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Analog Devices Inc. LTC3558EUD#TRPBF
- Part No.:
- LTC3558EUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3558EUD#TRPBF.pdf
- Description:
- IC USB BATTERY CHARGER 20-QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,393
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Product details
Overview
LTC3558EUD#TRPBF 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 3mm × 3mm QFN-20 package - enabling compact, high-efficiency power management in portable medical monitors.
For engineers reviewing the LTC3558EUD#TRPBF datasheet, LTC3558EUD#TRPBF pinout, LTC3558EUD#TRPBF application, or LTC3558EUD#TRPBF equivalent, key selection considerations include its dual-regulator architecture, HPWR-selectable charge current (20%/100%), NTC-based thermal qualification, internal timer termination, and guaranteed –40°C to +85°C operation without derating.
Technical Context
The LTC3558EUD#TRPBF integrates three independent power blocks: a linear USB battery charger with PROG-pin current programming and CHRG status monitoring; a pulse-skip/Burst Mode® buck regulator (PVIN1 → VOUT1) with internal compensation and 780–820mV FB1 reference; and a buck-boost regulator (PVIN2 → VOUT2) supporting 2.65–5.60V output with MODE-selectable PWM/Burst operation and VC2 compensation node.
Its control logic coordinates shared input sourcing (BAT/PVIN1/PVIN2 tied), manages thermal regulation via NTC interface with cold/hot fault thresholds at 75–78%VCC and 33.4–36.4%VCC, and enforces safety through differential UVLO (50mV hysteresis), bad-battery latching (0.5hr timeout below 2.9V), and 4-hour safety timer with recharge reset on VRECHRG (–95mV relative to VFLOAT).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Charge Current | Up to 950mA max; programmable via single PROG resistor (e.g., 1.74kΩ = 460mA @ HPWR=1); enables USB-compliant 100/500mA modes. |
| Regulator Output Current | 400mA per regulator (buck & buck-boost); supports simultaneous dual-rail loads like 1.2V core + 3.3V I/O in handheld devices. |
| Switching Frequency | 2.25MHz typical (1.91–2.59MHz range); allows use of small 2.2μH/4.7μH inductors and minimizes EMI in space-constrained layouts. |
| Operating Temperature | –40°C to +85°C; fully specified over industrial range with no derating - suitable for outdoor portable instrumentation. |
| Package | 20-lead 3mm × 3mm QFN (UD), 0.75mm profile; exposed pad (Pin 21) must be soldered to PCB ground for thermal performance (θJA = 68°C/W). |
| Feedback Reference | 800mV ±20mV for both FB1 and FB2; enables precise output regulation with standard resistor dividers and low-error voltage setting. |
| UVLO Threshold | VUVLO = 4.0V (typ), with 200mV hysteresis and differential lockout at 50mV (VCC–BAT); prevents unstable charging during weak USB source conditions. |
Pinout & Package
Package: 20-lead (3mm × 3mm) plastic QFN (UD), 0.75mm height, exposed thermal pad (Pin 21 = GND).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Power Ground | Primary ground return; connects directly to exposed pad (Pin 21) for thermal and electrical integrity. |
| BAT (2) | Battery Terminal | Charge current output and float voltage regulation node (4.2V); ties to PVIN1/PVIN2 for shared battery input. |
| MODE (3) | Regulator Operating Mode Select | High = Burst Mode® for both regulators; Low = Pulse Skip (buck) + PWM (buck-boost); critical for efficiency vs noise trade-off. |
| FB1 (4) | Buck Regulator Feedback | Monitors VOUT1 via resistor divider; 800mV reference enables accurate 1.2V output with <±1% load regulation. |
| EN1 (5) | Buck Regulator Enable | Active-high digital control; high-impedance input requires external pull-up/down; enables independent rail sequencing. |
| SW1 (6) | Buck Switch Node | Connects to external inductor; carries high di/dt switching current - requires tight layout and Kelvin grounding. |
| PVIN1 (7) | Buck Input Supply | Tied to BAT/PVIN2; accepts 2.7–4.2V; requires 10μF ceramic decoupling to GND for stability. |
| PVIN2 (8) | Buck-Boost Input Supply | Shared with BAT/PVIN1; same input range and decoupling requirement as PVIN1. |
| SWAB2 (9) | Buck-Boost Switch A/B Node | One end of coupled inductor; connects to SWCD2; handles bidirectional current in boost/buck transitions. |
| SWCD2 (10) | Buck-Boost Switch C/D Node | Second end of coupled inductor; forms full 4-switch buck-boost topology with SWAB2. |
| VOUT2 (11) | Buck-Boost Regulated Output | Programmable 2.65–5.60V output; delivers up to 400mA with dropout-free operation across full Li-ion range. |
| SUSP (12) | Charger Suspend Control | Logic input >1.2V disables charging and reduces IBAT to 1.5μA; internal weak pull-down ensures safe default state. |
| FB2 (13) | Buck-Boost Feedback | 800mV reference input; used with resistor divider to set VOUT2; supports precision 3.3V or 5V outputs. |
| VC2 (14) | Compensation Node | Error amplifier output; connects external Type I/III compensation network to FB2 for loop stability. |
| EN2 (15) | Buck-Boost Enable | Active-high control; independent of EN1 for flexible power rail enable sequencing. |
| HPWR (16) | Charge Current Scaling | Selects 100% (≥1.2V) or 20% (<0.4V) of programmed current; implements USB high-power/low-power mode switching. |
| NTC (17) | Thermistor Interface | Analog input for NTC thermistor; monitors battery temperature; disables charging outside 0°C–45°C range unless disabled by grounding. |
| PROG (18) | Charge Current Program/Monitor | Sets ICHG via resistor to GND; also provides real-time current monitor (IBAT = IPROG × 800) for system telemetry. |
| CHRG (19) | Open-Drain Status Output | Indicates charging/not charging/unresponsive battery/temperature fault; requires external pull-up for LED or MCU GPIO monitoring. |
| VCC (20) | USB Input Supply | Accepts 4.3–5.5V USB input; powers charger only; requires 1μF decoupling to GND. |
| Exposed Pad (21) | Thermal & Electrical Ground | Mandatory solder connection to PCB ground plane; essential for thermal dissipation and EMI reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated USB Charger + Dual Regulators | Eliminates need for discrete charger IC and two DC/DC converters - reduces BOM count by ≥5 components and saves ≥25mm² PCB area. |
| HPWR Pin Charge Scaling | Enables seamless transition between USB low-power (100mA) and high-power (500mA) modes without firmware changes or external logic. |
| Buck-Boost Dropout-Free Operation | Maintains regulated VOUT2 across full 2.7–4.2V battery range - extends usable runtime by up to 15% versus buck-only solutions. |
| NTC-Based Thermal Qualification | Prevents charging outside safe battery temperature window using standard NTC thermistor - meets IEC 62368-1 thermal safety requirements. |
| Internal 4-Hour Safety Timer | Guarantees automatic charge termination even if microcontroller fails - satisfies UL 1642 and UN38.3 cell safety compliance. |
| 2.25MHz Constant-Frequency Switching | Permits use of miniature 2.2μH inductors and avoids AM radio band interference - critical for hearing aids and wearable sensors. |
Applications
| Portable Medical Monitors | USB-Powered Handheld Scanners |
|---|---|
Use Scenario: Continuous glucose monitor (CGM) with Bluetooth LE and OLED display operating from single Li-Po cell. IC Role / Device Role / Timing Role: LTC3558EUD#TRPBF serves as primary power manager: linear charger maintains battery health, buck supplies 1.2V to MCU, buck-boost delivers stable 3.3V to RF transceiver and display driver. Use Value: Enables 7-day runtime with 2-hour USB recharge; NTC interface prevents charging at body temperature extremes; 2.25MHz switching avoids interference with physiological signal acquisition. | Use Scenario: Barcode scanner used in warehouse logistics with intermittent USB charging and 4G/LTE connectivity. IC Role / Device Role / Timing Role: LTC3558EUD#TRPBF powers ARM Cortex-M4 MCU (1.2V), image sensor (2.8V), and LTE modem (3.8V) while managing USB 5V input and Li-Ion battery. Use Value: Buck-boost regulator sustains 3.8V modem supply down to 2.7V battery voltage - avoids brownouts during data transmission; HPWR pin enables host-controlled fast/slow charge modes. |
| Low-Power IoT Edge Nodes | Wearable Fitness Trackers |
Use Scenario: Battery-operated environmental sensor node with LoRaWAN radio, temperature/humidity sensor, and flash memory. IC Role / Device Role / Timing Role: LTC3558EUD#TRPBF provides always-on 3.3V rail for LoRa transceiver and 1.8V rail (via external LDO) from buck output, while charging via micro-USB during docking. Use Value: 8.5μA suspend-mode IQ extends shelf life to >12 months; internal timer and bad-battery detection prevent field failures due to degraded cells. | Use Scenario: Optical heart-rate monitor worn continuously with nightly USB charging and optical sensor pulsing. IC Role / Device Role / Timing Role: LTC3558EUD#TRPBF charges battery, powers 1.2V ASIC and 3.3V LED drivers, and uses CHRG pin to signal charge status to host MCU via GPIO. Use Value: Trickle-charge and automatic recharge ensure battery remains topped off during infrequent use; 0.75mm QFN fits ultra-thin wristband form factor. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multi-rail battery-powered applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ24232RGET | Single-input linear charger only (no integrated DC/DC regulators); supports 500mA max charge; lacks buck-boost capability and NTC interface. | Requires external buck converter for secondary rails; unsuitable for systems needing >1 regulated output or battery-voltage-independent 3.3V/5V supply. | Select when cost sensitivity outweighs integration needs and system has only one regulated rail. |
| MAX77818EWJ+T | PMIC with buck, boost, and charger; higher integration (LDOs, fuel gauge); 2.5MHz switching; but larger 32-pin WLP package and no HPWR pin for USB mode switching. | Better for complex SoC platforms (e.g., application processors); less optimal for simple MCU-based designs where footprint and USB mode control are critical. | Select for high-density designs requiring multiple LDOs and fuel gauging, accepting larger package and higher cost. |
Compared with BQ24232RGET and MAX77818EWJ+T, the LTC3558EUD#TRPBF uniquely combines USB-compliant charge scaling (HPWR), dropout-free buck-boost regulation, and minimal 3mm × 3mm footprint - making it optimal for space-constrained, dual-rail portable devices requiring robust thermal safety and long shelf life.
Availability
LTC3558EUD#TRPBF is available at Aetrix Electronics and suitable for portable medical monitors, USB-powered handheld scanners, and low-power IoT edge nodes requiring stable component supply, guaranteed industrial temperature operation, and long-term lifecycle support.
Supply support for LTC3558EUD#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, documentation, and manufacturing continuity for all Linear parts including the LTC3558 series.
The LTC3558 belongs to Linear's Power Management portfolio designed specifically for highly integrated, battery-powered portable electronics - emphasizing small size, high efficiency, and comprehensive safety features for consumer and medical applications.
FAQ
What is the maximum battery charge current supported by the LTC3558EUD#TRPBF?
The LTC3558EUD#TRPBF supports up to 950mA maximum battery charge current. This is programmable via the PROG pin resistor and scaled by the HPWR pin: at HPWR ≥1.2V, full current (e.g., 460mA with 1.74kΩ) is enabled; at HPWR ≤0.4V, current is reduced to 20% (e.g., 92mA). The absolute maximum BAT pin current rating is 1A per absolute maximum ratings.
How does the LTC3558EUD#TRPBF handle battery temperature monitoring?
The LTC3558EUD#TRPBF uses the NTC pin to interface with a negative temperature coefficient thermistor co-located with the battery. It compares the NTC voltage against cold (75–78%VCC) and hot (33.4–36.4%VCC) thresholds. If temperature is out of range, charging pauses until the battery re-enters specification - a mandatory safety feature for certified portable medical devices.
Can the LTC3558EUD#TRPBF operate with only the USB input and no battery connected?
No - the LTC3558EUD#TRPBF requires the BAT, PVIN1, and PVIN2 pins to be tied together for proper operation. Without a battery, the charger cannot regulate VFLOAT and the regulators lack a valid input source. The device will not deliver regulated outputs if BAT is floating or disconnected, as confirmed in the Applications Information section and Figure 1 of the datasheet.
What is the purpose of the CHRG pin on the LTC3558EUD#TRPBF?
The CHRG pin on the LTC3558EUD#TRPBF is an open-drain status indicator that signals four distinct battery charger states: active charging (pulled low), not charging (high impedance), unresponsive battery (latched fault), or temperature out-of-range. It requires an external pull-up resistor or LED and provides real-time telemetry to the host MCU without additional ADC resources.
Does the LTC3558EUD#TRPBF support automatic recharge after charge termination?
Yes - the LTC3558EUD#TRPBF implements automatic recharge when the battery voltage falls below VRECHRG (typically 4.105V, or –95mV relative to VFLOAT). Upon crossing this threshold, the safety timer resets and a new charge cycle begins. The 1.7ms filter time prevents false triggers from transient voltage dips, ensuring reliable top-off behavior during extended standby.
LTC3558EUD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3558EUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3558EUD#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 LTC3558EUD#TRPBF reliable?
The price and inventory of LTC3558EUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3558EUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3558EUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3558EUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3558EUD#TRPBF?
LTC3558EUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3558EUD#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 LTC3558EUD#TRPBF?
For technical support, including LTC3558EUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3558EUD#TRPBF requirements.
6.How does Aetrix verify that LTC3558EUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3558EUD#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 LTC3558EUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3558EUD#TRPBF?
All LTC3558EUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3558EUD#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 LTC3558EUD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3558EUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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