DS1746P-70

Real Time Clock Overview

The DS1746P-70 is a Y2K-compliant, nonvolatile timekeeping RAM featuring an integrated real-time clock/calendar and 128k x 8 static RAM. It utilizes a standard JEDEC byte-wide interface where RTC registers occupy the eight topmost memory locations. The device includes a built-in lithium energy source and crystal, housed in a 34-pin PowerCap module board package designed for surface mounting. Key features include automatic leap year compensation valid until 2100, power-fail write protection, and a battery voltage-level indicator flag. The component ensures data retention for over 10 years without power.

Real Time Clock Feature Summary

• Integrated NV SRAM (128k x 8), Real-Time Clock, Crystal, and Lithium Battery
• Y2K Compliant with Century Byte Register and Automatic Leap Year Compensation
• Power-Fail Write Protection with ±10% VCC Tolerance
• Battery Voltage-Level Indicator Flag and Replaceable PowerCap Design

Real Time Clock Applications

• Systems requiring nonvolatile timekeeping and data storage in compact surface-mount form factors
• Industrial equipment needing Y2K compliance and extended battery life
• Applications utilizing separate PowerCap modules for post-solder assembly of battery and crystal

Real Time Clock Procurement Notes

Verify the specific ordering suffix to confirm temperature range and RoHS status. The 'IND' suffix denotes the industrial temperature grade (-40°C to +85°C). The '+' suffix indicates lead-free/RoHS compliance. Ensure the correct package type (PowerCap vs. DIP) is selected, as the DS1746P requires a separate PowerCap module (DS9034PCX+ or DS9034I-PCX+) which must be ordered separately.

Real Time Clock Selection Notes

Select the DS1746P-70 when a surface-mountable RTC/NVRAM solution compatible with a replaceable external PowerCap is required. This model operates at 5.0V and supports the commercial temperature range (0°C to +70°C). For industrial environments, choose the DS1746P-70IND+. Note that this part is pin-compatible with other densities in the DS174xP family, allowing for potential density upgrades without layout changes.

Real Time Clock Part Context

The DS1746P-70 belongs to the DS1746/DS1746P family of Y2K-compliant nonvolatile timekeeping RAMs manufactured by Analog Devices Inc./Maxim Integrated. It is distinct from the DS1746 series, which integrates the crystal and battery within a 32-pin EDIP module. The 'P' designation specifically identifies the PowerCap module board variant, designed to allow the battery and crystal assembly to be mounted after the surface mount process to avoid thermal damage.

Real Time Clock Replacement Considerations

The DS1746P-70IND+ serves as the industrial temperature range replacement for the commercial grade DS1746P-70. Both parts share identical electrical characteristics and pinouts but differ in operating temperature specifications.