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Analog Devices Inc./Maxim Integrated DS1238AS-10+
- Part No.:
- DS1238AS-10+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DS1238AS-10+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:529
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Product details
Overview
DS1238AS-10+ from Maxim Integrated (now part of Analog Devices) is a microprocessor supervisory IC providing power-fail detection, watchdog timer, non-maskable interrupt, and battery-backed SRAM control. It features 4.37 V reset threshold (10% tolerance), 200 nA battery current, dual active-low/active-high RST outputs, and supports 16-pin SOIC packaging. Used in embedded systems requiring orderly shutdown during brownout.
For engineers reviewing the DS1238AS-10+ datasheet, DS1238AS-10+ pinout, DS1238AS-10+ application, or DS1238AS-10+ equivalent, key selection criteria include precise 4.37 V VCC trip point, NMI-driven early warning capability, watchdog timeout programmability via OSCSEL/OSCIN, and dual RST polarity support for legacy microprocessor compatibility.
Technical Context
The DS1238AS-10+ integrates a bandgap voltage reference and precision comparator to monitor VCC with ±125 mV accuracy at 4.37 V trip point. Its watchdog timer supports both internal oscillator (2.7 s typical long period) and external clock/capacitor timing, with ST input requiring high-to-low strobe before timeout to prevent reset assertion.
It delivers early warning via NMI using user-configurable IN pin voltage sensing (1.27 V threshold), with built-in 30 kHz sampling and triple-sampling hysteresis to reject noise. Memory backup is implemented through VCCO switching between VCC and VBAT, CEO-controlled write protection with tCE = 5 µs delay, and freshness seal to prevent pre-power-up battery drain.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Trip Point | 4.37 V (typical), 4.25–4.50 V range - ensures reset activation before microprocessor instability at 5 V supply. |
| Battery Current (IBAT) | <200 nA at VBAT = 3.0 V - enables multi-year SRAM data retention on coin cell. |
| Reset Pulse Width (tRST) | 40–150 ms - guarantees sufficient hold time for microprocessor initialization after power recovery. |
| Watchdog Timeout (Int Clock) | 1.7–2.7 s long period - provides ample software recovery window before forced reset. |
| NMI Response Delay (tIPD) | 40–175 µs - enables deterministic early-warning interrupt for critical save operations. |
| VCCO Output Capability | 100 mA at VCC − 0.3 V - powers SRAM directly without external regulator in standard 5 V systems. |
| CEO Propagation Delay | 20 ns - ensures tight timing alignment between CEI and CEO for glitch-free memory access. |
Pinout & Package
DS1238AS-10+ is supplied in a 16-pin SOIC (300-mil) package, pin-compatible with 16-pin DIP variants. Package dimensions conform to JEDEC MS-012AC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBAT | +3 V battery input | Provides backup power path; disconnects via freshness seal until VCC applied. |
| VCCO | Switched SRAM supply output | Auto-selects higher of VCC or VBAT; diode-drop limited to prevent battery charging. |
| VCC | +5 V primary supply input | Monitored for reset generation; powers internal circuitry and VCCO during normal operation. |
| GND | Ground reference | Common return for all analog/digital functions; referenced for all voltage thresholds. |
| PF | Power-fail indicator (active high) | Drives external MOSFET for high-current switchover between VCC and VBAT. |
| RVT | Reset voltage threshold indicator | Active-high signal indicating VCC has fallen below VCCTP; used for system-level monitoring. |
| OSCIN | Oscillator input/timing capacitor node | Accepts external capacitor (e.g., 47 pF) or clock source to set watchdog/reset timing. |
| OSCSEL | Oscillator select control | Configures internal vs. external timing source; tri-stated when VCC < VBAT. |
| IN | Early warning sense input | High-impedance (±1 µA) node for resistor-divider-based voltage monitoring at 1.27 V threshold. |
| NMI | Non-maskable interrupt output | Active-low interrupt triggered by IN falling below VTP; includes 100 µs noise immunity. |
| ST | Watchdog strobe input | High-to-low transition resets watchdog timer; must occur before timeout to avoid reset. |
| CEO | Chip enable output | Controls SRAM CE; delayed by tCE = 5 µs to complete current memory cycle before write protect. |
| CEI | Chip enable input | Passes through to CEO under nominal conditions; gates CEO behavior during power fail. |
| WDS | Watchdog status output | Latched active-low flag indicating watchdog timeout occurred; cleared by ST strobe or VCC recovery. |
| RST | Reset output (active low) | Primary microprocessor reset signal; held active ≥40 ms after VCC rises above VCCTP. |
| RST | Reset output (active high) | Complementary reset signal for processors requiring active-high reset assertion. |
Key Features
| Feature | Design Value |
|---|---|
| Unconditional write protection | CEO forced high within 144 µs of VCC falling below VCCTP, preventing SRAM corruption during brownout. |
| Delay-to-write-protect | tCE = 5 µs ensures current memory cycle completes before CEO asserts, preserving data integrity. |
| Triple-sampled NMI detection | 3 consecutive 33 µs samples below VTP required before NMI assertion - eliminates false triggers from supply noise. |
| Freshness seal | Electrically isolates VBAT until VCC is first applied, preventing premature battery discharge during assembly. |
| External power switch control | PF output drives external FETs to handle >100 mA loads, extending battery life beyond internal VCCO limits. |
Applications
| Industrial Data Logger | Medical Diagnostic Device |
|---|---|
Use Scenario: Battery-powered field recorder capturing sensor data during intermittent AC power outages. IC Role / Device Role / Timing Role: DS1238AS-10+ monitors VCC, issues NMI at 4.8 V (via resistor divider on IN), then asserts RST at 4.37 V to halt CPU and trigger SRAM write-protect via CEO. Use Value: Enables guaranteed 100+ ms of safe shutdown time between NMI and RST, preserving last valid measurement before power loss. | Use Scenario: Portable ultrasound unit with volatile configuration storage requiring zero-data-loss power transition. IC Role / Device Role / Timing Role: DS1238AS-10+ uses VCCO to power SRAM, CEO to gate write access, and PF to control external boost converter enabling seamless VCC-to-VBAT switchover. Use Value: Prevents SRAM bit flips during 10 µs VCC-to-VBAT transition (tFB1 = 10 µs), meeting IEC 62304 Class C safety requirements. |
| Point-of-Sale Terminal | Smart Energy Meter |
Use Scenario: Retail terminal performing transaction logging during grid voltage sags below 4.5 V. IC Role / Device Role / Timing Role: DS1238AS-10+ detects sag via RVT, triggers NMI to initiate flash commit, then asserts dual-polarity RST to freeze CPU and secure EEPROM interface. Use Value: Dual RST outputs ensure compatibility with both legacy 8051 (active-low) and modern ARM Cortex-M (active-high) controllers in same BOM. | Use Scenario: ANSI C12.20-compliant meter storing tariff schedules and consumption history during utility brownouts. IC Role / Device Role / Timing Role: DS1238AS-10+ configures IN for 9.0 V sense point (12 V rail), generating NMI 200 ms before VCC collapse to allow AES encryption of final kWh reading. Use Value: 1.27 V internal reference + resistor-divider flexibility allows precise early-warning at any system rail, satisfying ANSI tamper-detection timing windows. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691CPD+ | Pin-compatible but lacks NMI output and IN sense input; fixed 4.65 V reset threshold. | No early-warning capability; requires external circuitry for brownout notification. | Select MAX691CPD+ only if NMI functionality is unnecessary and 4.65 V trip point matches system margin. |
| TPS3823-50DBVR | Single-supply 5 V supervisor with 4.63 V threshold; no watchdog, no NMI, no VCCO switching. | Supports basic reset only; cannot replace DS1238AS-10+ in SRAM backup or watchdog-critical designs. | Choose TPS3823-50DBVR for cost-sensitive applications needing only reset generation without memory or watchdog features. |
Compared with MAX691CPD+ and TPS3823-50DBVR, DS1238AS-10+ uniquely integrates NMI-driven early warning, dual-RST polarity, and battery-switched VCCO - making it irreplaceable in systems requiring deterministic shutdown sequencing and nonvolatile SRAM retention without external logic.
Availability
DS1238AS-10+ is available at Aetrix Electronics and suitable for industrial data loggers, medical diagnostic devices, point-of-sale terminals, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for DS1238AS-10+ 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 (via acquisition of Maxim Integrated) designs precision analog, mixed-signal, and power management ICs for high-reliability industrial, automotive, and medical applications.
The DS1238AS-10+ belongs to Maxim's MicroManager family of supervisory ICs, engineered specifically for microprocessor-based systems needing coordinated power monitoring, reset control, and nonvolatile memory backup in space-constrained designs.
FAQ
What is the reset voltage threshold of DS1238AS-10+ and how is it specified?
The DS1238AS-10+ has a nominal reset voltage threshold of 4.37 V, with a guaranteed range of 4.25 V to 4.50 V at 0°C to 70°C. This 10% tolerance is factory-trimmed using a bandgap reference and precision comparator. The RVT pin asserts high when VCC falls below this threshold, and both RST outputs activate simultaneously. DS1238AS-10+ is distinct from the DS1238A-5 variant, which uses a 4.62 V threshold.
How does DS1238AS-10+ support early warning of power failure?
DS1238AS-10+ supports early warning via its IN pin and NMI output. The IN pin accepts a user-defined voltage sense point (e.g., 4.8 V on a 5 V rail) using an external resistor divider. When that voltage falls below the internal 1.27 V threshold, DS1238AS-10+ asserts NMI after three consecutive 33 µs samples - providing noise-immune, deterministic notification up to 100+ ms before RST activation.
Can DS1238AS-10+ be used to back up SRAM without external components?
Yes, DS1238AS-10+ provides integrated SRAM backup via its VCCO and CEO pins. VCCO automatically selects the higher of VCC or VBAT (with 0.8 V diode drop), while CEO controls SRAM chip enable with a 5 µs delay (tCE) to complete the current memory cycle before write-protection. No external switches or regulators are needed for basic battery-backed SRAM operation.
What watchdog timeout options does DS1238AS-10+ support?
DS1238AS-10+ supports four watchdog timeout configurations via OSCSEL and OSCIN: internal oscillator (2.7 s long / 170 ms short), external clock (5120 clocks), or external capacitor (e.g., 47 pF yields ~2.2 sec). The ST pin must receive a high-to-low transition before timeout to reset the timer; failure results in latched WDS assertion and RST activation.
Is DS1238AS-10+ compatible with industrial temperature requirements?
DS1238AS-10+ is rated for 0°C to +70°C operation per its datasheet. While the DS1238A family offers an industrial-grade variant (-40°C to +85°C), the DS1238AS-10+ suffix specifically denotes the commercial temperature version in SOIC packaging. For extended temperature use, the DS1238AI-10+ (industrial) should be selected instead.
DS1238AS-10+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- MicroManager
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.37V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High/Active Low
- Reset Timeout:
- 40ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
DS1238AS-10+ FAQ
1.How can I place an order for DS1238AS-10+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1238AS-10+ 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 DS1238AS-10+ reliable?
The price and inventory of DS1238AS-10+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1238AS-10+ is usually 5 days.
3.What payment methods are accepted for DS1238AS-10+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1238AS-10+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1238AS-10+?
DS1238AS-10+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1238AS-10+ 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 DS1238AS-10+?
For technical support, including DS1238AS-10+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1238AS-10+ requirements.
6.How does Aetrix verify that DS1238AS-10+ is sourced from the original manufacturer or authorized distributors?
All DS1238AS-10+ 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 DS1238AS-10+ meets industry standards.
7.What is the process for return or replacement of DS1238AS-10+?
All DS1238AS-10+ units undergo pre-shipment inspection (PSI). If there is an issue with DS1238AS-10+, 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 DS1238AS-10+ part is unused and in its original packaging.
Return procedure for DS1238AS-10+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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