ZHCSKF4C March 2017 – October 2019 LMH1228
PRODUCTION DATA.
IN0 has a signal detect circuit to monitor the presence or absence of an input signal. When the input signal amplitude for the selected input exceeds the signal detect assert threshold, the LMH1228 operates in normal operation mode.
In the absence of an input signal, the LMH1228 automatically goes into Power Save Mode to conserve power dissipation. When a valid signal is detected, the LMH1228 automatically exits Power Save Mode and returns to the normal operation mode. If the ENABLE pin is pulled low, the LMH1228 is forced into Power-Down Mode. In Power Save Mode, both the signal detect circuit and the serial interface remain active. In Power-Down Mode, only the serial interface remains active.
Users can monitor the status of the signal detect through register programming. This can be done either by configuring the LOCK_N pin to output the SD_N status or by monitoring the signal detect status register.
| ENABLE | SIGNAL INPUT | OPERATING MODE |
|---|---|---|
| H | 100-Ω signal input at IN0± | Normal operation
Signal Detector at IN0± Serial interface active |
| H | No signal at IN0± | Power Save Mode
Signal Detector at IN0± Serial interface active |
| L | Input signal ignored | Power-Down Mode
Forced device power down Serial interface active |