TLV2470, TLV2471, TLV2472, TLV2473, TLV2474, TLV2475, TLV247xA
FAMILY OF 600−µA/Ch 2.8−MHz RAIL−TO−RAIL INPUT/OUTPUT
HIGH−DRIVE OPERATIONAL AMPLIFIERS WITH SHUTDOWN
SLOS232C - JUNE 1999 - REVISED AUGUST 2003
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
shutdown function (continued)
The amplifier’s output with a shutdown pulse is shown in Figures 33 and 34. The amplifier is powered with a
single 5-V supply and configured as a noninverting configuration with a gain of 5. The amplifier turnon and turnoff
times are measured from the 50% point of the shutdown pulse to the 50% point of the output waveform. The
times for the single, dual, and quad are listed in the data tables.
Figures 35 and 36 show the amplifier’s forward and reverse isolation in shutdown. The operational amplifier is
powered by ±1.35-V supplies and configured as a voltage follower (A
= 1). The isolation performance is plotted
across frequency using 0.1-V
, and 2.5-V
input signals. During normal operation, the amplifier
would not be able to handle a 2.5-V
input signal with a supply voltage of ±1.35 V since it exceeds the
common-mode input voltage range (V
). However, this curve illustrates that the amplifier remains in shutdown
even under a worst case scenario.
circuit layout considerations
To achieve the levels of high performance of the TLV247x, follow proper printed-circuit board design techniques.
A general set of guidelines is given in the following.
D Ground planes - It is highly recommended that a ground plane be used on the board to provide all
components with a low inductive ground connection. However, in the areas of the amplifier inputs and
output, the ground plane can be removed to minimize the stray capacitance.
D Proper power supply decoupling - Use a 6.8-µF tantalum capacitor in parallel with a 0.1-µF ceramic
capacitor on each supply terminal. It may be possible to share the tantalum among several amplifiers
depending on the application, but a 0.1-µF ceramic capacitor should always be used on the supply terminal
of every amplifier. In addition, the 0.1-µF capacitor should be placed as close as possible to the supply
terminal. As this distance increases, the inductance in the connecting trace makes the capacitor less
effective. The designer should strive for distances of less than 0.1 inches between the device power
terminals and the ceramic capacitors.
D Sockets - Sockets can be used but are not recommended. The additional lead inductance in the socket pins
will often lead to stability problems. Surface-mount packages soldered directly to the printed-circuit board
is the best implementation.
D Short trace runs/compact part placements - Optimum high performance is achieved when stray series
inductance has been minimized. To realize this, the circuit layout should be made as compact as possible,
thereby minimizing the length of all trace runs. Particular attention should be paid to the inverting input of
the amplifier. Its length should be kept as short as possible. This will help to minimize stray capacitance at
the input of the amplifier.
D Surface-mount passive components - Using surface-mount passive components is recommended for high
performance amplifier circuits for several reasons. First, because of the extremely low lead inductance of
surface-mount components, the problem with stray series inductance is greatly reduced. Second, the small
size of surface-mount components naturally leads to a more compact layout thereby minimizing both stray
inductance and capacitance. If leaded components are used, it is recommended that the lead lengths be
kept as short as possible.