LTC1068IN#PBF

Overview

The LTC1068IN#PBF is a clock-tunable, quad second-order switched-capacitor filter building block housed in a 24-lead PDIP package. It operates within an industrial temperature range of –40°C to 85°C and supports supply voltages from 3.14V single supply to ±5V dual supply. The device features four matched filter sections with a nominal clock-to-center frequency ratio of 100:1. Key electrical specifications include a typical center frequency error of ±0.3%, a DC open-loop gain of 85 dB, and a gain-bandwidth product of 6 MHz. Power supply current typically ranges from 6.5 mA at 4.75V to 9.5 mA at ±5V.

Feature Summary

• Contains four identical second-order switched-capaculator filter sections within a single monolithic package.
• Offers low noise performance per section, with typical RMS noise values as low as 50µV for Q ≤ 5.
• Supports flexible filter topologies including lowpass, highpass, bandpass, and notch configurations via external resistor networks.
• Provides precise center frequency tuning through an external clock signal with minimal temperature coefficient.

Applications

• Dual matched fourth-order Butterworth lowpass filters
• Clock-tunable bandpass or bandreject (notch) filters
• High-performance audio signal processing stages

Procurement Notes

Verify the suffix IN indicates the industrial temperature grade (-40°C to 85°C) and the N package type (24-lead PDIP). Confirm lead-free finish compliance via the #PBF designation. Ensure the specific variant matches the required clock-to-center frequency ratio, as the base model implies a 100:1 ratio distinct from -200, -50, or -25 variants.

Selection Notes

Select this component when a 100:1 clock-to-center frequency ratio is required for second-order filtering applications. Consider the 24-lead PDIP package if through-hole mounting is necessary. Evaluate power supply constraints, as the device supports both single and dual supplies, but verify that the required center frequency range aligns with the operational limits defined in the maximum Q vs center frequency graphs.

Part Context

This part belongs to the LTC1068 series, which includes variants with different nominal clock-to-center frequency ratios: 200:1 (LTC1068-200), 50:1 (LTC1068-50), and 25:1 (LTC1068-25). All variants share similar internal architectures and pinouts but differ in their default tuning characteristics. The IN suffix specifically denotes the industrial temperature range version of the standard LTC1068.

Replacement Considerations

Direct replacements must match the 100:1 clock-to-center frequency ratio. Verify package compatibility between 24-lead PDIP and alternative packages like SSOP. Ensure substitute components support the same supply voltage range and meet the required noise and accuracy specifications for the target application.