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3V lithium coin cell battery backup – CR1220
Battery holder will accept CR1216, CR1220, or CR1225
Absolute Maximum Ratings
DC Input …………………………………+4.2V to + 27V
Power ……….………………………………………1000mW
RS485 EIA/TIA-485 Differential half-duplex
Maximum ………………….………… +/-14V
RS232 EIA/TIA-232
Rx ….….……………….………..…… +/- 25V
TX ……..…………………….….…… +/- 13.2V
EIA/TIA-562 TTL Line Buffered (non-inverting)
Input Maximum ……………...….……5.5V
Output ………………….………………….3.3V
Logic Low …………….………0.4V (16mA)
Logic High……………………2.4V (-16mA)
Serial baud rate …………………… 9600 - 230400 [115200 baud is recommended]