Datasheet LTC1419 (Analog Devices) - 10
| Fabricante | Analog Devices |
| Descripción | 14-Bit, 800ksps Sampling A/D Converter with Shutdown |
| Páginas / Página | 20 / 10 — APPLICATIONS INFORMATION. LT®1220:. LT1223:. LT1227:. LT1229/LT1230:. … |
| Formato / tamaño de archivo | PDF / 270 Kb |
| Idioma del documento | Inglés |
APPLICATIONS INFORMATION. LT®1220:. LT1223:. LT1227:. LT1229/LT1230:. LT1360:. Figure 6. tACQ vs Source Resistance. LT1363:
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LTC1419
U U W U APPLICATIONS INFORMATION
that the amplifier driving the analog input(s) must settle
LT®1220:
30MHz unity-gain bandwidth voltage feedback after the small current spike before the next conversion amplifier. ±5V to ±15V supplies. Excellent DC specifica- starts (settling time must be 200ns for full throughput tions. rate).
LT1223:
100MHz video current feedback amplifier. ±5V 10 to ±15V supplies, 6mA supply current. Low distortion at frequencies above 400kHz. Low noise. Good for AC applications. µs) 1
LT1227:
140MHz video current feedback amplifier. ±5V to ±15V supplies, 10mA supply current. Lowest distor- tion at frequencies above 400kHz. Low noise. Best for AC 0.1 applications. ACQUISITION TIME (
LT1229/LT1230:
Dual/quad 100MHz current feedback amplifiers. ±2V to ±15V supplies, 6mA supply current 0.010.01 0.1 1 10 100 each amplifier. Low noise. Good AC specs. SOURCE RESISTANCE (kΩ) 1419 F06
LT1360:
50MHz voltage feedback amplifier. ±5V to ±15V supplies, 3.8mA supply current. Good AC and DC specs.
Figure 6. tACQ vs Source Resistance LT1363:
70MHz, 1000V/µs op amps, 6.3mA supply cur- rent. Good AC and DC specs.
Choosing an Input Amplifier LT1364/LT1365:
Dual and quad 70MHz, 1000V/ Choosing an input amplifier is easy if a few requirements µs op amps. 6.3mA supply current per amplifier. are taken into consideration. First, to limit the magnitude of the voltage spike seen by the amplifier from charging
Input Filtering
the sampling capacitor, choose an amplifier that has a low output impedance (< 100Ω) at the closed-loop band- The noise and the distortion of the input amplifier and width frequency. For example, if an amplifier is used in a other circuitry must be considered since they will add to gain of +1 and has a unity-gain bandwidth of 50MHz, then the LTC1419 noise and distortion. The small-signal band- the output impedance at 50MHz should be less than width of the sample-and-hold circuit is 20MHz. Any noise 100Ω. The second requirement is that the closed-loop or distortion products that are present at the analog inputs bandwidth must be greater than 20MHz to ensure will be summed over this entire bandwidth. Noisy input adequate small-signal settling for full throughput rate. If circuitry should be filtered prior to the analog inputs to slower op amps are used, more settling time can be minimize noise. A simple 1-pole RC filter is sufficient for provided by increasing the time between conversions. 50Ω 1 The best choice for an op amp to drive the LTC1419 will ANALOG INPUT +AIN depend on the application. Generally applications fall into 1000pF 2 two categories: AC applications where dynamic specifi- –AIN cations are most critical and time domain applications LTC1419 3 where DC accuracy and settling time are most critical. VREF The following list is a summary of the op amps that are 4 REFCOMP suitable for driving the LTC1419. More detailed informa- 10µF tion is available in the Linear Technology databooks, the 5 AGND LinearViewTM CD-ROM and on our web site at www.linear- 1419 F07 tech. com. LinearView is a trademark of Linear Technology Corporation.
Figure 7. RC Input Filter
1419fb 10
U U W U APPLICATIONS INFORMATION
that the amplifier driving the analog input(s) must settle
LT®1220:
30MHz unity-gain bandwidth voltage feedback after the small current spike before the next conversion amplifier. ±5V to ±15V supplies. Excellent DC specifica- starts (settling time must be 200ns for full throughput tions. rate).
LT1223:
100MHz video current feedback amplifier. ±5V 10 to ±15V supplies, 6mA supply current. Low distortion at frequencies above 400kHz. Low noise. Good for AC applications. µs) 1
LT1227:
140MHz video current feedback amplifier. ±5V to ±15V supplies, 10mA supply current. Lowest distor- tion at frequencies above 400kHz. Low noise. Best for AC 0.1 applications. ACQUISITION TIME (
LT1229/LT1230:
Dual/quad 100MHz current feedback amplifiers. ±2V to ±15V supplies, 6mA supply current 0.010.01 0.1 1 10 100 each amplifier. Low noise. Good AC specs. SOURCE RESISTANCE (kΩ) 1419 F06
LT1360:
50MHz voltage feedback amplifier. ±5V to ±15V supplies, 3.8mA supply current. Good AC and DC specs.
Figure 6. tACQ vs Source Resistance LT1363:
70MHz, 1000V/µs op amps, 6.3mA supply cur- rent. Good AC and DC specs.
Choosing an Input Amplifier LT1364/LT1365:
Dual and quad 70MHz, 1000V/ Choosing an input amplifier is easy if a few requirements µs op amps. 6.3mA supply current per amplifier. are taken into consideration. First, to limit the magnitude of the voltage spike seen by the amplifier from charging
Input Filtering
the sampling capacitor, choose an amplifier that has a low output impedance (< 100Ω) at the closed-loop band- The noise and the distortion of the input amplifier and width frequency. For example, if an amplifier is used in a other circuitry must be considered since they will add to gain of +1 and has a unity-gain bandwidth of 50MHz, then the LTC1419 noise and distortion. The small-signal band- the output impedance at 50MHz should be less than width of the sample-and-hold circuit is 20MHz. Any noise 100Ω. The second requirement is that the closed-loop or distortion products that are present at the analog inputs bandwidth must be greater than 20MHz to ensure will be summed over this entire bandwidth. Noisy input adequate small-signal settling for full throughput rate. If circuitry should be filtered prior to the analog inputs to slower op amps are used, more settling time can be minimize noise. A simple 1-pole RC filter is sufficient for provided by increasing the time between conversions. 50Ω 1 The best choice for an op amp to drive the LTC1419 will ANALOG INPUT +AIN depend on the application. Generally applications fall into 1000pF 2 two categories: AC applications where dynamic specifi- –AIN cations are most critical and time domain applications LTC1419 3 where DC accuracy and settling time are most critical. VREF The following list is a summary of the op amps that are 4 REFCOMP suitable for driving the LTC1419. More detailed informa- 10µF tion is available in the Linear Technology databooks, the 5 AGND LinearViewTM CD-ROM and on our web site at www.linear- 1419 F07 tech. com. LinearView is a trademark of Linear Technology Corporation.
Figure 7. RC Input Filter
1419fb 10