1 Features
• Wide high-side supply range: 3 V to 27 V
• Low-side supply range: 2.7 V to 5.5 V
• Adjustable threshold:
– Window-comparator mode: ±20 mV to ±300 mV
– Positive-comparator mode: 600 mV to 2.7 V
• Reference for threshold adjustment: 100 μA, ±1%
• Trip threshold error: ±1% (max) at 250 mV
• Open-drain output with optional latch mode
• Propagation delay: 280 ns (typ)
• High CMTI: 55 V/ns (min)
• Functional Isolation:
– Working voltage: 200 VRMS, 280 VDC
– Transient overvoltage (60 s): 570 VRMS, 800
VDC
• Small, 0.65-mm pitch, leadless package with 1-mm
creepage and clearance
• Fully specified over the extended industrial
temperature range: –40°C to +125°C

2 Applications
• Overcurrent or overvoltage detection in:
– Telecom power supplies
– Analog I/O modules
– Motor drives
– Frequency inverters

3 Description
The AMC21C12 is an isolated window comparator
with a short response time. The open-drain output
is galvanically isolated from the input circuitry by an
isolation barrier that is highly resistant to magnetic
interference. The isolation barrier supports a working
voltage up to 200 VRMS or 280 VDC and transient over
voltages of up to 570 VRMS or 800 VDC.
The comparison window is centered at 0 V, meaning
that the comparator trips if the absolute value of the
input voltage exceeds the trip threshold value. The
trip threshold is adjustable from 20 mV to 300 mV
through a single external resistor and, therefore, the
comparison window ranges from ±20 mV to ±300
mV. When the voltage on the REF pin is greater
than 550 mV, the negative comparator is disabled
and only the positive comparator is functional. The
reference voltage in this mode can be as high as
2.7 V. This mode is particularly useful for monitoring
voltage supplies.
The open-drain output on the device supports
transparent mode (LATCH input tied to GND2) where
the output follows the input state, or latch mode,
where the output is cleared on the falling edge of the
latch input signal.
The AMC21C12 is available in an 8-pin, 0.65-mm
pitch VSON package and is specified over the
extended industrial temperature range of –40°C to
+125°C.