Smartwatch Solution

Smartwatch, which is large and charge is frequently required, is not smart? Designing the power supply circuit of mobile devices for wearable applications, such as smartwatch, is to solve many technical problems to realize the customers’ high expectations. Reduction of the current consumption and the frequency of battery charging can be realized by using Toshiba's advanced and high-performance power management ICs. In addition to these power management ICs, Toshiba is contributing to the evolution of mobile devices by providing operational amplifiers for amplifying sensor signals, a key feature of mobile devices, as well as high-performance and small size package discrete products such as MOSFETs, TVS diodes (ESD protection diodes), SBDs, and transistors.

• Support to design of power supply circuit with abundant line-up of power management ICs to meet many requirements
• Reduced current consumption of power management ICs to reduce battery charging frequency
• Miniaturization of packages ideal for mobile devices to reduce power supply circuit space
• Compliance with New Safety Standard (IEC-62368-1) (eFuse IC)
• Useful application notes, reference designs, and other documents on the web save design cycle time

In the design of the charging circuit, not only the realization of reliable control, whether for wireless charging or charging with a cable, but also the protection of the circuit from unexpected short-circuits of the power supply, external noise such as EMI, and other abnormal conditions are required.

Toshiba's load switch ICs and eFuse ICs have built-in protection circuits such as overvoltage protection and overcurrent protection. These power management ICs perform better by using a combination of Toshiba's FETs and diodes.

For power management in the later stage circuit from PMIC of integrated power supply ICs, modules such as sensitive sensors and chipsets may have higher performance requirements for power supply. Toshiba's LDO regulators and load switch ICs deliver high performance with minimal current consumption and are packaged in small wafer-level chip-scale packages.

Generally, when using a MOSFET as a load switch, large capacitor for voltage stabilization is connected to the output side of the MOSFET. When the MOSFET turns on, inrush current flows to charge this capacitor. For MOSFET gate drive circuit that suppresses inrush current, please refer to “MOSFET Gate Drive Circuit: Power MOSFET Application Notes.” 

Application Notes

Load switch IC is power supply IC with built-in output transistor and output driver circuit manufactured using CMOS process. It is much smaller than the conventional discrete configuration. It also features low voltage operation, low on-resistance characteristics and low current consumption, and is equipped with various additional functions.

When an excessive current flows, the internal detection circuit operates and the built-in MOS is turned off, thus providing a high-speed current breaking function for conventional fuses. Furthermore, it is not destroyed by a single overcurrent, and can be used repeatedly. It also has the advantage that it can incorporate a variety of protection functions such as overvoltage protection. This product is also effective in reducing maintenance costs and restoration time required for repairs.

The line-up covers from general-purpose packages to compact packages with low noise, high Power Supply Rejection Ratio (PSRR), high output current stability (load transient response), low current consumption and other high performance requirements required for the analog circuits.

This is a compact N-ch MOSFET driver with built-in voltage boost and protection circuits. The compact, low loss power supply can be configured by using it with MOSFET.

This diode protects the device from surge voltages such as static electricity that penetrates from external terminals and prevents malfunction of the IC. We have realized high electrostatic immunity and circuit protection performance with our proprietary process technology. We offer a broad lineup of products ranging from general purpose to high speed signal application.

The Schottky barrier diode, which uses a Schottky junction of metal and n-type semiconductors, has a very small V_F characteristic and enables high speed operation because it does not use holes as carriers.

Consideration should also be given to the design of the interface circuit. This interface circuit includes a subsystem that inputs sensor output signals to MCU accurately or outputs signals to control the display or wireless module.

Sensors require high-precision sensing. For accurate transmission of the sensed signal to the next stage system, for example the AD converter input of the MCU, an operational amplifier with ultra-low offset voltage and low noise is required to amplify to a larger signal level. Toshiba offers operational amplifiers that meet these requirements.

In addition, Toshiba offers TVS diodes (ESD protection diodes) to protect internal circuits from unexpected external ESDs that destroy mobile devices. This TVS diode is designed to minimize insertion loss to minimize attenuation of electrical signals and is available for signal lines up to 10Gbps speed.

This diode protects the device from surge voltages such as static electricity that penetrates from external terminals and prevents malfunction of the IC. We have realized high electrostatic immunity and circuit protection performance with our proprietary process technology. We offer a broad lineup of products ranging from general purpose to high speed signal application.

By using an ultra-low noise operational amplifier, signals sensed and amplified to larger signal levels can be accurately transmitted to the MCU.