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Texas Instruments LM3705XBBP-232
- Part No.:
- LM3705XBBP-232
- Manufacturer:
- Texas Instruments
- Category:
- Supervisors
- Package:
- 9-VFBGA
- Datasheet:
-
LM3705XBBP-232.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 9USMD
- Quantity:
- Payment:
- Shipping:
Inventory:4,629
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Product details
Overview
LM3705XBBP-232 from Texas Instruments (formerly National Semiconductor) is a microprocessor supervisory IC providing power-on reset, brownout detection, manual reset initiation, power-fail warning, and early low-line alert for embedded systems. It features a 3.08V reset threshold, 28ms reset timeout, totem-pole active-high RESET output, and operates from 1.2V to 5.5V supply. Used in battery-backed instrumentation and automotive control modules requiring reliable power monitoring.
For engineers reviewing the LM3705XBBP-232 datasheet, LM3705XBBP-232 pinout, LM3705XBBP-232 application, or LM3705XBBP-232 equivalent, key selection criteria include reset polarity (active-high), micro SMD package footprint, ±2% reset threshold accuracy over temperature, and integrated low-line comparator with 1.02×VRST trip point.
Technical Context
The LM3705XBBP-232 implements independent comparators for VCC monitoring (reset), PFI input (1.225V reference), and LLO generation (1.02×VRST threshold). Its internal timer ensures 28ms minimum reset pulse width after VCC rise or MR release, with guaranteed RESET assertion down to VCC = 1.2V.
It integrates a 56kΩ internal pull-up on MR, supports daisy-chained reset coordination via MR, and provides separate open-drain–capable outputs (PFO, LLO) alongside the totem-pole RESET. All thresholds exhibit 0.0032×VRST hysteresis for noise immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 3.08V ±2% over −40°C to +85°C - defines brownout detection level for 3.3V systems |
| Reset Timeout Period | 28ms - ensures µP remains held in reset long enough for stable clock and supply settling | RESET Output Type | Totem-pole active-high - drives high without external pull-up, compatible with standard logic inputs |
| VCC Operating Range | 1.2V to 5.5V - supports wide-input industrial and automotive supplies, including Li-ion battery systems |
| Supply Current | 28µA typical - enables ultra-low-power operation in always-on monitoring circuits |
| Low-Line Threshold | 1.02 × VRST = 3.14V - triggers early warning ~100mV above reset threshold for NMI generation |
| Power-Fail Input Threshold | 1.225V ±25mV - allows precise external voltage divider design for auxiliary supply monitoring |
Pinout & Package
LM3705XBBP-232 is packaged in a 9-bump micro SMD (BPA09FFB), 1.412mm × 1.412mm × 0.850mm, non-solder-mask-defined (NSMD) pad layout. Pin mapping is validated per National Semiconductor DS101369 Rev D.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Power supply input | Primary system supply rail monitored for reset; must be ≥1.2V for full functionality |
| GND | Ground reference | Common return for all analog comparators and digital outputs; requires low-impedance connection |
| RESET | Active-high reset output | Drives high after timeout; asserts low only during power-up/down/brownout or MR activation |
| PFI | Power-fail comparator input | Accepts divided-down voltage from secondary supply; trips PFO when <1.225V |
| LLO | Low-line logic output | Open-drain early-warning signal; pulled low when VCC drops below 1.02×VRST |
| PFO | Power-fail logic output | Open-drain fault indicator; asserted low when PFI falls below 1.225V threshold |
| MR | Manual reset input | Active-low trigger with 1.225V threshold and internal 56kΩ pull-up; debounced with 25µs min pulse width |
| NC | No-connect terminal | Two NC pins (A1, B2) - must remain unconnected; B2 is factory test-only |
Key Features
| Feature | Design Value |
|---|---|
| Factory-programmed 28ms reset timeout | Eliminates external timing components and ensures consistent reset duration across production units |
| ±2% reset threshold accuracy over temperature | Guarantees reliable brownout detection across −40°C to +85°C without calibration |
| Integrated low-line comparator (LLO) | Provides 100mV advance warning before reset assertion, enabling firmware-level graceful shutdown |
| Dedicated power-fail input (PFI) | Enables independent monitoring of auxiliary rails (e.g., backup battery, isolated DC/DC) with 1.225V reference |
| Micro SMD 9-bump package | Reduces PCB area by >70% vs MSOP-10, critical for space-constrained portable and automotive modules |
Applications
| Industrial PLC I/O Modules | Automotive Body Control Units |
|---|---|
Use Scenario: Monitoring 3.3V microcontroller supply in programmable logic controller field I/O cards subject to load-switch transients and ESD events. IC Role / Device Role / Timing Role: Supervisory IC asserting active-high RESET to hold MCU in known state during 10–100ms brownouts; LLO triggers NMI for register save before shutdown. Use Value: Prevents corrupted EEPROM writes and bus lockups by guaranteeing 28ms minimum reset hold time and early 3.14V warning threshold. | Use Scenario: Power integrity monitoring in vehicle door module controlling window lift, mirror adjustment, and lighting functions. IC Role / Device Role / Timing Role: Detects battery voltage sag during cold-cranking (e.g., 9.5V → 7.2V); PFI monitors 5V regulator output while VCC tracks main 12V rail. Use Value: Enables fail-safe behavior (e.g., park windows, disable motors) using PFO and LLO signals before MCU reset occurs at 3.08V. |
| Medical Portable Infusion Pumps | Smart Energy Meters |
Use Scenario: Ensuring safe shutdown and data retention during lithium primary battery depletion in battery-powered infusion devices. IC Role / Device Role / Timing Role: Monitors 3.3V LDO output; LLO alerts MCU at 3.14V to initiate flash save and motor coast-down; RESET holds MCU until battery recovers or reaches 3.08V. Use Value: Meets IEC 60601-1 safety requirements by preventing erratic actuator motion during power collapse. | Use Scenario: Maintaining metrology accuracy and secure firmware state during AC line sags and capacitor discharge in DIN-rail energy meters. IC Role / Device Role / Timing Role: VCC tied to supercap backup rail; MR connected to tamper switch; PFO monitors isolated 3.3V metrology supply. Use Value: Guarantees secure erase of encryption keys and metering registers via MR-initiated reset before power loss completes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS3808G33DBVR | 3.3V fixed reset threshold; 200ms default timeout (adjustable); SOT-23-6 package | Lacks dedicated PFI and LLO outputs; single-supply monitor only | Select when only basic reset supervision is needed and board space permits SOT-23 |
| MAX6369KA29+T | 2.93V reset threshold; 140ms timeout; includes watchdog timer; 8-pin SOIC | Includes watchdog capability but no low-line output or separate PFI input | Choose when system-level software supervision (watchdog) is required alongside reset |
Compared with LM3705XBBP-232, TPS3808G33DBVR offers simpler integration for single-rail systems but omits dual-comparator warning features, while MAX6369KA29+T adds watchdog functionality at the cost of larger footprint and no LLO/PFI separation-making LM3705XBBP-232 optimal for multi-rail early-warning architectures.
Availability
LM3705XBBP-232 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical portable infusion pumps, and smart energy meters requiring stable component supply and long-term lifecycle support.
Supply support for LM3705XBBP-232 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
Texas Instruments acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for legacy supervisory products.
The LM3705XBBP-232 belongs to TI's precision voltage-monitoring portfolio, designed specifically for systems needing coordinated power-fail warning, manual reset, and brownout protection without external components.
FAQ
What is the reset output polarity of the LM3705XBBP-232?
The LM3705XBBP-232 features an active-high RESET output (totem-pole), meaning it drives high under normal operation and pulls low only during reset assertion. This differs from the LM3704 series, which provides active-low RESET. The LM3705XBBP-232's output is compatible with µP reset inputs expecting high-valid logic levels and eliminates need for external pull-up resistors.
Does the LM3705XBBP-232 support operation below 1.8V?
Yes, the LM3705XBBP-232 operates down to VCC = 1.2V, with guaranteed RESET functionality across its full −40°C to +85°C temperature range. Below 1.2V, reset behavior is not specified. Its 3.08V reset threshold and 1.02×VRST low-line threshold (3.14V) are optimized for 3.3V systems, but the device remains functional as a supervisor for lower-voltage rails when used with appropriate external dividers on PFI.
How is the 28ms reset timeout period implemented in the LM3705XBBP-232?
LM3705XBBP-232 uses a factory-laser-trimmed internal RC oscillator to generate its 28ms reset timeout period. This value is fixed and non-adjustable, eliminating external timing components and ensuring consistent reset duration across temperature and voltage. The timeout begins when VCC rises above the 3.08V threshold or when the MR input releases, holding RESET low for exactly 28ms before releasing.
Can the PFI pin of the LM3705XBBP-232 monitor a 5V supply directly?
No - the PFI pin has an absolute maximum rating of VCC + 0.3V and a 1.225V internal reference. To monitor a 5V supply, a resistor divider must scale the voltage so that PFI sees ≤1.225V when the 5V rail is at nominal. For example, a 3.09MΩ/1MΩ divider yields 1.22V at PFI when Vin = 5V, satisfying the threshold requirement while staying within input voltage limits.
What is the function of the LLO output on the LM3705XBBP-232?
The LLO (Low-Line Output) on the LM3705XBBP-232 is an open-drain signal that goes low when VCC falls to 1.02×VRST (≈3.14V for the 3.08V threshold), providing early warning ~100mV before the actual reset threshold. It is intended to trigger a non-maskable interrupt (NMI) in the host µP, allowing time-critical actions like register save, flash write abort, or controlled peripheral shutdown before RESET asserts.
LM3705XBBP-232 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 9-VFBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.32V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 20ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 9-DSBGA
LM3705XBBP-232 FAQ
1.How can I place an order for LM3705XBBP-232 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3705XBBP-232 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 LM3705XBBP-232 reliable?
The price and inventory of LM3705XBBP-232 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3705XBBP-232 is usually 5 days.
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We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3705XBBP-232 transactions.
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LM3705XBBP-232 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3705XBBP-232 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 LM3705XBBP-232?
For technical support, including LM3705XBBP-232 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3705XBBP-232 requirements.
6.How does Aetrix verify that LM3705XBBP-232 is sourced from the original manufacturer or authorized distributors?
All LM3705XBBP-232 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 LM3705XBBP-232 meets industry standards.
7.What is the process for return or replacement of LM3705XBBP-232?
All LM3705XBBP-232 units undergo pre-shipment inspection (PSI). If there is an issue with LM3705XBBP-232, 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 LM3705XBBP-232 part is unused and in its original packaging.
Return procedure for LM3705XBBP-232:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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