LTC2645IMS-L12#PBF

Overview

The LTC2645IMS-L12#PBF is a quad 12-bit PWM-to-voltage output DAC from Analog Devices, housed in a 16-lead MSOP package. It integrates a high-accuracy, low-drift 10ppm/°C reference, providing a 2.5V full-scale output. The device measures PWM period and pulse width, updating outputs within 8µs typically. It operates on a single 2.7V to 5.5V supply with rail-to-rail buffered outputs capable of sourcing/sinking up to 5mA (3V) or 10mA (5V). Key specifications include ±2.5LSB max INL, ±1LSB max DNL, and guaranteed monotonicity over the industrial temperature range of –40°C to 85°C.

Feature Summary

• Quad 12-bit resolution with integrated 10ppm/°C reference for 2.5V full-scale output
• No-latency PWM-to-voltage conversion with settling time under 8µs
• Rail-to-rail output buffers supporting up to 10mA sink/source current
• Pin-selectable internal or external reference modes

Applications

• Digital Calibration
• Trimming and Adjustment
• Level Setting
• Process Control and Industrial Automation
• Instrumentation

Procurement Notes

Verify the suffix #PBF indicates lead-free packaging and tube shipping format. Confirm the IMS designation corresponds to the industrial temperature grade (-40°C to 85°C) and MSOP package. Ensure compatibility with the required PWM input voltage levels (1.71V to 5.5V) and supply voltage range (2.7V to 5.5V) for the specific application design.

Selection Notes

Select this part for applications requiring direct PWM input without external filtering or buffering. The 12-bit resolution and ±2.5LSB INL suit precision calibration tasks. Consider the idle mode options (zero-scale, full-scale, hold, or power-down) via the IDLSEL pin for system initialization requirements. External reference mode is available if a different full-scale voltage is needed.

Part Context

This component belongs to the LTC2645 family, which includes 10-bit and 8-bit variants (LTC2645-L10, LTC2645-L8). The L12 suffix specifically denotes the 12-bit resolution version. Other family members share the same package, interface, and reference architecture but differ in linearity specifications and maximum PWM input frequencies.

Replacement Considerations

Publicly confirmed substitute part numbers are not provided in the source documentation. Designers should evaluate other Analog Devices PWM DACs or general-purpose voltage output DACs based on interface compatibility and performance metrics if substitution is necessary.

FAQ

How does the LTC2645 handle PWM input signals?

The device measures the period and pulse width of the PWM input signals. It updates the corresponding voltage output after each rising edge of the PWM input, calculating the duty cycle to determine the digital code.

What is the function of the IDLSEL pin?

The IDLSEL pin selects the behavior of the DAC output when no PWM rising edge is received for more than 60ms. It can be configured for zero-scale, full-scale, hold previous state, or power-down with high impedance output.

Can the LTC2645 operate with an external reference?

Yes, by connecting the REFSEL pin to VCC, the device enters external reference mode. In this mode, the voltage supplied to the REF pin sets the full-scale output voltage, ranging from 1V to VCC.