LTC4125
1
4125f
Typical applicaTion
FeaTures
DescripTion
5W AutoResonant Wireless
Power Transmitter
is a simple and high performance monolithic
full bridge resonant driver capable of delivering over 5W of
power wirelessly to a properly tuned receiver. The device
controls the current flow in a series connected transmit coil
LC network to create a simple, safe and versatile wireless
power transmitter.
The LTC4125 automatically adjusts its driving frequency
to match the LC network resonant frequency. This
AutoResonant switching allows the device to deliver
maximum power from a low voltage input supply (3V to
5.5V) to a tuned receiver. To optimize system efficiency,
the LTC4125 employs a periodic transmit power search
and adjusts the transmission power based on the receiver
load requirements. The device stops delivering power
during a fault condition, or if a foreign object is detected.
The LTC4125 also includes a programmable maximum
average input current limit and an NTC input as additional
means for foreign object and overload protection. The
LTC4125 is available in a 20-lead low profile (0.75mm)
4mm
×
5mm QFN package.
applicaTions
n
Monolithic 5W Wireless Power Transmitter
n
AutoResonant
TM
Switching Frequency Adjusts to Res-
onant Capacitance and Transmit Coil Inductance*
n
Transmit Power Automatically Adjusts to Receiver
Load*
n
Input Voltage Range: 3V to 5.5V
n
Integrated 100mΩ Full Bridge Switches
n
Multiple Foreign Object Detection Methods
n
Programmable Average Input Current Limit and
Monitor
n
NTC Input for System/Component Temperature
Qualified Power Transfer
n
Wide Operating Switching Frequency Range:
50kHz to 250kHz
n
Thermally Enhanced 4mm
×
5mm QFN 20-Lead Package
n
Hermetically and/or Electrically Insulated Devices
n
Military Sensors and Devices
n
Medical Equipment
n
Industrial Handhelds
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
AutoResonant is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 9041254.
*The AutoResonant and Auto Load Detect features use patent pending circuits and algorithms.
C
TX
100nF
+–
STAT
IS
–
IS+
EN
FTH
PTHM
NTC
SW1
SW2
FB
59.0k
100k
2.21k
470pF
10nF
10nF
1µF
11.3k
20mΩ
4.7nF
100µF
10k
100k
R
L
V
IN
348k
5.23k
L
TX
24µH
L
TX
COIL
L
RX
COIL
V
IN
V
IN
V
IN
3V TO 5.5V
10k
TRANSMITTER
CIRCUIT
RECEIVER
CIRCUIT
C
FB1
0.1µF
4125 TA01
AIR GAP
IMON
CTD
CTS
GND
IN
IN1 IN2
LTC4125
5W Wireless Transmitter
