On the Notecarrier XS V1.2, what are the specs for the battery we can connect to VBAT besides 3.7-4.4V?
Are there limits on capacity or max discharge?
Does the LIPO battery controller on Notecarrier XS prevent over/under charging?
We are also seeing different info about voltage input to the system.
If we are supplying +5V to Notecarrier and want to the Notecarrier XS LiPo Charger to maintain the battery, should we be connecting to +VUSB or +VESLOV?
Docs indicate to power via +VMAIN but schematics show a comparator (LM66200DRLR) and +VUSB/+VESLOV seem like the better place to supply power if we want the Notecarrier to maintain the battery. Can someone clarify? Thanks!
You can find the schematic for the Notecarrier XS v1.2, in the note-hardware repo, which should help with your design efforts!
Based on the datasheet for the BQ25628E Battery Charger, it’s designed for Li-ion and
Li-polymer batteries, with over/under voltage protection. From the datasheet I cannot see any limitations on battery capacity. RMS discharge current (continuously) 6 A is specified along with the Peak discharge current (up to 50 ms) of 10 A. It can supply a single-cell 2 A of charging current.
You can supply 5 V to either +VUSB or +VESLOV as they are OR’d together, but we would recommend using +VUSB as the +VESLOV JST connector will limit the current you can supply it (I believe 1 A is the limit).
+VMAIN is an output, so should not be used to power the system. Could you please point toward where you are seeing it suggested as an input? We’ll get that corrected!
Thanks Alex… we were having trouble finding a definitive explanation for VMAIN so we relied on Google AI which states VMAIN is an INPUT.
Thanks for answering all our questions. We’re slowly getting our prototypes working but we’ve been dogged by power issues the whole way. Some from noisy charge controllers, some from our own design issues and I guess just recently from plugging it in the wrong way round! Thanks. - Bill
From Google…
The VMAIN pin on a Blues Notecarrier refers to a power input pin that can be used to provide power to the Notecarrier and subsequently the Notecard. It is designed to accept a voltage range of 2.5V to 5.5V DC and is commonly used with DC power supplies or non-rechargeable batteries.
Key points about VMAIN on Blues Notecarriers:
Purpose: It provides a direct power input to the Notecarrier and the Notecard, especially in situations where USB power is not available.
Power Source: Typically used with DC power supplies or non-rechargeable batteries.
Voltage Range: Accepts 2.5V to 5.5V DC.
Current Requirements: Can require a significant amount of current, particularly during cellular communication (up to 2A surge for GSM networks).
Function on Notecarrier B v2.1: On the Notecarrier B v2.1, VMAIN is an output pin that provides a diode union of the VUSB, VBAT, and V+ sources.
Caution: When powering the Notecarrier through VMAIN, ensure you do not connect a USB power source or a battery to the JST connector simultaneously, to avoid potential conflicts.