MTX-H15 UMTS-HSDPA terminal modem | http://www.matrix.es |
3.6 Real Time Clock
The MTX-H15 contains a real time clock (RTC) to maintain accurate timekeeping and to enable “time stamping” of messages.
The RTC is powered with the signal VRTC present in pin 5 of the POWER CONNECTOR. See section 3.1.
The user must connect this pin to an external energy device like a battery or super-capacitor to provide back-up power to maintain the RTC. Example: If using a 300mF supercap the RTC can be maintain for at least 12 hours.
The internal Real Time Clock of MTX-H15 is supplied from a separate voltage regulator in the analog controller which is also active when MTX-H15 is in POWER DOWN status.
In addition, you can use the VRTC pin on the connector to backup the RTC from an external capacitor or a battery (rechargeable or non-chargeable). The capacitor is charged by the BATT+ line of internal HC15. If the voltage supply at BATT+ is disconnected the RTC can be powered by the capacitor.
The size of the capacitor determines the duration of buffering when no voltage is applied to MTX-H15, i.e. the larger the capacitor the longer MTX-H15 will save the date and time.
A serial 1kΩ resistor placed on the board next to VDDLP limits the charge current of an empty capacitor or battery.
The following figures show various sample configurations. Please refer to Table 26 for the parameters required.
The MTX-H15 can accommodate this battery or super-cap inside, and the MTX-H15 can be ordered with this special option by request. Please contact your sales nearest distributor.
MTX-H15 User Manual V.2.0Pag. 17 Preliminary. Subject to change without prior notice
