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Analog Devices Inc. LTC2939HMS#PBF
- Part No.:
- LTC2939HMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 16-TFSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC2939HMS#PBF.pdf
- Description:
- IC SIX PWR SUPPLY MONITOR 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:466
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Product details
Overview
LTC2939HMS#PBF from Analog Devices (formerly Linear Technology) is a six-supply voltage monitor IC with integrated watchdog timer, reset output, and programmable threshold configuration via external resistive divider. It monitors up to six independent supply rails (e.g., 12V, 5V, 3.3V, 2.5V, 1.8V, 1.2V), provides ±1.5% threshold accuracy over temperature, supports adjustable reset (2–4 ms/nF) and watchdog (20–40 ms/nF) timeouts, and operates reliably down to VCC = 1V - ideal for multivoltage server power sequencing and fault detection.
For engineers reviewing the LTC2939HMS#PBF datasheet, LTC2939HMS#PBF pinout, LTC2939HMS#PBF application, or LTC2939HMS#PBF equivalent, key selection criteria include guaranteed RST assertion at VCC ≥ 1V, 16 preset voltage combinations (including ±ADJ modes), 80μA typical supply current, high-temperature operation to 125°C, and MSOP-16 package compatibility with industrial embedded systems requiring robust brownout and watchdog supervision.
Technical Context
The LTC2939HMS#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) with fixed 0.5V reference for fully adjustable monitoring. Configuration is performed once at power-up via VPG input sampling, selecting one of sixteen voltage combinations using a precision 1% resistive divider referenced to the internal 1.210V buffered VREF.
Its watchdog circuit relies on edge-triggered WDI transitions to reset a capacitor-based timeout (CWT); expiration forces WDO low and triggers RST after one tRST delay. The device guarantees glitch-immune reset assertion within 150μs of undervoltage detection (tUV = 150μs), with RST and WDO outputs featuring weak 6μA pull-ups to V2 - requiring external pull-ups when V2 ≤ 2.5V to meet downstream VIH requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Count | Monitors six independent voltage rails (V1–V6) simultaneously - enables full-system power integrity validation in dense multivoltage designs. |
| Threshold Accuracy | ±1.5% over –40°C to +125°C - ensures reliable reset triggering without false trips across automotive/industrial thermal ranges. |
| Reset Timeout | Adjustable 2–4 ms per nF on CRT pin - allows precise match to microprocessor reset hold-time requirements (e.g., 94ms with 47nF). |
| Watchdog Timeout | Adjustable 20–40 ms per nF on CWT pin - supports software execution window tuning (e.g., 940ms with 47nF). |
| Supply Current | 80μA typical - minimizes standby power impact in always-on telecom/network equipment. |
| Operating Temp | –40°C to +125°C (H-grade) - qualified for under-hood automotive control modules and industrial PLCs. |
| VCC Min for RST | 1V - guarantees correct RST logic state during deep brownout, enabling fail-safe shutdown before core logic corruption. |
Pinout & Package
Package: 16-Lead Plastic MSOP (3mm × 4.9mm), exposed pad optional, θJA = 110°C/W. RoHS-compliant lead-free finish (Pb-free, NiPdAu plating).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| V1, V2 | Primary supply inputs | Greater of V1/V2 powers internal circuitry (VCC); V1 selects 5V/3.3V, V2 selects 3.3V/2.5V/1.8V/1.5V/1.2V - sets internal operating voltage and output pull-up rail. |
| V3, V4 | Configurable supply inputs | Support ADJ (0.5V ref) or –ADJ (negative sensing via VREF level shift); enable custom trip points for non-standard rails like 1.1V or –5V. |
| V5, V6 | Adjustable-only inputs | Fixed 0.5V threshold comparators - dedicated for user-defined positive rails (e.g., FPGA core, DDR termination) without mode selection overhead. |
| VPG | Configuration select input | Sampled once at power-up to select one of 16 voltage combinations; requires 1% resistive divider from VREF to GND - no capacitance allowed. |
| VREF | Buffered reference output | 1.210V ±18mV, capable of sourcing/sinking ±1mA - used for VPG divider and negative ADJ biasing; stable to 1000pF load. |
| RST, WDO | Open-drain reset/watchdog outputs | Weak 6μA pull-up to V2; must use external pull-up to higher rail (e.g., 3.3V) when V2 ≤ 2.5V to ensure VOH > VIH of host MCU. |
| WDI | Watchdog trigger input | Three-state (high/low/floating); rising/falling edges clear watchdog timer; floating disables watchdog - compatible with MCU GPIO with weak internal pull. |
| CRT, CWT | Timing capacitor connections | CRT sets reset delay (2ms/nF); CWT sets watchdog timeout (20ms/nF); both require low-leakage ceramic caps (e.g., X7R) for timing stability. |
Key Features
| Feature | Design Value |
|---|---|
| 16 Preset Voltage Combinations | Reduces BOM count and layout complexity by eliminating discrete resistor networks - single part covers 5V/3.3V/2.5V/1.8V/1.5V/1.2V system variants including mixed positive/negative rails. |
| Guaranteed RST at VCC ≥ 1V | Enables deterministic reset assertion during severe brownout - prevents undefined MCU behavior and memory corruption in unregulated auxiliary supplies. |
| Adjustable Watchdog & Reset Timing | Eliminates need for fixed-timing supervisors; supports software-driven timeout optimization (e.g., matching bootloader execution time) without firmware changes. |
| –ADJ Input Mode (V4) | Allows direct monitoring of negative rails (e.g., –12V, –5V) using only VREF as level-shift source - no external op-amp or charge pump required. |
| High-Temp H-Grade Rating | Validated for continuous operation at 125°C ambient - suitable for engine-control units, base station power modules, and industrial motor drives without derating. |
Applications
| Server Power Sequencing | Automotive ADAS Domain Controller |
|---|---|
Use Scenario: Monitors 12V main, 5V PCIe, 3.3V I/O, 1.8V SerDes, 1.2V CPU core, and 1.0V DDR termination in a dual-socket rack server. IC Role / Device Role / Timing Role: Six-rail supervisor enforcing strict power-good order and asserting RST if any rail falls outside ±5% tolerance during hot-swap or transient events. Use Value: Prevents boot failure due to out-of-spec rail sequencing; watchdog detects firmware hangs during BIOS POST or UEFI initialization. | Use Scenario: Supervises 5V sensor supply, 3.3V camera interface, 1.8V radar processor, 1.2V AI accelerator, –12V analog front-end, and 1.0V CAN transceiver in a Level 3 autonomous driving ECU. IC Role / Device Role / Timing Role: Fault-detection hub with –ADJ capability for negative analog rails and H-grade thermal resilience for under-hood placement. Use Value: Enables ASIL-B compliance via redundant voltage monitoring and watchdog-triggered safe state entry upon processor lockup. |
| Industrial PLC Backplane | 5G Remote Radio Unit (RRU) |
Use Scenario: Tracks 24V field power, 12V I/O isolation, 5V logic, 3.3V FPGA config, 1.8V transceiver, and 1.2V DSP core across modular PLC chassis slots. IC Role / Device Role / Timing Role: Centralized supply health monitor with CRT/CWT timing tuned to PLC scan cycle and firmware watchdog window. Use Value: Reduces diagnostic latency by correlating rail faults with communication errors - accelerates root-cause analysis in distributed control networks. | Use Scenario: Validates 48V PoE-derived 12V PA bias, 5V fronthaul interface, 3.3V clock generator, 1.8V RFIC, 1.2V ADC/DAC, and 1.0V FPGA fabric in outdoor macro-cell RRU. IC Role / Device Role / Timing Role: High-reliability supervisor with 80μA quiescent current minimizing standby loss in solar-powered deployments. Use Value: Extends battery backup runtime during grid outage while maintaining RF subsystem integrity via early brownout detection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar six-supply monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6369EEE+T | Four-supply monitor (V1–V4 only); no V5/V6 inputs; fixed 5V/3.3V/2.5V/1.8V thresholds; no –ADJ mode; 12-pin TDFN. | Limited to quad-rail systems; cannot replace LTC2939HMS#PBF in six-rail or negative-rail applications without redesign. | Select only when system uses ≤4 rails and requires lower cost; verify timing compatibility - MAX6369 reset timeout is fixed at 140ms. |
| TPS3808G33DBVR | Single-channel 3.3V supervisor; no multi-rail capability; no watchdog; SOT-23-6 package; 1.6μA IQ. | Cannot monitor multiple supplies or provide watchdog functionality - requires multiple units and external logic for equivalent coverage. | Use only for simple single-rail reset; not a functional alternative for LTC2939HMS#PBF's integrated six-rail + watchdog architecture. |
Compared with MAX6369EEE+T and TPS3808G33DBVR, the LTC2939HMS#PBF uniquely delivers six-rail monitoring, programmable thresholds including –ADJ, and integrated watchdog in a single MSOP-16 package - reducing component count, PCB area, and system-level validation effort for complex multivoltage platforms.
Availability
LTC2939HMS#PBF is available at Aetrix Electronics and suitable for telecom equipment, automotive control systems, and network servers requiring stable component supply with extended temperature support and long-term lifecycle assurance.
Supply support for LTC2939HMS#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, serving industrial, automotive, communications, and healthcare markets.
The LTC2939HMS#PBF belongs to ADI's Linear Technology legacy supervisor product line, engineered specifically for high-accuracy, low-power, multirail power monitoring in mission-critical infrastructure where reliability across extreme temperatures is non-negotiable.
FAQ
What is the maximum number of supply voltages the LTC2939HMS#PBF can monitor simultaneously?
The LTC2939HMS#PBF monitors up to six independent supply voltages (V1 through V6) concurrently. V1 and V2 support fixed thresholds (5V, 3.3V, 2.5V, 1.8V, 1.5V, 1.2V), V3 and V4 support both fixed and adjustable (ADJ/–ADJ) modes, and V5/V6 are dedicated adjustable inputs with 0.5V reference. This enables comprehensive coverage of complex multivoltage systems such as servers and ADAS controllers without external multiplexing.
How does the LTC2939HMS#PBF achieve ±1.5% threshold accuracy over temperature?
The LTC2939HMS#PBF achieves ±1.5% threshold accuracy via laser-trimmed internal voltage references and comparator offsets, validated across –40°C to +125°C. Its 1.210V VREF buffer exhibits ±18mV variation over temperature, and each fixed threshold (e.g., VRT33 = 3.086V typ) is trimmed to stay within ±1.5% of nominal across the full range - critical for avoiding false resets in thermally stressed environments like automotive under-hood applications.
Can the LTC2939HMS#PBF monitor negative supply voltages, and if so, how?
Yes, the LTC2939HMS#PBF supports negative rail monitoring exclusively on the V4 input using the –ADJ mode. In this configuration, VREF (1.210V) serves as a level-shift reference: an external resistive divider connects between the negative supply and VREF, with the tap point fed to V4. The resulting trip point is calculated as VTRIP = –(VREF × R3/R4), enabling accurate supervision of rails like –12V or –5V without external op-amps or charge pumps.
What are the requirements for external pull-up resistors on RST and WDO when V2 ≤ 2.5V?
When V2 is configured to monitor 2.5V or lower (e.g., 1.8V, 1.2V), the internal 6μA pull-up to V2 is insufficient to meet typical MCU VIH requirements (e.g., >2.0V for 3.3V logic). An external pull-up resistor to a higher rail (e.g., 3.3V) must be used on both RST and WDO. For 3.3V logic, a 10kΩ resistor ensures VOH > 2.4V while limiting current to <330μA - preserving noise immunity and drive strength.
How is the watchdog timeout period set on the LTC2939HMS#PBF, and what happens if WDI is left floating?
The watchdog timeout period on the LTC2939HMS#PBF is set by connecting a capacitor (CWT) between the CWT pin and GND; tWD = 20ms/nF (e.g., 47nF → 940ms). If WDI is left floating (high-impedance), the watchdog timer is disabled - WDO remains high and no watchdog-initiated reset occurs. This provides a hardware-safe default for systems where watchdog functionality is optional or controlled via firmware enablement.
LTC2939HMS#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 ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LTC2939HMS#PBF FAQ
1.How can I place an order for LTC2939HMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC2939HMS#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 LTC2939HMS#PBF reliable?
The price and inventory of LTC2939HMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC2939HMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC2939HMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC2939HMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC2939HMS#PBF?
LTC2939HMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC2939HMS#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 LTC2939HMS#PBF?
For technical support, including LTC2939HMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC2939HMS#PBF requirements.
6.How does Aetrix verify that LTC2939HMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC2939HMS#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 LTC2939HMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC2939HMS#PBF?
All LTC2939HMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC2939HMS#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 LTC2939HMS#PBF part is unused and in its original packaging.
Return procedure for LTC2939HMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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