The L4987 is a very low drop regulator available
in PPAK. The very low drop-voltage (0.5V Max at
200 mA) and the very low quiescent current make
it particularly suitable for low noise, low power
applications, and in battey powered systems. The
input dump protection up to 40V makes it ideal for
automotive applications. a shutdown Logic
Control function is available (pin2, TTL
compatible). This means that when the device is
used as a local regulator, it is possible to put a
part of the boad in standby, decreasing the total
power consumption. The regulator employs an
output pin (open collector) providing a logic signal
when the pass transistor is in saturation at low
input voltage, this signal can be used to prevent
the pop-up phenomenon in the car radio. In
battery powered systems (the cellular phone,
notebook) it is possible to use the flag to monitor
the battery charge status through the dropout of
the regulator.