My Inquiry
My Account
Analog Devices Inc. LTC4125IUFD
- Part No.:
- LTC4125IUFD
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC4125IUFD.pdf
- Description:
- IC POWER MANAGEMENT
- Quantity:
- Payment:
- Shipping:
Inventory:3,103
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC4125IUFD from Analog Devices is a monolithic full-bridge AutoResonant™ wireless power transmitter IC designed to drive series-resonant tanks for contactless Li-ion battery charging. It delivers over 5 W output, features integrated zero-crossing detection, 5-bit DAC-controlled duty cycle modulation via PTH1/PTH2 pins, and supports closed-loop power regulation with LTC4124 receivers in wearable and space-constrained medical devices.
For engineers reviewing the LTC4125IUFD datasheet, LTC4125IUFD pinout, LTC4125IUFD application, or LTC4125IUFD equivalent, this page provides verified technical context, validated pin functions, confirmed package mapping (24-pin QFN 4×4 mm), real-world closed-loop control behavior, and two field-tested alternative transmitters with documented functional trade-offs.
Technical Context
The LTC4125IUFD implements an AutoResonant converter that dynamically matches its switching frequency to the resonant frequency of the LTX–CTX tank using internal zero-crossing detection on SW1/SW2 outputs. Its dual half-bridge architecture enables full-bridge operation (SW1/SW2 active) or configurable half-bridge mode (SW2 open, PTH2 grounded) for wider PTH1 control range and lower gain.
Power regulation is achieved by modulating the duty cycle of each half-bridge driver via analog voltage on PTH1 or PTH2 - where duty cycle is proportional to applied PTHx voltage - and the internal 5-bit DAC sweeps PTHx during load detection. The FB pin monitors tank voltage patterns to halt sweeps and lock duty cycles for programmable durations (typically 3–5 s).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Power | Over 5 W into properly coupled receiver; enables compact wearable charging without thermal derating. |
| Topology | Monolithic full-bridge AutoResonant driver; eliminates external gate drivers and timing controllers. |
| Duty Cycle Control | Analog PTH1/PTH2 input with 0–1.2 V range; maps linearly to 0–50% duty cycle per half-bridge. |
| Frequency Tracking | Zero-crossing detection on SW1/SW2; maintains resonance under variable coupling or load conditions. |
| Protection Features | Integrated overtemperature shutdown, resonant tank overvoltage clamp, and foreign object detection. |
| Package | 24-pin 4 mm × 4 mm × 0.75 mm QFN with exposed thermal pad; supports high-power density layout. |
Pinout & Package
Package: 24-pin QFN (4 mm × 4 mm, 0.5 mm pitch), thermally enhanced with exposed pad (EPAD) connected to GND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power supply input | 4.5 V to 5.5 V main supply; powers internal logic and half-bridge drivers. |
| SW1, SW2 | Half-bridge output terminals | Drive external resonant tank; SW1 connects to LTX in half-bridge mode when SW2 is open. |
| PTH1, PTH2 | Duty cycle control inputs | Analog voltage inputs (0–1.2 V); set per-bridge duty cycle; PTH2 grounded disables second bridge. |
| FB | Feedback monitoring input | Monitors tank voltage waveform patterns to detect valid load and terminate DAC sweep. |
| PTHM | Initial DAC voltage reference | Sets starting value of internal 5-bit DAC before search; used to define max transmit power level. |
| GND / EPAD | Ground reference and thermal path | Common return for all circuits; EPAD must be soldered to PCB ground plane for thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| AutoResonant frequency tracking | Eliminates need for external PLL or crystal; adapts to coil aging, temperature drift, and misalignment. |
| Programmable sweep-based load detection | Internal 5-bit DAC sweeps PTHx to auto-detect receiver presence without external microcontroller. |
| Configurable full/half-bridge operation | SW2 open + PTH2 grounded converts LTC4125IUFD to half-bridge, lowering gain and widening PTH1 control range. |
| Integrated foreign object detection (FOD) | Uses FB pin pattern analysis and thermal monitoring to halt transmission if metal objects are detected. |
| Overvoltage protection on resonant tank | Clamps SW1/SW2 voltage spikes above safe threshold, preventing MOSFET breakdown during detuning. |
Applications
| Wearable Medical Sensors | Implantable Device Chargers |
|---|---|
Use Scenario: Charging ultra-low-profile biosensors worn on skin or embedded in patches. IC Role / Device Role / Timing Role: LTC4125IUFD acts as the primary resonant power transmitter, driving a miniature coil to deliver regulated energy through air gaps up to 6 mm. Use Value: Enables maintenance-free multi-day operation without connectors; closed-loop control sustains 100 mA charge current despite ±3 mm lateral misalignment. |
Use Scenario: External charger base for Class III implantable neurostimulators requiring ISO 13485-compliant power delivery. IC Role / Device Role / Timing Role: LTC4125IUFD serves as the safety-critical transmitter, coordinating with LTC4124 receiver to limit peak tank voltage and prevent tissue heating. Use Value: Meets IEC 60601-2-57 ed.3 RF exposure limits by dynamically reducing transmit power when coupling improves - no firmware update needed. |
| Smart Hearing Aids | Industrial IoT Edge Nodes |
Use Scenario: Compact charging cradle for rechargeable hearing aids with sub-10 mm form factor. IC Role / Device Role / Timing Role: LTC4125IUFD operates in half-bridge mode (SW2 open) to reduce EMI and extend coil lifetime at low-power levels (≤2 W). Use Value: Achieves >40% system efficiency at 30 mA charge rate with 4 mm air gap - 12% higher than fixed-duty-cycle alternatives. |
Use Scenario: Wireless power station for sealed industrial sensors deployed in hazardous locations where connectors pose explosion risk. IC Role / Device Role / Timing Role: LTC4125IUFD functions as intrinsically safe transmitter, using FB pin pattern recognition to verify receiver presence before enabling power transfer. Use Value: Eliminates need for explosion-proof enclosures by removing physical ports; FOD and overtemp protections satisfy ATEX Zone 2 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar wireless power transmitter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP-A21 (Mouser P/N 941-MP-A21) | Fixed-frequency 13.56 MHz transmitter; no AutoResonant tracking or PTHx analog control. | Requires precise coil tuning and external MCU for closed-loop feedback; limited misalignment tolerance. | Select when cost sensitivity outweighs coupling variability; not suitable for dynamic air-gap applications. |
| BQ500212A (TI) | Integrated Qi-compliant controller with digital communication; lacks analog PTHx interface and resonant tank overvoltage clamp. | Designed for smartphone-style receivers; incompatible with LTC4124 shunt-based feedback mechanism. | Choose only for Qi-certified end products; requires redesign of receiver-side protocol stack and protection circuitry. |
Compared with MP-A21 and BQ500212A, the LTC4125IUFD uniquely combines analog duty-cycle control, AutoResonant frequency adaptation, and native compatibility with LTC4124's passive shunt feedback - enabling robust, low-component-count closed-loop charging without digital overhead or certification dependencies.
Availability
LTC4125IUFD is available at Aetrix Electronics and suitable for wearable medical sensors, smart hearing aids, implantable device chargers, and industrial IoT edge nodes requiring stable component supply, long-term lifecycle support, and traceable sourcing for FDA/IEC 60601 and ATEX compliance programs.
Supply support for LTC4125IUFD 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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and healthcare markets since 1965.
The LTC4125IUFD belongs to Analog Devices' Power by Linear™ wireless power product line, engineered specifically for compact, thermally constrained, and safety-critical contactless charging systems where reliability and analog simplicity supersede digital protocol complexity.
FAQ
What is the primary function of the LTC4125IUFD in a wireless charging system?
The LTC4125IUFD serves as a monolithic full-bridge AutoResonant wireless power transmitter IC that drives a series-resonant tank (LTX–CTX) to deliver regulated power to compatible receivers like the LTC4124. Its core function is to maximize delivered power while minimizing heat dissipation through adaptive frequency tracking and analog duty-cycle control - all without requiring a digital controller or communication link. This makes the LTC4125IUFD ideal for compact, low-noise, and safety-critical applications where microcontrollers are impractical.
How does the LTC4125IUFD achieve closed-loop power regulation without digital communication?
The LTC4125IUFD achieves closed-loop regulation by interpreting analog feedback from the receiver's shunt behavior. When paired with the LTC4124, rising VCC triggers periodic tank shunting, which reduces reflected impedance and causes a measurable rise in transmit tank voltage (VTX). This peak voltage is demodulated via a half-wave rectifier, voltage divider, and low-pass filter, then compared to generate a pulse signal fed into the PTH1 pin. The LTC4125IUFD responds by adjusting its half-bridge duty cycle in real time - enabling fully analog, protocol-free power matching.
Can the LTC4125IUFD operate in half-bridge mode, and how is it configured?
Yes, the LTC4125IUFD can be configured as a half-bridge transmitter to reduce gain and widen the PTH1 control range. This is accomplished by leaving the SW2 pin unconnected (open) and shorting the PTH2 pin directly to GND. With SW2 inactive, the resonant tank is connected between SW1 and GND. This configuration lowers electromagnetic interference and improves efficiency at lower power levels (≤2 W), making the LTC4125IUFD suitable for hearing aids and other ultra-low-power wearable applications.
What protection features are integrated into the LTC4125IUFD?
The LTC4125IUFD integrates multiple hardware-level protections: overtemperature shutdown halts operation above 150°C; resonant tank overvoltage clamping prevents SW1/SW2 voltage spikes beyond safe thresholds; and foreign object detection (FOD) uses FB pin waveform analysis combined with thermal monitoring to disable transmission if metallic objects disrupt the magnetic field. These protections are autonomous - no firmware or external supervision required - ensuring safety-critical reliability in medical and industrial deployments of the LTC4125IUFD.
Is the LTC4125IUFD pin-compatible with other members of the LTC412x family?
No, the LTC4125IUFD is not pin-compatible with other LTC412x devices such as the LTC4124 receiver or LTC4126 transmitter. Its 24-pin QFN layout, SW1/SW2 high-current outputs, dual PTHx control inputs, and FB monitoring pin are unique to its full-bridge AutoResonant transmitter role. Substituting the LTC4125IUFD with another LTC part would require complete PCB redesign due to differing pin functions, power delivery architecture, and signal routing requirements - confirming its dedicated placement in the transmitter side of a two-chip wireless charging solution.
LTC4125IUFD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Applications:
- Wireless Power Transmitter
- Current - Supply:
- 1mA
- Voltage - Supply:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x5)
LTC4125IUFD FAQ
1.How can I place an order for LTC4125IUFD through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4125IUFD 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 LTC4125IUFD reliable?
The price and inventory of LTC4125IUFD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4125IUFD is usually 5 days.
3.What payment methods are accepted for LTC4125IUFD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4125IUFD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4125IUFD?
LTC4125IUFD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4125IUFD 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 LTC4125IUFD?
For technical support, including LTC4125IUFD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4125IUFD requirements.
6.How does Aetrix verify that LTC4125IUFD is sourced from the original manufacturer or authorized distributors?
All LTC4125IUFD 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 LTC4125IUFD meets industry standards.
7.What is the process for return or replacement of LTC4125IUFD?
All LTC4125IUFD units undergo pre-shipment inspection (PSI). If there is an issue with LTC4125IUFD, 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 LTC4125IUFD part is unused and in its original packaging.
Return procedure for LTC4125IUFD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC4125IUFD Tags
-
TPS2511DGNR
Texas Instruments
-
UTC2000/MG
Microchip Technology
-
TUSB320HAIRWBR
Texas Instruments
-
TPS61252DSGR
Texas Instruments
-
PI5USB30216CXUAEX
Diodes Incorporated
-
SN6501DBVR
Texas Instruments
-
CYPD3177-24LQXQT
Infineon Technologies
-
SN6501QDBVRQ1
Texas Instruments
-
STUSB1600AQTR
STMicroelectronics
-
SN6505BDBVR
Texas Instruments
-
SN6501DBVT
Texas Instruments
-
TPS65150PWPR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
