LT1467L 데이터 시트보기 (PDF) - Linear Technology
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LT1467L Datasheet PDF : 12 Pages
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LT1466L/LT1467L
APPLICATIONS INFORMATION
I1 then flows through Q5 to the current mirror D3-Q6,
furnishing the tail current for the NPN differential pair
Q3-Q4. The switchover point between stages occurs when
VCM is equal to the base voltage of Q5, which is biased
approximately 1.3V below the positive supply.
The collector currents of the two input pairs are combined
in the second stage, consisting of Q7-Q11. Most of the
voltage gain in the amplifier is contained in this stage. The
output of the second stage is buffered and applied to the
output devices Q12 and Q13. Capacitors C1 and C2 form
local feedback loops around the output devices, lowering
the output impedance at high frequencies. Capacitor CC
sets the amplifier bandwidth.
Input Offset Voltage
Since the amplifier has two input stages, the input offset
voltage changes depending upon which stage is active.
When the amplifier switches between stages, the offset
voltage may go up, down or remain flat. Both stages of the
LT1466L/LT1467L are trimmed; one at the negative sup-
ply and the other at the positive supply. The resulting
common mode rejection ratio of 83dB minimum is much
better than typical rail-to-rail amplifiers.
Overdrive Protection
The LT1466L/LT1467L contain circuits that prevent the
output from reversing polarity when the input voltage
exceeds either supply. For these circuits to work properly,
the input current should be limited to –10mA when the
input is below the negative supply, and 0.5mA when the
input is above the positive supply. If the amplifier is to be
severely overdriven, an external resistor should be used to
limit the current.
Output
The output voltage swing and current sinking capability of
the LT1466L/LT1467L are affected by input overdrive as
shown in the Typical Performance Characteristics. When
monitoring voltages within 100mV of either rail, gain
should be taken to keep the output from clipping.
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