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Analog Devices Inc. LTC3558EUD#PBF
- Part No.:
- LTC3558EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3558EUD#PBF.pdf
- Description:
- IC USB BATTERY CHARGER 20-QFN
- Quantity:
- Payment:
- Shipping:
Inventory:468
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Product details
Overview
LTC3558EUD#PBF from Analog Devices (formerly Linear Technology) is a monolithic USB battery charger with integrated synchronous buck and buck-boost regulators for single-cell Li-Ion/Polymer systems. It delivers up to 950mA charge current, 400mA per regulator output, and operates at 2.25MHz switching frequency in a thermally enhanced 20-lead 3mm × 3mm QFN package - enabling compact, high-efficiency power management in portable audio players and handheld instrumentation.
For engineers reviewing the LTC3558EUD#PBF datasheet, LTC3558EUD#PBF pinout, LTC3558EUD#PBF application, or LTC3558EUD#PBF equivalent, key selection considerations include its dual-regulator architecture, HPWR-selectable charge current scaling (100%/20%), NTC-based thermal qualification, internal timer termination, and guaranteed –40°C to +85°C operation in the E-grade QFN package.
Technical Context
The LTC3558EUD#PBF integrates three independent power subsystems on a single die: a linear USB battery charger with PROG-pin current programming and CHRG status monitoring; a pulse-skip/burst-mode synchronous buck regulator (PVIN1 → VOUT1) with internal compensation and 780–820mV FB1 reference; and a dual-switch synchronous buck-boost regulator (PVIN2 → VOUT2) supporting 2.65–5.60V output with MODE-selectable PWM/Burst operation and VC2-based Type I/III compensation.
Its control logic coordinates shared input sourcing (BAT/PVIN1/PVIN2 tied), manages thermal regulation via NTC interface, enforces safety limits including 4-hour charge timer and bad-battery detection (<2.9V for >0.5hr), and implements differential UVLO (50mV threshold) to prevent brownout-induced instability during battery voltage sag.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Charge Current | Up to 950mA max (HPWR = high); programmable via single resistor on PROG pin with 800× scaling ratio |
| Buck Regulator Output | 1.2V @ 400mA, 2.25MHz fixed-frequency operation, 780–820mV feedback reference |
| Buck-Boost Regulator Output | Programmable 2.65–5.60V @ 400mA, supports dropout-free regulation across full Li-ion range (2.7–4.2V) |
| Switching Frequency | 2.25MHz typical (1.91–2.59MHz over temp), enabling small external inductors (e.g., 2.2μH) and low-profile designs |
| Operating Temperature | –40°C to +85°C (E-grade), validated by design and statistical process control per datasheet Note 3 |
| Package | 20-lead 3mm × 3mm × 0.75mm QFN with exposed thermal pad (Pin 21 = GND) |
| UVLO Threshold | 4.0V nominal (3.85–4.125V), with 200mV hysteresis and 50mV differential lockout relative to BAT |
Pinout & Package
20-lead (3mm × 3mm) plastic QFN package with 0.75mm profile and exposed thermal pad (Pin 21 = GND, soldered to PCB ground). Pin pitch: 0.5mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Power Ground Reference | Primary ground return for all regulators and charger; must be connected to exposed pad (Pin 21) |
| BAT (2) | Battery Charge Output | Delivers regulated charge current to Li-ion cell; also serves as input source for both regulators |
| MODE (3) | Regulator Operating Mode Select | High = Burst Mode for both regulators; Low = Pulse Skip (buck) + PWM (buck-boost) |
| FB1 (4) | Buck Regulator Feedback Input | Monitors VOUT1 via resistor divider; 800mV servo target enables precise 1.2V output setting |
| EN1 (5) | Buck Regulator Enable | Active-high digital control; high-impedance input requiring external pull-up/down to avoid floating |
| SW1 (6) | Buck Switch Node | Connects to external inductor; carries high di/dt switching current; requires local ceramic decoupling |
| PVIN1 (7) | Buck Input Supply | Tied directly to BAT and PVIN2; supplies buck regulator; requires 10μF input capacitor |
| PVIN2 (8) | Buck-Boost Input Supply | Tied directly to BAT and PVIN1; supplies buck-boost regulator; requires 10μF input capacitor |
| SWAB2 (9) | Buck-Boost Switch A/B Node | Connects to one end of external inductor; interfaces with internal PMOS/NMOS switches A and B |
| SWCD2 (10) | Buck-Boost Switch C/D Node | Connects to other end of same inductor; interfaces with internal NMOS/PMOS switches C and D |
| VOUT2 (11) | Buck-Boost Regulated Output | Delivers programmable output (e.g., 3.3V @ 400mA); requires feedback divider to FB2 and compensation to VC2 |
| SUSP (12) | Charger Suspend Control | ≥1.2V disables charging and resets timer; internal weak pull-down ensures safe default state |
| FB2 (13) | Buck-Boost Feedback Input | 800mV servo reference; used with external resistor divider to set VOUT2 voltage |
| VC2 (14) | Buck-Boost Compensation Node | Connects external Type I or Type III compensation network between FB2 and VC2 for loop stability |
| EN2 (15) | Buck-Boost Regulator Enable | Active-high digital control; high-impedance input requiring defined logic level |
| HPWR (16) | Charge Current Scaling Select | ≥1.2V = 100% programmed current; ≤0.4V = 20% current; enables USB-compliant low/high-power modes |
| NTC (17) | Thermistor Interface Input | Monitors battery temperature via NTC thermistor; pauses charging if outside valid range (cold/hot fault thresholds) |
| PROG (18) | Charge Current Program/Monitor | Resistor-to-ground sets current (IBAT = 800 × IPROG); voltage reflects real-time charge current (1V or 0.2V servo) |
| CHRG (19) | Open-Drain Status Output | Indicates charging/not charging/unresponsive battery/temperature fault; requires external pull-up or LED |
| VCC (20) | USB Input Supply | Accepts 4.3–5.5V USB source; powers charger only; requires 1μF decoupling capacitor |
| Exposed Pad (21) | Thermal & Electrical Ground | Mandatory solder connection to PCB ground plane for thermal dissipation and electrical integrity |
Key Features
| Feature | Design Value |
|---|---|
| Integrated USB Charger + Dual Regulators | Eliminates need for separate charger IC and two DC/DC converters - reduces BOM count and board area in space-constrained devices |
| HPWR-Selectable Charge Current | Enables dynamic compliance with USB 2.0 (100mA) and USB Battery Charging (500mA/950mA) specifications using one resistor and logic pin |
| NTC-Based Thermal Qualification | Prevents charging outside safe battery temperature range using standard NTC thermistor, improving safety and longevity |
| Internal 4-Hour Safety Timer | Guarantees charge termination even if float voltage is never reached - prevents overcharge and thermal runaway |
| Buck-Boost Dropout-Free Operation | Maintains regulated output across entire Li-ion voltage range (2.7–4.2V), extending usable battery runtime by ~15% |
| 2.25MHz Constant-Frequency Switching | Allows use of sub-3mm inductors and low-ESR ceramic capacitors, minimizing solution footprint and EMI filtering requirements |
Applications
| Portable Audio Players | Handheld Medical Instruments |
|---|---|
Use Scenario: SD/Flash-based MP3 players requiring dual-rail power (1.2V core, 3.3V I/O) and USB-sourced battery charging. IC Role / Device Role / Timing Role: LTC3558EUD#PBF acts as system power manager - linearly charges Li-ion cell while simultaneously regulating two independent supply rails from the same battery source. Use Value: Enables single-chip power solution with <1.5mm² footprint, eliminating discrete charger + dual DC/DC, and supporting USB-host charging without firmware intervention. | Use Scenario: Battery-powered glucose meters or pulse oximeters needing reliable, temperature-qualified charging and stable analog/digital rails. IC Role / Device Role / Timing Role: LTC3558EUD#PBF provides NTC-monitored charging and low-noise, high-efficiency regulation for sensitive analog front-ends and microcontroller subsystems. Use Value: Ensures safe charging under clinical temperature conditions and delivers <10mV load/line regulation on both outputs - critical for ADC accuracy and display backlight consistency. |
| Industrial Handheld Scanners | Wearable Diagnostic Sensors |
Use Scenario: Rugged barcode scanners operating in variable ambient temperatures with USB field recharging capability. IC Role / Device Role / Timing Role: LTC3558EUD#PBF serves as robust power subsystem - managing battery health via thermal qualification and delivering burst-mode efficiency during intermittent scan bursts. Use Value: Extends runtime by 22% vs. linear regulators in pulsed-load scenarios and prevents field failures due to cold-weather charging attempts. | Use Scenario: Disposable or reusable wearable sensors monitoring vital signs, powered by coin-cell–sized Li-Poly batteries and charged via USB. IC Role / Device Role / Timing Role: LTC3558EUD#PBF functions as ultra-low-quiescent power manager - drawing only 8.5μA in suspend mode while maintaining accurate battery voltage monitoring. Use Value: Achieves >12-month shelf life before first charge and supports automatic recharge when battery self-discharges below 4.105V - no host MCU intervention required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery charger + dual-regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3559EUD#PBF | Same pinout and package; adds integrated USB OTG boost (5V @ 500mA) and improved NTC accuracy (±1.5% vs ±2.5%) | Required when device must act as USB host (e.g., peripheral docking); not needed for charger-only or slave-only roles | Select LTC3559EUD#PBF only if OTG functionality is mandatory; otherwise LTC3558EUD#PBF offers lower cost and identical core performance |
| BQ24160RGET | Single-input (VBUS-only) charger with integrated buck; no buck-boost regulator; uses I²C interface instead of analog pins | Suitable for simpler systems needing only one regulated rail; lacks autonomous thermal/timeout safety features of LTC3558EUD#PBF | Choose BQ24160RGET for cost-sensitive, MCU-managed designs where second rail is generated externally or not required |
Compared with LTC3559EUD#PBF and BQ24160RGET, the LTC3558EUD#PBF uniquely balances autonomous analog control, dual-output flexibility, and USB-compliant charge scaling - making it optimal for standalone, firmware-light portable devices requiring both 1.2V and 3.3V rails from a single Li-ion cell.
Availability
LTC3558EUD#PBF is available at Aetrix Electronics and suitable for portable audio players, handheld medical instruments, industrial scanners, wearable sensors, and USB-rechargeable IoT edge nodes requiring stable component supply across extended product lifecycles.
Supply support for LTC3558EUD#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for all Linear power management products.
The LTC3558EUD#PBF belongs to Linear's integrated power management IC family, designed specifically for space-constrained, battery-powered portable electronics requiring autonomous, multi-rail power conversion with robust safety and thermal management.
FAQ
What is the maximum battery charge current supported by the LTC3558EUD#PBF?
The LTC3558EUD#PBF supports up to 950mA maximum charge current at the BAT pin when HPWR is high and the PROG resistor is selected accordingly (e.g., 845Ω yields ~500mA; 1.74kΩ yields ~230mA). The actual current scales linearly with PROG resistance and is precisely monitored via the PROG pin voltage (1V servo).
How does the LTC3558EUD#PBF handle battery temperature monitoring?
The LTC3558EUD#PBF uses the NTC pin to interface with an external NTC thermistor connected between VCC and ground. It compares the resulting voltage against cold (75–78% VCC) and hot (33.4–36.4% VCC) thresholds. If the battery temperature falls outside the valid range, charging pauses until the condition clears - ensuring safe operation per IEC 62133.
Can the LTC3558EUD#PBF regulate both output rails independently?
Yes - the LTC3558EUD#PBF regulates VOUT1 (buck) and VOUT2 (buck-boost) independently. VOUT1 is set by the FB1 resistor divider (target 800mV), while VOUT2 is set by the FB2 divider and stabilized via external compensation on VC2. Each has dedicated enable pins (EN1/EN2) and MODE-selectable operating modes.
What happens to the LTC3558EUD#PBF during input undervoltage conditions?
When VCC drops below the 4.0V UVLO threshold (with 200mV hysteresis), the LTC3558EUD#PBF disables the battery charger. Additionally, if VCC falls within 50mV of BAT voltage (differential UVLO), charging halts to prevent instability during battery sag - a critical safeguard for USB-powered systems with weak hosts.
Is the LTC3558EUD#PBF RoHS-compliant and lead-free?
Yes - the LTC3558EUD#PBF carries the #PBF suffix, indicating 100% matte tin lead finish and full compliance with RoHS Directive 2011/65/EU. The device meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL3) and is qualified for reflow soldering per IPC/JEDEC J-STD-020.
LTC3558EUD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Handheld/Mobile Devices
- Current - Supply:
- 200µA
- Voltage - Supply:
- 4.35V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x3)
LTC3558EUD#PBF FAQ
1.How can I place an order for LTC3558EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3558EUD#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 LTC3558EUD#PBF reliable?
The price and inventory of LTC3558EUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3558EUD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3558EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3558EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3558EUD#PBF?
LTC3558EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3558EUD#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 LTC3558EUD#PBF?
For technical support, including LTC3558EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3558EUD#PBF requirements.
6.How does Aetrix verify that LTC3558EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3558EUD#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 LTC3558EUD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3558EUD#PBF?
All LTC3558EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3558EUD#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 LTC3558EUD#PBF part is unused and in its original packaging.
Return procedure for LTC3558EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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