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Analog Devices Inc./Maxim Integrated MAX690ACSA-T
- Part No.:
- MAX690ACSA-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690ACSA-T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,915
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Product details
Overview
The MAX690ACSA-T from Maxim Integrated is a microprocessor supervisory circuit providing precision reset generation, battery-backup switchover, watchdog timer, and power-fail detection in a single 8-pin SOIC package. It asserts a 200ms active-low RESET pulse when VCC drops below 4.65V, supports 1.6s watchdog timeout, delivers 50nA quiescent current in battery-backup mode, and monitors external supplies via a 1.25V PFI threshold-used in battery-powered controllers and critical μP power monitoring.
For engineers reviewing the MAX690ACSA-T datasheet, MAX690ACSA-T pinout, MAX690ACSA-T application, or MAX690ACSA-T equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, ±2% power-fail accuracy (shared with MAX802L), 40mV battery switchover hysteresis, and compatibility with lithium backup batteries up to 4.80V.
Technical Context
The MAX690ACSA-T integrates four independent functional blocks: a precision voltage monitor with 4.65V reset threshold and 40mV hysteresis, a 1.6s watchdog timer cleared by WDI edges or RESET assertion, a battery switchover circuit using dual PMOS switches (5Ω for VCC→VOUT, 80Ω for VBATT→VOUT), and a 1.25V reference-based power-fail comparator driving PFO.
Its internal architecture ensures deterministic behavior during brownout: RESET remains low while VCC < 4.65V and holds for 200ms after VCC rises above threshold; VBATT connects to VOUT only when VCC < 4.65V *and* VBATT > VCC + 20mV, with 40mV hysteresis preventing chatter during slow VCC decay.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - guarantees reliable μP reset initiation before 5V supply collapse |
| Reset Pulse Width | 200ms typ - meets minimum reset hold time for Intel 80C51 and similar μPs |
| Watchdog Timeout | 1.6s ±0.65s - provides sufficient window for firmware servicing without false triggers |
| Quiescent Current | 200µA max at VCC = 5V - enables long-term operation in always-on embedded systems |
| Battery-Backup Current | 50nA typ at VCC = 0V, VBATT = 2.8V - preserves lithium battery life for >10 years |
| Power-Fail Accuracy | ±2% (guaranteed) - enables precise undervoltage warning for regulated +5V supplies |
| VBATT Max Voltage | 4.80V - sets absolute upper limit for direct lithium battery connection without external regulation |
Pinout & Package
MAX690ACSA-T is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package with standard 1.27mm pitch, JEDEC MS-012AC compliant, RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 5Ω PMOS) and VBATT (via 80Ω PMOS) based on reset threshold crossing |
| 2 - VCC | +5V main supply input | Primary power source; powers internal circuitry and drives VOUT when above 4.65V |
| 3 - GND | Ground reference | Common return path for all analog and digital functions; substrate connection point |
| 4 - PFI | Power-fail comparator input | Monitors external voltage divider; asserts PFO low when input falls below 1.25V |
| 5 - PFO | Power-fail open-drain output | Signals impending supply failure to μP interrupt line; requires external pull-up |
| 6 - WDI | Watchdog timer input | Edge-sensitive; resets 1.6s timer on rising/falling transitions; floating disables watchdog |
| 7 - RESET | Active-low reset output | Guaranteed logic low down to VCC = 1V; pulses low for 200ms on power-up/brownout/watchdog timeout |
| 8 - VBATT | Backup battery input | Provides switchover power to VOUT; diode-connected to substrate when VCC > VBATT − 0.6V |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset threshold | 4.65V with ±150mV tolerance over 0°C to +70°C - eliminates need for external resistor divider calibration |
| Ultra-low backup current | 50nA typical in battery mode - extends CR2032 lithium cell life beyond 10 years in standby |
| Dual-path battery switchover | 5Ω VCC switch + 80Ω VBATT switch - minimizes VOUT droop during transition while limiting battery discharge rate |
| Guaranteed reset at low VCC | RESET asserted valid down to VCC = 1V - ensures robust reset even during deep brownout conditions |
| Integrated 1.25V reference | Stable bandgap reference used for both PFI comparison and internal biasing - enables accurate power-fail warning without external components |
Applications
| Battery-Powered Controllers | Critical μP Power Monitoring |
|---|---|
Use Scenario: Industrial programmable logic controller (PLC) retains RAM state during AC mains interruption using a 3.6V lithium coin cell. IC Role / Device Role / Timing Role: MAX690ACSA-T monitors +5V rail, triggers RESET on brownout, and seamlessly switches VOUT from VCC to VBATT within 200ns. Use Value: Prevents RAM corruption and ensures deterministic restart after power recovery without external switchover MOSFETs or timing RC networks. | Use Scenario: Medical infusion pump validates +5V supply integrity before motor activation and logs fault events. IC Role / Device Role / Timing Role: MAX690ACSA-T generates 200ms RESET pulse on VCC dip below 4.65V and asserts PFO to signal power-fail interrupt 10ms before threshold crossing. Use Value: Enables safe shutdown sequence and nonvolatile event logging prior to complete supply collapse. |
| Intelligent Instruments | Embedded Data Loggers |
Use Scenario: Handheld multimeter maintains real-time clock and calibration data during battery replacement. IC Role / Device Role / Timing Role: MAX690ACSA-T detects VCC drop during battery swap and activates VBATT-to-VOUT switchover with 40mV hysteresis to prevent oscillation. Use Value: Eliminates need for supercapacitor charging circuits while guaranteeing uninterrupted RTC and SRAM operation. | Use Scenario: Environmental sensor node samples temperature/humidity every 10s and stores data in battery-backed SRAM. IC Role / Device Role / Timing Role: MAX690ACSA-T monitors regulator output, asserts RESET if supply sags during RF transmission, and uses WDI to detect firmware lockup. Use Value: Provides dual-layer protection-hardware reset on supply fault and watchdog recovery on software hang-without increasing BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802LCSA | Identical 4.65V reset threshold, ±2% power-fail accuracy, same pinout and function set | No functional difference; MAX802LCSA is second-source variant with identical qualification and test flow | Select MAX802LCSA when dual-sourcing or extended lifecycle assurance is required |
| MAX706PESA | Lower 2.63V reset threshold, no battery switchover, no PFI/PFO comparator, 140ms reset pulse | Suitable only for 3.3V systems or auxiliary supply monitoring-not a drop-in replacement for 5V battery-backed designs | Choose MAX706PESA only for cost-sensitive 3.3V applications where battery backup is unnecessary |
Compared with MAX802LCSA, MAX690ACSA-T offers identical functionality and qualification; versus MAX706PESA, it provides full 5V supervisory capability including battery switchover and power-fail warning-critical for legacy industrial μP systems requiring guaranteed 4.65V reset and lithium backup support.
Availability
MAX690ACSA-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 and long-lifecycle programs.
Supply support for MAX690ACSA-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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.
The MAX690A family was designed specifically for 5V microprocessor systems requiring integrated reset, watchdog, battery switchover, and power-fail warning-replacing discrete solutions in space-constrained embedded controllers.
FAQ
What is the guaranteed minimum VCC level at which MAX690ACSA-T asserts RESET?
The MAX690ACSA-T guarantees RESET assertion down to VCC = 1.0V, ensuring reliable reset initiation even during deep brownout conditions where supply voltage collapses below normal operating range. This specification is validated across the full 0°C to +70°C temperature range and allows μPs like the 80C51 to enter known state before supply becomes invalid. The MAX690ACSA-T maintains this behavior regardless of VBATT presence or state.
Does MAX690ACSA-T support active-high reset outputs?
No, the MAX690ACSA-T provides only active-low RESET output. For active-high reset functionality, the pin-compatible MAX805LCSA must be used instead-it features inverted RESET output guaranteed valid down to VCC = 1.1V. The MAX690ACSA-T's RESET pin is strictly open-drain or push-pull active-low; no internal inversion or configuration option exists to change polarity.
What is the maximum allowable VBATT voltage for MAX690ACSA-T?
The maximum allowable VBATT voltage for MAX690ACSA-T is 4.80V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1) when VCC approaches the reset threshold, causing unintended current flow from VBATT to VCC and potential device malfunction. Lithium coin cells (3.0–3.6V) and properly regulated backup sources comply safely.
How does the watchdog timer in MAX690ACSA-T respond to floating WDI input?
When WDI is left floating, the MAX690ACSA-T watchdog timer is automatically disabled due to internal 35% VCC biasing and high input impedance (50kΩ), placing WDI in an indeterminate but non-triggering state. No RESET pulse occurs from watchdog timeout under floating conditions. To enable watchdog functionality, WDI must be actively driven high/low with edges at least every 1.6s-or tied to a controlled GPIO that toggles reliably.
Can MAX690ACSA-T monitor negative supply rails?
Yes, MAX690ACSA-T can monitor negative rails using an external resistor network that level-shifts the negative voltage to the PFI input, as shown in Figure 7 of the datasheet. When the negative rail degrades (e.g., −12V → −5V), PFI voltage rises above 1.25V, causing PFO to go high-an inverse logic indication. Accuracy depends on resistor tolerance and PFI input current (≤25nA), so 1% metal-film resistors are recommended for ≤1% trip-point error.
MAX690ACSA-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:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX690ACSA-T FAQ
1.How can I place an order for MAX690ACSA-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690ACSA-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 MAX690ACSA-T reliable?
The price and inventory of MAX690ACSA-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690ACSA-T is usually 5 days.
3.What payment methods are accepted for MAX690ACSA-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690ACSA-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690ACSA-T?
MAX690ACSA-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690ACSA-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 MAX690ACSA-T?
For technical support, including MAX690ACSA-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690ACSA-T requirements.
6.How does Aetrix verify that MAX690ACSA-T is sourced from the original manufacturer or authorized distributors?
All MAX690ACSA-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 MAX690ACSA-T meets industry standards.
7.What is the process for return or replacement of MAX690ACSA-T?
All MAX690ACSA-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX690ACSA-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 MAX690ACSA-T part is unused and in its original packaging.
Return procedure for MAX690ACSA-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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