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Analog Devices Inc. LTC4009CUF#PBF
- Part No.:
- LTC4009CUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC4009CUF#PBF.pdf
- Description:
- IC BAT CHG MULT-CHEM 1-4CL 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:724
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Product details
Overview
LTC4009CUF#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down constant-current/constant-voltage battery charger controller for multi-chemistry Li-ion, Li-polymer, NiMH, and lead-acid battery packs. It delivers up to 3A charge current with ±0.5% float voltage accuracy, 550kHz quasi-constant-frequency PWM operation, and programmable AC adapter input current limiting (±3% accuracy). It is used in notebook computers and portable instruments requiring high-efficiency, low-noise charging with external microcontroller-based charge termination.
For engineers reviewing the LTC4009CUF#PBF datasheet, LTC4009CUF#PBF pinout, LTC4009CUF#PBF application, or LTC4009CUF#PBF equivalent, key selection criteria include its 20-pin 4mm × 4mm QFN package, adjustable 2V–28V output voltage range, ±4% charge current accuracy, analog PROG pin current monitoring, and absence of built-in termination-requiring external algorithm control.
Technical Context
The LTC4009CUF#PBF implements a current-mode synchronous buck topology with internal 5V INTVDD regulator, dual gate drivers (TGATE/BGATE), and cycle-by-cycle peak current sensing via ITH. Its error amplifier compares VFB (1.2085V reference) against a resistor-divided BAT voltage and integrates input current limit feedback from CLP–CLN differential sense.
It features three open-drain status outputs-CHRG (triple-state: strong pull-down, 25µA weak pull-down, or high-Z), ACP (AC present), and ICL (input current limit active)-all referenced to GND and compatible with 3.3V/5V logic. Shutdown is controlled by SHDN (active-low, 300mV threshold) and DCDIV (1.2V AC-present detection).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Synchronous step-down (buck) PWM controller with TGATE/BGATE drivers for external N-channel MOSFETs. |
| Switching Frequency | 550kHz typical; enables compact 6.8µH inductor and ceramic bulk capacitors without audible noise. |
| Output Voltage Range | 2V to 28V; programmed externally via FBDIV–VFB resistor divider (LTC4009 variant). |
| Charge Current Accuracy | ±4% over temperature; set by RSENSE, RIN, and RPROG with linearized PROG pin monitoring. |
| Input Current Limit Accuracy | ±3%; configured via CLP–CLN differential sense resistor, with ICL pin indicating activation. |
| Float Voltage Accuracy | ±0.5% at 25°C; ensures precise CV-phase regulation critical for Li-ion cell longevity. |
| Package | 20-pin 4mm × 4mm × 0.75mm QFN with exposed thermal pad (Pin 21 = GND); θJA = 37°C/W. |
Pinout & Package
20-pin (4mm × 4mm) plastic QFN package with exposed GND pad (Pin 21). Thermal performance requires soldering the exposed pad to PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CLN (1) | Current limit sense negative | Differential input for AC adapter current limiting; threshold = CLP – 100mV; must be filtered for noise immunity. |
| CLP (2) | Current limit sense positive / power input | Primary power source for IC; also provides current limit reference; supports 6V–28V operation. |
| DCIN (3) | DC input supply | Secondary power path (e.g., battery backup); isolated from CLP by diode; bypassed with ≥0.1µF capacitor. |
| ICL (4) | Input current limit indicator | Open-drain active-low output signaling reduction of charge current due to input current limiting. |
| DCDIV (5) | AC adapter presence comparator input | Resistor-divider input detecting DC adapter presence (1.2V threshold) and overvoltage (1.825V OVP). |
| SHDN (6) | Active-low shutdown control | Drives IC into micropower shutdown (<215µA) when pulled below 300mV; internal 50kΩ pull-down. |
| ACP (7) | AC adapter present indicator | Open-drain output active-low when adequate adapter voltage is detected at DCDIV. |
| CHRG (8) | Charge status indicator | Three-state open-drain output: strong pull-down (bulk charge), 25µA weak pull-down (C/10), or high-Z (no charge). |
| FBDIV (9) | Battery feedback divider source | Open-drain PFET connecting BAT to external resistor divider; enables precise float voltage programming. |
| VFB (10) | Battery voltage feedback input | High-impedance input (±20nA bias) referenced to 1.2085V internal bandgap; sets CV regulation point. |
| BAT (11) | Battery pack connection | Main battery terminal; voltage sensed for PWM control and overvoltage protection (106% of float voltage). |
| ITH (12) | PWM control voltage node | Error amplifier output setting peak inductor current threshold; external RC network provides loop compensation. |
| PROG (13) | Charge current programming & monitor | Linearized voltage output proportional to charge current; sets max current with RPROG and senses real-time ICHRG. |
| CSN (14) | Current sense negative input | Low-side current sense input; operates within (BAT – 50mV) to (BAT + 200mV) common-mode range. |
| CSP (15) | Current sense positive input | High-side current sense input; matched with CSN for accurate RSENSE measurement. |
| BGATE (16) | Synchronous rectifier gate driver | Drives NMOS bottom-FET for synchronous rectification; improves efficiency vs. diode-based buck. |
| INTVDD (17) | Internal 5V regulator output | Stable 5V ±1% supply for gate drivers; shuts down during SHDN; capable of sourcing 20mA load. |
| SW (18) | Switch node | Connection to external inductor and bootstrap network; critical for EMI and layout; swings from GND to CLN. |
| TGATE (19) | Top-FET gate driver output | Drives NMOS high-side switch; rail-to-rail swing up to CLN + 5V; requires BOOST bootstrap capacitor. |
| BOOST (20) | Bootstrap supply input | Return node for bootstrap capacitor; supplies TGATE driver; voltage range = (INTVDD – 1V) to (CLN + 5V). |
Key Features
| Feature | Design Value |
|---|---|
| No-audible-noise PWM operation | Quasi-constant 550kHz frequency enables use of small ceramic capacitors without piezoelectric squeal in portable devices. |
| Programmable input current limiting | External CLP–CLN resistor sets adapter current limit independently of battery charge current, enabling shared-input systems. |
| Analog charge current monitoring | PROG pin provides linear voltage output (11.67µA/mV) directly proportional to actual ICHRG for real-time MCU feedback. |
| Triple-state CHRG indicator | Single pin conveys bulk charge (strong pull-down), C/10 transition (25µA weak pull-down), or idle (high-Z) without external logic. |
| Micropower shutdown | 215µA max shutdown current extends battery standby time; all regulators, drivers, and comparators disabled except ACP monitoring. |
Applications
| Notebook Computers | Portable Instruments |
|---|---|
Use Scenario: Charging multi-cell Li-ion battery packs while simultaneously powering system loads from AC adapter. IC Role / Device Role / Timing Role: Synchronous buck controller managing CC/CV charge profile, input current sharing, and status reporting to host MCU. Use Value: Enables full-system operation during charge with no thermal throttling, thanks to 550kHz switching and synchronous rectification. | Use Scenario: Rechargeable handheld test equipment requiring long runtime and reliable charge termination under varying ambient temperatures. IC Role / Device Role / Timing Role: High-accuracy battery charger controller interfaced to precision ADC and temperature sensor for adaptive charge algorithms. Use Value: ±0.5% float voltage accuracy prevents overcharging, extending Li-ion cycle life beyond 500 cycles in field-deployed units. |
| Battery Backup Systems | Industrial Portable Radios |
Use Scenario: Maintaining sealed lead-acid or LiFePO₄ backup batteries in telecom edge nodes with limited AC input capacity. IC Role / Device Role / Timing Role: Multi-chemistry charger controller using external MCU to implement Pb-acid absorption/float or LiFePO₄ 3.6V CV profiles. Use Value: Programmable 2V–28V output and ±4% current accuracy allow safe charging of diverse chemistries without hardware redesign. | Use Scenario: Ruggedized two-way radios operating in extreme temperatures (-40°C to +85°C) with hot-swap battery capability. IC Role / Device Role / Timing Role: Battery management front-end providing reverse-current protection, C/10 detection, and adapter presence signaling to radio baseband processor. Use Value: CHRG's triple-state output eliminates need for external comparators or GPIO expanders, reducing BOM count and board area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery charger controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4009CUF-1#PBF | Pin-programmable 4.1V/cell output for 1–4S Li-ion; fixed internal resistors replace FBDIV/VFB divider. | Eliminates external feedback resistors but locks float voltage to four preset values; not adjustable. | Select when designing for standard 4.1V/cell Li-ion packs and seeking reduced component count. |
| LTC4009CUF-2#PBF | Pin-programmable 4.2V/cell output for 1–4S Li-ion; identical pinout and feature set as -1 variant. | Same fixed-voltage architecture as LTC4009CUF-1#PBF but optimized for 4.2V/cell nominal Li-ion chemistry. | Select for mainstream 4.2V/cell Li-ion applications where precision external voltage programming is unnecessary. |
Compared with LTC4009CUF-1#PBF and LTC4009CUF-2#PBF, the LTC4009CUF#PBF offers full external float voltage adjustability across 2V–28V, making it suitable for non-standard battery configurations and multi-chemistry designs where flexibility outweighs component count savings.
Availability
LTC4009CUF#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instruments, and battery backup systems requiring stable component supply, extended temperature support (0°C to 85°C), and RoHS-compliant packaging.
Supply support for LTC4009CUF#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC4009 family belongs to Linear's Power Management product line, designed specifically for high-efficiency, flexible battery charging in space-constrained portable and industrial systems requiring external algorithm control.
FAQ
What is the primary function of the LTC4009CUF#PBF in a battery charging system?
The LTC4009CUF#PBF is a synchronous step-down constant-current/constant-voltage battery charger controller. It does not include built-in charge termination logic; instead, it provides precise current and voltage regulation, status indicators (CHRG, ACP, ICL), and analog monitoring (PROG pin) for external microcontroller-based charge management. The LTC4009CUF#PBF enables high-efficiency, low-noise charging of Li-ion, Li-polymer, NiMH, and lead-acid batteries across 2V–28V output range.
How does the LTC4009CUF#PBF achieve ±0.5% float voltage accuracy?
The LTC4009CUF#PBF achieves ±0.5% float voltage accuracy through a precision 1.2085V internal bandgap reference and low-bias-current VFB input (±20nA). When used with a high-accuracy external resistor divider between FBDIV and GND, the feedback network minimizes gain error and temperature drift. This specification is guaranteed over the 0°C to 85°C operating range for the C-grade LTC4009CUF#PBF, ensuring reliable CV-phase regulation for sensitive Li-ion cells.
Can the LTC4009CUF#PBF be used for lithium iron phosphate (LiFePO₄) battery charging?
Yes, the LTC4009CUF#PBF supports LiFePO₄ charging via its fully adjustable 2V–28V output voltage range. Unlike fixed-voltage variants (LTC4009CUF-1#PBF/LTC4009CUF-2#PBF), the LTC4009CUF#PBF uses an external FBDIV–VFB resistor divider to set the float voltage precisely to 3.6V per cell. Its ±4% charge current accuracy and programmable input current limiting make it suitable for LiFePO₄ applications requiring strict voltage control and thermal-aware charge profiles.
What is the role of the PROG pin on the LTC4009CUF#PBF?
The PROG pin on the LTC4009CUF#PBF serves dual functions: it programs maximum charge current via RPROG to GND and provides a linearized analog voltage output proportional to actual charge current (11.67µA/mV scaling). During charging, VPROG = ICHRG × RPROG × (11.67µA/mV), enabling real-time current monitoring by an external ADC without additional sensing circuitry. This eliminates the need for separate current-sense amplifiers in MCU-based battery management systems using the LTC4009CUF#PBF.
Does the LTC4009CUF#PBF require external MOSFETs, and what are their roles?
Yes, the LTC4009CUF#PBF requires two external N-channel MOSFETs: one driven by TGATE (high-side switch) and one driven by BGATE (synchronous rectifier). The TGATE MOSFET controls energy transfer from CLP/DCIN to the inductor, while the BGATE MOSFET replaces the traditional Schottky diode to reduce conduction losses and improve efficiency-especially at high currents. Both gates are driven with rail-to-rail signals and include non-overlap timing to prevent shoot-through, a core feature of the LTC4009CUF#PBF's synchronous buck architecture.
LTC4009CUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Battery Chemistry:
- Multi-Chemistry
- Number of Cells:
- 1 ~ 4
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- -
- Fault Protection:
- Over Voltage, Reverse Current
- Charge Current - Max:
- -
- Battery Pack Voltage:
- 16.8V
- Voltage - Supply (Max):
- 28V
- Interface:
- -
- Operating Temperature:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x4)
LTC4009CUF#PBF FAQ
1.How can I place an order for LTC4009CUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4009CUF#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 LTC4009CUF#PBF reliable?
The price and inventory of LTC4009CUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4009CUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC4009CUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4009CUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4009CUF#PBF?
LTC4009CUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4009CUF#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 LTC4009CUF#PBF?
For technical support, including LTC4009CUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4009CUF#PBF requirements.
6.How does Aetrix verify that LTC4009CUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC4009CUF#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 LTC4009CUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC4009CUF#PBF?
All LTC4009CUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4009CUF#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 LTC4009CUF#PBF part is unused and in its original packaging.
Return procedure for LTC4009CUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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