Electronic Components Datasheet Search |
|
AD8500 Datasheet(PDF) 18 Page - Analog Devices |
|
|
AD8500 Datasheet(HTML) 18 Page - Analog Devices |
18 / 24 page AD8546/AD8548 Data Sheet Rev. B | Page 18 of 24 OUTPUT STAGE The AD8546/AD8548 feature a complementary output stage consisting of the M16 and M17 transistors (see Figure 61). These transistors are configured in a Class AB topology and are biased by the voltage source, VB2. This topology allows the output voltage to go within millivolts of the supply rails, achieving a rail-to-rail output swing. The output voltage is limited by the output imped- ance of the transistors, which are low RON MOS devices. The output voltage swing is a function of the load current and can be estimated using the output voltage to supply rail vs. load current graphs (see Figure 15, Figure 16, Figure 18, and Figure 19). RAIL-TO-RAIL INPUT AND OUTPUT The AD8546/AD8548 feature rail-to-rail input and output with a supply voltage from 2.7 V to 18 V. Figure 62 shows the input and output waveforms of the AD8546/AD8548 configured as a unity- gain buffer with a supply voltage of ±9 V and a resistive load of 1 MΩ. With an input voltage of ±9 V, the AD8546/AD8548 allow the output to swing very close to both rails. Additionally, the AD8546/AD8548 do not exhibit phase reversal. TIME (200µs/DIV) VSY = ±9V RL = 1MΩ INPUT OUTPUT Figure 62. Rail-to-Rail Input and Output RESISTIVE LOAD The feedback resistor alters the load resistance that an amplifier sees. Therefore, it is important to carefully select the value of the feedback resistors used with the AD8546/AD8548. The amplifiers are capable of driving resistive loads down to 100 kΩ. The Inverting Op Amp Configuration section and the Noninverting Op Amp Configuration section show how the feedback resistor changes the actual load resistance seen at the output of the amplifier. Inverting Op Amp Configuration Figure 63 shows the AD8546/AD8548 in an inverting config- uration with a resistive load, RL, at the output. The actual load seen by the amplifier is the parallel combination of the feedback resistor, R2, and the load, RL. For example, the combination of a feedback resistor of 1 kΩ and a load of 1 MΩ results in an equivalent load resistance of 999 Ω at the output. Because the AD8546/AD8548 are incapable of driving such a heavy load, performance degrades greatly. To avoid loading the output, use a larger feedback resistor, but consider the effect of resistor thermal noise on the overall circuit. AD8546/ AD8548 R1 R2 RL –VSY RL, EFF = RL || R2 +VSY VIN VOUT Figure 63. Inverting Op Amp Configuration Noninverting Op Amp Configuration Figure 64 shows the AD8546/AD8548 in a noninverting config- uration with a resistive load, RL, at the output. The actual load seen by the amplifier is the parallel combination of R1 + R2 and RL. R1 R2 RL –VSY RL, EFF = RL || (R1 + R2) +VSY VIN VOUT AD8546/ AD8548 Figure 64. Noninverting Op Amp Configuration |
Similar Part No. - AD8500 |
|
Similar Description - AD8500 |
|
|
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 |