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TLV2472CD

Part # TLV2472CD
Description DUAL OPAMP LOW POWER RAIL TORAIL I/O - Rail/Tube
Category IC
Availability In Stock
Qty 75
Qty Price
1 - 15 $1.35464
16 - 31 $1.07755
32 - 47 $1.01598
48 - 63 $0.94414
64 + $0.84152
Manufacturer Available Qty
Texas Instruments
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Texas Instruments
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Technical Document


DISCLAIMER: The information provided herein is solely for informational purposes. Customers must be aware of the suitability of this product for their application, and consider that variable factors such as Manufacturer, Product Category, Date Codes, Pictures and Descriptions may differ from available inventory.

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
16
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
APPLICATION INFORMATION
general configurations
When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often
required. The simplest way to accomplish this is to place an RC filter at the noninverting terminal of the amplifier
(see Figure 44).
V
I
V
O
C1
+
-
R
G
R
F
R1
f
3dB
+
1
2pR1C1
V
O
V
I
+ ǒ 1 )
R
F
R
G
Ǔ
ǒ
1
1 ) sR1C1
Ǔ
Figure 44. Single-Pole Low-Pass Filter
If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this
task. For best results, the amplifier should have a bandwidth that is 8 to 10 times the filter frequency bandwidth.
Failure to do this can result in phase shift of the amplifier.
V
I
C2
R2R1
C1
R
F
R
G
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
(
=
1
Q
2 -
)
R
G
R
F
_
+
f
3dB
+
1
2pRC
Figure 45. 2-Pole Low-Pass Sallen-Key Filter
shutdown function
Three members of the TLV247x family (TLV2470/3/5) have a shutdown terminal for conserving battery life in
portable applications. When the shutdown terminal is tied low, the supply current is reduced to 350 nA/channel,
the amplifier is disabled, and the outputs are placed in a high impedance mode. To enable the amplifier, the
shutdown terminal can either be left floating or pulled high. When the shutdown terminal is left floating, care
should be taken to ensure that parasitic leakage current at the shutdown terminal does not inadvertently place
the operational amplifier into shutdown. The shutdown terminal threshold is always referenced to V
DD
/2.
Therefore, when operating the device with split supply voltages (e.g. ±2.5 V), the shutdown terminal needs to
be pulled to V
DD
- (not GND) to disable the operational amplifier.
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
17
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
APPLICATION INFORMATION
shutdown function (continued)
The amplifiers 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 amplifiers forward and reverse isolation in shutdown. The operational amplifier is
powered by ±1.35-V supplies and configured as a voltage follower (A
V
= 1). The isolation performance is plotted
across frequency using 0.1-V
PP
, 1.5-V
PP
, and 2.5-V
PP
input signals. During normal operation, the amplifier
would not be able to handle a 2.5-V
PP
input signal with a supply voltage of ±1.35 V since it exceeds the
common-mode input voltage range (V
ICR
). 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.
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
18
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
APPLICATION INFORMATION
general PowerPAD design considerations
The TLV247x is available in a thermally-enhanced PowerPAD family of packages. These packages are
constructed using a downset leadframe upon which the die is mounted [see Figure 46(a) and Figure 46(b)]. This
arrangement results in the lead frame being exposed as a thermal pad on the underside of the package [see
Figure 46(c)]. Because this thermal pad has direct thermal contact with the die, excellent thermal performance
can be achieved by providing a good thermal path away from the thermal pad.
The PowerPAD package allows for both assembly and thermal management in one manufacturing operation.
During the surface-mount solder operation (when the leads are being soldered), the thermal pad can also be
soldered to a copper area underneath the package. Through the use of thermal paths within this copper area,
heat can be conducted away from the package into either a ground plane or other heat dissipating device.
The PowerPAD package represents a breakthrough in combining the small area and ease of assembly of
surface mount with the, heretofore, awkward mechanical methods of heatsinking.
DIE
Side View (a)
End View (b) Bottom View (c)
DIE
Thermal
Pad
NOTE A: The thermal pad is electrically isolated from all terminals in the package.
Figure 46. Views of Thermally Enhanced DGN Package
Although there are many ways to properly heatsink the PowerPAD package, the following steps illustrate the
recommended approach.
68 mils x 70 mils) with 5 vias
(Via diameter = 13 mils
78 mils x 94 mils) with 9 vias
(Via diameter = 13 mils)
Thermal Pad Area
Single or Dual
Quad
Figure 47. PowerPAD PCB Etch and Via Pattern
PowerPAD is a trademark of Texas Instruments Incorporated.
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