LT1457 Linear Technology, LT1457 Datasheet - Page 6

• Manufacturer Part Number: LT1457
• Description: Dual/ Precision JFET Input Op Amp
• Manufacturer: Linear Technology

APPLICATIONS
LT1457
TYPICAL PERFORMANCE CHARACTERISTICS
Phase Reversal Protection
Most industry standard JFET input single, dual, and quad
op amps (e.g., LF156, LF351, LF353, LF411, LF412,
OP-15, OP-16, OP-215, and TL084) exhibit phase reversal
at the output when the negative common-mode limit at the
input is exceeded (i.e., below –12V with 15V supplies).
The photos show a 16V sine wave input (A), the response
6
(A) 16V Sine Wave Input
Large-Signal Response
A
V
= 1, C
L
= 100pF
U
INFORMATION
LT1457 AI01
U
W
LT1457 TPC19
All Photos 5V/Div Vertical Scale, 50 s/Div Horizontal Scale
U
W
Small-Signal Response
A
U
V
= 1, C
(B) LF412A Output
L
= 1000pF
of an LF412A in the unity gain follower mode (B), and the
response of the LT1457 (C).
The phase reversal of photo (B) can cause lock-up in servo
systems. The LT1457 does not phase-reverse due to a
unique phase reversal protection circuit.
LT1457 AI02
LT1457 TPC20
Small-Signal Response
A
V
= 1, C
(C) LT1457 Output
L
= 10,000pF
LT1457 TPC21
LT1457 AI03