DS275+

Overview

The DS275 is a low-power CMOS line-powered RS-232 transceiver designed for battery-backed systems. It provides a half-duplex interface to RS-232 serial ports by stealing current from the receive signal line during negative states, significantly reducing static power consumption. The device operates with a logic supply (VCC) of 4.5V to 5.5V and a transmit driver supply (VDRV) ranging from 4.5V to 13.0V. It features one receiver and one transmitter, supporting data rates up to 20kbps. The package options include an 8-pin DIP, an 8-pin SOIC, and a 14-pin TSSOP.

Feature Summary

• Steals power from the receive signal line to minimize static current drain in idle states
• Compatible with standard RS-232-E signals without requiring complex charge-pump circuits
• Internal current-limiting circuitry protects against output short circuits

Applications

• Battery-operated handheld products
• Laptop computers
• Remote sensors
• Portable medical instruments

Procurement Notes

Verify the specific package variant required, as the base model number covers multiple physical footprints including DIP, SOIC, and TSSOP. Confirm that the VDRV supply voltage aligns with the system's available power rails, as it must be greater than or equal to VCC. Ensure the application environment remains within the specified operating temperature range of 0°C to 70°C.

Selection Notes

Select this component when ultra-low static power consumption is critical for battery life in serial communication interfaces. It is suitable for applications where the RS-232 connector remains attached for extended periods. Designers should ensure the cable length does not exceed 10 feet to maintain signal integrity, as the device prioritizes power efficiency over full compliance with all RS-232 electrical specifications under heavy loads.

Part Context

The DS275 belongs to the Maxim Integrated/Analog Devices family of low-power interface ICs. It is distinct from higher-speed or full-compliance RS-232 drivers by its unique line-powered architecture. The device is often used in legacy portable systems where power conservation outweighs the need for high-speed data transmission or long-distance signaling capabilities.

Replacement Considerations

DS275S

FAQ

How does the DS275 reduce static power consumption?

It steals current from the receive RS-232 signal line when that signal is in a negative state (marking), which is the typical idle state for asynchronous communication.

What is the relationship between VDRV and VCC?

VDRV must always be greater than or equal to VCC. VDRV powers the positive transitions of the transmit output, while VCC powers the internal logic.

Can the DS275 operate in full-duplex mode?

Yes, it can operate in full-duplex with most RS-232-E ports, although it is primarily intended for half-duplex operation. External components like capacitors may be needed for optimal performance in full-duplex scenarios.