TPS3610: TPS3610 Design Guidelines

Priyanka,

Do you want to be able to force the device into batty-backup mode from normal operation? If this is the case, MSWITCH should be connected to VDD otherwise if not being used connect MSWITCH to GND.

The rest of the pins are as shown in the datasheet configuration for typical operating circuit.

Vbat should be connected directly to the battery and will automatically switch over if Vdd fails.

This device has chip enable input and output along with battery status outputs, manual reset feature, and watchdog timer. You might also want to consider the more basic battery-backup supervisor TPS3613 or TPS3617. These are battery-backup supervisors with less features/extra pins. What is your application?

-Michael

Thank you Michael. We are using the chip in a Battery Backup mode. We have connected the battery through 0 ohm resistor and diode DB27314 to Vbat input. I wanted to know if it is ok to keep unused pins of TPS3610U18PWR OPEN ? because WDI, BATTOK, BATTON, NRESET and NLL pins are left open in our application. What is the recommended levels of this pins ?

Thanks,
Priyanka

Also the MSWITCH is connected to GND is it correct. As per your comment it looks like MSWITCH should be connected to VDD for Battery Backup mode.

Priyanka,

If MSWITCH is connected to VDD, the device will switch from normal operation to battery-backup mode. If PFI (power fail input) is being unused, connect PFI to GND and leave /PFO unconnected. If you want to operate in only battery-backup mode and disable manual switchover feature (MSWITCH) then you must connect MSWITCH to GND. If Watchdog feature is unused, leave WDI pin unconnected. The Chip-enable (/CEIN) pin should be connected to the Chip-enable pin of the microcontroller you are connecting this device to. This feature prevents any data from being written if the supply voltage is low (and device is in reset condition). If you aren't using the chip-enable, I recommend you choose a voltage supervisor device without Chip-enable gating feature otherwise connect this pin to logic high which will always writes data regardless of reset condition (this may be undesirable - depends on your application).

-Michael

Thank you Michael. I am just worried that open unused pins may cause current consumption which is what I observed on our board. Also above pins seems to be connected correctly only BATTOK, BATTON, LL and WDI are left unconnected/open.

For PFI input we have 820k and 270K resistors both 1% in voltage divider connected to 5V supply which applies 4.644V to PFI however VCC is 3.3 V should it be ok?

Priyanka,

Yes that should work fine. Since you have so many features unused, you might want to look into another device like previously mentioned. This could make your system more efficient and cheaper. Like TPS3617 for example.

-Michael

Thank you Michael. I will recommend the part to our team. Thank you again for your time and consideration.

Regards,
Priyanka