OPA369 datasheet(9/20 Pages) TI

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APPLICATION INFORMATION

PROTECTING INPUTS FROM

OPERATING VOLTAGE

5kW

OPA369

10mAmax

OUT

OVERLOAD

Current-limitingresistor

requiredifinputvoltage

exceedssupplyrailsby

³ 0.5V.

INPUT COMMON-MODE VOLTAGE RANGE

OPA369

OPA2369

www.ti.com ............................................................................................................................................ SBOS414B – AUGUST 2007 – REVISED DECEMBER 2008

The

OPA369

family

operational

amplifiers

The input common-mode voltage range of the

minimizes power consumption and operates on

OPA369 family typically extends to each supply rail.

supply voltages as low as 1.8V. Power-supply

CMRR is specified from the negative rail to the

rejection ratio (PSRR), common-mode rejection ratio

positive rail. See Figure 4, Normalized Offset Voltage

(CMRR), and open-loop gain (AOL) typical values are

vs Common-Mode Voltage.

in the range of 100dB or better.

When designing for ultralow power, choose system

OVER-VOLTAGE

components

carefully.

minimize

current

consumption,

select

large-value

resistors.

Any

Input currents are typically 10pA. However, large

resistors will react with stray capacitance in the circuit

inputs (greater than 500mV beyond the supply rails)

and the input capacitance of the operational amplifier.

can cause excessive current to flow in or out of the

These parasitic RC combinations can affect the

input pins. Therefore, in addition to keeping the input

stability of the overall system. A feedback capacitor

voltage between the supply rails, it is also important

may

required

assure

stability

and

limit

to limit the input current to less than 10mA. This

overshoot or gain peaking.

limiting is easily accomplished with an input resistor,

as shown in Figure 24.

Good layout practice mandates the use of a 0.1

µF

bypass capacitor placed closely across the supply

pins.

OPA369 series op amps are fully specified and tested

from +1.8V to +5.5V (±0.9V to ±2.75V). Parameters

that vary significantly with supply voltage are shown

in the Typical Characteristic curves.

Figure 24. Input Current Protection for Voltages

The OPA369 family is designed to eliminate the input

Exceeding the Supply Voltage

offset transition region typically present in most

rail-to-rail

complementary

stage

operational

amplifiers, which allows the OPA369 family of

amplifiers

provide

superior

common-mode

performance over the entire input range.

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Product Folder Link(s): OPA369 OPA2369

OPA369 Datasheet(PDF) 9 Page - Texas Instruments

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