 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC1857 Datasheet(PDF) 26 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC1857 Datasheet(HTML) 26 Page - Linear Technology |
|
|
26 / 40 page  LTC2358-16 26 Rev A For more information www.analog.com LTC6655-2.048offers0.025%(maximum)initialaccuracy and 2ppm/°C (maximum) temperature coefficient for high precision applications. The LTC6655-2.048 is fully speci- fied over the H-grade temperature range, complementing the extended temperature range of the LTC2358-16 up to 125°C.BypassingtheLTC6655-2.048witha2.7µFto100µF ceramic capacitor close to the REFIN pin is recommended. External Reference with Disabled Internal Buffer The internal reference buffer supports VREFBUF = 4.4V maximum. By grounding REFIN, the internal buffer may be disabled allowing REFBUF to be overdriven with an external reference voltage between 2.5V and 5V, as shown in Figure 9c. Maximum input signal swing and SNR are achieved by overdriving REFBUF using an external 5V reference. The buffer feedback resistors load the REFBUF pin with 13kΩ even when the reference buffer is disabled. The LTC6655-5 offers the same small size, accuracy, drift, and extended temperature range as the LTC6655-2.048, and achieves a typical SNR of 94.8dB when paired with the LTC2358-16. Bypass the LTC6655-5 to GND (Pin 20) close to the REFBUF pin with at least a 47μF ceramic ca- pacitor (X7R, 10V, 1210 size or X5R, 10V, 0805 size) to absorb transient conversion currents and minimize noise. The LTC2358-16 converter draws a charge (QCONV) from the REFBUF pin during each conversion cycle. On short time scales most of this charge is supplied by the external REFBUF bypass capacitor, but on longer time scales all of the charge is supplied by either the reference buffer, or when the internal reference buffer is disabled, the external reference. This charge draw corresponds to a DC current equivalentofIREFBUF=QCONV • fSMPL,whichisproportional to sample rate. In applications where a burst of samples is taken after idling for long periods of time, as shown in Figure 10, IREFBUF quickly transitions from approximately 0.4mA to 1.5mA (VREFBUF = 5V, fSMPL = 200kHz). This current step triggers a transient response in the external reference that must be considered, since any deviation in VREFBUFaffectsconverteraccuracy.Ifanexternalreference is used to overdrive REFBUF, the fast settling LTC6655 family of references is recommended. Internal Reference Buffer Transient Response Foroptimumperformanceinapplicationsemployingburst sampling, the external reference with internal reference bufferconfigurationshouldbeused.Theinternalreference buffer incorporates a proprietary design that minimizes movements in VREFBUF when responding to a burst of conversions following an idle period. Figure 11 compares the burst conversion response of the LTC2358-16 with an input near full scale for two reference configurations. The first configuration employs the internal reference buffer with REFIN externally overdriven by an LTC6655-2.048, while the second configuration disables the internal ref- erence buffer and overdrives REFBUF with an external LTC6655-4.096. In both cases REFBUF is bypassed to GND with a 47µF ceramic capacitor. INTERNAL REFERENCE BUFFER EXTERNAL REFERENCE ON REFBUF ±10.24V RANGE IN+ = 10V IN– = 0V TIME (µs) 0 100 200 300 400 500 –5.0 –2.5 0 2.5 5.0 7.5 10.0 235816 F11 Figure 11. Burst Conversion Response of the LTC2358-16, fSMPL = 200ksps APPLICATIONS INFORMATION CNV IDLE PERIOD IDLE PERIOD 235816 F10 Figure 10. CNV Waveform Showing Burst Sampling |
Similar Part No. - LTC1857 |
|
Similar Description - LTC1857 |
|
|
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
