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Analog Devices Inc./Maxim Integrated MAX805LCSA+T
- Part No.:
- MAX805LCSA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX805LCSA+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,683
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Product details
Overview
The MAX805LCSA+T from Maxim Integrated is a microprocessor supervisory circuit providing active-high reset output, battery-backup switching, 1.6s watchdog timer, and 1.25V power-fail comparator for +5V systems. It asserts RESET when VCC drops below 4.65V, guarantees reset assertion down to VCC = 1.1V, and delivers 200ms reset pulse width. Used in battery-powered controllers and critical μP monitoring where reliable power-up/down sequencing and brownout protection are required.
For engineers reviewing the MAX805LCSA+T datasheet, MAX805LCSA+T pinout, MAX805LCSA+T application, or MAX805LCSA+T equivalent, key selection factors include its active-high RESET output (vs. active-low on MAX690A), guaranteed operation down to 1.1V VCC, 4.65V reset threshold with ±150mV hysteresis, 200μA quiescent current, and 50nA battery-backup mode current - all in an 8-pin SO package.
Technical Context
The MAX805LCSA+T integrates four core functions in a single monolithic IC: precision voltage monitoring with fixed 4.65V reset threshold, 200ms reset time delay, 1.6s watchdog timeout with WDI edge-triggered clearing, and bidirectional battery switchover using internal PMOS switches (5Ω in VCC mode, 80Ω in VBATT mode). Its PFI input compares against a trimmed 1.25V reference to generate PFO low on undervoltage.
Unlike earlier MAX690A variants, the MAX805LCSA+T provides an active-high RESET output (labeled RESET) instead of active-low RESET, enabling direct interface with Intel 80C51-family and other μPs requiring high-asserted reset. The device maintains guaranteed RESET validity down to VCC = 1.1V and supports backup-battery operation with <1μA supply current when VCC is >1V below VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - triggers reset during brownout; matches standard +5V ±5% supply tolerance |
| Reset Pulse Width | 200ms - ensures μP completes full reset initialization before release |
| Watchdog Timeout | 1.6s - detects firmware lockup without requiring external timing components |
| Quiescent Current | 200μA - minimizes standby power draw in always-on embedded systems |
| Battery-Backup Current | 50nA - extends lithium battery life beyond 10 years in CMOS RAM retention |
| Power-Fail Reference | 1.25V ±25mV - enables accurate undervoltage detection of unregulated supplies via external divider |
| RESET Output Type | Active-high - drives high during reset; compatible with Intel 80C51, Z80, and other legacy μPs |
Pinout & Package
MAX805LCSA+T is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package, RoHS-compliant, with 1.27mm pitch and surface-mount footprint. Pin 1 is marked by a beveled corner or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | CMOS RAM supply output | Switches between VCC and VBATT based on voltage comparison; connects to VCC via 5Ω PMOS when VCC > 4.65V |
| VCC | +5V main supply input | Primary power source; powers internal circuitry and defines reset threshold reference |
| GND | Ground reference | Common return path for all analog and digital functions; must be low-impedance |
| PFI | Power-fail comparator input | Accepts divided-down supply voltage; trips PFO low when input falls below 1.25V |
| PFO | Power-fail open-drain output | Asserts low to signal impending supply failure; requires external pull-up for interrupt generation |
| WDI | Watchdog timer input | Edge-sensitive; toggling within 1.6s prevents reset; floating disables watchdog |
| RESET | Active-high reset output | Drives high during reset condition; valid down to VCC = 1.1V; replaces active-low RESET |
| VBATT | Backup battery input | Supplies VOUT when VCC fails; switchover occurs only if VBATT > VCC + 20mV |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1.1V | Ensures deterministic reset behavior even during severe brownout conditions before VCC collapses |
| 40mV switchover hysteresis | Prevents oscillatory battery switching during slow VCC ramp-down or noisy supply conditions |
| 50nA battery-backup quiescent current | Enables multi-year data retention in SRAM using standard CR2032 lithium coin cells |
| 1.25V precision power-fail reference | Allows accurate monitoring of non-5V rails (e.g., +3.3V, +2.5V) using simple resistor dividers |
| Internal 1.6s watchdog timer | Eliminates need for external RC timing network; reduces BOM count and layout area |
Applications
| Battery-Powered Controllers | Critical μP Power Monitoring |
|---|---|
Use Scenario: Industrial programmable logic controllers (PLCs) operating on lithium primary batteries with infrequent wake-up cycles. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, battery switchover to retain configuration memory, and watchdog supervision of firmware execution. Use Value: Prevents corrupted state after power interruption; extends battery life via 50nA backup current; eliminates need for discrete reset generators and backup diodes. | Use Scenario: Medical infusion pump with safety-critical μP that must never execute undefined code due to supply instability. IC Role / Device Role / Timing Role: Primary reset supervisor ensuring clean power-up, detecting undervoltage events, and forcing hard reset on watchdog timeout. Use Value: Guarantees RESET remains asserted until VCC reaches 4.65V and holds for 200ms; meets IEC 62304 Class C software safety requirements. |
| Intelligent Instruments | Embedded Data Loggers |
Use Scenario: Portable handheld multimeter storing calibration coefficients and measurement history in battery-backed SRAM. IC Role / Device Role / Timing Role: Voltage monitor and battery switcher maintaining VOUT during main supply removal for hot-swap battery replacement. Use Value: Enables safe battery replacement without losing calibration data; active-high RESET directly interfaces with instrument's μP reset pin. | Use Scenario: Remote environmental sensor node logging temperature/humidity to SRAM, powered by solar-charged Li-ion with intermittent operation. IC Role / Device Role / Timing Role: Dual-role supervisor: asserting RESET on solar-panel dropout and triggering PFO interrupt to initiate graceful shutdown before power loss. Use Value: Uses PFI/PFO to detect falling input voltage early; allows 200ms to save volatile data before VCC drops below 4.65V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802LCSA+ | Provides active-low RESET output; same 4.65V threshold, 200ms pulse, and 1.6s watchdog; 200μA supply current | Requires external inverter or μP with active-low reset input; not drop-in compatible for active-high designs | Select MAX802LCSA+ only if system uses active-low reset architecture and no redesign is possible |
| MAX813LCSA+ | Identical pinout and function to MAX805LCSA+, but includes manual reset input (MR) pin; otherwise identical electrical specs | Supports operator-initiated reset via pushbutton; adds one external component (pull-up + switch) | Choose MAX813LCSA+ when field-serviceable manual reset capability is required alongside active-high reset |
Compared with MAX802LCSA+, the MAX805LCSA+ eliminates need for level-shifting circuitry in active-high reset systems; compared with MAX813LCSA+, it reduces BOM count and board space by omitting MR functionality where not needed.
Availability
MAX805LCSA+T is available at Aetrix Electronics and suitable for battery-powered controllers, critical μP power monitoring, and intelligent instrumentation requiring stable component supply across industrial temperature ranges (0°C to +70°C).
Supply support for MAX805LCSA+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 and mixed-signal ICs for industrial, medical, communications, and computing applications.
The MAX805LCSA+T belongs to Maxim's μP supervisory product line, engineered specifically for robust power-monitoring, reset generation, and battery-switchover in resource-constrained embedded systems.
FAQ
What is the reset threshold voltage for the MAX805LCSA+T?
The MAX805LCSA+T has a nominal reset threshold of 4.65V, with a guaranteed range of 4.50V to 4.75V over temperature and supply variation. This threshold is factory-trimmed and applies to VCC falling conditions. Hysteresis of 40mV ensures clean transition without chatter during slow voltage ramps. The MAX805LCSA+T does not support adjustable reset thresholds - it is a fixed-threshold device optimized for +5V systems.
Does the MAX805LCSA+T provide active-high or active-low reset output?
The MAX805LCSA+T provides an active-high reset output labeled RESET. When asserted, this pin drives high (to VCC or VBATT, whichever is higher); when deasserted, it goes high-impedance. This differs from the active-low RESET output found on MAX690A/MAX802L. The MAX805LCSA+T's active-high RESET is designed for direct interface with μPs such as the Intel 80C51 family that require high-asserted reset signals.
How does the battery switchover function work in the MAX805LCSA+T?
In the MAX805LCSA+T, battery switchover activates only when VCC falls below the 4.65V reset threshold AND VBATT exceeds VCC by at least 20mV. At that point, VOUT disconnects from VCC and connects to VBATT through an 80Ω PMOS switch. Once VCC rises above VBATT by 20mV, VOUT reconnects to VCC. This 40mV hysteresis prevents oscillation. During switchover, supply current drops to <1μA if VCC is >1V below VBATT, extending battery life significantly.
What is the watchdog timeout period for the MAX805LCSA+T?
The MAX805LCSA+T features a watchdog timer with a nominal timeout period of 1.6 seconds. The actual timeout is guaranteed between 1.00s and 2.25s over temperature and supply voltage. The timer clears on any rising or falling edge at the WDI pin, on RESET assertion, or when WDI is three-stated. If WDI remains static (high or low) for longer than the timeout, RESET is triggered. Leaving WDI floating disables the watchdog function entirely.
Can the MAX805LCSA+T monitor power supplies other than +5V?
Yes, the MAX805LCSA+T can monitor non-5V supplies using its PFI input and internal 1.25V reference. By connecting a resistor divider from the target supply rail to PFI, the voltage at PFI is scaled down to match the 1.25V trip point. For example, to monitor a +3.3V rail, use R1 = 100kΩ and R2 = 62kΩ so that 3.3V × (62/(100+62)) ≈ 1.25V. The PFI input draws only ±25nA, minimizing divider loading error and enabling high-impedance sensing.
MAX805LCSA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX805LCSA+T FAQ
1.How can I place an order for MAX805LCSA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805LCSA+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 MAX805LCSA+T reliable?
The price and inventory of MAX805LCSA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805LCSA+T is usually 5 days.
3.What payment methods are accepted for MAX805LCSA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805LCSA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805LCSA+T?
MAX805LCSA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805LCSA+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 MAX805LCSA+T?
For technical support, including MAX805LCSA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805LCSA+T requirements.
6.How does Aetrix verify that MAX805LCSA+T is sourced from the original manufacturer or authorized distributors?
All MAX805LCSA+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 MAX805LCSA+T meets industry standards.
7.What is the process for return or replacement of MAX805LCSA+T?
All MAX805LCSA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX805LCSA+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 MAX805LCSA+T part is unused and in its original packaging.
Return procedure for MAX805LCSA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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