LF398H

The LF398H from Texas Instruments is a monolithic sample-and-hold circuit utilizing BI-FET technology for high DC accuracy and fast signal acquisition. It achieves an acquisition time as low as 6 µs to 0.01% and a typical gain accuracy of 0.002%. The device operates from ±5V to ±18V supplies and features logic input compatibility with TTL, PMOS, and CMOS.

Designed for precision applications, the LF398H offers a low input offset and a typical hold step of 0.5 mV at Ch = 0.01 µF. Its wide bandwidth of 1 MHz allows it to be integrated within the feedback loop of operational amplifiers without causing stability issues. The input impedance is 10^10 Ω, enabling the use of high-source impedances without compromising accuracy.

The output amplifier combines P-channel junction FETs with bipolar devices, resulting in low droop rates as low as 5 mV/min with a 1 µF hold capacitor. The JFETs contribute to lower noise compared to MOS devices and avoid high-temperature instabilities. The circuit ensures no feedthrough from input to output in the hold mode, even with input signals at supply voltage levels.

Packaged in a TO-CAN (LMC) configuration with 8 pins, the LF398H is suitable for through-hole mounting. It operates within a temperature range of 0°C to 70°C. The device is space-qualified, indicated by JM38510.