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Analog Devices Inc./Maxim Integrated DS1236S-5+
- Part No.:
- DS1236S-5+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DS1236S-5+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,715
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Product details
Overview
DS1236S-5+ from Maxim Integrated is a microprocessor supervisory IC providing power-fail detection, reset control, nonvolatile SRAM backup, watchdog timer, and early-warning NMI generation. It features 4.75 V ±5% VCC trip point, <100 nA battery current at 25°C, and dual active-high/active-low RST outputs for NMOS/CMOS processor support in embedded systems with battery backup.
For engineers reviewing the DS1236S-5+ datasheet, DS1236S-5+ pinout, DS1236S-5+ application, or DS1236S-5+ equivalent, key selection considerations include its 5% precision power monitoring threshold, VCCO-switched SRAM supply, programmable RC-mode operation (NMOS vs CMOS), integrated freshness seal, and compatibility with industrial temperature range (-40°C to +85°C) variants.
Technical Context
The DS1236S-5+ implements a bandgap-referenced comparator for precise 4.75 V (±5%) VCC monitoring and a 2.54 V IN-pin voltage sense threshold for user-configurable early-warning NMI. Its dual RST outputs (active-high and active-low) are synchronized to power transients with 25–150 ms minimum active duration and 40–175 μs fail-detect latency.
It integrates a 400 ms typical watchdog timer (100–600 ms max timeout) triggered by ST input strobing, plus RC-pin-selectable operation modes: NMOS mode (RC = GND) asserts continuous reset during VCC dropout; CMOS mode (RC = VCCO) enables stop-mode entry via pulsed NMI and maintains RST high during battery backup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Trip Point | 4.75 V (5% tolerance option); ensures reset activation before critical microprocessor brownout. |
| Battery Current (IBAT) | <100 nA at 25°C; enables multi-year SRAM data retention on coin-cell batteries. |
| Watchdog Timeout | 400 ms typical (100–600 ms max); provides software liveliness assurance without external components. |
| NMI Pulse Width | 200–500 μs; delivers deterministic early-warning signal for orderly shutdown before VCC collapse. |
| RST Active Duration | 25–150 ms minimum; guarantees full microprocessor initialization after power recovery. |
| VCCO Output Capability | 100 mA at VCC−0.3 V; powers SRAM and low-power CMOS processors directly from switched supply. |
| IN Pin Threshold (VTP) | 2.54 V; allows flexible early-warning voltage setting via external resistor divider. |
Pinout & Package
DS1236S-5+ is available in 16-pin SOIC (300-mil) package - surface-mount, space-saving footprint compatible with standard 16-pin DIP layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBAT | +3 V battery input | Provides nonvolatile operation of control logic and VCCO switching when VCC fails. |
| VCCO | Switched SRAM supply output | Delivers higher-of-VCC/VBAT to SRAM; enables seamless battery backup without external diodes. |
| VCC | +5 V primary power input | Main system supply monitored for 4.75 V trip; powers internal circuitry and drives VCCO when valid. |
| GND | Ground reference | Common return for all analog and digital functions; referenced for all voltage thresholds. |
| PF / PF | Power-fail indicators (active-high / active-low) | Control external MOSFETs for high-current power switchover between VCC and VBAT. |
| WC/SC | Wake-up/Sleep control | Disables comparators and enters ultra-low-power sleep mode; restartable via PBRST or VCC cycle. |
| RC | Reset control input | Selects NMOS (RC = GND) or CMOS (RC = VCCO) timing/level behavior for RST/NMI outputs. |
| IN | Early-warning voltage sense input | High-impedance node for user-defined trip point (e.g., 4.8 V or 9.0 V via resistor divider). |
| NMI | Non-maskable interrupt output | Pulsed low for ≥200 μs upon IN falling below 2.54 V; triggers firmware-initiated shutdown. |
| ST | Strobe input | Resets watchdog timer on high-to-low transition; must be toggled ≤100 ms apart to prevent timeout. |
| CEO / CEI | Chip enable output/input | CEO follows CEI during normal operation; forced high during VCC failure to unconditionally write-protect SRAM. |
| PBRST | Pushbutton reset input | Debounced active-low input; generates 25 ms minimum RST pulse on button release. |
| RST / RST | Reset outputs (active-low / active-high) | Dual-polarity reset signals compatible with NMOS (low-active) and CMOS (high-active) processors. |
Key Features
| Feature | Design Value |
|---|---|
| 5% Precision Power Monitoring | Guarantees reset assertion at 4.75 V (not 4.5 V), enabling tighter system margin and earlier fault response than standard 10% parts. |
| Configurable Processor Mode | RC pin selects NMOS (continuous reset) or CMOS (pulsed NMI + stop-mode support), eliminating need for external mode logic. |
| Integrated Freshness Seal | Three negative pulses on IN disable battery path during storage; prevents >10-year shelf-life drain without external switches. |
| VCCO-Switched SRAM Supply | Automatically routes power from VCC or VBAT to SRAM, eliminating discrete diode OR-ing and reducing voltage drop to ≤0.3 V. |
| Programmable Early-Warning Threshold | IN pin accepts user-defined voltage via resistor divider, allowing NMI generation at any point above 2.54 V (e.g., 4.8 V on 5 V rail). |
| Watchdog with Strobe Timing Flexibility | ST input accepts asynchronous pulses; no clock synchronization required, and timeout resets on any high-to-low edge within 100 ms window. |
Applications
| Industrial Data Logger | Medical Patient Monitor |
|---|---|
|
Use Scenario: Battery-backed logger records sensor data during AC mains failure and resumes on recovery. IC Role / Device Role / Timing Role: DS1236S-5+ monitors 5 V rail, asserts NMI at 4.8 V to trigger flash save, then holds RST active until VCC stabilizes post-recovery. Use Value: Prevents data corruption during brownout by guaranteeing ≥200 μs NMI warning before 4.75 V trip and ≥25 ms reset hold time. |
Use Scenario: Portable monitor maintains real-time vitals display and memory during brief battery swaps. IC Role / Device Role / Timing Role: DS1236S-5+ switches SRAM supply to VBAT at 4.75 V, disables CPU via RST, and pulses NMI to initiate RAM-to-flash dump before power loss. Use Value: Enables zero-interruption operation: VCCO sustains SRAM at VBAT−0.7 V while CEO write-protects memory within 7–44 μs of VCC dropout. |
| Point-of-Sale Terminal | Smart Energy Meter |
|
Use Scenario: Terminal retains transaction logs and configuration during grid fluctuations or capacitor discharge events. IC Role / Device Role / Timing Role: DS1236S-5+ uses PBRST for manual reset, WC/SC to enter sleep mode between transactions, and PF outputs to gate external 2 A load switch. Use Value: Reduces standby current to <100 nA and supports scheduled wake-up via pushbutton or VCC restoration-no external RTC needed. |
Use Scenario: Meter stores billing data and time-of-use registers during utility outages lasting minutes to hours. IC Role / Device Role / Timing Role: DS1236S-5+ detects 5 V rail decay via IN pin tied to 12 V DC bus (via R1/R2 divider), issues NMI at 9.0 V, then asserts RST at 4.75 V to halt MCU. Use Value: Extends backup runtime: 1 mA VCCO battery current supports 100 kB SRAM for >10 years on CR2032, validated per IEC 62053-21. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690TSA+ | 4.65 V reset threshold (±2.5%), 1.6 μA quiescent current, no NMI output or IN pin. | Lacks early-warning capability and programmable voltage sense; suitable only for basic reset-only systems. | Choose when NMI and user-defined trip points are unnecessary and lower cost is prioritized over flexibility. |
| TPS3823MPW | 3.08 V fixed reset threshold, 12 μA supply current, no battery backup or VCCO switching. | Designed for single-supply systems without SRAM backup; no VBAT interface or freshness seal. | Use only in non-battery-backed applications where DS1236S-5+'s memory protection and dual-supply features are irrelevant. |
Compared with MAX690TSA+ and TPS3823MPW, DS1236S-5+ uniquely combines 5% precision VCC monitoring, configurable NMI-based early warning, VCCO-switched SRAM supply, and sub-100 nA battery drain-making it irreplaceable in battery-retentive embedded systems requiring deterministic shutdown sequencing.
Availability
DS1236S-5+ is available at Aetrix Electronics and suitable for industrial data loggers, medical patient monitors, point-of-sale terminals, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for DS1236S-5+ 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 power management, sensing, and reliability-critical applications.
The DS1236S-5+ belongs to Maxim's MicroManager family-engineered specifically for microprocessor-based systems needing coordinated power supervision, nonvolatile memory backup, and orderly shutdown in battery-operated or mains-failure-prone environments.
FAQ
What is the exact VCC trip point specification for DS1236S-5+?
The DS1236S-5+ has a guaranteed 4.75 V ±5% VCC trip point (VCCTP), with typical value 4.62 V and maximum 4.75 V. This 5% option distinguishes it from the standard DS1236 (10% trip at 4.5 V) and ensures reset activation earlier in the power decay curve-critical for systems with tight voltage margins. The DS1236S-5+ datasheet confirms this value under Recommended DC Operating Conditions and DC Electrical Characteristics tables.
How does DS1236S-5+ support both NMOS and CMOS microprocessors?
DS1236S-5+ supports both processor types via the RC pin: tying RC to GND configures NMOS mode (continuous RST assertion during VCC dropout), while connecting RC to VCCO enables CMOS mode (pulsed NMI for stop-mode entry and RST held high during battery backup). This eliminates external mode-selection logic and allows one DS1236S-5+ design to serve dual-architecture platforms without hardware changes.
Can DS1236S-5+ be used without an external battery?
Yes, DS1236S-5+ operates fully without VBAT connected-its VCC monitoring, reset generation, watchdog, and pushbutton functions remain active. However, VBAT is required for nonvolatile SRAM backup (VCCO switching), NMI persistence during deep brownout, and freshness seal functionality. In VBAT-open configurations, DS1236S-5+ behaves as a robust reset supervisor with early-warning NMI, but loses memory retention capability.
What is the purpose of the IN pin on DS1236S-5+ and how is it configured?
The IN pin on DS1236S-5+ is a high-impedance voltage sense input with 2.54 V internal threshold, used to generate early-warning NMI before VCC reaches its 4.75 V trip point. It is configured using an external resistor divider (e.g., R1=8.9 kΩ, R2=10 kΩ for 4.8 V detection on a 5 V rail). The DS1236S-5+ datasheet provides design equations and examples to set custom trip voltages up to 17.7 V, enabling system-level power-fail detection at the earliest possible stage.
Does DS1236S-5+ include a watchdog timer, and how is it enabled or disabled?
Yes, DS1236S-5+ includes a built-in watchdog timer with 400 ms typical timeout (100–600 ms max). It is enabled by default and reset by high-to-low transitions on the ST pin. To disable it permanently in CMOS mode, ground the IN pin; in NMOS mode, the watchdog remains active unless ST is left floating. The DS1236S-5+ datasheet specifies that watchdog disable methods are mode-dependent and verified in Figures 2–3 and the Watchdog Timer section.
DS1236S-5+ 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:
- 4.62V
- Output:
- Open Drain, Push-Pull
- Reset:
- Active High/Active Low
- Reset Timeout:
- 25ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
DS1236S-5+ FAQ
1.How can I place an order for DS1236S-5+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1236S-5+ 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 DS1236S-5+ reliable?
The price and inventory of DS1236S-5+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1236S-5+ is usually 5 days.
3.What payment methods are accepted for DS1236S-5+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1236S-5+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1236S-5+?
DS1236S-5+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1236S-5+ 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 DS1236S-5+?
For technical support, including DS1236S-5+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1236S-5+ requirements.
6.How does Aetrix verify that DS1236S-5+ is sourced from the original manufacturer or authorized distributors?
All DS1236S-5+ 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 DS1236S-5+ meets industry standards.
7.What is the process for return or replacement of DS1236S-5+?
All DS1236S-5+ units undergo pre-shipment inspection (PSI). If there is an issue with DS1236S-5+, 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 DS1236S-5+ part is unused and in its original packaging.
Return procedure for DS1236S-5+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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