LT1499CS(RevE) View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LT1499CS
(Rev.:RevE)
(Rev.:RevE)
Linear Technology
LT1499CS Datasheet PDF : 20 Pages
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TYPICAL PERFORMANCE CHARACTERISTICS
LT1498/LT1499
5V Small-Signal Response
5V Large-Signal Response
VS = 5V
200ns/DIV
AV = 1
VIN = 20mVP-P AT 50kHz
RL = 1k
14989 G27
±15V Small-Signal Response
VS = 5V
2μs/DIV
AV = 1
VIN = 4VP-P AT 10kHz
RL = 1k
14989 G28
±15V Large-Signal Response
VS = p15V
200ns/DIV
AV = 1
VIN = 20mVP-P AT 50kHz
RL = 1k
14989 G29
VS = p15V
2μs/DIV
AV = 1
VIN = 20VP-P AT 10kHz
RL = 1k
14989 G30
APPLICATIONS INFORMATION
Rail-to-Rail Input and Output
The LT1498/LT1499 are fully functional for an input and
output signal range from the negative supply to the posi-
tive supply. Figure 1 shows a simplified schematic of the
amplifier. The input stage consists of two differential am-
plifiers, a PNP stage (Q1/Q2) and an NPN stage (Q3/Q4)
which are active over different ranges of input common
mode voltage. A complementary common emitter output
stage (Q14/Q15) is employed allowing the output to swing
from rail-to-rail. The devices are fabricated on Linear
Technology’s proprietary complementary bipolar process
to ensure very similar DC and AC characteristics for the
output devices (Q14/Q15).
The PNP differential input pair is active for input common
mode voltages, VCM, between the negative supply to
approximately 1.3V below the positive supply. As VCM
moves further toward the positive supply, the transistor
(Q5) will steer the tail current, I1, to the current mirror
(Q6/Q7) activating the NPN differential pair, and the PNP
differential pair becomes inactive for the rest of the input
common mode range up to the positive supply.
The output is configured with a pair of complementary
common emitter stages that enables the output to swing
from rail to rail. Capacitors (C1 and C2) form local
feedback loops that lower the output impedance at high
frequencies.
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