Electronic Components Datasheet Search |
|
SPT5510SIM Datasheet(PDF) 6 Page - Cadeka Microcircuits LLC. |
|
SPT5510SIM Datasheet(HTML) 6 Page - Cadeka Microcircuits LLC. |
6 / 8 page 6 9/27/00 SPT5510 The feedback resistor should be matched to RSET to reduce gain drift. Also, the op amp’s ground reference should be the same as RSET’s to reduce gain and offset errors. A com- posite amplifier may be required to obtain optimal dc perfor- mance. A differential circuit may be used; a common heat sink covering both sides (op amps and resistors) will help reduce temperature effects. Achieving good settling performance requires careful board layout with multiple decoupling circuits and very clean power and ground routing. It is important that digital switch- ing currents do not flow across analog input (REFIN) and output signals. Terminations must be broadband and near the device. Measuring settling performance is quite chal- lenging and requires several test systems to ensure settling errors from the instruments are not included. Dynamic performance characteristics (e.g., settling, rise and fall times, etc.) were measured with the outputs termi- nated to ground through 50 Ω resistors. SFDR was deter- mined using a transformer to convert the output from differ- ential to single-ended as shown in figure 5. The SPT5510 is designed primarily for step and settle or narrowband RF applications. The second harmonic generally dominates wideband SFDR measurements, although close-in spurs are very small. BANDGAP VOLTAGE REFERENCE The on-chip bandgap voltage reference is designed to bias the non-inverting input of the reference amplifier (AMPINB) through a resistor equal to RSET to help compensate the ref- erence amplifier (see the following section). If the bandgap voltage is required by another DAC, or elsewhere in the sys- tem, it must be buffered with a precision op amp configured as a high impedance (e.g., unity gain follower) buffer. A resistor, or RC filter, plus a ferrite bead will help isolate the output from the reference amplifier’s compensation and high-frequency charge pulses produced during operation. The output should always be very carefully checked for oscillations using a sensitive, wideband oscilloscope and spectrum analyzer. REFERENCE AMPLIFIER The reference amplifier is a highly temperature-stable driver to bias the precision current sinks. The reference amplifier should only be used to drive REFIN. Additional loads will change the amplifier’s compensation, which can lead to instability and other settling issues. There are two reference amplifier outputs: AMPOUT and AMPCC. AMPOUT has a 20 ohm series resistor between the output of the reference amplifier and the AMPOUT pin; AMPCC has a 10 ohm resistor. These parallel outputs aide compensation and decoupling. The open-loop output impedance is approximately 1200 ohms. Reference amplifier compensation is key to achieving high performance. Without proper compensation, oscillations that affect accuracy and settling time will occur. Figure 6 shows a typical reference amplifier compensation circuit. Note that several small value capacitors are used from REFIN to ground. This is to provide suitably low impedance IOUT 25 25 IOUT Figure 5 – Transformer Output Circuit Figure 6 – Reference Amplifier Circuit + – 20 Ω 10 Ω 19 20 AMPCC AMPOUT 50 Ω 15 VEE 20 pF 1 k Ω 1 k Ω RSET BGOUT 0.01 µF Ref Amp C1 C2 C3 47 pF each SPT5510 DAC 16 18 17 21 10 pF 0.01 µF All components are ceramic chip-type. AMPB REFIN |
Similar Part No. - SPT5510SIM |
|
Similar Description - SPT5510SIM |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |