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Analog Devices Inc. LTC1731EMS8-8.4#TRPBF
- Part No.:
- LTC1731EMS8-8.4#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1731EMS8-8.4#TRPBF.pdf
- Description:
- IC BATT CHG MULT-CHEM 2CEL 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,176
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Product details
Overview
LTC1731EMS8-8.4#TRPBF from Analog Devices (formerly Linear Technology) is a complete constant-current/constant-voltage linear charger controller for 2-cell lithium-ion batteries, delivering 500mA typical charge current with ±1% float voltage accuracy (8.4V), 7% current programming accuracy via external RPROG/RSENSE, and automatic trickle charge initiation below 4.95V battery voltage - deployed in handheld computers and charging docks requiring precise dual-cell Li-Ion management.
For engineers reviewing the LTC1731EMS8-8.4#TRPBF datasheet, LTC1731EMS8-8.4#TRPBF pinout, LTC1731EMS8-8.4#TRPBF application, or LTC1731EMS8-8.4#TRPBF equivalent, key selection considerations include C/10 end-of-charge detection, programmable 30-hour/µF timer termination, sleep-mode battery drain of 15µA, and MSOP-8 package compatibility with space-constrained portable designs.
Technical Context
The LTC1731EMS8-8.4#TRPBF implements a precision analog control loop using an internal 2.457V reference, trimmed 800Ω resistor, and current amplifier to servo an external P-channel MOSFET gate via the DRV pin. It integrates voltage-mode regulation with ±1% accuracy over –40°C to 85°C and current-mode control with 7% accuracy set by RPROG and RSENSE.
Charge sequencing includes automatic low-voltage trickle mode (10% full-scale current until VBAT > 4.95V), fast constant-current phase, and constant-voltage phase ending at C/10 detection or timer expiration. Sleep mode activates when VCC < VBAT + 54mV, reducing battery drain to 15µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Float Voltage | 8.4V ±1% - precisely regulates 2-cell Li-Ion battery termination voltage without external feedback components |
| Charge Current Accuracy | ±7% - determined by RPROG and RSENSE values; enables repeatable 500mA (RPROG=19.6kΩ, RSENSE=0.2Ω) design |
| C/10 Detection Threshold | 50mA typical - triggers CHRG pin state change to indicate near-full charge for system-level status monitoring |
| Sleep Mode Drain | 15µA typical - minimizes parasitic battery discharge when input supply is removed |
| Trickle Threshold Voltage | 4.95V - initiates 10% reduced current for deeply discharged cells to prevent damage |
| Timer Accuracy | ±10% - sets total charge duration via CTIMER capacitor (e.g., 0.1µF = 3 hours) |
| Input Voltage Range | 8.8V to 12V - supports standard 9V wall adapters and ensures stable operation above UVLO threshold of 8.2V |
Pinout & Package
Package: 8-pin MSOP (MS8), 3.0mm × 3.0mm body, 0.65mm pitch, exposed pad not electrically connected. Designed for high-density PCB layouts with thermal performance θJA = 200°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BAT (1) | Battery voltage sense input | Connects to battery positive; internal 720Ω/100kΩ divider sets 8.4V float point; requires ≥10µF bypass for stability |
| CHRG (2) | Open-drain charge status output | Pulled low during active charge; switches to 100µA sink at C/10; high-impedance after timer expiry or shutdown |
| TIMER (3) | Timer capacitor & CV disable input | CTIMER sets total charge time (30h/µF); tied to VCC disables timer and forces constant-current-only mode |
| GND (4) | Analog and power ground reference | Common return for all internal circuitry; must be low-impedance connection to minimize sensing error |
| PROG (5) | Charge current programming & shutdown input | RPROG to GND sets IBAT; floating PROG (2.5µA pull-up) triggers shutdown at 2.457V threshold |
| DRV (6) | External pass device drive output | Drives gate of P-channel MOSFET; clamped to VCC – 6.5V to protect low-VGS FETs |
| VCC (7) | Main input supply input | Accepts 8.8–12V; powers internal circuitry; requires 1µF bypass; UVLO activates below 8.2V |
| SENSE (8) | Current sense amplifier input | Connected to low-side of RSENSE; senses voltage drop to regulate IBAT via closed-loop control |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 2.457V precision reference | Enables ±1% float voltage regulation without external trimming or calibration |
| Programmable C/10 end-of-charge detection | Provides reliable near-full-charge signal for host microcontroller status polling without firmware dependency |
| Automatic trickle charge activation | Initiates safe 10% current boost for cells below 4.95V, preventing over-discharge recovery failure |
| Low-power sleep mode | Reduces battery drain to 15µA when input is disconnected - extends standby time in portable devices |
| Constant-current-only mode | Enabled by tying TIMER to VCC; disables voltage regulation and timer for NiMH/NiCd charging with external termination |
Applications
| Handheld Computers | Charging Docks |
|---|---|
Use Scenario: Recharging dual-cell Li-Ion packs in ruggedized industrial PDAs with intermittent AC availability. IC Role / Device Role / Timing Role: Primary linear charger controller managing CC/CV transition, C/10 signaling, and sleep entry on adapter removal. Use Value: Eliminates need for external voltage references or timing ICs while maintaining ±1% battery voltage accuracy across temperature. | Use Scenario: Multi-bay desktop cradle charging up to four devices simultaneously with independent status indication. IC Role / Device Role / Timing Role: Per-bay charge controller providing CHRG pin-driven LED status and timer-based safety cutoff. Use Value: Enables compact layout via MSOP-8 footprint and reduces BOM count by integrating current programming, voltage regulation, and termination logic. |
| Cellular Phones (Legacy 2-Cell Designs) | Programmable Current Sources |
Use Scenario: Low-cost feature phone platforms using discrete 2-cell Li-Ion packs without embedded fuel gauging. IC Role / Device Role / Timing Role: Standalone charger IC handling full charge cycle including trickle, CC, CV, and auto-sleep. Use Value: Guarantees safe 8.4V termination and prevents overcharge even under varying ambient temperatures (–40°C to 85°C). | Use Scenario: Lab-grade bench current sources for battery testing and electrochemical characterization. IC Role / Device Role / Timing Role: Precision programmable current sink/source using SENSE/PROG interface and DRV-controlled external FET. Use Value: Delivers stable 500mA ±7% output with minimal external components - no DAC, op-amp, or current mirror required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar linear battery charger controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1731ES8-8.4 | SO-8 package (5.0mm × 4.0mm), higher θJA = 125°C/W, same electrical specs | Preferred for through-hole prototyping or legacy SO-8 board reuse; lower thermal efficiency in dense layouts | Select when MSOP-8 assembly capability is unavailable or thermal derating margin exceeds 20°C |
| LTC1732EMS8 | Includes AC adapter presence detection, automatic recharge, no fixed float voltage (adjustable via resistor divider) | Designed for consumer docks requiring plug/unplug event awareness and top-off cycles | Choose only if AC detect or auto-recharge functionality is mandatory; not a drop-in replacement due to different pinout and regulation architecture |
Compared with LTC1731ES8-8.4 and LTC1732EMS8, the LTC1731EMS8-8.4#TRPBF offers superior thermal performance in space-constrained designs and guaranteed 8.4V ±1% regulation without external resistors - making it optimal for production-critical 2-cell Li-Ion systems where layout area and voltage tolerance are primary constraints.
Availability
LTC1731EMS8-8.4#TRPBF is available at Aetrix Electronics and suitable for handheld computers, charging docks, and legacy cellular phones requiring stable component supply, long-lifecycle support, and guaranteed parametric compliance over –40°C to 85°C.
Supply support for LTC1731EMS8-8.4#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 technical and manufacturing continuity for all Linear battery management ICs.
The LTC1731 family delivers highly integrated, precision linear charging control for multi-cell Li-Ion systems - engineered for reliability in portable industrial and medical equipment where firmware-free operation and tight voltage tolerances are essential.
FAQ
What is the exact float voltage accuracy of the LTC1731EMS8-8.4#TRPBF over temperature?
The LTC1731EMS8-8.4#TRPBF guarantees ±1% float voltage accuracy (8.4V ±84mV) over the full –40°C to 85°C operating range, as confirmed by internal trimmed resistor divider and 2.457V reference. This specification holds under VCC = 9V to 12V and applies to all production units without calibration.
Can the LTC1731EMS8-8.4#TRPBF be used to charge NiMH batteries?
Yes - the LTC1731EMS8-8.4#TRPBF supports NiMH charging in constant-current-only mode by connecting the TIMER pin to VCC, which disables voltage regulation and timer functions. External termination (e.g., –ΔV or temperature cutoff) remains required, as the LTC1731EMS8-8.4#TRPBF does not provide NiMH-specific algorithms.
What is the minimum recommended RSENSE value for the LTC1731EMS8-8.4#TRPBF?
The LTC1731EMS8-8.4#TRPBF requires RSENSE ≥ 0.1Ω to maintain stability and avoid excessive power dissipation. With RPROG = 19.6kΩ, a 0.2Ω sense resistor yields 500mA nominal current; lower values increase current but risk thermal overload and reduced accuracy per datasheet Figure 10.
How does the LTC1731EMS8-8.4#TRPBF enter sleep mode, and what is its impact on battery life?
The LTC1731EMS8-8.4#TRPBF enters sleep mode automatically when VCC drops below VBAT + 54mV (e.g., adapter removal), reducing battery drain current to 15µA typical. This extends shelf life and standby runtime significantly - for a 2000mAh battery, self-discharge due to LTC1731EMS8-8.4#TRPBF is less than 0.01% per day.
Is the CHRG pin on the LTC1731EMS8-8.4#TRPBF compatible with direct microcontroller GPIO reading?
Yes - the CHRG pin provides three distinct states readable by a microcontroller GPIO: low (active charge), ~1V (C/10 via 100µA sink with 10kΩ pull-up), and high-impedance (timer expiry or shutdown). No level-shifting is needed for 3.3V or 5V I/O, as CHRG operates within VCC range and sinks up to 5mA.
LTC1731EMS8-8.4#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Battery Chemistry:
- Multi-Chemistry
- Number of Cells:
- 2
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- Timer
- Fault Protection:
- -
- Charge Current - Max:
- 500mA
- Battery Pack Voltage:
- 8.4V
- Voltage - Supply (Max):
- 12V
- Interface:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
LTC1731EMS8-8.4#TRPBF FAQ
1.How can I place an order for LTC1731EMS8-8.4#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1731EMS8-8.4#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 LTC1731EMS8-8.4#TRPBF reliable?
The price and inventory of LTC1731EMS8-8.4#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1731EMS8-8.4#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1731EMS8-8.4#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1731EMS8-8.4#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1731EMS8-8.4#TRPBF?
LTC1731EMS8-8.4#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1731EMS8-8.4#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 LTC1731EMS8-8.4#TRPBF?
For technical support, including LTC1731EMS8-8.4#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1731EMS8-8.4#TRPBF requirements.
6.How does Aetrix verify that LTC1731EMS8-8.4#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1731EMS8-8.4#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 LTC1731EMS8-8.4#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1731EMS8-8.4#TRPBF?
All LTC1731EMS8-8.4#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1731EMS8-8.4#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 LTC1731EMS8-8.4#TRPBF part is unused and in its original packaging.
Return procedure for LTC1731EMS8-8.4#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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