13.56MHz (NFC) wireless charging chip set, "ML7630 / ML7631"

Advantages of 13.56 MHz (NFC) Wireless Charging
for Compact Device under 200mW

13.56MHz Wireless charging system
implementation image

Save the space for charging
"No constraints on design" of devices

Compared to the charging from a USB connector, the conventional charging method for compact devices such as wearables, the wireless charging system equipped with LAPIS Technology's 13.56 MHz (NFC) wireless charging chip set, "ML7630/7631", can save the space for charging function.
Using an ultra-compact antenna as well as an antenna for NFC communication simultaneously can reduce the implementation area down to "about 50%" for compact cube antenna, and "about 75%" for a flexible antenna.
When compared to other charging systems, the 13.56 MHz (NFC) wireless charging that can use ultra compact antennas offers more "compact implementation".

Occupancy area comparison of 13.56 MHz (NFC) ML7630/7631 wireless charging

Wireless Charging Makes Wearable Device
"Completely Water-Proof"

Wearable device, headset, earphone
Expected to be used in underwater or waterfront

Water-proof cap or USB connector to protect the contacts and components required to charge the conventional devices from water, along with applicable designs and design limitations are no longer needed for the wireless charging.

Non-contact wireless charging makes the design and BOM (Bill of Materials) simple.

The NFC Tag function (NFC Forum Type3 Tag), a prerequisite for wearable device, is also incorporated. Integrating the wireless charging and the NFC Tag function into one single chip also reduces the BOM cost.

ML7630 / 7631 NFC Forum Type3 Tag function

Mechanism of Wireless Charging and Charge Capability

Mechanism of 13.56 MHz (NFC) Wireless Charging

The 13.56 MHz (NFC) wireless charging LSI, "ML7630/7631", uses the magnetic field resonance method to supply power through 13.56 MHz magnetic fields.

The magnetic field resonance method supplies power by using two coils as "oscillator", at power transmitter and receiver. Place these coils face-to-face with one coil being connected to the charging and the other coil being received the power.

13.56MHz (NFC) is Capable of Detecting Foreign Object as IC Card

Regardless of its method, the existing wireless charging system can damage the data, if any IC card including credit card or electronic money exists in proximity while strong power is supplied.
13.56 MHz (NFC) wireless charging can reduce the potential risk of damaging data because it detects foreign object in the IC card easily as it uses the same resonance frequency as the IC card.

Mechanism of 13.56 MHz (NFC) Wireless Charging

How about charge capability?

Comparison of "charging time to 90 % of the battery capacity" between USB charge and 13.56 MHz wireless charging 1C charge*

*1C charge : Charging with the same amount of electric current as the discharge capacity of battery for an hour

When the battery capacity is within 50 mAh,
13.56 MHz wireless charging and USB cable show "almost the same charging time".

Expected devices with the battery capacity within 50mAh are
wearable device, Bluetooth^® headset, wireless earphone, etc.

Specifications

"ML7630" 13.56MHz (NFC) power receiver LSI

Product name	ML7630
Data Flash	1K Byte
Operating Frequency	13.56MHz
Power Supply	Generate from magnetic fields
I/F	NFC Forum Type3 Tag v1.0 I²C slave × 1ch
Charging Control	Power receiver/ rectifier/power charging voltage output
ADC (Method)	10bit (SA type)
Operating Temperature	- 40°C to + 85°C
Package	WL-CSP 34 pin 2.6mm × 2.6mm 0.4mm pitch

Power receiver and Tag function integrated in one chip

200mW LDO output
Wireless charging protocol auto-run
Monitoring electric current, voltage, temperature (A/D converter, comparator)
NFC Forum Type3 Tag

"ML7631" 13.56MHz (NFC) power transmitter LSI

Product name	ML7631
Data Flash	1K Byte
Operating Frequency	13.56MHz
Operating Voltage	5V
I/F	I²C slave × 1ch
Operating Temperature	- 40°C to + 85°C
Package	WQFN 32 pin 5.0mm × 5.0mm 0.5mm pitch