PT7C4337WE

Real Time Clock Overview

The PT7C4337WE is a Real-Time Clock (RTC) module manufactured by Diodes Incorporated, housed in an 8-pin SOIC package. It operates via a 2-wire I2C bus interface with a maximum clock frequency of 400 kHz. The device supports both 12-hour and 24-hour time formats and tracks seconds, minutes, hours, days of the week, dates, months, and years. It features two independent alarm outputs (INTA and SQW/INTB), a programmable square wave output, and oscillator failure detection. Electrical specifications include a supply voltage range of 1.8 V to 5.5 V for full operation, with timekeeping capability down to 1.2 V. Operating temperatures span from -40 °C to +85 °C.

Real Time Clock Feature Summary

• I2C Bus Interface: Supports standard mode up to 400 kHz with open-drain SDA and SCL pins requiring external pull-up resistors.
• Dual Alarm System: Includes Alarm 1 (seconds through day/date) and Alarm 2 (minutes through day/date) with configurable mask bits for interrupt generation on INTA or SQW/INTB.
• Programmable Outputs: Features a programmable square wave output selectable at 1 Hz, 4.096 kHz, 8.192 kHz, or 32.768 kHz.
• Low Power Operation: Timekeeping current is typically 450 nA at 1.8–1.8V; data retention current is under 160 nA when the oscillator is disabled.

Real Time Clock Applications

• Embedded systems requiring precise timekeeping and calendar functions.
• Battery-backed devices needing low standby current consumption.
• Industrial equipment operating within -40 °C to +85 °C temperature ranges.
• Consumer electronics utilizing I2C communication protocols.

Real Time Clock Procurement Notes

Verify the ordering suffix 'WE' corresponds to the 8-pin Wide SOIC package in Tape & Reel configuration. Confirm RoHS compliance requirements, as the component is lead-free and halogen-antimony free. Ensure external pull-up resistors are selected for SDA, SCL, INTA, and SQW/INTB pins based on the specific bus capacitance limits defined in the datasheet.

Real Time Clock Selection Notes

Select this component if an I2C-compatible RTC with dual alarms and a wide supply voltage range (1.8 V to 5.5 V) is required. Consider the 8-pin SOIC package constraints for PCB layout. Verify that the application can accommodate the necessary external 32.768 kHz crystal and matching capacitors, as the internal load capacitors are specified at 12 pF each.

Real Time Clock Part Context

The PT7C4337 series includes variants such as PT7C4337WEX (SOIC), PT7C4337UEX (MSOP), PT7C4337LEX (TSSOP), and PT7C4337ZEEX (TDFN). The 'W' indicates the SOIC package, while 'E' denotes lead-free and green status, and 'X' signifies tape and reel packaging. All variants share identical electrical and functional specifications.

Real Time Clock Replacement Considerations

Direct pin-to-pin replacements within the same family include PT7C4337WEX, PT7C4337UEX, PT7C4337LEX, and PT7C4337ZEEX. Cross-manufacturer substitutions require verification of I2C address compatibility, register mapping, and power consumption characteristics.

Real Time Clock FAQ

How does the INTCN bit affect alarm interrupts?

When INTCN is set to 1, Alarm 1 triggers INTA and Alarm 2 triggers SQW/INTB. When INTCN is 0, both alarms trigger INTA, and SQW/INTB outputs a square wave.

What is the default square wave frequency?

The default square wave frequency is 32.768 kHz, determined by the RS2 and RS1 bits being set to 11 in the Control Register.

Can the oscillator be disabled to save power?

Yes, setting the /ETIME bit to 1 disables the oscillator and time count chain, reducing current consumption to the data retention level (typically <160 nA).