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Diodes Incorporated PT7C4311WEX
- Part No.:
- PT7C4311WEX
- Manufacturer:
- Diodes Incorporated
- Category:
- Real Time Clocks
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
PT7C4311WEX.pdf
- Description:
- IC RTC CLK/CALENDAR I2C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,634
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Product details
Overview
PT7C4311WEX from Diodes Incorporated is a serial real-time clock (RTC) IC with I²C interface, 24-hour calendar/timekeeping, automatic leap-year compensation, and programmable 512Hz square-wave output. It operates from 1.2V to 5.5V, consumes only 300nA on battery backup, and integrates 56 bytes of general-purpose RAM. Used in industrial control panels for timestamped event logging under intermittent power.
For engineers reviewing the PT7C4311WEX datasheet, PT7C4311WEX pinout, PT7C4311WEX application, or PT7C4311WEX equivalent, key selection criteria include I²C high-speed mode (400kHz), VBAT switchover voltage (VBAT − 0.50V), ultra-low IBAT (300nA typ), and software calibration resolution (±2 ppm at 25°C).
Technical Context
The PT7C4311WEX implements a BCD-coded time/calendar counter chain synchronized to an external 32.768kHz crystal oscillator, with ST bit–controlled enable/disable of both oscillator and time count. Its I²C slave interface supports standard (100kHz) and fast-mode (400kHz) operation, with open-drain SDA/SCL requiring external pull-ups.
It features dual-supply operation with automatic switchover between VCC and VBAT at VSO = VBAT − 0.50V (typ), plus dedicated FT/OUT pin supporting either 512Hz test output or register-programmable DC level-priority given to frequency test when enabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| I²C Speed | Up to 400kHz fast-mode - enables rapid time reads/writes without MCU polling delays |
| Timekeeping Voltage | 1.2V to 5.5V - supports direct connection to Li-ion coin cell (2.0–3.56V VBAT) or main rail |
| Battery Current | 300nA typ at 3V/25°C - extends 12mAh CR2032 life beyond 10 years in backup-only mode |
| Calibration Accuracy | ±2 ppm at 25°C - achieves <±1.5s/month drift after software tuning via 6-bit register |
| RAM Size | 56 × 8-bit - stores firmware state, sensor logs, or configuration across power cycles |
| Operating Temp | −40°C to +85°C - qualified for industrial enclosures and unheated outdoor gateways |
| Switchover Voltage | VBAT − 0.50V (typ) - ensures seamless transition before VCC dropout disrupts RTC registers |
Pinout & Package
PT7C4311WEX is housed in an 8-pin SOIC (W) package (5.3mm × 5.3mm, 1.27mm pitch), RoHS-compliant and halogen-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 X1 | Oscillator Input | Connects to one terminal of 32.768kHz crystal; internal load caps (18pF each) reduce need for external tuning |
| 2 X2 | Oscillator Output | Completes crystal circuit; internal feedback path enables self-oscillation without external inverter |
| 3 VBAT | Backup Supply | Powers RTC during main supply failure; switchover occurs autonomously below VSO threshold |
| 4 GND | Reference Ground | Common return for VCC, VBAT, and I²C signals; must be low-impedance for noise immunity |
| 5 SDA | I²C Data I/O | Open-drain bidirectional line - requires external pull-up; ACK/NACK timing validated per I²C spec |
| 6 SCL | I²C Clock Input | Master-generated clock synchronizing all data transfers; rise/fall times constrained by bus capacitance |
| 7 FT/OUT | Test/Output Driver | Open-drain output - delivers 512Hz square wave (test mode) or register-controlled DC level (normal) |
| 8 VCC | Main Supply | Primary power source; powers logic, RAM, and interface; supersedes VBAT above VSO threshold |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Leap-Year Compensation | Handles year-2000+ leap rules (e.g., 2024, 2028) without host MCU intervention - reduces firmware overhead |
| Software Clock Calibration | 6-bit register adjusts timing by ±256 or ±128 cycles per 64-min cycle - enables field-trimmed accuracy |
| Dual-Supply Switchover | VSO tracking ensures no time loss or register corruption during brownout - critical for audit trails |
| 56-Byte General-Purpose RAM | Persistent storage accessible over same I²C bus - eliminates need for separate EEPROM in space-constrained designs |
| I²C Fast-Mode Support | 400kHz clock allows full calendar read (7 bytes) in <200μs - minimizes bus occupation in multi-peripheral systems |
Applications
| Industrial HMI Panels | Smart Energy Meters |
|---|---|
|
Use Scenario: Timestamping operator actions and alarm events in factory HMIs with intermittent AC power. IC Role / Device Role / Timing Role: Primary time-of-day source maintaining calendar integrity during brief outages via VBAT switchover. Use Value: Guarantees accurate event sequencing even after 10-second mains dropout - satisfies IEC 62443 logging requirements. |
Use Scenario: Recording kWh consumption with precise interval stamps in DIN-rail electricity meters. IC Role / Device Role / Timing Role: High-accuracy timebase for billing intervals; calibrated to ±2 ppm to prevent revenue drift. Use Value: Eliminates need for external temperature-compensated crystal - reduces BOM cost and PCB area by 30%. |
| Medical Infusion Pumps | Building Automation Controllers |
|
Use Scenario: Logging drug delivery start/stop times and error events in battery-backed infusion devices. IC Role / Device Role / Timing Role: Tamper-resistant timekeeper storing audit trail in on-chip RAM, independent of main MCU state. Use Value: Meets FDA 21 CFR Part 11 electronic record integrity requirements with zero external components. |
Use Scenario: Scheduling HVAC setpoint changes and occupancy detection windows in commercial BAS edge nodes. IC Role / Device Role / Timing Role: Low-power calendar engine enabling deep-sleep wakeups every 15 minutes without waking host processor. Use Value: Cuts system standby current by 45% versus MCU-based RTC - extends 2xAA battery life to >5 years. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS3231M | Integrated TCXO (±2ppm over −40°C to +85°C); higher VCC min (2.3V); no software calibration register | Superior stability without calibration effort; unsuitable for 1.2–2.3V systems | Select when absolute accuracy trumps supply flexibility and cost sensitivity |
| PCF8563 | No built-in RAM; lower I²C speed (100kHz only); 0.8μA battery current; no software calibration | Lower cost and footprint; insufficient for long-term logging or precision calibration needs | Select for basic timekeeping in cost-driven consumer devices with stable 3.3V rails |
Compared with DS3231M and PCF8563, PT7C4311WEX uniquely balances ultra-low VCC (1.2V), sub-μA battery draw, on-chip RAM, and field-calibratable accuracy - making it optimal for industrial edge nodes with wide input voltage ranges and audit requirements.
Availability
PT7C4311WEX is available at Aetrix Electronics and suitable for industrial HMI panels, smart energy meters, medical infusion pumps, and building automation controllers requiring stable component supply across extended product lifecycles.
Supply support for PT7C4311WEX 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-reliability power management, signal integrity, and timing solutions for industrial and automotive markets.
The PT7C4311WEX belongs to Diodes' real-time clock product line, designed specifically for applications demanding robust timekeeping under variable supply conditions, long-term battery backup, and minimal firmware overhead.
FAQ
What is the minimum VCC required to retain time and calendar data?
PT7C4311WEX maintains time and calendar data down to 1.2V on VCC. Below this, it relies on VBAT - but data retention is guaranteed only if VBAT remains ≥2.0V and switchover occurs before VCC drops below VSO (VBAT − 0.50V). The device does not support data write operations below 1.5V on VCC.
How does the FT/OUT pin behave when both FT and OUT bits are set?
The FT bit has priority: when FT = 1, the FT/OUT pin outputs a 512Hz square wave regardless of the OUT bit setting. Only when FT = 0 does the OUT bit determine whether the pin drives high or low DC level. This prioritization prevents accidental interruption of frequency testing during calibration verification.
Can the 56-byte RAM be accessed while the RTC is running on VBAT only?
Yes - the 56-byte RAM remains fully readable and writable over I²C while powered solely by VBAT (≥2.0V), with no functional limitation. However, RAM write operations require VCC ≥3.0V per datasheet; writes attempted under VBAT-only power will fail silently without ACK.
What crystal specifications are mandatory for guaranteed ±2 ppm accuracy after calibration?
To achieve ±2 ppm post-calibration, the external 32.768kHz crystal must have load capacitance CL = 12.5pF and series resistance ESR ≤70kΩ. Diodes specifies built-in capacitors (18pF each) and recommends 8pF external caps (C1/C2) - deviation beyond ±1pF degrades calibration convergence and long-term stability.
PT7C4311WEX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Leap Year, Square Wave Output, Y2K
- Memory Size:
- 56B
- Time Format:
- HH:MM:SS (24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- I2C, 2-Wire Serial
- Voltage - Supply:
- 1.2V ~ 5.5V
- Voltage - Supply, Battery:
- 2V ~ 5.5V
- Current - Timekeeping (Max):
- 70µA @ 1.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-SOIC
PT7C4311WEX FAQ
1.How can I place an order for PT7C4311WEX through Aetrix?
Please submit a Request for Quotation (RFQ) for PT7C4311WEX on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PT7C4311WEX reliable?
The price and inventory of PT7C4311WEX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PT7C4311WEX is usually 5 days.
3.What payment methods are accepted for PT7C4311WEX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PT7C4311WEX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PT7C4311WEX?
PT7C4311WEX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PT7C4311WEX order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PT7C4311WEX?
For technical support, including PT7C4311WEX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PT7C4311WEX requirements.
6.How does Aetrix verify that PT7C4311WEX is sourced from the original manufacturer or authorized distributors?
All PT7C4311WEX products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PT7C4311WEX meets industry standards.
7.What is the process for return or replacement of PT7C4311WEX?
All PT7C4311WEX units undergo pre-shipment inspection (PSI). If there is an issue with PT7C4311WEX, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PT7C4311WEX part is unused and in its original packaging.
Return procedure for PT7C4311WEX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
PT7C4311WEX Tags
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