex for such a small practical advantage.
Why the MPPT anyway. It has no big advantage over a 5volt panel with a straight linear Lipo charger like the TP4056. What is the end goal. powering an Arduino?
No, It's a lora P2P repeater placed in a not full sunny side of a tree...
Understood. MPPT could be better in handling an over-sized and higher voltage panel in the shade. Extending the panel to a place in the sun was not an option?
Not permitted by the autority (neighbor). I oversized the panel: it works near Voc at 25mA right now! It can do better! My first attempt was use a buck step down 18 to 6V and then use the tp4056 integrated in the CubeCell, but after days the battery (1x3600mA) was not enough...
2x3600 and 1h equivalent of full sun gives me all I want!
Where are you measuring that 25mA. At J1 (INA) or at the battery.
J1 (vin) current is ofcourse lower that battery charge current due to the chip being a buck converter. Currents roughly being a ratio of V-in and V-batt.
What are the specs of the panel and what is Voc.
Did you measure the current sense resistor (0.1 Ohm). Is it rated for 1A.
You can get a proper one from an INA219 board.
I’m measuring the current on the solar side with the INA, so that value is not the battery current itself. After accounting for the buck conversion, it corresponds to roughly [70/80] mA on the battery side, assuming an ideal conversion ratio.
I also calibrated the current register for the proper range and used an appropriate shunt resistor of [0.5ohm] for the low voltage range.
That said, the LED still turns on even though it should only do so at [C/10 = 100] mA, and more importantly, in full sunlight the charge current should increase much more than what I’m seeing.
I also checked with a UT210E clamp meter, and it gives values very similar to the INA219 reading, so the measurement itself seems consistent.
Note that charge current of a MPPT chip also depends on input voltage.
Lower than the MPPT panel setpoint and charge current will also drop, to keep the panel within it's voltage range. A solar panel is largely a current source. You can't just replace it with a constant voltage lab power supply.
Got It! But how can I test in order to esclude the panel?
Measuring the VIN_REG pin, it shows a voltage higher than 3.3 V (which is above the 2.7 V threshold), so the LT3652 should be able to increase the current while VIN_REG approaches 2.7 V, right? Why doesn’t it do that?
I think there are three (or four) conditions to stop an MPPT charging.
-
input voltage too low
-
battery voltage high enough
-
battery current too high (voltage across the current sense resistor > 100mV)
-
battery temp too high (if NTC is fitted)
Which one didn't you check yet.
- No, measured and Vin reg > 2.7
- That's a point Vfb =3.3 (but the battery Is not charged according to resistore dovider 330/1200k)
- How can I measure the dV over the shount resistor?
- No, FLTP PIN Is High
You really need a dual channel scope for faul-finding circuits like this.
My small DSO TC3 wont be enough, isn't?
I Wil try the change the CUS with SS14 of 1N... (Mentioned before....
There is no D5.
I see two D4s, how were you able to do that and create a PCB?