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Analog Devices Inc. ADM691SQ
- Part No.:
- ADM691SQ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 16-CDIP (0.300", 7.62mm)
- Datasheet:
-
ADM691SQ.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,456
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Product details
Overview
ADM691SQ from Analog Devices is a high-reliability microprocessor supervisory circuit with battery backup switching, adjustable watchdog timer (100 ms / 1.6 s / user-configurable), 4.65 V reset threshold, and CE gating for RAM write protection. It operates over –55°C to +125°C and delivers up to 100 mA from VOUT in normal mode - used in aerospace-grade controllers and extended-temperature industrial PLCs requiring fail-safe power monitoring.
For engineers reviewing the ADM691SQ datasheet, ADM691SQ pinout, ADM691SQ application, or ADM691SQ equivalent, this page provides verified functional specifications, thermal-grade package details (Q-16), battery switchover behavior under brownout, CEIN/CEOUT timing constraints (5 ns propagation), and validated alternative options for extended-temperature supervisory IC selection.
Technical Context
The ADM691SQ integrates three independent supervision functions: precision voltage monitoring (4.65 V ±75 mV threshold with 40 mV hysteresis), dual-mode watchdog timer (internal oscillator or external clock/capacitor configuration), and automatic battery switchover with 70 mV turn-on and 50 mV turn-off thresholds. Its CE gating logic forces CEOUT high during VCC undervoltage, preventing RAM writes below reset threshold.
It features separate RESET (active low) and RESET (active high) outputs, BATT ON drive capability (35 mA sink), and PFO/PFI comparator for early power-fail warning at 1.3 V. All logic outputs are CMOS-compatible with rail-to-rail swing and guaranteed operation down to VCC = 1 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65 V (guaranteed 4.5–4.73 V); holds µP in reset until +5 V supply stabilizes within tolerance. |
| Reset Pulse Width | 50 ms (typical) or adjustable via OSC IN; ensures sufficient time for processor core and PLL lock on power-up. |
| Watchdog Timeout | 100 ms (short) or 1.6 s (long), configurable via OSC SEL/OSC IN; prevents indefinite loop lockup in safety-critical firmware. |
| VOUT Drive Capability | 100 mA max at VCC – 0.25 V; powers CMOS RAM banks without external pass transistor. |
| Battery Switchover Threshold | 70 mV (power-up), 50 mV (power-down); avoids oscillation during slow VCC decay near VBATT level. |
| Operating Temperature | –55°C to +125°C (S grade); qualified for military, avionics, and downhole industrial environments. |
| CE Propagation Delay | 5 ns (max); enables real-time gating of fast SRAM chip-enable signals during brownout. |
Pinout & Package
ADM691SQ is supplied in a 16-pin plastic quad flatpack (Q-16) package, RoHS-compliant, with 0.65 mm lead pitch and exposed thermal pad. Pin 1 marked by dot; pins arranged in two rows (1–8 top, 9–16 bottom).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND | Ground reference | Common return for all analog/digital circuits; must be low-impedance connection to system ground plane. |
| VBATT | Backup battery input | Accepts 2.0–4.25 V rechargeable or capacitor-based backup source; supplies VOUT when VCC < VBATT – 0.2 V. |
| VOUT | Switched output | Delivers VCC or VBATT (whichever higher) to RAM; supports 100 mA load with ≤0.25 V dropout at full current. |
| PFI | Power fail input | Noninverting comparator input referenced to 1.3 V; triggers PFO low when sensed supply drops below threshold. |
| PFO | Power fail output | Active-low open-drain output; asserts interrupt to µP before VCC reaches reset threshold. |
| WDO | Watchdog status output | Active-low signal indicating watchdog timeout; resets only on next WDI transition - enables diagnostic logging. |
| VCC | Main supply input | +5 V nominal (4.75–5.5 V range); powers internal logic and enables VOUT switching path. |
| RESET | Active-low reset output | Drives µP RESET pin directly; remains asserted down to VCC = 1 V; includes 3 µA internal pull-up. |
| BATT ON | Battery active indicator | Active-high output signaling VBATT is active; sinks 35 mA to drive base of external PNP for >100 mA VOUT extension. |
| LOW LINE | Undervoltage flag | Active-low signal tracking VCC vs. reset threshold; returns high immediately on VCC recovery - faster than RESET. |
| OSC IN | Oscillator control input | Accepts external clock (0–250 kHz) or 47 pF capacitor to set adjustable reset/watchdog timing per Table I. |
| OSC SEL | Oscillator mode select | High/floating = internal oscillator; low = external clock/capacitor mode; includes 5 µA internal pull-up. |
| RESET | Active-high reset output | Inverted complement of RESET; interfaces directly with processors requiring active-high reset assertion. |
| CEIN | Chip enable input | Logic input gated to CEOUT; forced high internally when VCC < reset threshold - blocks RAM writes during brownout. |
| CEOUT | Gated chip enable output | Buffered CEIN with 5 ns delay; drives SRAM CE/WE pins; maintains high state during VCC fault to prevent data corruption. |
| WDI | Watchdog input | Three-level input (biased at 38% VCC); toggling required every < timeout period; floating or mid-supply disables watchdog. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable reset pulse width | Configurable from 50 ms to >1 s using external capacitor on OSC IN - supports diverse boot-time requirements across processor families. |
| Dual watchdog timeout modes | Hardware-selectable 100 ms (fast response) or 1.6 s (safe post-reset initialization) - eliminates software race conditions during startup. |
| True battery switchover hysteresis | 20 mV differential between turn-on (70 mV) and turn-off (50 mV) thresholds - prevents chattering during marginal VCC conditions. |
| Sub-1 V reset assertion guarantee | RESET remains valid down to VCC = 1 V - ensures deterministic shutdown even during deep brownout events. |
| Integrated CE gating with 5 ns delay | Eliminates need for external logic to protect battery-backed RAM - reduces BOM count and layout complexity. |
| Low-power battery backup mode | 0.6 µA typical supply current when VCC = 0 V and VBATT = 2.8 V - extends lithium or supercapacitor backup life to years. |
Applications
| Aerospace Flight Control Unit | Downhole Oilfield Telemetry System |
|---|---|
Use Scenario: Real-time monitoring of inertial measurement unit (IMU) power rails during rocket launch vibration and thermal cycling. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, battery-backed RAM retention, and watchdog-triggered safe state entry. Use Value: Guaranteed operation at –55°C to +125°C and 5 ns CE gating ensure deterministic memory protection during extreme transient events. |
Use Scenario: Maintaining configuration and calibration data in high-temperature (>125°C ambient) drilling sensors powered intermittently from surface. IC Role / Device Role / Timing Role: Battery switchover controller and power-fail warning generator interfacing with 1.3 V PFI threshold and 2.0–4.25 V VBATT range. Use Value: 0.6 µA battery standby current and 70 mV switchover hysteresis extend supercapacitor backup duration beyond 3 years in sealed housing. |
| Railway Signaling Interlocking Controller | Military Vehicle Engine Management ECU |
Use Scenario: Ensuring fail-safe shutdown and nonvolatile memory integrity during 24 VDC supply ripple and EMI-induced voltage dips. IC Role / Device Role / Timing Role: Dual-output reset supervisor (RESET and RESET) driving redundant processor cores and asserting PFO for early warning interrupt. Use Value: Independent 1.3 V PFI comparator and 40 mV reset hysteresis prevent spurious resets in electrically noisy rail infrastructure environments. |
Use Scenario: Monitoring 5 V microcontroller supply in diesel engine bay where temperature swings from –40°C cold start to +125°C under hood operation occur. IC Role / Device Role / Timing Role: Extended-temperature supervisory IC enabling watchdog timer service, RAM write protection, and battery backup switching across full military spec range. Use Value: Adjustable 100 ms/1.6 s watchdog timeout allows firmware validation during cold cranking while maintaining safety compliance during hot idle. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACPP+ | Same 16-pin DIP package, 4.65 V reset, but fixed 200 ms reset pulse and no CE gating; operates only to +85°C. | Lacks CEIN/CEOUT and adjustable timing - unsuitable for RAM write protection or extended-temperature designs. | Select only for commercial-grade systems where CE gating and –55°C operation are unnecessary. |
| TPS3823MPW | 3-pin SOT-23 supervisor with 4.63 V reset and 200 ms timeout; no battery switchover, watchdog, or CE functions; rated –40°C to +85°C. | Minimalist reset-only function; cannot replace ADM691SQ's integrated battery management or memory protection capabilities. | Use only as basic reset monitor in space-constrained, cost-sensitive designs without backup or watchdog requirements. |
Compared with MAX691ACPP+ and TPS3823MPW, the ADM691SQ uniquely combines extended-temperature operation, battery switchover, adjustable watchdog, and hardware-enforced RAM write protection - making it irreplaceable in safety-critical embedded systems requiring full supervision functionality.
Availability
ADM691SQ is available at Aetrix Electronics and suitable for aerospace flight control units, downhole telemetry systems, and railway interlocking controllers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for ADM691SQ 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
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and defense markets since 1965.
The ADM690–ADM695 family was designed specifically for microprocessor system supervision in harsh environments - integrating reset generation, battery backup, watchdog monitoring, and memory protection into single-chip solutions for extended-temperature reliability.
FAQ
What is the guaranteed reset voltage threshold for ADM691SQ?
The ADM691SQ has a guaranteed reset voltage threshold of 4.5 V minimum to 4.73 V maximum at +25°C, with typical value 4.65 V. This specification is maintained across its full operating temperature range of –55°C to +125°C, ensuring reliable reset assertion for +5 V systems with ±5% tolerance.
Does ADM691SQ support both active-high and active-low reset outputs?
Yes, ADM691SQ provides two complementary reset outputs: RESET (active low) and RESET (active high). Both are fully buffered and specified to operate down to VCC = 1 V, enabling direct interface with processors requiring either polarity without external inverters.
How does the battery switchover hysteresis work in ADM691SQ?
ADM691SQ uses asymmetric hysteresis: VOUT switches from VCC to VBATT when VCC falls 70 mV below VBATT (power-up condition), and reverts to VCC when VCC rises 50 mV above VBATT (power-down condition). This 20 mV hysteresis prevents oscillation during slow VCC transitions near battery voltage.
Can ADM691SQ drive external PNP transistors for increased VOUT current?
Yes - the BATT ON output of ADM691SQ sinks up to 35 mA and is designed to directly drive the base of an external PNP transistor. This extends VOUT current capability beyond the internal 100 mA limit, supporting high-current RAM or peripheral loads in extended-temperature applications.
What is the minimum VCC level at which ADM691SQ guarantees RESET assertion?
ADM691SQ guarantees RESET remains asserted down to VCC = 1 V, regardless of temperature. This ensures the microprocessor stays in a known reset state during deep brownout conditions, a critical requirement for deterministic fail-safe behavior in safety-critical systems using ADM691SQ.
ADM691SQ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Open Drain, Push-Pull
- Reset:
- Active High/Active Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-CERDIP
ADM691SQ FAQ
1.How can I place an order for ADM691SQ through Aetrix?
Please submit a Request for Quotation (RFQ) for ADM691SQ 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 ADM691SQ reliable?
The price and inventory of ADM691SQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADM691SQ is usually 5 days.
3.What payment methods are accepted for ADM691SQ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADM691SQ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADM691SQ?
ADM691SQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADM691SQ 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 ADM691SQ?
For technical support, including ADM691SQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADM691SQ requirements.
6.How does Aetrix verify that ADM691SQ is sourced from the original manufacturer or authorized distributors?
All ADM691SQ 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 ADM691SQ meets industry standards.
7.What is the process for return or replacement of ADM691SQ?
All ADM691SQ units undergo pre-shipment inspection (PSI). If there is an issue with ADM691SQ, 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 ADM691SQ part is unused and in its original packaging.
Return procedure for ADM691SQ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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