Wireless Charging Chipset with Built-in Software and Foreign Object DetectionAugust 26, 2018 by Paul Shepard
LAPIS Semiconductor's wireless charging chip set, the ML7630 and ML7361, are designed for wireless charging system using 13.56MHz for power transfer. Small devices such as wearable and hearable devices with a limited space for antenna implementation can be "connectorless" because the antenna can be downsized by using this bandwidth.
The ML7630 receiver can provide 200mW of a charging output. It also includes Tag function to allow Bluetooth® pairing, etc. by NFC touch. These functions are included in a WL-CSP package of 2.6 × 2.6mm.
The ML7631 transmitter integrates functions necessary for power transmission such as detecting the dropout of the power receiver device, setting the power transmission output level, etc. into one chip, controlling the operating voltage to 5V to ensure the operation from a USB power supply such as mobile battery.
LAPIS Semiconductor's 13.56 MHz wireless charging chip set is useful for building a wireless charging system for compact devices with a limited space such as wearable devices with a rechargeable battery about 50mAh, Bluetooth® headset, earphone, etc.
It can also mobilize the entire power charging system and has been optimized specifically for achieving a wireless power supply solution for small devices such as wearables.
Product features include:
1) A small chip with the power receiver function the ML7630 includes built-in software removing the need for software development
The ML7630 power receiver LSI incorporates the power receiver function in a 2.6mm WL-CSP package, with only external parts of a condenser in addition to a charger IC and four rectifier diodes.
Both the ML7630 and ML7631 have a built-in software and no further development is necessary. Settings for each user can be configured separately from the PC tools provided by LAPIS Semiconductor.
2) Equipped with NFC Forum Type3 tag function
This is a ROM function that can read a fixed data written in advance in NDEF format to a build-in 1 KB data flash. It can also communicate with an external NFC reader/writer via the tag data. It employs the NDEF format (NFC Data Exchange Format), a data format used for data exchange in NFC.
3) Highly reliable Li-ion battery charging
The ML7630 power receiver LSI ensures a highly reliable Li-ion battery charge using two charging temperature control methods. ML7630 can control the LDO output within the proper temperature range by using an external thermistor for measuring a charging temperature. Temperature can be measured in two ways: by the build-in 10 bit ADC with software and by the build-in hardware comparator.
Charging temperature can be controlled by both methods to ensure a highly reliable Li-ion battery charge, for which the charging temperature is important.
4) Driven at 5V can mobilize the entire system
The power supply voltage of the ML7631 is 5V, which can be driven by a USB power supply such as mobile battery. Since the ML7630 does not need power supply, mobile battery + ML7631 + ML7630 + target device to be charged, for example, can be configured and the entire system can be mobilized.
5) Optimization of power transmitter
The ML7630 determines the voltage after rectification by the build-in ADC as well as any power shortage or surplus from unnecessary current passing through the build-in shunt regulator, and then notifies that information to the ML7631, allowing the ML7631 to eliminate unnecessary power transmission and to optimize the amount of power transmission.
6) High-level safety by the detection function of foreign object and the dropout of the device
The ML7631 detects changes in power transmitter current/voltage by the build-in 10-bit ADC and stops the LDO output. It detects a metal piece or IC card to prevent heat or damage.
It also detects when the ML7630 goes out of the wireless charging range to prevent unnecessary power transmission.