Dear Team,
We are using the LTC4419 for switching between two power sources. The primary path is a battery of a type ER14250 (3.8V) and the secondary source is a battery of a type CR927 (3.0V).
The issue we have at the moment with the design is that when the primary battery is connected (secondary battery is disconnected), the LTC4419 will not output the power to the board.
We have investigated the issue by measuring the input voltage at the primary side to the IC and we have noticed that the input voltage drops to a value of 2.4V for a very short duration and it repeats at every 69.6ms intervals (please see attached files “Primary-Input-Voltage-1” and “Primary-Input-Voltage-2”).
In a condition where the primary battery voltage is above 1.55V and the ADJ (Adjustable V1 Switchover Threshold Input) voltage is above 1.097V the IC should output the primary battery voltage (based on the datasheet) but due to the short voltage drop on the primary input, the voltage at the ADJ input to the IC falls below the threshold value of 1.097V hence no output voltage. (please see attached files “ADJ-Voltage-1” and “ADJ-Voltage-2”)
To understand the issue more we have tested the design using different types of batteries and the results shows that the design works with batteries with small internal resistances. We have also tested the design using a bench power supply and the issue explained above was not observed and the design was fully functional.
What we would like to know is how we can configure the LTC4419 to work with batteries of the type ER14250 and CR927 that have higher internal resistances compared to other batteries such as Alkaline batteries.
Could you please provide your technical feedback and possible solutions to fix the issue?
Best regards,
Arash
