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Le79M576A
Metering Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
I Programmable constant-resistance feed I Programmable loop-detect threshold I Ground-key detect I Performs polarity reversal I Ring relay driver I Supports 2.
2 Vrms metering (12 and 16 kHz) I Line feed characteristics independent of battery variations I On-chip switching
regulator for low-power dissipation I Two-wire impedance set by single external impedance I Tip Open state for ground-start lines I On-hook transmission
BLOCK DIAGRAM
A(TIP) Ring Relay Driver Ground-Key Detector Input Decoder and Control VCCRING RINGOUT/DGND C1 C2 C3 E0 E1 HPB Two-Wire Interface DET Signal Transmission VTX...