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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:4,586
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Product details
Overview
DS1238A-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 typical reset threshold (10% VCC tolerance), 200 nA battery current, dual active-low/high RST outputs, and supports 16-pin DIP/SOIC packages. Used in embedded systems requiring orderly shutdown and data retention during brownout.
For engineers reviewing the DS1238A-10+ datasheet, DS1238A-10+ pinout, DS1238A-10+ application, or DS1238A-10+ equivalent, key selection criteria include precise 4.25–4.50 V VCCTP window, 100 ms typical reset timeout, NMI-driven early warning at user-defined IN voltage, and VCCO-controlled SRAM backup with freshness seal.
Technical Context
The DS1238A-10+ integrates a bandgap voltage reference and precision comparator for 5 V supply monitoring, triggering RST/RST and RVT when VCC falls below 4.37 V (typ). Its watchdog timer uses either internal ring oscillator (~30 kHz) or external clock/capacitor to generate 110 ms–2.7 s timeout periods, resettable via ST strobe.
It provides dual-path memory protection: CEO output enables write-protection of external SRAM upon power failure, delayed until CEI returns high or tCE (5 µs) expires; VCCO switches between VCC and VBAT (≤4.0 V) with 0.3 V drop, while freshness seal prevents VCCO activation until VCC is applied.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold (VCCTP) | 4.25–4.50 V (10% tolerance on 5 V); ensures reset assertion before critical logic voltage margin loss |
| Battery Current (IBAT) | 0–200 nA at VBAT = 3.0 V; enables multi-year SRAM data retention on coin cell |
| Reset Timeout (tRPU) | 40–150 ms; guarantees stable power-up sequencing for microprocessors after VCC crosses VCCTP |
| NMI Trip Point (VTP) | 1.15–1.35 V; allows configurable early-warning threshold via resistor divider on IN pin |
| VCCO Output Capability | 100 mA at VCC − 0.3 V; powers SRAM directly during main supply operation |
| Watchdog Timeout (Int Clk) | 110–170 ms (short), 1.7–2.7 s (long); software must strobe ST within interval to prevent forced reset |
| CEO Propagation Delay | 20 ns; ensures minimal latency between CEI transition and SRAM enable/disable control |
Pinout & Package
DS1238A-10+ is available in 16-pin plastic DIP (300-mil) and 16-pin SOIC (300-mil) packages. Both share identical pin mapping and thermal characteristics per Maxim's mechanical drawings.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBAT | +3 V battery input | Provides backup power path; disconnects from VCCO until VCC applied (freshness seal) |
| VCCO | Switched SRAM supply output | Auto-selects higher of VCC or VBAT; drops ≤0.3 V under load to preserve SRAM VDD margin |
| VCC | +5 V primary supply input | Monitored for reset generation; powers internal circuitry and drives VCCO during normal operation |
| GND | Ground reference | Common return for all analog/digital functions; referenced for VCCTP, VTP, and output thresholds |
| PF | Power-fail indicator (active high) | Drives external MOSFET/switch to transfer load from VCC to VBAT during brownout |
| RVT | Reset voltage threshold indicator | Active-high open-drain signal indicating VCC < VCCTP; used for system-level power status monitoring |
| OSCIN | Oscillator timing input | Accepts external clock or capacitor (e.g., 47 pF) to set watchdog/reset timing intervals |
| OSCSEL | Oscillator select | Configures internal vs. external timing source; tri-stated when VCC < VBAT |
| IN | Early-warning voltage sense input | High-impedance node for resistor-divider-based VSENSE; triggers NMI when VIN < VTP |
| NMI | Non-maskable interrupt output | Active-low signal giving processor time to save state before RST assertion |
| ST | Watchdog strobe input | Falling edge resets watchdog timer; if unasserted, forces RST/WDS active after timeout |
| CEO | Chip enable output | Controls SRAM CE; held high during power fail to write-protect memory after tCE delay |
| CEI | Chip enable input | Synchronizes CEO behavior with host memory controller; delays write-protect until CEI returns high |
| WDS | Watchdog status output | Latched active-low flag indicating watchdog timeout occurred; cleared by ST strobe or VCC recovery |
| RST | Reset output (active low) | Drives microprocessor /RESET; guaranteed minimum 40 ms active duration after VCC rise |
| RST | Reset output (active high) | Complementary to active-low RST; supports processors requiring active-high reset assertion |
Key Features
| Feature | Design Value |
|---|---|
| Unconditional SRAM write protection | CEO forced high within 144 µs of VCC falling below VCCTP, preventing data corruption during brownout |
| Programmable early-warning NMI | IN pin accepts user-defined voltage threshold (via resistor divider) to trigger NMI ≥100 µs before RST activation |
| Freshness seal for battery conservation | VCCO remains inactive until VCC is first applied, eliminating pre-deployment battery drain |
| Dual reset outputs | Simultaneous active-low and active-high RST signals eliminate need for external inverters in mixed-logic systems |
| Debounced pushbutton reset support | RST pin includes internal RC debounce circuit enabling direct connection to mechanical reset switches |
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: DS1238A-10+ monitors 5 V rail, asserts NMI to initiate flash storage commit, then triggers RST after safe shutdown completes. Use Value: Prevents data loss during brownout by guaranteeing ≥100 µs NMI warning and 100 ms reset hold time for EEPROM write completion. | Use Scenario: Portable ultrasound unit with volatile buffer memory requiring retention during battery swap. IC Role / Device Role / Timing Role: DS1238A-10+ switches SRAM supply from VCC to VBAT via VCCO, holds CEO high to freeze writes, and maintains RST until power stabilizes. Use Value: Enables hot-swap battery replacement without image buffer corruption, leveraging 200 nA IBAT and freshness seal. |
| Point-of-Sale Terminal | Smart Energy Meter |
Use Scenario: Retail terminal performing transaction logging during grid voltage sags. IC Role / Device Role / Timing Role: DS1238A-10+ detects 4.37 V trip point, activates PF to switch auxiliary power, and uses CEO to lock flash memory access. Use Value: Ensures ACI-compliant transaction integrity by coordinating power switchover and memory protection within 144 µs of fault detection. | Use Scenario: Utility meter storing consumption data during seasonal brownouts in rural grids. IC Role / Device Role / Timing Role: DS1238A-10+ monitors 5 V DC-DC output, generates NMI at 4.8 V (via IN divider), then asserts RST at 4.37 V to halt计量 cycle. Use Value: Extends operational window before shutdown by 430 mV margin, enabling full billing-cycle data capture before power collapse. |
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; same 4.37 V VCCTP, but lacks IN/NMI input and freshness seal; 500 nA IBAT vs. 200 nA | No early-warning capability; requires external circuitry for battery conservation | Select MAX691CPD+ only if NMI and freshness seal are unnecessary and legacy board reuse is required |
| TPS3823-50DBVR | Fixed 4.63 V reset threshold (±0.5%); no watchdog, NMI, or SRAM control; 12 µA ICC vs. 4 mA DS1238A-10+ | Basic reset-only function; cannot replace DS1238A-10+ in memory backup or watchdog-critical designs | Choose TPS3823-50DBVR only for cost-sensitive, single-function reset applications without SRAM or watchdog needs |
Compared with MAX691CPD+ and TPS3823-50DBVR, DS1238A-10+ uniquely integrates power-fail warning, battery-switched SRAM control, and programmable watchdog in one 16-pin package-enabling compact, reliable data retention where coordinated shutdown and memory protection are mandatory.
Availability
DS1238A-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 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
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 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 backup in space-constrained designs.
FAQ
What is the exact reset voltage threshold for DS1238A-10+?
The DS1238A-10+ has a guaranteed reset voltage threshold (VCCTP) of 4.25 V minimum to 4.50 V maximum, with 4.37 V typical at 25°C. This 10% tolerance on nominal 5 V supply ensures deterministic reset assertion before microprocessor logic levels become unreliable, and is factory-trimmed using a bandgap reference for stability across temperature and voltage.
How does DS1238A-10+ support battery-backed SRAM without data corruption?
The DS1238A-10+ prevents SRAM data corruption through three coordinated actions: (1) VCCO automatically switches from VCC to VBAT when main supply fails; (2) CEO is held high within 144 µs of VCCTP crossing to disable chip enable; and (3) write protection is delayed until CEI returns high or tCE (5 µs) expires-ensuring current memory cycle completes before protection engages.
Can DS1238A-10+ generate an early warning before reset assertion?
Yes, DS1238A-10+ provides early warning via its IN pin and NMI output. By configuring a resistor divider to set VSENSE at a user-selected voltage above VCCTP (e.g., 4.8 V), the DS1238A-10+ asserts active-low NMI when that threshold is crossed-giving the microprocessor ≥100 µs to save critical data before RST activates at 4.37 V.
What is the purpose of the freshness seal in DS1238A-10+?
The freshness seal in DS1238A-10+ electrically isolates VBAT from VCCO until VCC is first applied, preventing battery discharge during manufacturing, shipping, or storage. Once VCC powers up, the seal is permanently broken-ensuring zero standby drain on the backup battery prior to system deployment and extending shelf life.
Does DS1238A-10+ support both internal and external timing for its watchdog function?
Yes, DS1238A-10+ supports dual timing sources for its watchdog: OSCSEL selects between internal ring oscillator (~30 kHz) or external clock/capacitor on OSCIN. With internal timing, timeout periods are 110–170 ms (short) or 1.7–2.7 s (long); with external 47 pF capacitor, short timeout is ≈550 ms and long is ≈2.2 sec-providing design flexibility for different software recovery requirements.
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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