LT6703-2/LT6703-3
LT6703HV-2/LT6703HV-3
11
670323fd
APPLICATIONS INFORMATION
Comparator Input
The comparator input can range from ground to 18V (36V
for LT6703HV), regardless of the supply voltage used. The
typical input current for inputs well above the threshold
(i.e., >800mV) is a few pA leaking into the input. With
decreasing input voltage, a small bias current begins
to be drawn out of the input, reaching a few nA when at
ground potential. The input may be forced 100mV below
ground without causing an improper output, though some
additional bias current will begin to fl ow from the ESD
input protection diode. Inputs driven further negative than
100mV below ground will not cause damage provided the
current is limited to 10mA.
Comparator Output
The comparator output is open collector and capable of
sinking 40mA typical. Load currents are directed out of
the GND pin of the part. The output off-state voltage may
range between –0.3V and 18V (36V for LT6703HV) with
respect to ground, regardless of the supply voltage used.
When the output high state bias voltage is above 18V, a
100k minimum pull-up resistor is required and no total load
capacitor greater than 100nF should be used. If the output
high state is above 18V, caution has to be taken to prevent
a short from the output directly to the bias voltage, even
if the output is in the off state. As with any open-collector
device, the outputs of multiple comparators may be tied
together to implement wire-AND logic functions.
Power Supplies
The comparator circuitry operates from a single 1.4V
to 18V supply. A minimum 0.1μF bypass capacitor is
required between the V
S
pin and GND. When an output
load is connected to the supply rail near the part and the
output is sinking more than 5mA, a 1μF bypass capacitor is
recommended. In instances where the supply is relatively
“soft” (such as with small batteries) and susceptible to
load steps, an additional 47Ω series decoupling resistor
can further improve isolation of supply transients from
the V
S
pin.
