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Analog Devices Inc./Maxim Integrated DS1231S-20N+
- Part No.:
- DS1231S-20N+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DS1231S-20N+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,783
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Product details
Overview
DS1231S-20N+ from Maxim Integrated (now Analog Devices) is a precision power monitor IC that detects impending AC/DC power failure and initiates orderly microprocessor shutdown before VCC drops below 4.75 V (–5% threshold), provides NMI warning via high-impedance input sensing, and delivers automatic restart after power recovery. It operates from +5 V supply, supports both linear and switching power supplies, and requires no external capacitors.
For engineers reviewing the DS1231S-20N+ datasheet, DS1231S-20N+ pinout, DS1231S-20N+ application, or DS1231S-20N+ equivalent, key selection considerations include VCC trip accuracy (±5% at 4.75 V), dual-reset outputs (RST active-high and RST open-drain), NMI generation with programmable input mode (VTP− = 2.3 V), TOL-selectable threshold (5% or 10%), and compatibility with opto-isolated or resistor-divider high-voltage sense networks.
Technical Context
The DS1231S-20N+ integrates two independent comparators: one monitors VCC against a temperature-compensated reference to assert RST/RST at precise thresholds (4.75 V or 4.5 V), while the second monitors the IN pin using user-configurable input characteristics-high-impedance (Mode = VCC, VTP− = 2.3 V) or current-source (Mode = GND, VTP+ = 2.5 V, 30 µA sink). Hysteresis of ±60 mV ensures noise immunity on both inputs.
On power-up, RST and RST remain asserted for ≥150 ms to allow supply stabilization; on power-down, NMI triggers first (tIPU = 200 µs), followed by RST/RST (tRPD = 100 ns, tRPU = 150–1000 ms), enabling time-proportional shutdown aligned with system hold-up time. The device replaces discrete reset circuits and eliminates need for external timing capacitors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Trip Threshold | 4.75 V (TOL = GND) or 4.50 V (TOL = VCC); enables precise early detection of +5 V rail collapse before processor corruption. |
| IN Trip Voltage (Mode = VCC) | 2.3 V (VTP−); allows direct interface to resistor-divider networks sensing AC line or unregulated DC rails. |
| RST Output Type | Active-high push-pull; drives standard microprocessor reset inputs without external pull-up. |
| RST Output Type | Active-low open-drain; requires external pull-up but enables wired-OR reset bus sharing. |
| NMI Propagation Delay | 200 µs (tIPU); provides deterministic early warning window between power anomaly onset and VCC failure. |
| Power-Up Reset Hold Time | ≥150 ms; guarantees stable reset assertion during +5 V ramp-up, eliminating need for RC timing network. |
| Operating Temperature | 0°C to +70°C; validated for commercial-grade embedded systems with regulated thermal environments. |
Pinout & Package
DS1231S-20N+ is housed in a 16-pin SOIC package (300 mil width), with 8 pins assigned functional roles and 8 marked NC (no connection). Pin 1 (IN) serves as configurable voltage-sense input; Pins 5 and 6 provide complementary reset outputs; Pin 7 (NMI) delivers non-maskable interrupt; Pin 3 (TOL) selects VCC threshold tolerance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Voltage sense input | Configurable high-Z (Mode = VCC) or 30 µA current sink (Mode = GND); trip point = 2.3 V or 2.5 V. |
| 2 (MODE) | Input configuration select | Connect to VCC for high-impedance sensing; connect to GND for opto-isolator-compatible current-source mode. |
| 3 (TOL) | VCC threshold select | Ground for –5% trip (4.75 V); tie to VCC for –10% trip (4.50 V). |
| 4 (GND) | Ground reference | Common return for all analog and digital circuitry; must be low-impedance path to system ground plane. |
| 5 (RST) | Active-high reset output | Push-pull driver; asserts high during power-up and power-fail; compatible with 8051, Z80, and x86 reset inputs. |
| 6 (RST) | Active-low reset output | Open-drain output; requires external pull-up; supports shared reset busing and level translation. |
| 7 (NMI) | Non-maskable interrupt output | Asserts low upon input voltage drop below VTP; triggers immediate firmware response before VCC failure. |
| 8 (VCC) | +5 V supply input | Accepts 4.5–5.5 V; powers internal reference, comparators, and output drivers; decoupling capacitor recommended. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable VCC monitoring threshold | Selectable 5% (4.75 V) or 10% (4.50 V) trip point via TOL pin; eliminates need for external resistor dividers on VCC rail. |
| Dual-mode input sensing | High-impedance (≤0.1 µA leakage) or 30 µA current-source input; supports direct AC-line sensing or opto-isolated interfaces. |
| Complementary reset outputs | RST (push-pull, active-high) and RST (open-drain, active-low); enables flexible reset architecture across diverse MCU families. |
| No external timing components | Internal digital delay and sampling eliminate external capacitors; reduces BOM count and layout area vs. RC-based reset ICs. |
| Guaranteed power-up reset hold time | ≥150 ms minimum assertion; ensures reliable initialization even with slow-ramping or noisy +5 V supplies. |
Applications
| Industrial PLC Power Supervision | Medical Device UPS Handoff |
|---|---|
|
Use Scenario: Monitors main AC input and +5 V DC rail in programmable logic controllers during brownout or grid interruption. IC Role / Device Role / Timing Role: DS1231S-20N+ generates NMI at first sign of AC sag, then asserts RST/RST when VCC reaches 4.75 V, halting I/O scanning before memory corruption. Use Value: Provides ≥200 µs NMI warning and deterministic reset timing, enabling safe state save to EEPROM before power loss. |
Use Scenario: Embedded in battery-backed medical instruments (e.g., infusion pumps) to manage transition from mains to backup battery. IC Role / Device Role / Timing Role: DS1231S-20N+ detects falling VCC and triggers controlled shutdown sequence, preserving therapy log data and preventing unsafe actuator motion. Use Value: Eliminates need for external supervisor ICs; single-chip solution meets IEC 60601-1 power-fail response timing requirements. |
| Telecom Line Card Power Monitoring | Point-of-Sale Terminal Power Integrity |
|
Use Scenario: Installed on telecom line cards to supervise -48 V DC input conversion and +5 V regulation under load transients. IC Role / Device Role / Timing Role: DS1231S-20N+ uses Mode = GND to interface with opto-isolator sensing the -48 V rail, delivering isolated NMI before regulator dropout. Use Value: Enables UL-approved isolation without additional components; maintains signal integrity across safety boundaries. |
Use Scenario: Secures retail POS terminals against data loss during brief AC interruptions or power supply glitches. IC Role / Device Role / Timing Role: DS1231S-20N+ monitors +5 V rail and asserts RST within 100 ns of VCC crossing 4.75 V, freezing transaction processing mid-cycle. Use Value: Prevents partial database writes or corrupted receipt printing; satisfies PCI DSS requirement for atomic transaction rollback. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar power monitor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690TSA+ | Single active-low reset output; no NMI or dual-reset capability; fixed 4.65 V VCC threshold; requires external capacitor for reset timeout. | Lacks early-warning NMI and complementary reset outputs; suitable only for basic reset generation, not orderly shutdown sequencing. | Choose MAX690TSA+ only if system requires minimal reset functionality and has no need for pre-failure warning or dual-output flexibility. |
| TPS3823-50DBVR | Single reset output (active-low); fixed 4.63 V threshold; no input sense pin or NMI; includes manual reset input; higher quiescent current (20 µA vs. 2 mA max). | Cannot monitor external high-voltage rails or generate NMI; designed for simple supply supervision, not multi-stage power-fail response. | Choose TPS3823-50DBVR only for cost-sensitive applications where only basic VCC monitoring and reset are required. |
Compared with MAX690TSA+ and TPS3823-50DBVR, the DS1231S-20N+ uniquely combines VCC monitoring, programmable threshold, isolated NMI generation, and dual-reset outputs in a single chip-enabling full power-fail response sequencing without external logic or timing components.
Availability
DS1231S-20N+ is available at Aetrix Electronics and suitable for industrial PLCs, medical backup systems, telecom line cards, and point-of-sale terminals requiring stable component supply and long-term lifecycle support.
Supply support for DS1231S-20N+ 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 communications systems.
The DS1231S-20N+ belongs to Maxim's legacy Power Monitor family, engineered specifically for deterministic power-fail detection and orderly microprocessor shutdown in mission-critical embedded systems.
FAQ
What is the exact VCC trip voltage for DS1231S-20N+ when TOL is grounded?
The DS1231S-20N+ has a nominal VCC trip voltage of 4.75 V when TOL is connected to GND, corresponding to a –5% threshold of the +5 V supply. Electrical specifications confirm VCCTP = 4.50 V (min), 4.62 V (typ), and 4.74 V (max) under these conditions, ensuring reliable detection before processor operation becomes unstable.
How does the MODE pin affect the input behavior of DS1231S-20N+?
When MODE is tied to VCC, DS1231S-20N+ configures Pin 1 as a high-impedance input (IIL ≤ 0.1 µA) with VTP− = 2.3 V, ideal for resistor-divider networks sensing AC or unregulated DC. When MODE is grounded, Pin 1 becomes a 30 µA current sink with VTP+ = 2.5 V, enabling direct interface to opto-isolators or switched inputs.
Does DS1231S-20N+ require external pull-up resistors on its outputs?
Yes-DS1231S-20N+ requires an external pull-up resistor on RST (Pin 6, open-drain) to ensure proper logic-high level during inactive state. RST (Pin 5, push-pull) does not require a pull-up. Typical values range from 4.7 kΩ to 10 kΩ, selected based on bus capacitance and drive strength requirements.
Can DS1231S-20N+ monitor voltages above 5 V directly on its IN pin?
No-DS1231S-20N+ limits the absolute maximum voltage on Pin 1 (IN) to 5 V. To monitor higher voltages (e.g., AC line or –48 V DC), external circuitry is mandatory: a resistor divider for high-impedance mode (MODE = VCC) or an opto-isolator with zener clamping for current-source mode (MODE = GND).
What is the guaranteed minimum reset pulse width for DS1231S-20N+ on power-up?
DS1231S-20N+ guarantees a minimum RST and RST assertion time of 150 ms on power-up, independent of VCC slew rate. This ensures sufficient time for +5 V supply stabilization and microprocessor initialization before release, eliminating reliance on external RC timing networks.
DS1231S-20N+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.37V, 4.62V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High/Active Low
- Reset Timeout:
- 150ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
DS1231S-20N+ FAQ
1.How can I place an order for DS1231S-20N+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1231S-20N+ 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 DS1231S-20N+ reliable?
The price and inventory of DS1231S-20N+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1231S-20N+ is usually 5 days.
3.What payment methods are accepted for DS1231S-20N+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1231S-20N+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1231S-20N+?
DS1231S-20N+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1231S-20N+ 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 DS1231S-20N+?
For technical support, including DS1231S-20N+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1231S-20N+ requirements.
6.How does Aetrix verify that DS1231S-20N+ is sourced from the original manufacturer or authorized distributors?
All DS1231S-20N+ 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 DS1231S-20N+ meets industry standards.
7.What is the process for return or replacement of DS1231S-20N+?
All DS1231S-20N+ units undergo pre-shipment inspection (PSI). If there is an issue with DS1231S-20N+, 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 DS1231S-20N+ part is unused and in its original packaging.
Return procedure for DS1231S-20N+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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