LT1716 Linear Technology, LT1716 Datasheet - Page 9

• Manufacturer Part Number: LT1716
• Description: Precision Rail-to-Rail Comparator
• Manufacturer: Linear Technology

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DataSheet
APPLICATIO S I FOR ATIO
The LT1716 comparator features low power operation
with exceptional input precision with rail-to-rail input and
output swing. The comparator operates flawlessly even
when the inputs are pulled over the positive rail or below
the negative rail.
Supply Voltage
The LT1716 operates from 2.7V to 44V. The comparator
can be shut down by removing V
input bias current is typically less than 3nA, even if the
inputs are 44V above the negative supply. The LT1716 is
protected against reverse battery voltages of up to 20V.
The reverse battery current is resistive as shown in the
reverse supply current graph.
Inputs
The comparator inputs can swing from 0.5V above to 44V
above V
can be forced up to 5V below V
occuring at the output.
The LT1716 has three stages—NPN, PNP and common
base (see Simplified Schematic)—resulting in three dis-
tinct operating regions and two transition regions as
shown in the Input Bias Current vs Common Mode typical
performance curve.
For input voltages about 0.8V or more below V
input stage is active and the input bias current is typically
– 4nA. The PNP differential input stage will have bias
current that flows out of the device. With a differential
input voltage of even just 100mV or so, there will be zero
bias current into the higher of the two inputs, while the
current flowing out of the lower input will be twice the
measured bias current.
When the input voltage is about 0.5V or less from V
NPN state is operating and the input bias current is
typically 10nA. Increases in temperature will cause the
voltage at which operation switches from the PNP stage to
the NPN stage to move towards V
voltage of the NPN stage is untrimmed and is typically
500 V.
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–
. If one input is within this range, the other input
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without phase reversal
. In this condition, the
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. The input offset
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A Schottky diode in the collector of each NPN transistor of
the NPN input stage allows the LT1716 to operate with
either or both of its inputs above V
V
current is typically 4 A at room temperature. The input
offset voltage is typically 500 V when operating above V
The LT1716 will operate with its input 44V above V
regardless of V
The transition to the negative common mode input stage
occurs at 0.3V above V
stage is active. When the inputs are 0.3V below V
common base input stage is active in addition to the PNP
stage. The input bias current out of each input becomes
V
input falls below the negative supply. Internal resistors
protect the inputs for faults below the negative supply of
up to 5V without phase reversal. The built-in 5k resistor
limits the current at each input to 1mA at 5V below the
negative supply. External matched input resistors can be
added for increased voltage fault operation below the
negative supply but the maximum input current should be
kept under 1mA.
Input Protection
The inverting and noninverting input pins of the LT1716
have on-chip protection. ESD protection is provided to
prevent damage during handling. The input transistors
have voltage clamping and limiting resistors to protect
against excursions as much as 5V below V
clamping diodes between the inputs and the maximum
differential input voltage is 44V.
Output
The output stage of the LT1716 can drive loads connected
to a supply more positive than the device, the same as
comparators with open collector output stages. The out-
put of the LT1716 can be pulled up to 44V above V
regardless of V
IN
+
, the NPN transistor is fully saturated and the input bias
/5k . The LT1716 is designed to operate when either
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.
–
. Above this trip point the PNP
+
. At about 0.3V above
–
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