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LF398 -
Monolithic Sample and Hold Circuit
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Features
| | Operates from ±5V to ±18V supplies |
| | Less than 10 µs acquisition time |
| | TTL, PMOS, CMOS compatible logic input |
| | 0.5 mV typical hold step at Ch = 0.01 µF |
| | Low input offset |
| | 0.002% gain accuracy |
| | Low output noise in hold mode |
| | Input characteristics do not change during hold mode |
| | High supply rejection ratio in sample or hold |
| | Wide bandwidth |
| | Space qualified, JM38510 |
Logic inputs on the LF198 are fully differential with low input current, allowing direct connection to TTL, PMOS, and CMOS. Differential threshold is 1.4V. The LF198 will operate from ±5V to ±18V supplies.
An "A" version is available with tightened electrical specifications.
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General Description
The LF198/LF298/LF398 are monolithic sample-and-hold circuits which utilize BI-FET technology to obtain ultra-high dc accuracy with fast acquisition of signal and low droop rate. More...
| Parameters | Values |
| Temperature Min |
0 deg C |
| Temperature Max |
70 deg C |
| Offset Voltage max, 25C |
3, 10 mV |
Additional Resources
Application Notes

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Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
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| LF198/LF298/LF398, LF198A/LF398A Monolithic Sample-and-Hold Circuits |
520 Kbytes |
23-Aug-00 |
Download |
LF198/LF298/LF398, LF198A/LF398A Monolithic Sample-and-Hold Circuits (Japanese)
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532 Kbytes |
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Package Availability, Models, Samples & Pricing
| Obsolete Part | Alternate Part or
Supplier | Source | Last Time Buy Date |
LF398AH
| LF198AH
| NATIONAL SEMICONDUCTOR
| 03 Dec 2008
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General Description
The LF198/LF298/LF398 are monolithic sample-and-hold circuits which utilize BI-FET technology to obtain ultra-high dc accuracy with fast acquisition of signal and low droop rate. Operating as a unity gain follower, dc gain accuracy is 0.002% typical and acquisition time is as low as 6 µs to 0.01%. A bipolar input stage is used to achieve low offset voltage and wide bandwidth. Input offset adjust is accomplished with a single pin, and does not degrade input offset drift. The wide bandwidth allows the LF198 to be included inside the feedback loop of 1 MHz op amps without having stability problems. Input impedance of 1010Ohm allows high source impedances to be used without degrading accuracy.
P-channel junction FET's are combined with bipolar devices in the output amplifier to give droop rates as low as 5 mV/min with a 1 µF hold capacitor. The JFET's have much lower noise than MOS devices used in previous designs and do not exhibit high temperature instabilities. The overall design guarantees no feed-through from input to output in the hold mode, even for input signals equal to the supply voltages.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
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LF398 MDC | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398 MWC | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398AH | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398AN | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398H | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398M | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398MX | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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LF398N | BIFET | 0 | 12875 | 0 | 0 | 1065000 | 4 | 302196657
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Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR.
The Long Term Failure Rates were calculated
at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress
temperature of 150°C to an application temperature of 55°C.
For more information on Reliability Metrics, please click here.
Application Notes
| Title | Size in Kbytes |
Date |
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| AN-298: Application Note 298 Isolation Techniques for Signal Conditioning |
379 Kbytes |
2-Oct-02 |
Download |
| AN-775: Specifications and Architectures of Sample-and-Hold Amplifiers |
111 Kbytes |
5-Aug-95 |
Download |
AN-775 (Japanese): Specifications and Architectures of Sample-and-Hold Amplifiers
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251 Kbytes |
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| AN-266: Application Note 266 Circuit Applications of Sample-Hold Amplifiers |
508 Kbytes |
2-Oct-02 |
Download |
| AN-258: Application Note 258 Data Acquisition Using the ADC0816 and ADC0817 8-Bit A/D Converter with On-Chip 16 Channel Multiplexer |
683 Kbytes |
4-Oct-04 |
Download |
| AN-301: Application Note 301 Signal Conditioning for Sophisticated Transducers |
579 Kbytes |
2-Oct-02 |
Download |
| AN-247: Application Note 247 Using the ADC0808/ADC0809 8-Bit µP Compatible A/D Converters with 8-Channel Analog Multiplexer |
547 Kbytes |
3-Oct-02 |
Download |
| AN-294: Application Note 294 Special Sample and Hold Techniques |
233 Kbytes |
4-Oct-04 |
Download |
More Application Notes
| Title | Size in Kbytes |
Date |
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| AN-292: Application Note 292 Applications of the LM3524 Pulse-Width-Modulator |
239 Kbytes |
3-Oct-02 |
Download |
[Information as of 8-Nov-2009]
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