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Analog Devices Inc./Maxim Integrated DS1238A-10
- Part No.:
- DS1238A-10
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
DS1238A-10.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,383
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Product details
Overview
DS1238A-10 from Maxim Integrated (formerly Dallas Semiconductor) is a microprocessor supervisory IC providing power-fail detection, watchdog timer, non-maskable interrupt, and battery-backed SRAM control. It monitors VCC at 4.37 V typical trip point (10% tolerance), delivers active-low/high reset outputs with 100 ms typical pulse width, and consumes <200 nA battery current. Used in industrial embedded systems requiring orderly shutdown and data retention during brownouts.
For engineers reviewing the DS1238A-10 datasheet, DS1238A-10 pinout, DS1238A-10 application, or DS1238A-10 equivalent, key selection criteria include its dual-reset output polarity, programmable watchdog timeout (110 ms to 2.7 s), early-warning NMI via user-defined IN threshold, VCCO-controlled SRAM backup switching, and PF-driven external power switch control - all critical for reliable microcontroller-based data logging and telemetry systems.
Technical Context
The DS1238A-10 integrates a precision bandgap voltage reference and comparator for 5 V supply monitoring, with VCCTP fixed at 4.37 V (10% drop). Its dual RST outputs (active-low and active-high) ensure compatibility with diverse microprocessor reset logic families, while the RVT pin provides real-time trip status independent of reset timing.
Watchdog operation supports internal or external clock sources via OSCSEL/OSCIN, enabling configurable timeout periods: 110–170 ms (short) or 1.7–2.7 s (long) with internal oscillator, or scalable clock-cycle-based timeouts with external clock/capacitor. The ST input requires high-to-low strobes before timeout to prevent unintended resets.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Trip Point | 4.37 V typical (10% tolerance); ensures reset activation before microprocessor operational failure at 4.5 V. |
| Reset Pulse Width | 100 ms typical after VCC rise above trip point; guarantees stable power-up sequencing for 8/16-bit MCUs. |
| Battery Current | <200 nA at VBAT = 3.0 V; enables >10-year SRAM data retention on standard lithium coin cells. |
| Watchdog Timeout | 110 ms (short) or 2.7 s (long) with internal oscillator; configurable via OSCSEL/OSCIN for firmware safety margins. |
| NMI Activation Delay | 100 µs minimum; built-in 3-sample hysteresis prevents false triggers from power supply noise. |
| VCCO Output Capability | 100 mA at VCC − 0.3 V; powers typical 32K×8 CMOS SRAM without external regulation. |
| IN Pin Threshold | 1.27 V ±0.12 V; allows user-defined early-warning voltage sense point via resistor divider. |
Pinout & Package
DS1238A-10 is available in 16-pin DIP (300-mil) and 16-pin SOIC (300-mil) packages, both RoHS-compliant and rated for 0°C to +70°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBAT | +3 V battery input | Provides backup power path for control logic and VCCO when VCC fails; enables nonvolatile operation. |
| VCCO | Switched SRAM supply output | Automatically selects higher of VCC or VBAT (with 0.7 V diode drop) to power SRAM during switchover. |
| VCC | +5 V primary supply input | Main power rail monitored for 4.37 V trip; powers internal circuitry and drives CEO/CEI interface. |
| GND | Ground reference | Common return for analog comparators, digital logic, and power-switching paths. |
| PF | Power-fail indicator (active high) | Drives external MOSFET/switch to transfer load from VCC to VBAT during brownout; threshold tracks VBAT. |
| RVT | Reset voltage threshold indicator | Open-drain output signaling VCC < VCCTP; used for system-level power status monitoring independent of reset timing. |
| OSCIN | Oscillator timing input | Accepts external clock or timing capacitor (e.g., 47 pF) to set watchdog and reset timeout periods. |
| OSCSEL | Oscillator select | Configures internal vs. external clock source for watchdog/reset timing; Hi/Open enables internal oscillator. |
| IN | Early warning input | High-impedance sense node for user-defined voltage divider; triggers NMI before VCC reaches VCCTP. |
| NMI | Non-maskable interrupt output | Active-low signal notifying MCU of impending power loss; enables time-critical save operations. |
| ST | Strobe input | High-to-low transition resets watchdog timer; tied to MCU address/data/control lines for software liveness check. |
| CEO | Chip enable output | Controls SRAM CE pin; held high during power fail to unconditionally write-protect memory after tCE delay. |
| CEI | Chip enable input | Synchronizes CEO with external memory access; delays write protection until current memory cycle completes. |
| WDS | Watchdog status output | Latched active-low flag indicating watchdog timeout occurred; cleared only by ST strobe or VCC recovery. |
| RST | Reset output (active low) | Drives standard active-low MCU reset pin; guaranteed 100 ms minimum pulse width after power-up. |
| RST | Reset output (active high) | Provides complementary active-high reset signal for processors requiring high-asserted reset (e.g., some ARM cores). |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity reset outputs | Simultaneous active-low and active-high RST signals eliminate level-shifting requirements for mixed-logic systems. |
| User-configurable early warning | IN pin with 1.27 V threshold enables precise pre-fail notification via resistor divider, extending safe shutdown window. |
| Programmable watchdog timeout | Internal oscillator supports 110 ms or 2.7 s timeout; external clock option allows fine-grained adjustment for firmware execution profiles. |
| SRAM write-protection sequencing | tCE = 5 µs maximum delay ensures memory cycle completion before CEO asserts, preventing data corruption on power loss. |
| Freshness seal function | Electrically isolates VBAT until VCC is applied, eliminating battery drain during manufacturing and initial system integration. |
| PF-driven external power switching | PF output switches loads between VCC and VBAT with VBAT-referenced threshold, enabling high-current battery backup beyond IC limits. |
Applications
| Industrial Data Logger | Medical Telemetry Device |
|---|---|
Use Scenario: Continuous sensor data acquisition with periodic flash storage, operating in remote locations with unstable AC mains or aging batteries. IC Role / Device Role / Timing Role: DS1238A-10 acts as power supervisor and SRAM guardian - detecting brownouts, triggering NMI for last-second data save, then asserting RST to halt CPU before VCC collapse. Use Value: Prevents loss of critical patient vitals or environmental readings during grid fluctuations by guaranteeing ≥100 µs NMI warning and full SRAM write-protection before reset. |
Use Scenario: Portable ECG monitor with battery backup, required to retain waveform buffers during brief power interruptions or battery swaps. IC Role / Device Role / Timing Role: DS1238A-10 manages VCCO switchover from main supply to coin cell, controls CEO to freeze SRAM writes, and uses PF to gate external boost converter for sustained display operation. Use Value: Enables seamless 500+ ms runtime extension on backup power without data loss, leveraging VCCO's 100 mA capability and PF's VBAT-synchronized switching. |
| Point-of-Sale Terminal | Smart Energy Meter |
Use Scenario: Transaction processing terminal exposed to frequent power cycling and surges in retail environments. IC Role / Device Role / Timing Role: DS1238A-10 provides pushbutton-debounced reset, watchdog supervision of payment firmware, and dual-RST compatibility with legacy x86 and ARM SoCs. Use Value: Eliminates transaction corruption via tCF ≤144 µs CEO assertion and guarantees deterministic 100 ms reset hold time across temperature and voltage variations. |
Use Scenario: Utility meter storing billing intervals and tamper logs in battery-backed SRAM, subject to long-term thermal stress and wide VCC ripple. IC Role / Device Role / Timing Role: DS1238A-10 serves as lifecycle-critical supervisor - using RVT for continuous VCC health monitoring, WDS for firmware crash detection, and freshness seal to preserve battery life over 15-year field deployment. Use Value: Reduces field failure rate by 92% versus discrete solutions through integrated hysteresis, 200 nA IBAT, and guaranteed tREC ≤0.1 µs CEI/CEO timing. |
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 IN/NMI functionality; fixed 4.65 V trip point; no programmable watchdog timeout. | Supports basic reset/power-fail but cannot provide early-warning NMI or user-defined voltage sensing. | Select when only fundamental reset supervision is needed and NMI-driven graceful shutdown is unnecessary. |
| TPS3823-50DBVR | Single 5 V reset IC with 4.63 V threshold; no VCCO output, NMI, or watchdog; 2.5 µA quiescent current. | Provides only reset generation and power-fail flag; requires external circuitry for SRAM backup and early warning. | Choose for cost-sensitive designs where SRAM control and NMI are handled separately, and ultra-low ICC is secondary to BOM count. |
Compared with MAX691CPD+ and TPS3823-50DBVR, DS1238A-10 uniquely integrates NMI-triggered firmware response, dual-RST polarity, and autonomous SRAM power switchover - making it the only solution that eliminates external comparators, level shifters, and discrete power switches in battery-critical embedded systems.
Availability
DS1238A-10 is available at Aetrix Electronics and suitable for industrial data loggers, medical telemetry devices, point-of-sale terminals, and smart energy meters requiring stable component supply across extended product lifecycles.
Supply support for DS1238A-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
Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for industrial, automotive, and communications applications, with expertise in power management and reliability-critical subsystems.
The DS1238A-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 protection under harsh electrical conditions.
FAQ
What is the exact power supply trip voltage for DS1238A-10?
The DS1238A-10 has a nominal VCC trip point (VCCTP) 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 threshold ensures the DS1238A-10 activates reset and power-fail signals before most 5 V microprocessors lose functional stability, and is factory-trimmed - not adjustable in-circuit.
Does DS1238A-10 support both active-low and active-high reset outputs simultaneously?
Yes, DS1238A-10 provides two dedicated RST pins: one active-low and one active-high. Both outputs are asserted concurrently during power failure or watchdog timeout, with identical 100 ms typical pulse width. This dual-polarity capability eliminates external inverters or level translators when interfacing with heterogeneous processor families in the same design.
How does the DS1238A-10 prevent data corruption during SRAM write cycles on power loss?
The DS1238A-10 delays CEO assertion until the current memory cycle completes, enforced by the tCE parameter (5 µs maximum). When VCC falls below VCCTP, DS1238A-10 holds CEO in its prior state if CEI is low, ensuring write operations finish before write-protection engages - a feature confirmed in the DS1238A-10 datasheet's MEMORY BACKUP section.
Can DS1238A-10 drive high-current loads directly through its VCCO pin?
DS1238A-10 delivers up to 100 mA at VCCO when VCC is present (VCC − 0.3 V), sufficient for typical 32K×8 SRAMs. For loads exceeding this - such as multi-chip SRAM banks or peripheral regulators - the DS1238A-10's PF output must gate an external MOSFET, as specified in its POWER SWITCHING application note.
What is the purpose of the freshness seal function in DS1238A-10?
The DS1238A-10's freshness seal electrically disconnects VBAT from VCCO until VCC is first applied, preventing battery discharge during PCB assembly and initial system integration. Once activated by VCC, the seal is irreversible without physically removing and reattaching the battery - a feature critical for preserving shelf life in long-distribution-channel products.
DS1238A-10 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- MicroManager
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- 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:
- Through Hole
- Supplier Device Package:
- 16-PDIP
DS1238A-10 FAQ
1.How can I place an order for DS1238A-10 through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1238A-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 DS1238A-10 reliable?
The price and inventory of DS1238A-10 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1238A-10 is usually 5 days.
3.What payment methods are accepted for DS1238A-10?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1238A-10 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1238A-10?
DS1238A-10 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1238A-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 DS1238A-10?
For technical support, including DS1238A-10 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1238A-10 requirements.
6.How does Aetrix verify that DS1238A-10 is sourced from the original manufacturer or authorized distributors?
All DS1238A-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 DS1238A-10 meets industry standards.
7.What is the process for return or replacement of DS1238A-10?
All DS1238A-10 units undergo pre-shipment inspection (PSI). If there is an issue with DS1238A-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 DS1238A-10 part is unused and in its original packaging.
Return procedure for DS1238A-10:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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