Linear公司的LTC4120是無(wú)線電源接收器和 400mA 降壓型電池充電器,具有動(dòng)態(tài)協(xié)調(diào)控制可優(yōu)化寬?cǎi)詈戏秶鷥?nèi)的無(wú)線充電,寬輸入電壓從4.3V 至 40V,可調(diào)電池浮動(dòng)電壓從3.5V 至 11V,采用單個(gè)電阻器設(shè)置的 50mA 至 400mA 充電電流, ±1%反饋電壓準(zhǔn)確度, 準(zhǔn)確度為 5% 的可編程充電電流,以及無(wú)需微處理器和無(wú)變壓器磁芯等特性,主要用在手持儀表,工業(yè)/軍用傳感器,手持醫(yī)療設(shè)備以及電隔離設(shè)備.本文介紹了LTC4120主要特性,框圖,典型應(yīng)用電路以及演示板DC1969A主要特性,電路圖和材料清單.
The LTC.4120 is a constant-current/constant-voltage wireless receiver and battery charger. An external programming resistor sets the charge current up to 400mA. The programmable float voltage of the LTC4120 accommodates several battery chemistries. The LTC4120 uses a Dynamic Harmonization Control (DHC) technique that allows high efficiency contactless charging across an air gap. The LTC4120 regulates its input voltage via the DHC pin.
This technique modulates the resonant frequency of a receiver tank to automatically adjust the power received as well as the power transmitted to provide an efficient solution for wirelessly charging battery-powered devices.
Wireless charging with the LTC4120 provides a method to power devices in harsh environments without requiring expensive failure-prone connectors. This allows products to be charged while locked within sealed enclosures, or in moving or rotating equipment, or where cleanliness or sanitation is critical.
This full featured battery charger includes accurate RUN pin threshold, low voltage battery preconditioning and bad battery fault detection, timer termination, auto-recharge, and NTC temperature qualified charging. The FAULT pin provides an indication of bad battery or temperature faults.
Once charging is terminated, the LTC4120 signals end-ofcharge via the CHRG pin, and enters a low current sleep mode. An auto-restart feature starts a new charging cycle if the battery voltage drops by 2.5%.

LTC4120主要特性:
 Dynamic Harmonization Control Optimizes Wireless Charging Over a Wide Coupling Range
 Wide Input Voltage Range: 4.3V to 40V
 Adjustable Battery Float Voltage: 3.5V to 11V
 50mA to 400mA Charge Current Programmed with a Single Resistor
 ±1% Feedback Voltage Accuracy
 Programmable 5% Accurate Charge Current
 No Microprocessor Required
 No Transformer Core
 Thermally Enhanced, Low Profile 16-Lead (3mm × 3mm × 0.75mm) QFN Package

LTC4120應(yīng)用:
 Handheld Instruments
 Industrial/Military Sensors and Devices
 Harsh Environments
 Portable Medical Devices
 Physically Small Devices
 Electrically Isolated Devices


圖1.LTC 4120框圖

圖2.LTC 4120典型應(yīng)用電路

演示板DC1969A
Demonstration circuit DC1969A is a kit of: the DC1967A-X LTC®4120EUD demonstration board, the DC1968A basic wireless transmitter, a 35mm receiver ferrite disk, and an assortment of different length standoffs. The basic transmitter can deliver 2W to the receive board with up to 10mm spacing between the transmit and the receive coils. The basic transmitter does not support foreign object detection, i.e. coins or other metallic objects.

演示板DC1969A套件包括:
 1X DC1967A-X* (LTC4120EUD) Demo Board
 1X DC1968A (Wireless Basic Transmitter) Demo Board
 1X 35mm Ferrite Bead
 4X 6.25mm (0.25") Nylon Standoffs
 4X 12.5mm (0.50") Nylon Standoffs
 4X 15.875mm (0.625") Nylon Standoffs


圖3.DC1967A-B LTC4120接收板外形圖

圖4.DC1968A Basic發(fā)送板外形圖

圖5.無(wú)線充電系統(tǒng)功能框圖

圖6.LTC4120發(fā)送器電路圖

圖7.DC1967A電路圖(1)

圖8.DC1967A電路圖(2)

圖9.DC1968A電路圖
演示板DC1969A材料清單: