DS1338U-33+T&R

Real Time Clock Overview

The DS1338U-33+T&R is a low-power serial real-time clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It features full binary-coded decimal (BCD) timekeeping with automatic leap-year compensation valid until 2100. The device includes 56 bytes of battery-backed NV SRAM and communicates via an I²C interface. It operates on a primary supply voltage range of 3V to 5.5V, with a backup supply range of 1.3V to 3.7V. Active current consumption ranges from 125µA to 200µA at 3.63V to 5.5V. The component is housed in an 8-uMAX/uSOP surface-mount package and supports industrial temperatures from -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated BCD clock/calendar with automatic date adjustments for month lengths and leap years.
• 56-byte non-volatile static RAM accessible via the I²C serial bus.
• Built-in power-fail detection circuitry that automatically switches between VCC and VBAT supplies.
• Programmable square-wave output signal with selectable frequencies: 1Hz, 4.096kHz, 8.192kHz, or 32.768kHz.

Real Time Clock Applications

• Handheld devices such as GPS units and POS terminals
• Consumer electronics including set-top boxes and digital recorders
• Office equipment like fax machines, printers, and copiers
• Medical devices such as glucometers and medicine dispensers
• Telecommunications infrastructure including routers, switches, and servers

Real Time Clock Procurement Notes

Verify the specific suffix 'U-33' corresponds to the 8-pin uSOP package and the 3.0V minimum operating voltage requirement. Confirm RoHS compliance status indicated by the '+' symbol. Ensure the ordering quantity matches the tape-and-reel packaging specifications provided by the distributor. Check for any regional distribution restrictions or limited availability notices associated with this part number.

Real Time Clock Selection Notes

Select the DS1338U-33 variant when the system requires a minimum VCC of 3.0V. Choose the 'U' package designation for space-constrained designs requiring the 8-lead micro-SOP form factor. Ensure the application utilizes an external 32.768kHz crystal with a 12.5pF load capacitance, as this model does not integrate the oscillator crystal internally unlike the DS1338C series.

Real Time Clock Part Context

This component belongs to the DS1338 family of serial RTCs. The 'U' suffix denotes the 8-lead micro-SOP package, while '33' indicates the 3.0V minimum supply voltage version. It is functionally similar to the DS1338Z-33 but differs in physical footprint. The '+T&R' suffix specifies lead-free/RoHS-compliant manufacturing and tape-and-reel packaging format.

Real Time Clock Replacement Considerations

DS1338Z-33+T&R offers identical electrical characteristics in an 8-SOIC package. DS1338U-3+T&R provides the same functionality with a lower 2.7V minimum supply voltage. DS1338C-33# integrates the crystal but uses a 16-lead SOIC package.