 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
OPA2353UA2K5 Datasheet(PDF) 9 Page - Texas Instruments |
|
||||||||||||||||||||||||||||||
OPA2353UA2K5 Datasheet(HTML) 9 Page - Texas Instruments |
|
|
9 / 26 page  9 ® OPA353, 2353, 4353 A double-folded cascode adds the signal from the two input pairs and presents a differential signal to the class AB output stage. Normally, input bias current is approximately 500fA. However, large inputs (greater than 300mV beyond the supply rails) can turn on the OPA353’s input protection diodes, causing excessive current to flow in or out of the input pins. Momentary voltages greater than 300mV beyond the power supply can be tolerated if the current on the input pins is limited to 10mA. This is easily accomplished with an input resistor as shown in Figure 3. Many input signals are inherently current-limited to less than 10mA, therefore, a limiting resistor is not required. FEEDBACK CAPACITOR IMPROVES RESPONSE For optimum settling time and stability with high-imped- ance feedback networks, it may be necessary to add a feedback capacitor across the feedback resistor, RF, as shown in Figure 4. This capacitor compensates for the zero created by the feedback network impedance and the OPA353’s input capacitance (and any parasitic layout capacitance). The effect becomes more significant with higher impedance networks. FIGURE 3. Input Current Protection for Voltages Exceeding the Supply Voltage. RAIL-TO-RAIL OUTPUT A class AB output stage with common-source transistors is used to achieve rail-to-rail output. For light resistive loads (>10k Ω), the output voltage swing is typically ten millivolts from the supply rails. With heavier resistive loads (600 Ω to 10k Ω), the output can swing to within a few tens of milli- volts from the supply rails and maintain high open-loop gain. See the typical performance curves “Output Voltage Swing vs Output Current” and “Open-Loop Gain vs Output Voltage.” CAPACITIVE LOAD AND STABILITY OPA353 series op amps can drive a wide range of capacitive loads. However, all op amps under certain conditions may become unstable. Op amp configuration, gain, and load value are just a few of the factors to consider when determin- ing stability. An op amp in unity gain configuration is the most susceptible to the effects of capacitive load. The capacitive load reacts with the op amp’s output impedance, along with any additional load resistance, to create a pole in the small-signal response which degrades the phase margin. In unity gain, OPA353 series op amps perform well with large capacitive loads. Increasing gain enhances the amplifier’s ability to drive more capacitance. The typical performance curve “Small-Signal Overshoot vs Capacitive Load” shows performance with a 1k Ω resistive load. In- creasing load resistance improves capacitive load drive ca- pability. FIGURE 4. Feedback Capacitor Improves Dynamic Perfor- mance. It is suggested that a variable capacitor be used for the feedback capacitor since input capacitance may vary be- tween op amps and layout capacitance is difficult to determine. For the circuit shown in Figure 4, the value of the variable feedback capacitor should be chosen so that the input resistance times the input capacitance of the OPA353 (typically 9pF) plus the estimated parasitic layout capacitance equals the feedback capacitor times the feed- back resistor: RIN • CIN = RF • CF where CIN is equal to the OPA353’s input capacitance (sum of differential and common-mode) plus the layout capacitance. The capacitor can be varied until optimum performance is obtained. DRIVING A/D CONVERTERS OPA353 series op amps are optimized for driving medium speed (up to 500kHz) sampling A/D converters. However, they also offer excellent performance for higher speed converters. The OPA353 series provides an effective means of buffering the A/D’s input capacitance and resulting charge injection while providing signal gain. For applica- tions requiring high accuracy, the OPA350 series is recom- mended. 5k Ω OPAx353 10mA max V+ V IN V OUT I OVERLOAD OPA353 V+ V OUT V IN R IN R IN • CIN = RF • CF R F C L C IN C IN C F Where C IN is equal to the OPA353’s input capacitance (approximately 9pF) plus any parastic layout capacitance. |
Similar Part No. - OPA2353UA2K5 |
|
Similar Description - OPA2353UA2K5 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
