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Analog Devices Inc. LTC2939IMS#PBF
- Part No.:
- LTC2939IMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 16-TFSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC2939IMS#PBF.pdf
- Description:
- IC SIX PWR SUPPLY MONITOR 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,012
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Product details
Overview
LTC2939IMS#PBF from Analog Devices (formerly Linear Technology) is a configurable six-supply voltage monitor IC with integrated watchdog timer, reset output, and programmable threshold selection via VPG pin. It monitors up to six independent supply rails-including 5V, 3.3V, 2.5V, 1.8V, 1.5V, 1.2V, ADJ, and –ADJ-with ±1.5% threshold accuracy over temperature, 80μA typical supply current, and guaranteed RST operation down to VCC = 1V. It is used in multivoltage embedded systems requiring reliable power-up sequencing and software fault detection.
For engineers reviewing the LTC2939IMS#PBF datasheet, LTC2939IMS#PBF pinout, LTC2939IMS#PBF application, or LTC2939IMS#PBF equivalent, this page delivers verified technical context, exact pin functions, real-world timing configurations (tRST/tWD), confirmed six-rail monitoring capability, and validated alternatives for multivoltage supervisor replacement in telecom, computing, and automotive control designs.
Technical Context
The LTC2939IMS#PBF implements six independent high-impedance comparators-four with selectable fixed thresholds (5V/3.3V/2.5V/1.8V/1.5V/1.2V) and two (V5/V6) permanently configured as adjustable 0.5V-reference inputs-plus one dedicated –ADJ input (V4). Its single-pin configuration interface (VPG) selects among 16 predefined voltage combinations using a resistive divider referenced to the internal 1.210V buffered VREF.
Reset and watchdog timeout periods are externally set via CRT and CWT capacitors (2ms/nF and 20ms/nF scaling, respectively), enabling precise adaptation to microprocessor boot time and software execution cycles. The device guarantees glitch-immune operation, correct RST state at VCC ≥ 1V, and status outputs weakly pulled to V2-with external pull-up support required when V2 ≤ 2.5V to meet downstream VIH requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Monitoring Channels | 6 independent inputs (V1–V6), supporting fixed (5V/3.3V/2.5V/1.8V/1.5V/1.2V), ADJ (0.5V ref), and –ADJ modes |
| Threshold Accuracy | ±1.5% over full temperature range - ensures no false resets within system supply tolerance bands |
| Supply Current | 80μA typical - enables use in battery-backed or ultra-low-power systems without compromising supervision integrity |
| Minimum Operating VCC | 1V - guarantees valid RST assertion during deep brownout or partial power-down of primary rails |
| Reset Timeout Range | 20μs to >1s via CRT capacitor (2ms/nF scaling) - supports short MCU initialization or long FPGA configuration sequences |
| Watchdog Timeout Range | 200μs to >1s via CWT capacitor (20ms/nF scaling) - aligns precisely with software loop timing margins |
| Operating Temperature | –40°C to +85°C - qualified for industrial and extended-temperature embedded applications |
Pinout & Package
Package: 16-Lead Plastic MSOP (3mm × 4.9mm, 0.65mm pitch), exposed pad optional for thermal enhancement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| V1, V2 | Primary supply inputs / internal VCC source | Greater of V1 or V2 powers the IC; both require ≥0.1μF bypass; define reference for RST/WDO pull-up |
| V3, V4, V5, V6 | Configurable voltage monitor inputs | V3/V4 support fixed/ADJ/–ADJ; V5/V6 are fixed ADJ (0.5V ref); all high-impedance (>100MΩ) |
| VPG | Configuration select input | Accepts 0–1.21V ratio from VREF–GND divider to choose one of 16 preset rail combinations |
| VREF | Buffered 1.210V reference output | Stable, low-noise reference for VPG programming and –ADJ level shifting; ±1mA drive capability |
| RST | Open-drain reset output | Pulls low on any undervoltage or watchdog timeout; weak internal 6μA pull-up to V2; requires external pull-up if V2 ≤ 2.5V |
| WDO | Open-drain watchdog output | Latches low on watchdog expiration; cleared by WDI edge or undervoltage; same pull-up constraints as RST |
| WDI | Watchdog input control | Three-state: floating disables watchdog; toggling (low↔high) resets timer; minimum 2μs pulse width |
| CRT, CWT | Timing capacitor connections | CRT sets reset delay (2ms/nF); CWT sets watchdog timeout (20ms/nF); both connect to GND |
| GND | Device ground reference | Return path for all analog and digital circuitry; exposed pad may be connected to PCB GND |
| NC | No internal connection | Pins 4 and 13 in MSOP package - must remain unconnected per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| 16-programmable voltage combinations | Single VPG pin + resistor divider eliminates firmware or hardware configuration overhead for diverse multirail systems |
| Guaranteed RST operation at VCC ≥ 1V | Ensures fail-safe reset assertion even during severe brownout conditions where other supervisors lose functionality |
| Adjustable tRST and tWD via passive capacitors | Enables precise, drift-free timing alignment with MCU boot code and software loop deadlines without trimming or calibration |
| –ADJ mode for negative rail monitoring | Supports direct supervision of negative supplies (e.g., –12V, –5V) using VREF as level-shift reference, eliminating external op-amps |
| Glitch-immune comparators with 150μs response | Rejects short transients (<150μs) on supply lines, preventing spurious resets during switching noise or load dumps |
Applications
| Telecom Power Shelf Supervision | Industrial PLC Multirail Control |
|---|---|
Use Scenario: Monitoring 12V, 5V, 3.3V, 2.5V, 1.8V, and 1.2V rails in a distributed telecom power shelf with hot-swap capability. IC Role / Device Role / Timing Role: LTC2939IMS#PBF acts as centralized six-rail supervisor, asserting RST during any rail undervoltage and triggering watchdog reset if host controller fails to service WDI. Use Value: Eliminates need for six discrete supervisors; ±1.5% threshold accuracy prevents false trips during line regulation ripple; tRST/tWD tuning matches shelf firmware boot sequence. | Use Scenario: Supervising isolated 24V, 5V, 3.3V, ±15V, and ±12V analog/digital rails in an industrial programmable logic controller backplane. IC Role / Device Role / Timing Role: LTC2939IMS#PBF monitors positive rails via V1–V4 and negative rails (–15V, –12V) via V4's –ADJ mode, using VREF for level shift. Use Value: Single-chip solution replaces multiple discrete supervisors + level shifters; –ADJ capability enables direct negative rail sensing without external components. |
| Automotive ADAS Domain Controller | Server CPU VRM Sequencing |
Use Scenario: Validating power integrity across 12V, 5V, 3.3V, 1.8V, 1.2V, and 0.85V core rails in an autonomous driving domain controller with ASIL-B functional safety requirements. IC Role / Device Role / Timing Role: LTC2939IMS#PBF provides redundant voltage monitoring and watchdog supervision, with RST tied to processor nPOR and WDO feeding safety monitor logic. Use Value: 80μA quiescent current minimizes always-on power draw; guaranteed operation to 125°C (H-grade variant available) supports under-hood deployment. | Use Scenario: Coordinating startup timing and fault response across CPU core (0.85V), I/O (1.8V), memory (1.2V), PCIe (3.3V), BMC (5V), and auxiliary (12V) rails in a dual-socket server motherboard. IC Role / Device Role / Timing Role: LTC2939IMS#PBF configures V1–V6 to match exact rail order and thresholds, with CRT/CWT tuned to BIOS POST duration and watchdog window. Use Value: Programmable thresholds avoid custom BOM variants; tRST > 100ms accommodates slow VRM ramp-up; watchdog timeout prevents silent hangs during UEFI initialization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar six-supply monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6816ESE+ | Four-supply monitor only; no watchdog; fixed 5V/3.3V/2.5V/1.8V thresholds; no ADJ/–ADJ support | Suitable only for simpler quad-rail systems without software supervision needs | Select when supervising ≤4 rails with no timing flexibility or negative rail requirements |
| TPS3808G33DBVR | Single-supply monitor with adjustable threshold (0.4–5V); includes watchdog but no multi-rail capability | Requires six separate ICs to match LTC2939IMS#PBF's integration; higher board area and BOM cost | Choose only for point-of-load supervision where individual rail control and minimal footprint outweigh integration benefits |
Compared with MAX6816ESE+ and TPS3808G33DBVR, the LTC2939IMS#PBF uniquely delivers six-rail monitoring, programmable thresholds, –ADJ capability, and independently adjustable reset/watchdog timing in a single 16-pin MSOP-reducing component count, layout complexity, and qualification effort for multivoltage systems.
Availability
LTC2939IMS#PBF is available at Aetrix Electronics and suitable for telecom equipment, industrial PLCs, automotive ADAS controllers, and server motherboard designs requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to +85°C.
Supply support for LTC2939IMS#PBF 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, acquired Linear Technology in 2017 to strengthen its precision power and interface portfolio.
The LTC2939IMS#PBF belongs to ADI's Linear-supervisor product line, designed specifically for high-reliability multivoltage systems where deterministic reset behavior, tight threshold accuracy, and integrated watchdog supervision are critical-targeting computing, communications, and industrial control markets.
FAQ
What is the maximum number of supply voltages the LTC2939IMS#PBF can monitor simultaneously?
The LTC2939IMS#PBF can monitor up to six supply voltages simultaneously-V1 through V6-with flexible configuration including fixed thresholds (5V, 3.3V, 2.5V, 1.8V, 1.5V, 1.2V), adjustable (ADJ), and negative-adjustable (–ADJ) modes. This distinguishes it from the four-channel LTC2938 and makes the LTC2939IMS#PBF ideal for complex multirail systems such as servers and telecom infrastructure where consolidated supervision reduces component count and improves reliability.
How does the LTC2939IMS#PBF achieve ±1.5% threshold accuracy over temperature?
The LTC2939IMS#PBF achieves ±1.5% threshold accuracy over temperature through factory-trimmed bandgap references and matched comparator architectures, validated across –40°C to +85°C. Electrical characteristics tables confirm VRT50 (4.600V–4.750V), VRT33 (3.036V–3.135V), and VRTA (492.5mV–507.5mV) tolerances-all specified with the "l" symbol indicating full-temperature-range compliance. This accuracy prevents false resets in systems with tight supply tolerances, such as 5V ±5% rails, where the LTC2939IMS#PBF's guaranteed 4.600V lower bound avoids overlap with the 4.75V system minimum.
Can the LTC2939IMS#PBF monitor negative supply voltages, and if so, how?
Yes, the LTC2939IMS#PBF supports negative supply monitoring via its V4 input in –ADJ mode. In this configuration, V4 connects to the tap of a resistive divider between the negative rail and the internal 1.210V VREF output, using VREF as a level-shift reference. The trip point is calculated as VTRIP = –(VREF × R3/R4), enabling direct supervision of rails like –12V or –5V without external op-amps or charge pumps. This capability is explicitly documented in the Applications Information section and confirmed by the –ADJ row in the Voltage Configuration Table for LTC2939IMS#PBF.
What are the recommended capacitor values for achieving a 94ms reset timeout and 940ms watchdog timeout with the LTC2939IMS#PBF?
To achieve a 94ms reset timeout (tRST), connect a 47nF capacitor between CRT and GND (scaling factor: 2ms/nF → 47nF × 2ms/nF = 94ms). For a 940ms watchdog timeout (tWD), use a 47nF capacitor between CWT and GND (scaling factor: 20ms/nF → 47nF × 20ms/nF = 940ms). These values are explicitly cited in the Typical Application diagram and confirmed in the PIN FUNCTIONS section. Ceramic capacitors with low leakage (e.g., X7R, C0G) are recommended to maintain timing accuracy.
Does the LTC2939IMS#PBF require external pull-up resistors on RST and WDO, and under what conditions?
Yes, external pull-up resistors are required on RST and WDO when V2 is configured to monitor supplies ≤2.5V (e.g., 2.5V, 1.8V, 1.5V, 1.2V), because the internal 6μA pull-up to V2 cannot guarantee VOH above downstream VIH thresholds. The datasheet states: "For V2 configured to monitor 1.2V, 1.5V, 1.8V and 2.5V supplies, external pull-up resistors are required to ensure that the output voltage, high, is above the VIH input threshold." The LTC2939IMS#PBF's design mandates this for interoperability with standard logic families, and the pull-up target should be the host processor's I/O supply voltage-not V2.
LTC2939IMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Applications:
- Six Power Supply Monitor
- Voltage - Input:
- -
- Voltage - Supply:
- 1V ~ 5V
- Current - Supply:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LTC2939IMS#PBF FAQ
1.How can I place an order for LTC2939IMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC2939IMS#PBF 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 LTC2939IMS#PBF reliable?
The price and inventory of LTC2939IMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC2939IMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC2939IMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC2939IMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC2939IMS#PBF?
LTC2939IMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC2939IMS#PBF 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 LTC2939IMS#PBF?
For technical support, including LTC2939IMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC2939IMS#PBF requirements.
6.How does Aetrix verify that LTC2939IMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC2939IMS#PBF 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 LTC2939IMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC2939IMS#PBF?
All LTC2939IMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC2939IMS#PBF, 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 LTC2939IMS#PBF part is unused and in its original packaging.
Return procedure for LTC2939IMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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