Diodes Incorporated
Back to Real Time Clock (RTC)

PT7C4302 (Not Recommended for New Design (NRND))

NRND = Not Recommended for New Design

3-wire interface RTC with 31Byte NVRAM

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The PT7C4302 serial real-time clock is a lowpower
clock/calendar with a programmable square-wave
output and 31 bytes of nonvolatile RAM.
Address and data are transferred serially via a 3-
wire bus. The clock/calendar provides seconds, minutes,
hours, day, date, month, and year information. The date
at the end of the month is automatically adjusted for
months with fewer than 31 days, including corrections
for leap year. The clock operates in either the 24-hour or
12-hour format with AM/PM indicator.
Table 1 shows the basic functions of PT7C4302.
More details are shown in section: overview of functions.


  • Using external 32.768kHz quartz crystal
  • Real-time clock (RTC) counts seconds, minutes, hours, date of the month, month, day of the week, and year with leap-year compensation valid up to 2099
  • 31-byte, nonvolatile (NV) RAM for data storage
  • Time keeping voltage: 1.5V to 5.5V
  • Uses less than 300nA at 2.0V
  • Simple 3-wire interface
  • Serial I/O for minimum pin count
  • Burst mode for reading/writing successive addresses in clock/RAM
  • TTL-compatible (VCC = 5V)
  • Optional industrial temperature range: -40°C to +85°C
  • Battery backup
  • Trickle charger on chip for rechargeable energy source backup


Product Specifications

Product Parameters

Compliance(Only Automotive supports PPAP) Standard
Time Display 12, 24
NV Ram 31x8
Interface 3-Wire
Alarm Interrupt 0
Battery Backup 1
Clock Calibration 0

Technical Documents

Recommended Soldering Techniques


Additional Technical Documents are available upon request:
Application information, Evaluation board, and Other technical documents

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Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN # Issue Date Implementation Date Subject
PCN-2651 2023-11-13 2023-11-13 Qualified Additional Fab Source, Assembly Test Sites, Die Revision, BOM, Datasheet, Tape and Reel Packing Quantity.
PCN-2642 2023-09-05 2024-03-05 Device End of Life (EOL)
PCN-2505 2021-01-26 2021-07-26 Device End of Life (EOL)