A low voltage detect circuit is provided herein for detecting when an
external voltage (Vext) drops below a predetermined minimum voltage. In
general, the low voltage detect circuit described herein may be
configured to detect a low voltage condition based on a threshold voltage
difference between a non-zero threshold transistor having a substantially
non-zero threshold voltage, and a zero threshold transistor having a
threshold voltage relatively close to zero. According to a particularly
advantageous aspect of the invention, the low voltage detect circuit
described herein comprises substantially no resistors or reference
voltage generation circuits, and therefore, provides significant savings
in both current and die area consumption without sacrificing accuracy.
The low voltage detect circuit of the present invention is particularly
useful in power regulators, such as those used in memory systems or
devices.