After we finish updating our website, you will be able to set your cookie preferences. AuthorĪnalog Devices is in the process of updating our website. Isolation of the data acquisition function from the processor support is important for elimination of grounding errors and safety hazards and is readily provided by the LTM2883 SPI isolator module. The 12V units are measured by summing the readings of three input channels that have been hardware configured to split the 12V into sub-measurements, thus achieving an effective full-scale range of 16.1V for each battery. The LTC6803 provides a flexible solution for telecom battery stack measurement, including stacks using 12V lead-acid batteries. The LTM2883 also provides isolated DC power rails that can furnish several hundred mW if needed. Voltage-divider structure for each 12V battery measurement.Īn LTM2883 SPI data isolator is used so that the circuit accommodates any grounding differential with respect to the associated microprocessor circuitry. In this way, each channel is converting a 4V nominal potential.įigure 2. Here the cell-balancing controls (S N output discharge switches) are re-purposed to continually activate voltage dividers using external 10k resistors by setting all DCC configuration bits to 1. Each battery potential is acquired by summing triplets of input channel readings (C N inputs). Since the ADC range for an individual LTC6803 input channel maxes out at 5.37V, divider networks are used to spread each 12V battery potential across three channels. Ideally, these batteries should be measured by circuitry that is independent of the relative grounding between the batteries and the central-office equipment, thus Galvanic isolation is desirable. Regardless of cell chemistry, all the measuring potentials are below ground or possibly floating during maintenance procedures. Although the LTC6803 is ostensibly designed to monitor lithium-based battery systems, it can just as well be used to support traditional –48V lead-acid battery stacks. The LTC6803 is designed to measure and digitize individual cell potentials in large lithium cell stacks with total potentials beyond 60V (surviving surges to 75V). ![]() Enter the LTC6803 multicell battery stack monitor. ![]() In fact, although stacking batteries is easy, it can be difficult to build a monitoring system that can measure and digitize both the condition of individual cells, and monitor the high voltage potential of the combined cells. These power backup systems traditionally comprise four 12V lead-acid batteries in series, though newer lithium cell technology promises to make inroads as systems are updated.Įvery battery backup system must be continually monitored for the charge state and health of the batteries. Telcos typically use –48V power, with backup power supplied by large battery arrays to carry the system through utility outages. Telecommunications infrastructure has always been powered by voltages that are negative with respect to ground to minimize corrosion in buried cable. Simple Circuit Monitors Health of –48V Telecom Lead-Acid Battery Backup Systems
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