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Analog Devices Inc. LTC1729CS8-8.4#TRPBF
- Part No.:
- LTC1729CS8-8.4#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1729CS8-8.4#TRPBF.pdf
- Description:
- IC BATT CHG LI-ION 2CELL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,435
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Product details
Overview
LTC1729CS8-8.4#TRPBF from Analog Devices (formerly Linear Technology) is a lithium-ion battery charge termination controller for 2-cell (8.4V nominal) systems. It provides C/10 current detection, 3-hour time-out termination, trickle-charge preconditioning below 5.4V, temperature qualification via NTC thermistor (0°C–50°C), and automatic battery/charger presence detection. It interfaces with step-down or SEPIC chargers such as LT1505, LT1512, and LT1513 in portable power management.
For engineers reviewing the LTC1729CS8-8.4#TRPBF datasheet, LTC1729CS8-8.4#TRPBF pinout, LTC1729CS8-8.4#TRPBF application, or LTC1729CS8-8.4#TRPBF equivalent, key selection criteria include its 8.4V VMAX threshold, ±2.5mV SENSE pin C/10 offset, 10.4V UVLO high threshold, NTC-based thermal lockout, and compatibility with external 2A–4A switching chargers in space-constrained handheld devices.
Technical Context
The LTC1729CS8-8.4#TRPBF implements a state-machine-driven termination logic with six internal comparators (COMP1–COMP6), a 131kHz trimmed oscillator, and timer-based transitions between Reset, Precondition, Charger "ON", Pause, Done, and Hold modes. Its OVP pin uses a precision 0.2% internal resistor divider to reference 2.465V for accurate 8.4V battery voltage monitoring.
It features dual-level NTC monitoring: cold hold at 2.79V (0°C), hot hold at 0.405V (50°C), and reset at <0.2V. The SENSE pin sinks 100µA to set C/10 threshold via external sense resistor, while BAT sources 12mA during preconditioning and 1.3mA during full charge - both clamped to 9.0V max (8.4V + 0.6V margin).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VMAX Threshold | 8.5V to 9.5V high-going; enables overvoltage clamp and pause mode when battery exceeds 8.4V nominal. |
| VMIN Threshold | 4.9V to 5.5V low-going; triggers 12mA trickle-charge preconditioning if cell voltage drops below ~5.2V. |
| UVLO High | 9.5V to 11.4V; disables IC until input supply rises above this level - ensures stable operation for 2-cell charger inputs. |
| C/10 Offset Accuracy | ±1mV to ±2.5mV; defines precision of current-sense comparator trip point for reliable end-of-charge detection. |
| NTC Cold Hold | 2.70V to 2.90V high-going; freezes charging and timers when thermistor indicates <0°C - prevents low-temp lithium plating. |
| Timer2 Duration | 2.61–3.55 hours; sets maximum constant-voltage charge time before forced termination - critical for safety compliance. |
| STATUS Output | Open-drain with 3mA sink capability and 50µA soft pull-down; supports 3-state microprocessor interface (charging/C/10/done). |
Pinout & Package
Package: 8-lead plastic SO (S8), 0.150" wide, RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OVP (1) | Voltage feedback monitor input | Connects to internal 55kΩ precision divider; used to detect 8.4V battery voltage with ±0.2% accuracy. |
| BAT (2) | Battery voltage sensing & current source | Sources 12mA (precondition) or 1.3mA (charge); clamped to 9.0V; enables battery presence detection and VMAX/VMin monitoring. |
| SENSE (3) | C/10 current threshold input | Sinks 100µA; develops 20mV offset across external resistor to set C/10 trip point - requires 0.2Ω sense resistor for 1A full-scale. |
| GND (4) | Analog and power ground reference | Common return for all internal comparators, bias currents, and logic - must be low-impedance connection to minimize noise coupling. |
| NTC (5) | Thermistor voltage monitor input | 100µA bias current; detects 0°C (2.79V) and 50°C (0.405V); forces Hold mode outside range or Reset mode if <0.2V. |
| STATUS (6) | Charge status open-drain output | HARD pull-down during charge; switches to 50µA soft pull-down after C/10 detected for ≥3 sec; floats after timer expiry. |
| VC (7) | Charger enable/disable open-drain output | Pulled low to disable external charger (e.g., LT1505/LT1512); open-circuit = charger active; driven low in Hold/Reset/Pause/Done. |
| VCC (8) | Supply input | Operates from 12V min to 30V max; UVLO activates at 9.6V typical; powers all internal circuits and bias sources. |
Key Features
| Feature | Design Value |
|---|---|
| Trickle-charge preconditioning | Automatically applies 12mA current when battery voltage falls below 5.2V - prevents damage to deeply discharged Li-ion cells. |
| 3-hour hard time-out termination | Guarantees charge stops after ≤3.55 hours regardless of C/10 status - meets IEC 62133 safety requirements for portable equipment. |
| Integrated NTC thermal qualification | Locks charging outside 0°C–50°C using factory-trimmed thresholds - eliminates need for external ADC or microcontroller thermal management. |
| Automatic battery detection | Detects battery insertion/removal via BAT pin voltage ramp and VMAX comparator - enables seamless restart without manual reset. |
| Compatible with multi-topology chargers | Interfaces with step-down (LT1505/LT1769) and SEPIC (LT1512/LT1513) chargers using only 6 pins - reduces BOM and layout complexity. |
Applications
| Cellular Phones | PDAs |
|---|---|
Use Scenario: Dual-cell Li-ion charging in slim smartphone designs with thermal safety enforcement. IC Role / Device Role / Timing Role: Charge termination controller coordinating with LT1505/LT1512; manages 3-hour timeout, C/10 detection, and NTC-based thermal hold. Use Value: Enables compact, certified charging solution without firmware - reduces development time and avoids MCU dependency for safety-critical timing. | Use Scenario: Portable digital assistant with removable battery pack requiring automatic presence detection and low-temp charge inhibition. IC Role / Device Role / Timing Role: Battery interface manager providing VBAT monitoring, preconditioning, and STATUS/VC control signals to external charger IC. Use Value: Eliminates need for discrete comparators and timers; supports hot-swap battery operation with zero-delay restart on reinsertion. |
| Cradle Chargers | Camcorders |
Use Scenario: Desktop cradle charger for 2-cell camcorder batteries with wall adapter input and LED status indication. IC Role / Device Role / Timing Role: System-level charge supervisor generating STATUS-driven LED states (amber/green) and VC-controlled charger enable. Use Value: Provides user-visible charge progress (precondition/C/10/done) using single open-drain pin - simplifies front-panel design and reduces component count. | Use Scenario: High-reliability camcorder battery charging under variable ambient temperatures (e.g., outdoor use). IC Role / Device Role / Timing Role: Thermal guard and termination enforcer interfacing with LT1513 SEPIC charger; halts charge if NTC reads <0°C or >50°C. Use Value: Prevents lithium dendrite formation and electrolyte decomposition - extends battery cycle life and meets UL 2054 field reliability requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar charge termination controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1729CMS8-8.4 | Same functionality and specs; MSOP-8 package (3mm × 3mm) vs. SO-8 (0.150" wide); θJA = 200°C/W vs. 150°C/W. | Preferred for ultra-compact PCBs where board area is constrained; requires different land pattern and reflow profile. | Select when footprint size or thermal resistance is prioritized over standard SO lead spacing. |
| BQ24075RGTR | Integrated linear charger (500mA) with built-in LDO, USB/AC detection, and I2C interface; no external charger required. No NTC hold mode or 3-hour timer. | Targets low-power USB-powered devices; lacks support for high-current switching chargers or dual-cell configurations. | Choose only for simple single-cell, low-current applications where integration outweighs flexibility and safety timer independence. |
Compared with LTC1729CMS8-8.4, the LTC1729CS8-8.4#TRPBF offers lower thermal resistance in SO packaging for higher ambient environments, while BQ24075RGTR trades standalone termination control for monolithic simplicity - making it unsuitable for 2-cell, >1A, or externally switched charger architectures.
Availability
LTC1729CS8-8.4#TRPBF is available at Aetrix Electronics and suitable for cellular phones, PDAs, cradle chargers, and camcorders requiring stable component supply, long-lifecycle support, and automotive-grade reliability validation.
Supply support for LTC1729CS8-8.4#TRPBF 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 acquired Linear Technology in 2017 and maintains full product support, datasheets, and application notes for the LTC portfolio.
The LTC1729CS8-8.4#TRPBF belongs to Linear's precision battery management IC family, designed specifically for safe, autonomous termination of multi-cell lithium-ion charging systems without host processor intervention.
FAQ
What is the primary function of the LTC1729CS8-8.4#TRPBF in a battery charging system?
The LTC1729CS8-8.4#TRPBF serves as a standalone charge termination controller for 2-cell (8.4V) lithium-ion batteries. Its core function is to autonomously stop charging after three hours or when current drops below C/10, while also enabling trickle preconditioning, thermal qualification, and battery presence detection - all without firmware. The LTC1729CS8-8.4#TRPBF integrates these functions into a single 8-pin SO package to reduce system complexity.
How does the LTC1729CS8-8.4#TRPBF handle low-temperature charging conditions?
The LTC1729CS8-8.4#TRPBF monitors battery temperature via an NTC thermistor connected to the NTC pin. When the voltage at that pin exceeds 2.79V (indicating <0°C), it enters Hold mode - freezing timers and pulling VC low to disable the external charger. This prevents lithium plating and ensures compliance with IEC 62133. The LTC1729CS8-8.4#TRPBF resumes charging only when the NTC voltage returns within 0.405V–2.79V (0°C–50°C).
Can the LTC1729CS8-8.4#TRPBF be used with a 1-cell 4.2V battery configuration?
No - the LTC1729CS8-8.4#TRPBF is factory-configured for 8.4V (2-cell) operation, with internal OVP divider calibrated to 2.465V for precise 8.4V detection. Using it with a 1-cell battery would result in premature overvoltage triggering and incorrect preconditioning thresholds. For 4.2V systems, the correct variant is LTC1729CS8-4.2 or LTC1729CS8-4.1. The LTC1729CS8-8.4#TRPBF is not software-configurable or pin-selectable for alternate voltages.
What external components are required to implement C/10 current detection with the LTC1729CS8-8.4#TRPBF?
To implement C/10 detection, the LTC1729CS8-8.4#TRPBF requires a current-sense resistor (e.g., 0.2Ω for 1A full-scale) between the charger output and battery positive, plus a 200Ω resistor from SENSE to ground. The 100µA internal sink develops 20mV across the 200Ω resistor, setting the C/10 threshold voltage. A 1µF capacitor from SENSE to ground provides 3-second digital filtering. No op-amps or external comparators are needed - the LTC1729CS8-8.4#TRPBF performs all signal conditioning internally.
Does the LTC1729CS8-8.4#TRPBF support automatic restart after AC adapter reconnection?
Yes - when the AC adapter is disconnected, VCC drops below UVLO (~9.6V), forcing the LTC1729CS8-8.4#TRPBF into high-impedance shutdown with minimal battery drain. Upon reconnection, VCC rises above UVLO, triggering a hardware reset: all timers clear, the state machine enters Reset mode, then transitions to Charge state. Battery presence is re-verified via BAT pin voltage, and preconditioning or full charge begins automatically - no external reset signal or microcontroller action is required for the LTC1729CS8-8.4#TRPBF.
LTC1729CS8-8.4#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Battery Chemistry:
- Lithium Ion
- Number of Cells:
- 2
- Current - Charging:
- -
- Programmable Features:
- -
- Fault Protection:
- -
- Charge Current - Max:
- -
- Battery Pack Voltage:
- 8.4V
- Voltage - Supply (Max):
- 28V
- Interface:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1729CS8-8.4#TRPBF FAQ
1.How can I place an order for LTC1729CS8-8.4#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1729CS8-8.4#TRPBF 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 LTC1729CS8-8.4#TRPBF reliable?
The price and inventory of LTC1729CS8-8.4#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1729CS8-8.4#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1729CS8-8.4#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1729CS8-8.4#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1729CS8-8.4#TRPBF?
LTC1729CS8-8.4#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1729CS8-8.4#TRPBF 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 LTC1729CS8-8.4#TRPBF?
For technical support, including LTC1729CS8-8.4#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1729CS8-8.4#TRPBF requirements.
6.How does Aetrix verify that LTC1729CS8-8.4#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1729CS8-8.4#TRPBF 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 LTC1729CS8-8.4#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1729CS8-8.4#TRPBF?
All LTC1729CS8-8.4#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1729CS8-8.4#TRPBF, 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 LTC1729CS8-8.4#TRPBF part is unused and in its original packaging.
Return procedure for LTC1729CS8-8.4#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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