I'm using the LTC3130 for DC-DC conversion. It is powered by a hight power Lithium battery with 7V output. The PCB was designed according to the reference design with an output voltage of 3,4V, as required by our µC and modem. This circuit works well, and the power consumption from the battery is around 8µA.
To power the modem (short current peaks of up to 2A), and to stabilise the output power of the LTC3130, we installed two 3900µF capacitors at the output of the LTC3130 circuit. This works very well too, and the output voltage is very stable. The only problem that appears is during the switching on of the system, when the capacitors are empty. In that case, there appears a kind of "oscillation" of the LTC3130 circuit, where the output power stays at around 2,89V, and the power consumption from the battery is up to 480µA (instead of 3,4V and 8µA). On the other hand, when the two output capacitors are charged and we remove the input power for several seconds, we re-obtain the right values after re powering on the LTC3130.
It seams that the capacitive load needed by the modem to smooth the short peaks is causing a fault state at the LTC3130, from witch it can't exit itself (even after 2 days powered on). The only solution is to re interrupt shortly the input power from the battery after a first powering on needed to charge the capacitors. Has someone an idea, how to resolve this problem, because we couldn't verify the output voltage of all devices each time we want changing the batteries. Thanks for your help.
