ADP5090

I am working with ADP5090 -2-EVALZ to generate voltage using Teg(SP1848) as a input source. The issue i am facing is with Cold start voltage i.e 380 mV ,the output only generates if my TEG provides input voltage greater than 380 mV.i used external battery to bypass this as you mentioned in data sheet.i connected 400mV dc supply to Back_up battery terminal acting as battery.but still no output was coming to my Vout(sys pin).My super cap voltage was 1.48v at that time.Why the output is not coming at my Vout ?.like it gives when input voltage reaches above 380 mV. The super cap i am using is 5v/2.5f.

• so isn't there any mechanism provided in the Chip itself to stop the flow of current from output to input ? when output is high and input is low.or we have to provide external switches or diodes to do so ?

• There is no current flowing from output to input. All the input energy would be charged to output. What here I mean is the rest of energy would be charged to BAT only when the input power is higher than output power.

• sir i need answer to following question as it is creating too much confusion here :

1. In the datasheet you have mentioned that
Input voltage operation range from 80 mV to 3.3 V . After
cold startup, the regulator is functional at an input voltage range
of 80 mV to 3.3 V.

but once the cold start condition occur after that if i reduce the input below 380 mV m not getting the Vout why?

2. Regarding back_up voltage how much exact  back_up voltage is required to bypass cold start. and get 3.3 V?

3. What will be the Back_up battery current consumption?

• 1. I tried with 90mV DC supply and the output can be run at 3.6V as the TERM threshold setting. Did you in series any resistance between supply and PVIN? That would limit the power and actually cannot sustain the output  voltage. Also MINOP function can help not switch if the MPPT voltage is lower than MINOP threshold.

2. It depends on the load current. More than 2.9V is more safe for bypassing cold start. it's better to use PGOOD to enable the system load.

3. if there is no any load current, the back_up battery power consumption is around quiescent current at SYS pin like 500nA.

• i did the following Testing on the ADP5090-2-EVALZ Board ,by setting the Output Voltage to 3.3 V in the setting i got the following results ,the output is not even reaching 3.3V ,but when selected 3.5V ia am getting 3.5V max output.what can be the reason.

Kept the input voltage constant and varied the backup voltage:

 input voltage(mV) backup voltage(V) super cap voltage(mV) output voltage(V) 104 0 214 0 104 0.232 214 0 104 1.692 214 0 104 1.592 214 0 63 1.933 214 0 62 3.031 215 0 67 3.091 215 2.408 67 4.00 215 2.409

Tested same condition by keeping the back-up voltage 0V.Here increased the input voltage

 input voltage(V) backup voltage(v) super cap voltage(v) output voltage(V) 0.210 0 0.230 0 2.25 0 1.32 0 3 0 1.4 0 2.86 0 2 0 2.86 0 2.38 2.4 2.86 0 3.52 2.408 3.5 0 3.57 2.408

But when i tested by changing the Vout setting to 3.5V(Ldo bypass) at 2.86V input i was able to get 3.5 V as Vout.