データシートサーチシステム |
|
AD204JN データシート(PDF) 7 Page - Analog Devices |
|
AD204JN データシート(HTML) 7 Page - Analog Devices |
7 / 12 page REV. D AD202/AD204 –7– FREQUENCY – Hz 180 10 160 140 120 100 80 60 40 20 50 60 100 200 500 1k 2k 5k G = 100 G = 1 R LO = 10k R LO = 500 R LO = 0 R LO = 0 R LO = 10k Figure 10b. AD202 Dynamics and Noise. Frequency response plots for the AD202 and AD204 are given in Figure 11. Since neither isolator is slew- rate limited, the plots apply for both large and small signals. Capacitive loads of up to 470 pF will not materially affect fre- quency response. When large signals beyond a few hundred Hz will be present, it is advisable to bypass –VISO and +VISO to IN COM with 1 mF tantalum capacitors even if the isolated supplies are not loaded. At 50 Hz/60 Hz, phase shift through the AD202/AD204 is typically 0.8 ∞ (lagging). Typical unit to unit variation is ±0.2∞ (lagging). FREQUENCY – Hz 10 60 –40 20 50 100 200 500 1k 2k 5k 40 20 0 –20 10k 20k AD204 AD202 AMPLITUDE RESPONSE PHASE RESPONSE (G = 1) 0 –50 –100 Figure 11. Frequency Response at Several Gains The step response of the AD204 for very fast input signals can be improved by the use of an input filter, as shown in Figure 12. The filter limits the bandwidth of the input (to about 5.3 kHz) so that the isolator does not see fast, out-of-band input terms that can cause small amounts ( ±0.3%) of internal ringing. The AD204 will then settle to ±0.1% in about 300 ms for a 10 V step. AD204 3.3k 0.01 F VS Figure 12. Input Filter for Improved Step Response Except at the highest useful gains, the noise seen at the output of the AD202 and AD204 will be almost entirely comprised of carrier ripple at multiples of 25 kHz. The ripple is typically 2 mV p-p near zero output and increases to about 7 mV p-p for outputs of ±5 V (1 MHz measurement bandwidth). Adding a capacitor across the output will reduce ripple at the expense of bandwidth: for example, 0.05 mF at the output of the AD204 will result in 1.5 mV ripple at ±5 V, but signal bandwidth will be down to 1 kHz. When the full isolator bandwidth is needed, the simple two-pole active filter shown in Figure 13 can be used. It will reduce ripple to 0.1 mV p-p with no loss of signal bandwidth, and also serves as an output buffer. An output buffer or filter may sometimes show output spikes that do not appear at its input. This is usually due to clock noise appearing at the op amp’s supply pins (since most op amps have little or no supply rejection at high frequencies). Another com- mon source of carrier-related noise is the sharing of a ground track by both the output circuit and the power input. Figure 13 shows how to avoid these problems: the clock/supply port of the isolator does not share ground or 15 V tracks with any signal circuits, and the op amp’s supply pins are bypassed to signal common (note that the grounded filter capacitor goes here as well). Ideally, the output signal LO lead and the supply com- mon meet where the isolator output is actually measured, e.g., at an A/D converter input. If that point is more than a few feet from the isolator, it may be useful to bypass output LO to sup- ply common at the isolator with a 0.1 mF capacitor. In applications where more than a few AD204s are driven by a single clock driver, substantial current spikes will flow in the power return line and in whichever signal out lead returns to a low impedance point (usually output LO). Both of these tracks should be made large to minimize inductance and resistance; ideally, output LO should be directly connected to a ground plane which serves as measurement common. Current spikes can be greatly reduced by connecting a small inductance (68 mH–100 mH) in series with the clock pin of each AD204. Molded chokes such as the Dale IM-2 series, with dc resistance of about 5 W, are suitable. AD202 OR AD204 10k 2200pF 10k 1000pF AD711 1.0 F 1.0 F POINT OF MEASUREMENT AD246 (IF USED) POWER SUPPLY –15V C +15V + + Figure 13. Output Filter Circuit Showing Proper Grounding (NOTE: Circuit figures shown on this page are for SIP-style packages. Refer to Page 3 for proper DIP package pinout.) |
同様の部品番号 - AD204JN |
|
同様の説明 - AD204JN |
|
|
リンク URL |
プライバシーポリシー |
ALLDATASHEET.JP |
ALLDATASHEETはお客様のビジネスに役立ちますか? [ DONATE ] |
Alldatasheetは | 広告 | お問い合わせ | プライバシーポリシー | リンク交換 | メーカーリスト 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 |