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Renesas ISL12028IBZ
- Part No.:
- ISL12028IBZ
- Manufacturer:
- Renesas
- Category:
- Real Time Clocks
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ISL12028IBZ.pdf
- Description:
- IC RTC CLK/CALENDAR I2C 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,995
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Product details
Overview
ISL12028IBZ from Intersil is a low-power real-time clock/calendar IC with integrated 512×8-bit EEPROM, I²C interface, dual non-volatile alarms, CPU supervisor (POR, watchdog timer, low-voltage reset), and automatic battery backup switching. It operates from 2.7V to 5.5V, maintains timekeeping down to 1.8V on VBAT, and uses an external 32.768kHz crystal for ±30ppm frequency adjustment via 64-position digital trim capacitor. It is deployed in utility meters and HVAC equipment for accurate time-stamped logging and power-fail event recovery.
For engineers reviewing the ISL12028IBZ datasheet, ISL12028IBZ pinout, ISL12028IBZ application, or ISL12028IBZ equivalent, this page delivers verified technical context, validated pin functions, confirmed timing accuracy behavior, battery-switching logic under VDD/VBAT crossover conditions, and real-world design implications of its BlockLock™ EEPROM protection and IRQ/FOUT dual-mode output.
Technical Context
The ISL12028IBZ implements a fully autonomous RTC subsystem with leap-year-corrected calendar logic valid through 2099, volatile timekeeping registers updated on STOP-bit completion, and alarm match detection performed in hardware against BCD-encoded clock/calendar values. Its oscillator compensation network integrates a 64-position digitally controlled trim capacitor and six discrete frequency adjustment settings (±30ppm), eliminating external load capacitors.
Power management includes intelligent VDD/VBAT switchover with 800nA battery supply current, hysteresis-controlled VTRIP threshold (2.6V typ), and legacy-mode BSW=1 configuration - distinguishing it from the ISL12028A's standard mode. The watchdog timer offers three fixed timeout periods (225/750/1700ms) and asserts open-drain RESET on expiration, while I²C remains functional during battery backup only when explicitly enabled via register control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDD Range | 2.7V to 5.5V - supports wide-input industrial power rails without external regulation |
| VBAT Operating Minimum | 1.8V - enables reliable timekeeping during brownout or main supply loss |
| I²C Speed | 400kHz - compatible with standard Fast-Mode I²C controllers without clock stretching |
| Battery Current | 800nA at VBAT=1.8V - extends coin-cell life beyond 10 years in typical metering applications |
| EEPROM Endurance | >2,000,000 write cycles per byte - suitable for high-frequency logging of timestamps or fault events |
| RTC Accuracy Control | ±30ppm via 6 digital trim settings - enables factory calibration without manual capacitor tuning |
| Alarm Outputs | Two independent CMOS alarms with repeat mode - supports periodic wake-up or interrupt-driven event scheduling |
| Reset Threshold | 4.38V (VRESET) - matches common 5V system brownout detection requirements |
Pinout & Package
ISL12028IBZ is housed in a 14-lead SOIC package (Pb-free, RoHS compliant, M14.15 drawing), with thermal resistance θJA = 90°C/W. Pin 1–2 connect to external 32.768kHz crystal; pins 13 (VBAT) and 14 (VDD) enable seamless power-source handover; pin 12 (IRQ/FOUT) provides configurable interrupt or 1Hz/4.096kHz/32.768kHz clock output; pin 6 (RESET) is open-drain active-low with 250ms power-on delay.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| X1 | Oscillator input | Connects to one terminal of 32.768kHz crystal; internal inverting amplifier input requiring no external components |
| X2 | Oscillator output | Drives second crystal terminal; must not drive external loads - dedicated crystal node only |
| RESET | Open-drain reset output | Asserts LOW on VDD undervoltage or watchdog timeout; requires 5kΩ pull-up to VDD |
| GND | Ground reference | Primary return path for all analog/digital circuitry; must be low-impedance connection |
| VDD | Main power supply | Primary operating voltage source (2.7–5.5V); powers I²C interface, EEPROM, and RTC logic |
| VBAT | Backup supply input | Provides continuous power to RTC and SRAM during VDD loss; minimum 1.8V required |
| IRQ/FOUT | Configurable I/O | Software-selectable as alarm interrupt (CMOS push-pull) or precision clock output (1Hz/4.096kHz/32.768kHz) |
| SCL | I²C clock input | Always-active input; requires pull-up to VDD; supports 400kHz Fast-Mode timing |
| SDA | I²C bidirectional data | Open-drain I/O; requires pull-up to VDD; supports multi-master arbitration and clock stretching |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 512×8-bit EEPROM | 16-byte page writes with 8 modes of BlockLock™ protection - enables secure storage of calibration data and firmware parameters |
| Dual non-volatile alarms | Settable on second/minute/hour/day-of-week/date/month with repeat mode - supports scheduled maintenance alerts or energy-use profiling |
| On-chip oscillator compensation | 64-position digital trim capacitor + 6 frequency settings (±30ppm) - eliminates need for external trim caps and reduces BOM count |
| Automatic battery backup switching | 800nA VBAT current + hysteresis-controlled VTRIP (2.6V) - ensures uninterrupted timekeeping during power transitions |
| CPU supervisor functions | Programmable reset voltage (4.38V), 3-speed watchdog (225/750/1700ms), and POR - simplifies system-level reliability design |
| Real-time calendar accuracy | Valid through 2099 with automatic leap-year correction and month-length adjustment - removes software date-handling overhead |
Applications
| Utility Metering | HVAC Control Systems |
|---|---|
Use Scenario: Time-stamping energy consumption data and detecting power outages in smart electricity/water/gas meters. IC Role / Device Role / Timing Role: Primary RTC and non-volatile alarm generator; maintains accurate wall-clock time and triggers interrupt on VDD failure. Use Value: Enables precise billing intervals and outage duration logging with 50-year EEPROM data retention and sub-microamp battery draw. |
Use Scenario: Scheduling fan operation, temperature setpoint changes, and filter replacement alerts in commercial HVAC units. IC Role / Device Role / Timing Role: Calendar-aware scheduler with dual alarms; drives timed events using day-of-week and month registers. Use Value: Eliminates external microcontroller real-time scheduling logic; supports seasonal programming without firmware updates. |
| Network Infrastructure | Industrial Test Equipment |
Use Scenario: Timestamping packet loss events, SNMP trap generation, and configuration change logs in routers/switches. IC Role / Device Role / Timing Role: System timekeeper and watchdog initiator; provides synchronized timebase across distributed network nodes. Use Value: Ensures traceable event correlation across devices; supports NTP-assisted synchronization with local holdover capability. |
Use Scenario: Logging calibration cycles, test pass/fail timestamps, and environmental stress test durations in benchtop analyzers. IC Role / Device Role / Timing Role: High-reliability time source with EEPROM-backed configuration storage; retains settings across power cycles. Use Value: Guarantees audit-trail integrity with >2M write endurance and 50-year data retention - meets ISO/IEC 17025 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock/calendar applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1339U+T&R | Lacks integrated EEPROM and CPU supervisor; no oscillator trim; 3.0V–5.5V VDD range only | Requires external EEPROM and reset IC; limited to basic timekeeping in cost-sensitive consumer gear | Select if board space allows discrete support components and application does not require alarm-triggered wake-up or secure parameter storage |
| PCF2129AATS/1 | Includes 256B EEPROM but no watchdog or BlockLock™; ±5ppm accuracy without trim; I²C up to 1MHz | Higher base accuracy but no field-adjustable compensation; lacks VBAT hysteresis and programmable reset voltage | Prefer for battery-powered portable devices needing minimal drift, where factory calibration suffices and supervisor functions are handled elsewhere |
Compared with DS1339U+T&R and PCF2129AATS/1, the ISL12028IBZ uniquely combines EEPROM security (BlockLock™), field-adjustable oscillator compensation, and full CPU supervision in a single 14-pin SOIC - reducing component count and enabling robust time-critical recovery in industrial infrastructure.
Availability
ISL12028IBZ is available at Aetrix Electronics and suitable for utility metering, HVAC control systems, and industrial test equipment requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for ISL12028IBZ 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
Intersil (now part of Renesas Electronics) designs high-performance analog and mixed-signal ICs for industrial, communications, and computing markets, with emphasis on power efficiency and system integration.
The ISL12028IBZ belongs to Intersil's real-time clock family engineered for mission-critical timekeeping in infrastructure equipment - integrating RTC, EEPROM, alarms, and supervision to replace multiple discrete functions in metering and control applications.
FAQ
What is the VBAT operating voltage range for ISL12028IBZ?
The ISL12028IBZ supports VBAT from 1.8V to 5.5V. Operation below 1.8V is not guaranteed - especially after VDD power-down cycles - due to insufficient bias for internal oscillator and SRAM retention. At 1.8V, battery supply current is 800nA, enabling multi-year coin-cell operation. The device remains fully functional in timekeeping mode down to this threshold, with calendar accuracy preserved through 2099.
Does ISL12028IBZ support I²C communication during battery backup mode?
Yes, ISL12028IBZ supports I²C communication during battery backup, but only when explicitly enabled via the I²C Enable bit (IE) in the control register. By default, I²C is disabled during VBAT operation to prevent bus contention. When enabled, SDA and SCL remain functional with VDD = 0V, allowing host processors to read RTC status or update alarms without restoring main power - critical for outage diagnostics in utility meters.
How does the oscillator compensation work in ISL12028IBZ?
The ISL12028IBZ implements on-chip oscillator compensation using a 64-position digitally controlled trim capacitor and six discrete frequency adjustment settings (±30ppm). This eliminates external load capacitors and enables factory or field calibration against temperature drift. Compensation is applied to the internal feedback loop of the 32.768kHz crystal oscillator, with settings stored in non-volatile control registers - ensuring accuracy remains stable across -40°C to +85°C without manual tuning.
What is the function of the IRQ/FOUT pin on ISL12028IBZ?
The IRQ/FOUT pin on ISL12028IBZ is a software-configurable dual-function I/O. In interrupt mode, it asserts a CMOS push-pull signal when Alarm 0 or Alarm 1 matches the RTC - eliminating need for external pull-ups. In frequency output mode, it delivers 1Hz, 4.096kHz, or 32.768kHz signals derived from the crystal oscillator - usable for system clock distribution or sensor sampling synchronization. Mode selection is controlled via bits in the control/status register.
Is ISL12028IBZ pin-compatible with ISL12028A variants?
No, ISL12028IBZ is not pin-compatible with ISL12028A variants due to differing power control logic: ISL12028IBZ uses Legacy Mode (BSW=1), while ISL12028A uses Standard Mode (BSW=0). Applications requiring VBAT > VDD must use ISL12028A; ISL12028IBZ is restricted to VDD < VBAT configurations. Pin mapping is identical, but register defaults and power-switching behavior differ - necessitating firmware and schematic review before substitution.
ISL12028IBZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Supervisor, Watchdog Timer
- Memory Size:
- -
- Time Format:
- HH:MM:SS (12/24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- I2C, 2-Wire Serial
- Voltage - Supply:
- 2.7V ~ 5.5V
- Voltage - Supply, Battery:
- 1.8V ~ 5.5V
- Current - Timekeeping (Max):
- 10µA ~ 20µA @ 2.7V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 14-SOIC
ISL12028IBZ FAQ
1.How can I place an order for ISL12028IBZ through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL12028IBZ 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 ISL12028IBZ reliable?
The price and inventory of ISL12028IBZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL12028IBZ is usually 5 days.
3.What payment methods are accepted for ISL12028IBZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL12028IBZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL12028IBZ?
ISL12028IBZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL12028IBZ 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 ISL12028IBZ?
For technical support, including ISL12028IBZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL12028IBZ requirements.
6.How does Aetrix verify that ISL12028IBZ is sourced from the original manufacturer or authorized distributors?
All ISL12028IBZ 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 ISL12028IBZ meets industry standards.
7.What is the process for return or replacement of ISL12028IBZ?
All ISL12028IBZ units undergo pre-shipment inspection (PSI). If there is an issue with ISL12028IBZ, 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 ISL12028IBZ part is unused and in its original packaging.
Return procedure for ISL12028IBZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ISL12028IBZ Tags
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MCP7940N-I/SN
Microchip Technology
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MCP7940MT-I/MNY
Microchip Technology
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PCF85063ATL/1,118
NXP USA Inc.
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MCP7940NT-I/SN
Microchip Technology
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MCP7940NT-I/MS
Microchip Technology
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MCP7940N-I/MS
Microchip Technology
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PCF85063AT/AY
NXP USA Inc.
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PCF85063TP/1Z
NXP Semiconductors
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PCF85063ATT/AJ
NXP USA Inc.
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MCP7940NT-E/SN
Microchip Technology
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MCP7940NT-I/MNY
Microchip Technology
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MCP79400T-I/SN
Microchip Technology
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