Features
- Real-Time Clock (RTC) counts seconds, minutes, hours, day, date, month, and year with leap-year compensation valid up to 2100
- 56-Byte battery-backed Non Volatile RAM for data storage
- Fast mode I2C Serial interface
- Automatic power-fail detect and switch circuitry
- Programmable square-wave output
- Packaged in 8-pin MSOP, 8-pin SOIC, or 16-pin SOIC (surface-mount package with an integrated crystal)
- Industrial temperature range (-40°C to +85°C)
Description
The 1338 is a serial real-time clock (RTC) device that consumes ultra-low power and provides a full binary-coded decimal (BCD) clock/calendar with 56 bytes of battery backed Non-Volatile Static RAM. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. Access to the clock/calendar registers is provided by an I2C interface capable of operating in fast I2C mode. Built-in Power-sense circuitry detects power failures and automatically switches to the backup supply, maintaining time and date operation.
Parameters
| Attributes | Value |
|---|---|
| Output Freq Range (MHz) | 1.0E-6 - 1.0E-6, 0.004096 - 0.004096, 0.008192 - 0.008192, 0.032768 - 0.032768 |
| Power Consumption Typ (mW) | 10 |
| Output Type | LVCMOS |
| Package Area (mm²) | 9, 19.1 |
| Interface | I2C |
| Alarms (#) | 0 |
| Supply Voltage Vcc (Min) (V) | 1.8 |
| Battery Backup | No |
| Battery Seal | No |
| CPU Supervisory Function POR | No |
| Crystal Frequency Trimming | No |
| Frequency Out Pin | No |
| Battery Current (nA) | 300 |
| Time Keeping Current (µA) | 1.4 |
| SRAM | 56 Bytes |
| Selectable Frequency Output | 1 |
| Accuracy | ±20 ppm |
| Inputs (#) | 1 |
| Input Freq (MHz) | 0.032768 - 0.032768 |
| Input Type | Crystal |
| Output Banks (#) | 1 |
| Core Voltage (V) | 2.5V, 3.3V, 5V, 5.5V |
| Output Voltage (V) | 2.5V, 3.3V, 5V, 5.5V |
| Product Category | Real-Time Clocks, Real-Time Clocks, Real-Time Clocks |
Application Block Diagrams
 | Multi-Display HMI SoM SOM with optimized power and timing supports multi-display embedded applications. |
 | Power & Timing SoM for RZ/G2E Power and timing SoM ensures precise timing and efficient power distribution. |
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Support Communities
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RTC freezes
... in function rtc_interrupt_cb takes longer than one second. The program freezes and the bluetooth disconnects. Is there a way to pause rtc_event while in rtc_interrupt_cb, or I'm doing something wrong that I'm missing. Using SDK_6.0.20.1338 Thanks. Best regards, Javier
Apr 9, 2024 -
TIMER0_RELATED
Hi renesas community, I am processing some data from timer0Callback ISR function, But my doubt is while process function executes what if the timer expired again? So I am disabling the timer interrupt before calling that processData() and I am enabling timer interrupt after the returned to the ISR. Is ...
Jun 18, 2025 -
SLG47115
... / 1332 0 // 1333 0 // 1334 0 // 1335 0 // 1336 0 // 1337 0 // 1338 0 // 1339 0 // 1340 0 // 1341 0 // 1342 0 // 1343 0 // 1344 ...
Dec 5, 2024
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