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onsemi CAT1021YI-25-G
- Part No.:
- CAT1021YI-25-G
- Manufacturer:
- onsemi
- Category:
- Supervisors
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
CAT1021YI-25-G.pdf
- Description:
- CAT1021 - SUPERVISORY CIRCUIT WI
- Quantity:
- Payment:
- Shipping:
Inventory:600
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Product details
Overview
CAT1021YI-25-G from onsemi is a supervisory circuit integrating 2 kbit I²C EEPROM, precision VCC monitor with 2.55–2.70 V reset threshold, active-high and active-low open-drain RESET outputs, manual reset (MR) input, and write-protect (WP) pin - all in an 8-pin TSSOP package. It operates from 2.7 V to 5.5 V, features 400 kHz I²C interface, 1.6 s watchdog timer monitoring SDA, and supports industrial temperature range (−40°C to +85°C). Used in microcontroller-based systems requiring brownout protection and nonvolatile configuration storage.
For engineers reviewing the CAT1021YI-25-G datasheet, pinout, applications, or equivalent options, key selection criteria include dual-reset polarity support, WP-enabled hardware write protection, SDA-monitored watchdog timeout, 2.55–2.70 V threshold compatibility with 3.0 V systems, and TSSOP-8 footprint suitability for space-constrained embedded designs.
Technical Context
The CAT1021YI-25-G implements a precision bandgap-based VCC sense circuit with 15 mV hysteresis and guaranteed reset validity down to VCC = 1.0 V. Its dual open-drain RESET outputs (active-high and active-low) enable direct interfacing with diverse microcontrollers without level-shifting.
Watchdog functionality is implemented via SDA line activity monitoring with 1.0–2.1 s timeout window; the internal 2 kbit EEPROM uses 16-byte page writes, supports 1,000,000 program/erase cycles, and enforces hardware write protection during reset or when WP = VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.55 V to 2.70 V - matches 3.0 V system brownout detection with margin |
| I²C Clock Frequency | 400 kHz - enables fast configuration read/write without bus contention |
| EEPROM Capacity | 2 kbit (256 bytes) - stores boot parameters, calibration data, or device ID in single IC |
| Watchdog Timeout | 1.6 s typical - provides reliable hang detection for firmware with known execution windows |
| Supply Voltage Range | 2.7 V to 5.5 V - supports mixed-voltage designs including 3.3 V and 5 V rails |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control environments |
| Power-Up Reset Delay | 130–270 ms - ensures stable VCC and clock before MCU release |
| Write Endurance | 1,000,000 cycles - enables frequent logging or runtime parameter updates |
Pinout & Package
Package: 8-pin TSSOP (Case 948S), 3.0 mm × 4.4 mm footprint, 1.1 mm max height, RoHS-compliant NiPdAu finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 MR | Manual Reset Input | Debounced active-low input; initiates 200 ms reset pulse when pulled low - eliminates need for external RC debounce |
| 2 RESET | Active-Low Reset Output | Open-drain output; requires external pull-up; asserts during brownout, power-up, or MR activation |
| 3 WP | Write Protect Input | Hardware lock: ties high to VCC to disable all EEPROM writes - prevents corruption during voltage transients |
| 4 VSS | Ground | Reference return for all analog and digital functions; must be low-impedance connection |
| 5 VCC | Power Supply | 2.7–5.5 V supply; powers supervisor logic, EEPROM, and reset comparators |
| 6 RESET | Active-High Reset Output | Open-drain output; requires external pull-down; complements active-low RESET for mixed-interface systems |
| 7 SCL | I²C Clock Input | Input-only clock line; synchronizes EEPROM read/write transfers at up to 400 kHz |
| 8 SDA | I²C Data I/O | Bidirectional open-drain line; carries address, data, and ACK/NACK; shared with watchdog monitor |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity RESET outputs | Simultaneous active-high and active-low signals eliminate need for external inverters or level translators |
| Hardware write protection | WP pin disables EEPROM writes when tied to VCC, preventing accidental overwrites during power instability |
| SDA-monitored watchdog | Uses existing I²C data line for watchdog triggering - no dedicated WDI pin required, saving PCB real estate |
| Guaranteed reset at 1.0 V | Ensures valid reset assertion even during deep brownout, protecting MCU state before core logic fails |
| 16-byte page write buffer | Reduces I²C transaction count for multi-byte updates - improves efficiency vs. byte-by-byte writes |
| 100-year data retention | Validated per MIL-STD-883 Method 1008 - suitable for long-lifecycle industrial equipment with infrequent field updates |
Applications
| Industrial PLC I/O Module | Smart Energy Meter |
|---|---|
Use Scenario: Configuring analog input scaling, channel calibration coefficients, and communication protocol settings at power-up. IC Role / Device Role / Timing Role: Supervisory IC providing power-on reset sequencing and nonvolatile storage of field-programmable parameters. Use Value: Eliminates external reset IC and discrete EEPROM, reducing BOM count while ensuring parameter integrity across 10+ year meter lifetime. |
Use Scenario: Storing tariff schedules, tamper-event logs, and meter serial number with write-protection during voltage sags. IC Role / Device Role / Timing Role: System supervisor with integrated EEPROM that locks writes during brownout via WP pin and VCC sensing. Use Value: Prevents corruption of billing-critical data during grid fluctuations - meets IEC 62056-21 reliability requirements. |
| Medical Diagnostic Handheld | Automotive Body Control Module (BCM) |
Use Scenario: Saving user preferences, sensor offset corrections, and last-used test mode between battery swaps. IC Role / Device Role / Timing Role: Dual-reset supervisor enabling clean MCU initialization and secure parameter storage in compact TSSOP package. Use Value: TSSOP-8 footprint fits tight PCB layouts; 1M endurance supports daily recalibration without wear-out concerns. |
Use Scenario: Storing door lock configuration, lighting profiles, and fault history in 12 V automotive subsystems with wide input variation. IC Role / Device Role / Timing Role: Brownout detector with 2.55–2.70 V threshold aligned to 3.3 V MCU rail, plus EEPROM for persistent settings. Use Value: Matches 3.0 V system tolerance; dual RESET outputs interface directly with both legacy 5 V and modern 3.3 V ASICs in same BCM design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supervisory + EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6361KA27+T | Single active-low RESET only; no active-high output; no WP pin; 1 kbit EEPROM | Lacks dual-reset polarity and hardware write protection - requires external components for equivalent robustness | Choose when board space allows discrete WP logic and only one reset polarity is needed |
| STM8AF6266TCY | MCU with integrated 2 kbit EEPROM and software-configurable reset logic; no dedicated watchdog on SDA | Requires firmware development for reset timing and watchdog behavior; higher design complexity | Prefer when system already uses STM8 and firmware resources permit custom supervision logic |
Compared with CAT1021YI-25-G, MAX6361KA27+T offers lower integration but simpler qualification, while STM8AF6266TCY trades off hardware reliability for programmable flexibility - CAT1021YI-25-G delivers deterministic, zero-firmware supervision with dual-reset and WP in one TSSOP-8 device.
Availability
CAT1021YI-25-G is available at Aetrix Electronics and suitable for industrial PLCs, smart energy meters, medical handhelds, and automotive body control modules requiring stable component supply with long-term lifecycle assurance.
Supply support for CAT1021YI-25-G 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.
The CAT1021 family targets microcontroller-based systems needing integrated power supervision and nonvolatile memory - designed to reduce component count, improve reliability, and simplify compliance with industrial and automotive power integrity standards.
FAQ
What is the reset threshold voltage range for CAT1021YI-25-G?
The CAT1021YI-25-G has a factory-trimmed reset threshold range of 2.55 V to 2.70 V, optimized for 3.0 V systems. This ensures reliable brownout detection while maintaining sufficient margin above the minimum operating voltage of downstream 3.3 V or 3.0 V logic. The hysteresis is 15 mV, preventing chatter near the threshold.
Does CAT1021YI-25-G support both active-high and active-low reset outputs?
Yes, CAT1021YI-25-G provides two independent open-drain reset outputs: one active-low (pin 2) and one active-high (pin 6). Both are asserted simultaneously during power-up, brownout, or manual reset. Each requires its own external pull-up (for active-low) or pull-down (for active-high) resistor to establish valid logic levels.
How does the watchdog timer function in CAT1021YI-25-G?
The CAT1021YI-25-G watchdog monitors the SDA line for activity; if no transition occurs within 1.6 seconds (1.0–2.1 s range), it asserts both RESET outputs. The timer resets on any SDA edge - no dedicated WDI pin is used. While RESET is asserted, the watchdog remains cleared and does not time out.
What is the role of the WP pin on CAT1021YI-25-G?
The WP (Write Protect) pin on CAT1021YI-25-G disables all EEPROM write operations when tied to VCC. When WP = VCC, the device ignores incoming write commands and does not acknowledge data bytes - providing hardware-level protection against corruption during power instability or software faults. WP has an internal pull-down resistor.
Is CAT1021YI-25-G compatible with standard I²C protocols?
Yes, CAT1021YI-25-G fully complies with standard I²C specifications: it supports 400 kHz clock frequency, 7-bit slave address (1010xxxR/W), ACK polling, and all standard read/write modes (current address, random, sequential). Its SDA and SCL pins meet I²C voltage thresholds and timing requirements per Table 8 in the datasheet.
CAT1021YI-25-G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- CAT1021
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.55V, 2.7V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High/Active Low
- Reset Timeout:
- 130ms Minimum
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
CAT1021YI-25-G FAQ
1.How can I place an order for CAT1021YI-25-G through Aetrix?
Please submit a Request for Quotation (RFQ) for CAT1021YI-25-G 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 CAT1021YI-25-G reliable?
The price and inventory of CAT1021YI-25-G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CAT1021YI-25-G is usually 5 days.
3.What payment methods are accepted for CAT1021YI-25-G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CAT1021YI-25-G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CAT1021YI-25-G?
CAT1021YI-25-G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CAT1021YI-25-G 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 CAT1021YI-25-G?
For technical support, including CAT1021YI-25-G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CAT1021YI-25-G requirements.
6.How does Aetrix verify that CAT1021YI-25-G is sourced from the original manufacturer or authorized distributors?
All CAT1021YI-25-G 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 CAT1021YI-25-G meets industry standards.
7.What is the process for return or replacement of CAT1021YI-25-G?
All CAT1021YI-25-G units undergo pre-shipment inspection (PSI). If there is an issue with CAT1021YI-25-G, 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 CAT1021YI-25-G part is unused and in its original packaging.
Return procedure for CAT1021YI-25-G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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