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Analog Devices Inc./Maxim Integrated MAX16021LTET+T
- Part No.:
- MAX16021LTET+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
MAX16021LTET+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16TQFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,271
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Product details
Overview
MAX16021LTET+T from Maxim Integrated is a low-power microprocessor supervisory circuit with integrated battery-backup switchover, chip-enable (CE) gating, and multi-threshold power monitoring. It provides active-low reset output, 145ms minimum reset timeout, 1.2µA supply current, and supports 1.53V–5.5V operation for 1.8V/2.5V/3V/3.3V/5V systems. It is used in real-time clock (RTC) backup and CMOS memory write protection during brownout.
For engineers reviewing the MAX16021LTET+T datasheet, MAX16021LTET+T pinout, MAX16021LTET+T application, or MAX16021LTET+T equivalent, key selection criteria include its fixed 2.63V reset threshold (suffix 'R'), 16-pin TQFN package with exposed pad, CEIN/CEOUT propagation delay of 1.5ns, battery-OK (BATTOK) and battery-on (BATTON) indicators, and watchdog timer with 1.2s typical timeout.
Technical Context
The MAX16021LTET+T implements a dual-path power-switching architecture: VCC-to-OUT under normal operation, and automatic switchover to BATT when VCC falls below both the reset threshold (2.63V) and VBATT. Its CE gating logic disables CEIN-to-CEOUT conduction during reset assertion, holding CEOUT low for 12µs if CEIN is low at reset onset.
It integrates five independent supervisory functions: µP reset generation with 20µs falling-edge delay, power-fail comparator (0.590V threshold, 30mV hysteresis), watchdog timer (1.235s typical timeout), low-line indicator (LL, 2.5% above reset threshold), and battery status signaling (BATTOK, BATTON, BATT_TEST).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.549V (min) to 2.755V (max), typ 2.63V - ensures reliable reset assertion before system instability in 2.5V/3V domains. |
| Reset Timeout Period | 145ms (min) to 285ms (max) - meets JEDEC JESD8-12B requirements for processor initialization hold time. |
| Supply Current | 3.4µA (typ) at VCC = 5.5V - enables ultra-low-power operation in always-on RTC/memories. |
| Battery-Backup Current | 0.25µA (typ) at VCC = 0V - extends coin-cell life beyond 10 years in standby applications. |
| CEIN-to-CEOUT Propagation Delay | 1.5ns (typ) - supports high-speed µP/DSP interfaces without timing violation in CE-gated SRAM access. |
| Watchdog Timeout | 0.83s (min) to 1.64s (max), typ 1.235s - provides robust firmware hang detection without false triggers. |
| Power-Fail Input Threshold | 0.572V–0.611V with 30mV hysteresis - allows precise low-voltage monitoring down to 0.6V via external resistor divider. |
Pinout & Package
MAX16021LTET+T is housed in a 16-pin 4mm × 4mm TQFN-EP package with exposed thermal pad (EP), rated for -40°C to +85°C operation. The exposed pad must be soldered to a large PCB ground plane for thermal management and EMI reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BATT | Backup battery input | Connects to coin cell or supercap; enables seamless switchover when VCC drops below 2.63V and VBATT > VCC. |
| MR | Active-low manual reset input | Internally pulled up to VCC (30kΩ); asserts reset on logic-low pulse ≥120ns; no external debounce needed. |
| PFI | Power-fail comparator input | Accepts resistive divider output; referenced to internal 0.590V threshold; hysteresis prevents noise-induced toggling. |
| WDI | Watchdog timer input | Edge-sensitive; clears internal timer on rising/falling edge; open-circuit disables watchdog function. |
| LL | Active-low low-line output | Asserts ~2.5% above reset threshold (e.g., ~2.695V for 2.63V VTH); provides early warning NMI before reset. |
| BATT_TEST | Open-drain battery-test output | Pulses low for 1.3s every 24h; used with external load to verify battery health without continuous drain. |
| BATTOK | Battery-OK status output | Asserts low when VBATT < 2.508V; indicates battery depletion before backup failure. |
| BATTON | Active-high battery-on indicator | Goes high only during valid battery-backup mode (VCC < VTH and VCC < VBATT); confirms switchover success. |
| WDO | Active-low watchdog output | Asserts independently of RESET; signals watchdog timeout without resetting CPU - useful for diagnostics. |
| PFO | Active-low power-fail output | Complements PFI; asserts when VPFI < 0.590V; drives interrupt or shutdown logic directly. |
| GND | Ground reference | Primary return path; EP pad must be connected to same ground plane for thermal and noise integrity. |
| RESET | Active-low reset output | Push-pull driver; VOL ≤ 0.3V @ 1mA; deasserts after tRP (145ms min) following VCC recovery and MR release. |
| OUT | Switched output | Delivers VCC or BATT to load (e.g., SRAM VDD); RON ≤ 5.5Ω @ VCC = 1.91V/10mA; bypass with ≥0.1µF capacitor. |
| CEOUT | Active-low chip-enable output | Driven by CEIN only when reset is inactive; pulled up to OUT during reset; 12µs hold time prevents partial writes. |
| CEIN | Chip-enable input | Directly connects to µP CE; low impedance path to CEOUT during normal operation; 8Ω–50Ω on-resistance. |
| VCC | Main supply input | 1.53V–5.5V range; bypass with 0.1µF ceramic capacitor close to pin; powers all internal circuits except BATTOK/BATTON. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated CE gating with 1.5ns propagation delay | Prevents erroneous SRAM writes during brownout by disabling CE path within one µP clock cycle. |
| Battery freshness seal | Reduces BATT leakage to ≤20nA at VBATT = 5.5V - preserves shelf life of unused backup batteries. |
| Dual-mode reset output (push-pull) | Drives loads up to 20mA without external pull-up; eliminates need for discrete components in reset net. |
| Debounced manual reset input (MR) | Internal 30kΩ pull-up and 100ns glitch immunity eliminate external RC network and reduce BOM count. |
| UL®-certified per IEC 60950-1 | Validates safety compliance for industrial and commercial end equipment without additional certification effort. |
Applications
| Real-Time Clock (RTC) Backup | CMOS Memory Write Protection |
|---|---|
|
Use Scenario: Maintaining timekeeping and calendar data in GPS modules during vehicle ignition-off periods. IC Role / Device Role / Timing Role: Supervisory IC providing VCC-to-BATT switchover, BATTON confirmation, and BATTOK health monitoring. Use Value: Ensures RTC retains accuracy for >10 years on CR2032 coin cell due to 0.25µA battery-backup current. |
Use Scenario: Preventing corruption of configuration SRAM in point-of-sale terminals during AC power interruption. IC Role / Device Role / Timing Role: Active CE gating that disables memory access within 12µs of reset assertion. Use Value: Eliminates need for external logic or software-based write-protection schemes during brownout. |
| Industrial Control System Monitoring | Portable Medical Device Power Management |
|
Use Scenario: Detecting undervoltage events in PLC I/O modules to trigger safe state transitions before lockup. IC Role / Device Role / Timing Role: Dual-threshold supervision using LL (early warning) and RESET (hard reset) outputs. Use Value: Enables deterministic 200ms window between LL assertion and RESET for orderly firmware shutdown. |
Use Scenario: Extending battery runtime in handheld ultrasound devices by minimizing quiescent current during sleep. IC Role / Device Role / Timing Role: Low-power supervisor with 1.2µA ICC and battery-test capability for field-replaceable packs. Use Value: Reduces baseline system current by >50% versus discrete reset + battery monitor solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supervisory circuit applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX16020LTET+ | Same pinout and core functionality, but lacks BATT_TEST output; uses active-high RESET instead of active-low RESET in MAX16021. | Suitable where battery self-test is not required and µP accepts active-high reset signal. | Select MAX16020LTET+ only if design does not require periodic battery health verification or active-low reset polarity. |
| TPS3808G33DBVR | Single-supply reset IC (no battery switchover, no CE gating, no BATTOK/BATTON); 3.3V fixed threshold; 1.8µA ICC. | Limited to basic reset generation in non-backup applications; cannot replace MAX16021LTET+ in RTC/memory backup roles. | Choose TPS3808G33DBVR only for cost-sensitive, single-rail systems without battery backup or memory write protection needs. |
Compared with MAX16020LTET+, the MAX16021LTET+ adds BATT_TEST for predictive maintenance and matches active-low RESET polarity required by many legacy µPs; compared with TPS3808G33DBVR, it delivers full battery-management integration-switchover, status signaling, and CE gating-in a single 16-pin device.
Availability
MAX16021LTET+T is available at Aetrix Electronics and suitable for real-time clock backup, industrial control monitoring, and portable medical device power management requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for MAX16021LTET+T 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
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.
The MAX16021LTET+T belongs to Maxim's µP supervisory family, engineered specifically for systems requiring coordinated power monitoring, battery-backed memory retention, and hardware-enforced write protection during voltage transients.
FAQ
What is the reset threshold voltage of the MAX16021LTET+T?
The MAX16021LTET+T has a fixed reset threshold of 2.549V (minimum), 2.63V (typical), and 2.755V (maximum), corresponding to suffix 'R' in its ordering code. This threshold is factory-trimmed and guaranteed over -40°C to +85°C, enabling reliable reset assertion in 2.5V and 3V systems without external resistor networks.
Does the MAX16021LTET+T support battery-backed SRAM write protection?
Yes, the MAX16021LTET+T provides hardware-enforced write protection via its CEIN/CEOUT gating function. When RESET asserts, CEOUT is disabled for 12µs if CEIN is low, preventing partial memory writes. CEIN-to-CEOUT propagation delay is 1.5ns (typ), ensuring compatibility with high-speed µPs and DSPs interfacing to SRAM.
How does the BATT_TEST function operate in the MAX16021LTET+T?
The MAX16021LTET+T pulses its BATT_TEST output low for 1.3 seconds every 24 hours to initiate a controlled battery voltage test. During this pulse, an external load (e.g., 10kΩ resistor) can be switched in series with BATT to measure voltage sag. If VBATT drops below 2.508V during testing, BATTOK deasserts, signaling battery depletion.
What package type and thermal characteristics does the MAX16021LTET+T use?
The MAX16021LTET+T uses a 16-pin 4mm × 4mm TQFN-EP package with exposed thermal pad. Its junction-to-ambient thermal resistance (θJA) is 40°C/W, and junction-to-case (θJC) is 6°C/W, measured per JEDEC JESD51-7 on a four-layer board. The EP pad must be soldered to a solid ground plane for optimal thermal performance and EMI suppression.
Can the MAX16021LTET+T be used without a backup battery?
Yes, the MAX16021LTET+T operates fully without a battery connected to BATT. All supervisory functions-including RESET, WDO, PFO, LL, and CE gating-remain active. Battery-related outputs (BATTON, BATTOK, BATT_TEST) remain in their default states (BATTON low, BATTOK high, BATT_TEST high-impedance), and VCC-to-OUT switching continues normally.
MAX16021LTET+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-WQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 3.1V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High/Active Low
- Reset Timeout:
- 145ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TQFN (4x4)
MAX16021LTET+T FAQ
1.How can I place an order for MAX16021LTET+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX16021LTET+T 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 MAX16021LTET+T reliable?
The price and inventory of MAX16021LTET+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX16021LTET+T is usually 5 days.
3.What payment methods are accepted for MAX16021LTET+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX16021LTET+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX16021LTET+T?
MAX16021LTET+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX16021LTET+T 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 MAX16021LTET+T?
For technical support, including MAX16021LTET+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX16021LTET+T requirements.
6.How does Aetrix verify that MAX16021LTET+T is sourced from the original manufacturer or authorized distributors?
All MAX16021LTET+T 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 MAX16021LTET+T meets industry standards.
7.What is the process for return or replacement of MAX16021LTET+T?
All MAX16021LTET+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX16021LTET+T, 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 MAX16021LTET+T part is unused and in its original packaging.
Return procedure for MAX16021LTET+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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