CHARGE CURRENT (mA)
LTC4120/LTC4120-4.2
Wireless Power Receiver and
400mA Buck Battery Charger
FEATURES DESCRIPTION
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Dynamic Harmonization Control Optimizes The LTC 4120 is a constant-current/constant-voltage wire-
less receiver and battery charger. An external program-
Wireless Charging Over a Wide Coupling Range
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ming resistor sets the charge current up to 400mA. The
Wide Input Voltage Range (12.5V to 40V)
n LTC4120-4.2 is suitable for charging Li-Ion/Polymer batter-
Adjustable Float Voltage (3.5V to 11V)
n ies, while the programmable float voltage of the LTC4120
Fixed 4.2V Float Voltage Option (LTC4120-4.2)
accommodates several battery chemistries. The LTC4120
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50mA to 400mA Charge Current Programmed with a
uses a Dynamic Harmonization Control (DHC) technique that
Single Resistor
allows high efficiency contactless charging across an air gap.
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1% Feedback Voltage Accuracy
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Programmable 5% Accurate Charge Current
The LTC4120 regulates its input voltage via the DHC pin.
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No Microprocessor Required
This technique modulates the resonant frequency of a
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No Transformer Core
receiver tank to automatically adjust the power received
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Thermally Enhanced, Low Profile 16-Lead as well as the power transmitted to provide an efficient
(3mm 3mm 0.75mm) QFN Package solution for wirelessly charging battery-powered devices.
Wireless charging with the LTC4120 provides a method
APPLICATIONS
to power devices in harsh environments without requiring
expensive failure-prone connectors. This allows products
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Handheld Instruments
to be charged while locked within sealed enclosures, or
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Industrial/Military Sensors and Devices
in moving or rotating equipment, or where cleanliness or
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Harsh Environments
sanitation is critical.
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Portable Medical Devices
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This full featured battery charger includes accurate RUN
Physically Small Devices
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pin threshold, low voltage battery preconditioning and bad
Electrically Isolated Devices
battery fault detection, timer termination, auto-recharge,
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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
Wireless Rx Voltage/Charge Current vs Spacing
26.7nF
40 400
IN INTV
CC
I
CHARGE
2.2F
RUN FREQ
MAX
35 333
BOOST
10F
V
IN
22nF 33H
LTC4120
6.5nF
SW 30 267
NOT
Tx CIRCUITRY DHC
CHGSNS
CHARGING
25 200
NTC
5H 47H BAT
FAULT
20 133
CHRG 1.01M
+
Li-Ion
T CHARGING
FB
4.2V
15
GND PROG FBG 67
1.35M
3.01k 22F
10 0
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
4120 TA01a
SPACING (cm)
4120 TA01b
Rev. G
1
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V (V)
IN(RX)LTC4120/LTC4120-4.2
ABSOLUTE MAXIMUM RATINGS (Note 1)
IN, RUN, CHRG, FAULT, DHC ...................... 0.3V to 43V I ............................................................... 350mA
DHC RMS
BOOST ................................... V 0.3V to (V + 6V) I , I , I ..................................................5mA
SW SW CHRG FAULT FBG
SW (DC) ........................................ 0.3V to (V + 0.3V) I .........................................................................5mA
IN FB
SW (Pulsed <100ns) ......................1.5V to (V + 1.5V) I .................................................................. 5mA
IN INTVCC
CHGSNS, BAT, FBG, FB ...............................0.3V to 12V Operating Junction Temperature Range
FREQ, NTC, PROG, INTV .......................... 0.3V to 6V (Note 2) .................................................. 40C to 125C
CC
I , I ..................................................... 600mA Storage Temperature Range .................. 65C to 150C
CHGSNS BAT
PIN CONFIGURATION
LTC4120 LTC4120-4.2
TOP VIEW TOP VIEW
16 15 14 13 16 15 14 13
INTV 1 12NTC INTV 1 12 NTC
CC CC
BOOST 2 11FBG BOOST 2 11 NC
17 17
GND GND
IN FB IN BATSNS
3 10 3 10
SW 4 9 BAT SW 4 9 BAT
5 6 7 8 5 6 7 8
UD PACKAGE UD PACKAGE
16-LEAD (3mm 3mm) PLASTIC QFN 16-LEAD (3mm 3mm) PLASTIC QFN
T = 125C, = 54C/W T = 125C, = 54C/W
JMAX JA JMAX JA
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB TO OBTAIN EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB TO OBTAIN
JA JA
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4120EUD#PBF LTC4120EUD#TRPBF LGHB 16-Lead (3mm 3mm) Plastic QFN 40C to 125C
LTC4120IUD#PBF LTC4120IUD#TRPBF LGHB 16-Lead (3mm 3mm) Plastic QFN 40C to 125C
LTC4120EUD-4.2#PBF LTC4120EUD-4.2#TRPBF LGMT 16-Lead (3mm 3mm) Plastic QFN 40C to 125C
LTC4120IUD-4.2#PBF LTC4120IUD-4.2#TRPBF LGMT 16-Lead (3mm 3mm) Plastic QFN 40C to 125C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
LTC4120 OPTIONS FLOAT VOLTAGE
LTC4120 Programmable
LTC4120-4.2 4.2V Fixed
Rev. G
2
For more information www.analog.com
GND RUN
DHC FAULT
FREQ CHRG
CHGSNS PROG
GND RUN
DHC FAULT
FREQ CHRG
CHGSNS PROG