|
|
PDF LMV841 Data sheet ( Hoja de datos )
| Número de pieza | LMV841 | |
| Descripción | Wide Supply Range Operational Amplifier | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LMV841 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
December 2006
LMV841
CMOS Input, RRIO, Wide Supply Range Operational
Amplifier
General Description
The LMV841 is a low-voltage and low-power operational am-
plifier that operates from supply voltages from 2.7V to 12V
and has rail-to-rail input and output capability.
The LMV841 is a low offset voltage and low supply current
amplifier with MOS inputs, characteristics that make the
LMV841 ideal for sensor interface and battery powered ap-
plications.
The LMV841 is offered in the space saving 5-Pin SC70 pack-
age. This small package is an ideal solution for area con-
strained PC boards and portable electronics.
Features
Unless otherwise noted, typical values at TA = 25°C, V+ = 5V
■ Space saving 5-Pin SC70 package
■ Supply voltage range 2.7V to 12V
■ Guaranteed at 3.3V, 5V and ±5V
■ Low supply current
1 mA
■ Unity gain bandwidth
4.5 MHz
■ Open loop gain
100 dB
■ Input offset voltage
500 μV max
■ Input bias current
0.3 pA
■ CMRR
100 dB
■ Input voltage noise
20 nV/
■ Temperature range
–40°C to 125°C
■ Rail-to-rail input
■ Rail-to-rail output
Applications
■ High impedance sensor interface
■ Battery powered instrumentation
■ High gain amplifiers
■ DAC buffer
■ Instrumentation amplifiers
■ Active Filters
Typical Application
Active Band-pass Filter
20168372
© 2006 National Semiconductor Corporation 201683
www.national.com
1 page  
Note 9: Short circuit test is a momentary test.
Note 10: Number specified is the slower of positive and negative slew rates.
Connection Diagram
5-Pin SC70
Ordering Information
Package
5-Pin SC70
Part Number
LMV841MG
LMV841MGX
Top View
20168302
Package Marking
A97
Transport Media
1k Units Tape and Reel
3k Units Tape and Reel
NSC Drawing
MAA05A
5 www.national.com
5 Page 
Application Information
INTRODUCTION
The LMV841 is an operational amplifier with near-precision
specifications: low noise, low temperature drift, low offset and
rail-to-rail input and output.
The low supply current, a temperature range of −40°C to 125°
C, the 12V supply with CMOS input and the small SC70 pack-
age make this a unique op amp.
Possible applications include instrumentation, medical, test
equipment, audio and automotive applications.
The small SC70 package and the low supply current, 1 mA,
makes the LMV841 a perfect choice for portable electronics.
INPUT PROTECTION
The LMV841 has a set of anti-parallel diodes D1 and D2 be-
tween the input pins, as shown in Figure 1. These diodes are
present to protect the input stage of the amplifier. At the same
time, they limit the amount of differential input voltage that is
allowed on the input pins.
A differential signal larger than one diode voltage drop might
damage the diodes. The differential signal between the inputs
needs to be limited to ±300 mV or the input current needs to
be limited to ±10 mA.
Note that when the op amp is slewing, a differential input volt-
age exists that forward biases the protection diodes. This may
result in current being drawn from the signal source. While
this current is already limited by the internal resistors R1 and
R2 (both 130Ω), a resistor of 1 kΩ can be placed in the feed-
back path, or a 500Ω resistor can be placed in series with the
input signal.
20168351
FIGURE 1. Protection diodes between the input pins
INPUT STAGE
The input stage of this Amplifier exists of a PMOS and an
NMOS input pair to achieve a more than rail-to-rail input
range.
For input voltages close to the negative rail, only the PMOS
pair is active. Close to the positive rail, only the NMOS pair is
active.
For intermediate signals, the transition from PMOS pair to
NMOS pair will result in a very small offset shift, which ap-
pears at approximately 1 volt from the positive rail.
To reduce this small offset shift, the amplifier is trimmed dur-
ing production, resulting in an input offset voltage of less then
1mV at room temperature over the total input range.
CAPACITIVE LOAD
The LMV841 can be connected as a non-inverting unity-gain
amplifier. This configuration is the most sensitive to capacitive
loading.
The combination of a capacitive load placed on the output of
an amplifier along with the amplifier’s output impedance cre-
ates a phase lag, which reduces the phase margin of the
amplifier. If the phase margin is significantly reduced, the re-
sponse will be underdamped which causes peaking in the
transfer and when there is too much peaking the op amp might
start oscillating.
In order to drive heavier capacitive loads, an isolation resistor,
RISO, should be used, as shown in Figure 2. By using this
isolation resistor, the capacitive load is isolated from the
amplifier’s output, and hence, the pole caused by CL is no
longer in the feedback loop. The larger the value of RISO, the
more stable the output voltage will be. If values of RISO are
sufficiently large, the feedback loop will be stable, indepen-
dent of the value of CL. However, larger values of RISO result
in reduced output swing and reduced output current drive.
20168350
FIGURE 2. Isolating Capacitive Load
REDUCING OVERSHOOT
When the output of the op amp is at its lower swing limit (i.e.
saturated near V−), rapidly rising signals can cause some
overshoot.
This overshoot can be reduced by adding a resistor from the
output to V+. Even in extreme situations at high temperatures,
a 10k resistor is sufficient to reduce the overshoot to negligible
levels.
The resistor at the output will however reduce the maximum
output swing, as would any resistive load at the output.
DECOUPLING AND LAYOUT
Care must be taken when creating the board layout for the op
amp.
For decoupling of the supply lines 10 nF capacitors are sug-
gested to be placed as close as possible to the op amp.
For single supply, place a capacitor between V+ and V−. For
dual supplies, place one capacitor between V+ and the board
ground, and the second capacitor between ground and V−.
NOISE DUE TO RESISTORS
The LMV841 has good noise specifications, and will frequent-
ly be used in low noise applications. Therefore it is important
to take in account the influence of the resistors to the total
noise contribution.
For applications with a voltage input configuration it is, in gen-
eral, beneficial to keep the resistor values low. In these con-
figurations high resistor values mean high noise levels.
However, using low resistor values will increase the power
consumption of the application. This is not always acceptable
for portable applications.
11 www.national.com
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LMV841.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LMV841 | LMV841 CMOS Input RRIO Wide Supply Range Op Amps (Rev. G) |  Texas Instruments |
| LMV841 | Wide Supply Range Operational Amplifier | National Semiconductor |
| LMV841 | (LMV841 - LMV844) Wide Supply Range Operational Amplifiers | National Semiconductor |
| LMV842 | LMV841 CMOS Input RRIO Wide Supply Range Op Amps (Rev. G) | Texas Instruments |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |