LTC4120_15 Datasheet, PDF (1/32 Pages) Linear Technology – Wireless Power Receiver and 400mA Buck Battery Charger

LTC4120/LTC4120-4.2
Wireless Power Receiver and
400mA Buck Battery Charger
Features
n _{Dynamic Harmonization Control Optimizes}
Wireless Charging Over a Wide Coupling Range
n _{Wide Input Voltage Range (12.5V to 40V)}
n _{Adjustable Float Voltage (3.5V to 11V)}
n _{Fixed 4.2V Float Voltage Option (LTC4120-4.2)}
n _{50mA to 400mA Charge Current Programmed with a}
Single Resistor
n _{±1% Feedback Voltage Accuracy}
n _{Programmable 5% Accurate Charge Current}
n _{No Microprocessor Required}
n _{No Transformer Core}
n _{Thermally Enhanced, Low Profile 16-Lead}
(3mm × 3mm × 0.75mm) QFN Package
Applications
n _{Handheld Instruments}
n _{Industrial/Military Sensors and Devices}
n _{Harsh Environments}
n _{Portable Medical Devices}
n _{Physically Small Devices}
n _{Electrically Isolated Devices}
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Description
The LTC^®4120 is a constant-current/constant-voltage wire-
less receiver and battery charger. An external program-
ming resistor sets the charge current up to 400mA. The
LTC4120-4.2 is suitable for charging Li-Ion/Polymer bat-
teries, while 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-of-
charge 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 2.2%.
Typical Application
26.7nF
Tx CIRCUITRY
6.5nF
5µH
47µH
IN
INTV_CC
RUN
FREQ
2.2µF
10µF
BOOST
LTC4120
22nF 33µH
SW
DHC
CHGSNS
NTC
FAULT
BAT
CHRG
1.01M _{Li-Ion +}
FB
4.2V
T
GND PROG FBG
1.35M
Wireless Rx Voltage/Charge Current vs Spacing
40
35
V_IN
30
25
NOT
CHARGING
400
I_CHARGE
MAX
333
267
200
20
133
CHARGING
15
67
3.01k
22µF
4120 TA01a
10
0.4 0.6
0.8 1.0 1.2 1.4
SPACING (cm)
0
1.6 1.8
4120 TA01b
4120fe
For more information www.linear.com/LTC4120
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