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Analog Devices Inc./Maxim Integrated MAX805TCSA
- Part No.:
- MAX805TCSA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX805TCSA.pdf
- Description:
- IC SUPERVISOR MAX805 MPU
- Quantity:
- Payment:
- Shipping:
Inventory:634
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Product details
Overview
MAX805TCSA from Maxim Integrated is a 3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 3.075V reset threshold (T-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC, asserts reset during power-up/brownout/watchdog timeout, and switches VOUT to VBATT when VCC falls below 2.40V-enabling reliable CMOS RAM retention in portable controllers.
For engineers reviewing the MAX805TCSA datasheet, MAX805TCSA pinout, MAX805TCSA application, or MAX805TCSA equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, ±4% reset threshold accuracy, 40µA VCC supply current, battery-leakage current <1µA, and compatibility with lithium coin-cell backup (VBATT > VCC allowed).
Technical Context
The MAX805TCSA integrates a precision reset comparator with 10mV hysteresis, a non-disableable 1.6s watchdog timer cleared by WDI edges, and a dual-path battery switchover circuit using PMOS switches (3Ω VCC-to-VOUT, 140Ω VBATT-to-VOUT). Its PFI input accepts external voltage dividers for auxiliary supply monitoring, while PFO provides an independent power-fail flag.
It operates across 0°C to +70°C (C-grade), supports VCC from 3.17V to 5.5V and VBATT up to 6.0V, and guarantees valid RESET behavior even when VBATT = 0V and VCC = 1.2V. The device lacks short-circuit protection on VOUT and requires 0.1µF local decoupling on VCC and VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 3.075V (±4%) - triggers reset before 3.3V supply drops below system stability margin |
| Reset Timeout Period | 200ms (140–280ms over temp) - ensures µP completes power-up initialization before release |
| VCC Supply Current | 40µA typical at VCC < 3.6V - enables multi-year operation on coin-cell backup |
| Watchdog Timeout | 1.6s (1.12–2.24s over temp) - detects firmware lockup without requiring µP intervention |
| Battery Leakage Current | <1µA (max) - preserves 10+ year shelf life of lithium backup cells |
| VBATT Switch Threshold | 2.40V (2.30–2.50V) - initiates switchover before CMOS RAM data retention fails (~2.0V) |
| PFO Input Threshold | 1.237V ±25mV - supports accurate undervoltage detection of auxiliary rails via resistor divider |
Pinout & Package
MAX805TCSA is housed in an 8-pin SOIC package (S8+4 outline, RoHS-compliant), with gull-wing leads, 1.27mm pitch, and 5.0mm × 6.2mm body size.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω PMOS); must be decoupled with 0.1µF |
| 2 - VCC | Main system supply input | Accepts 3.17–5.5V; powers internal circuitry and drives VOUT when above VSW |
| 3 - GND | Ground reference | Common return for all analog/digital functions; substrate tied to higher of VCC/VBATT |
| 4 - PFI | Power-fail input | Compares external voltage to 1.237V reference; triggers PFO low if below threshold |
| 5 - PFO | Power-fail open-drain output | Active-low flag indicating PFI undervoltage or VCC < VSW; can drive MR on MAX704/MAX806 |
| 6 - WDI | Watchdog input | Rising/falling edge clears 1.6s timer; static high/low triggers reset; no disable option |
| 7 - RESET | Active-high open-drain reset | Inverse of MAX690/MAX802 RESET; requires external pull-up to VCC for µP interface |
| 8 - VBATT | Backup battery input | Supports VBATT > VCC (e.g., 3.6V Li cell); connects to VOUT when VCC < 2.40V or < 1.75V |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout, critical for automotive or industrial power sequencing |
| Battery-backup switchover with VBATT > VCC support | Enables use of standard 3.6V lithium cells without level-shifting, simplifying BOM and layout |
| 200ms reset timeout with temperature compensation | Maintains 140–280ms window across -40°C to +85°C, preventing premature µP release |
| 1.6s watchdog timer with edge-triggered clear | Eliminates need for dedicated watchdog clock; compatible with GPIO toggling in resource-constrained µPs |
| Independent power-fail comparator (PFI/PFO) | Allows monitoring of secondary supplies (e.g., analog rail, sensor bias) without µP firmware involvement |
| 40µA VCC supply current (typ) | Reduces standby power in always-on systems, extending battery life in portable medical or IoT devices |
Applications
| Battery-Powered Portable Controllers | Embedded Industrial Data Loggers |
|---|---|
|
Use Scenario: Handheld test equipment powered by single CR2032 coin cell, requiring RAM retention during battery replacement. IC Role / Device Role / Timing Role: Supervisory IC providing VOUT switchover, brownout reset, and watchdog supervision. Use Value: Enables hot-swap battery replacement without data loss, leveraging 2.40V switchover threshold and <1µA battery leakage. |
Use Scenario: Remote environmental sensor node operating unattended for months on AA batteries, logging data to SRAM. IC Role / Device Role / Timing Role: Power monitor and reset controller ensuring µP recovery after voltage sag caused by RF transmission bursts. Use Value: 200ms reset timeout prevents spurious reboots during transient sags; 40µA quiescent current extends operational lifetime. |
| Critical µP Power Monitoring in Medical Devices | Intelligent Instrumentation with Auxiliary Rail Monitoring |
|
Use Scenario: Portable ECG monitor with flash memory and real-time DSP, where corrupted boot sequences could compromise patient safety. IC Role / Device Role / Timing Role: Fail-safe reset generator asserting RESET down to VCC = 1V and validating power integrity pre-boot. Use Value: Guaranteed reset assertion eliminates risk of executing invalid code during marginal supply conditions. |
Use Scenario: Digital multimeter with isolated analog front-end powered by ±15V rails, requiring fault detection on auxiliary supplies. IC Role / Device Role / Timing Role: Dual-function supervisor using PFI to monitor -15V rail (via resistor divider) and generate PFO interrupt. Use Value: Offloads rail monitoring from µP firmware, enabling immediate shutdown or alert on analog supply failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX804TCSA | Active-low RESET output (push-pull), identical reset threshold, timing, and switchover specs | Direct replacement where µP requires active-low reset signal without external inversion | Select MAX804TCSA when interfacing with legacy µPs lacking internal pull-ups or requiring asserted-low reset polarity |
| MAX806TCSA | Includes manual reset input (MR), same T-suffix threshold and watchdog, but no PFI/PFO | Suitable for systems needing user-initiated reset but not auxiliary supply monitoring | Choose MAX806TCSA when board space allows MR switch integration and PFI functionality is unnecessary |
Compared with MAX804TCSA and MAX806TCSA, the MAX805TCSA uniquely combines active-high open-drain RESET with full PFI/PFO capability-making it optimal for µPs with bidirectional reset pins and designs requiring dual-rail monitoring without adding discrete comparators.
Availability
MAX805TCSA is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded industrial data loggers, intelligent instrumentation, critical µP power monitoring, and portable medical devices requiring stable component supply and long-term lifecycle support.
Supply support for MAX805TCSA 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) is a semiconductor company specializing in analog and mixed-signal ICs for power management, sensing, and connectivity.
The MAX805TCSA belongs to Maxim's 3.0V/3.3V microprocessor supervisory circuit family, designed specifically to replace discrete reset generators and backup-switching circuits in space-constrained, battery-sensitive applications.
FAQ
What is the reset threshold voltage of the MAX805TCSA?
The MAX805TCSA has a nominal reset threshold voltage of 3.075V, with ±4% tolerance over temperature and supply variations. This value is specified for VCC falling conditions and ensures reset assertion before the 3.3V system supply drops below 3.0V-providing margin for power supply ripple and load-induced droop. The MAX805TCSA datasheet confirms this threshold applies specifically to the T-suffix variant, distinguishing it from S- and R-suffix versions.
Does the MAX805TCSA support battery-backup operation with VBATT higher than VCC?
Yes, the MAX805TCSA explicitly supports VBATT exceeding VCC-enabling direct connection of standard 3.6V lithium coin cells without level-shifting. Its internal battery switchover circuit activates when VCC falls below 2.40V (2.30–2.50V range), connecting VBATT to VOUT through a 140Ω switch. This feature is confirmed in the MAX805TCSA datasheet's "Backup-Battery Switchover" section and electrical characteristics table.
What is the function of the WDI pin on the MAX805TCSA?
The WDI (Watchdog Input) pin on the MAX805TCSA monitors µP activity: a rising or falling edge clears the internal 1.6s timer, while static high or low states trigger a reset pulse. Unlike some supervisory ICs, the watchdog function cannot be disabled. This behavior is documented in the MAX805TCSA's "Watchdog Input" section and verified in its timing diagrams and electrical characteristics table under tWD and WDI input thresholds.
How does the MAX805TCSA differ from the MAX804TCSA?
The MAX805TCSA features an active-high open-drain RESET output, whereas the MAX804TCSA provides an active-low push-pull RESET. Both share identical reset threshold (3.075V), timeout (200ms), watchdog (1.6s), and battery switchover specs. This difference dictates interface requirements: MAX805TCSA needs an external pull-up resistor to VCC for µP reset signaling, while MAX804TCSA drives reset directly low. The distinction is clearly stated in the MAX805TCSA pin description and functional comparison tables.
Can the MAX805TCSA monitor a second power supply?
Yes, the MAX805TCSA includes a dedicated PFI (Power-Fail Input) pin referenced to a precise 1.237V internal threshold, allowing monitoring of auxiliary supplies via an external resistor divider. When PFI falls below this threshold, PFO goes low-providing an interrupt-capable flag independent of the main reset function. This capability is confirmed in the MAX805TCSA's "Power-Fail Comparator" section and electrical characteristics table under VPFT and PFI input current specs.
MAX805TCSA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 3.075V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX805TCSA FAQ
1.How can I place an order for MAX805TCSA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805TCSA 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 MAX805TCSA reliable?
The price and inventory of MAX805TCSA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805TCSA is usually 5 days.
3.What payment methods are accepted for MAX805TCSA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805TCSA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805TCSA?
MAX805TCSA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805TCSA 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 MAX805TCSA?
For technical support, including MAX805TCSA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805TCSA requirements.
6.How does Aetrix verify that MAX805TCSA is sourced from the original manufacturer or authorized distributors?
All MAX805TCSA 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 MAX805TCSA meets industry standards.
7.What is the process for return or replacement of MAX805TCSA?
All MAX805TCSA units undergo pre-shipment inspection (PSI). If there is an issue with MAX805TCSA, 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 MAX805TCSA part is unused and in its original packaging.
Return procedure for MAX805TCSA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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