Diodes Incorporated PT7C4302WEX

Overview

PT7C4302WEX from Diodes Incorporated is a serial real-time clock (RTC) IC with integrated 31-byte RAM, 3-wire interface, and on-chip trickle charger for battery backup. It maintains time across seconds, minutes, hours, date, month, weekday, and year with leap-year compensation up to 2099, operates from 1.5V to 5.5V, consumes <300nA at 2.0V, and supports industrial temperature range (–40°C to +85°C).

For engineers reviewing the PT7C4302WEX datasheet, PT7C4302WEX pinout, PT7C4302WEX application, or PT7C4302WEX equivalent, this device serves as a low-power, battery-backed RTC solution for embedded systems requiring accurate calendar functionality, minimal pin count, and configurable trickle-charge backup power management.

Technical Context

The PT7C4302WEX implements a BCD-coded time counter chain synchronized to an external 32.768kHz crystal, with automatic end-of-month and leap-year correction logic valid through year 2099. Its 3-wire interface (SCLK, I/O, RST) uses command-byte addressing and supports burst-mode sequential access to clock registers (0x00–0x07) and RAM (0x20–0x3E).

Power management includes dual supply inputs (VCC1 for backup, VCC2 for main operation), internal 40kΩ pull-down resistors on RST/SCLK/I/O, and programmable trickle-charge control via register 0x08 - supporting one or two diodes and selectable resistors (2kΩ/4kΩ/8kΩ) to regulate charge current into supercapacitor or rechargeable backup sources.

Key Specifications

Pinout & Package

PT7C4302WEX is housed in an 8-pin SOIC (W) package (width: 5.3mm), RoHS-compliant and halogen-free. Pin functions are validated per Diodes DS43087 Rev 2-2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar real-time clock applications.

Compared with DS1307+ and PCF8563, PT7C4302WEX provides unique integration of 3-wire simplicity, sub-300nA power, and fully programmable on-chip trickle charging - reducing BOM count and simplifying backup power design for space-constrained industrial and portable devices.

Availability

PT7C4302WEX is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical wearables, and building automation systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for PT7C4302WEX includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, specializing in high-performance, energy-efficient solutions for industrial, computing, consumer, and automotive markets.

The PT7C4302WEX belongs to Diodes' real-time clock product line, designed specifically for ultra-low-power, battery-backed timekeeping in space- and cost-sensitive embedded systems where reliability and calendar accuracy through 2099 are critical.

FAQ

What is the function of the /EOSC bit in register 0x00?

The /EOSC (Enable Oscillator) bit in register 0x00 controls the 32.768kHz crystal oscillator. When set to 1, the oscillator stops but the time-count chain continues running using residual oscillation or stored timing state - allowing low-power suspension of crystal activity while preserving time accuracy. Writing 0 to this bit starts the oscillator and enables full RTC operation.

How does the PT7C4302WEX handle February 29 in leap years?

The PT7C4302WEX automatically adjusts the date counter for leap years using built-in logic that treats any year divisible by 4 (e.g., 2000, 2004…2096) as a leap year, correctly advancing from February 28 to 29 to March 1. This behavior is hardwired and requires no firmware intervention, remaining valid through year 2099.

Can the 31-byte RAM retain data during main power loss?

Yes - the 31-byte RAM retains data as long as VCC1 (backup supply) remains ≥1.5V. When VCC2 drops, the device seamlessly switches to VCC1, preserving both timekeeping and RAM contents. Data is volatile only if VCC1 falls below 1.5V or is disconnected entirely.

What crystal load capacitance is recommended for PT7C4302WEX?

Diodes specifies internal load capacitors CG = CD = 11pF. For a standard 32.768kHz crystal with 12.5pF load capacitance, external C1 = C2 = 12pF is recommended. For 6pF crystals, C1 = C2 = 0pF is used. The optimal CL is determined by the equation: Cpar + [(C1+CG)(C2+CD)] / [(C1+CG)+(C2+CD)] = CL.