Switch ICs: Introduction
One of the ways to reduce supply current of the running applications is to cut off the power supply for unnecessary circuits according to the operating state. By inserting a switch IC, it becomes able to easily turn ON/OFF and even protect the power supply line.
Switch ICs do not have voltage control functions like LDO regulators or DC/DC converters, but when a large current flows, they are more efficient in the perspectives of voltage drop and power loss.
Also, they are equipped with protections against such as over-current and over-temperature, which discreet FETs cannot have
Therefore, multi-functional protection circuits featuring small mounting area can be constructed with switch ICs.
We provide a lineup of switch ICs featuring low ON resistance and various protection functions.
Choose the best switch IC that matches the usage.
USB Switch IC
USB switch ICs perform ON/OFF control and protections of the power supply line.
The ON/OFF control is conducted by receiving an enable signal from a USB host controller.
Protection functions include a thermal shutdown for abnormal heating, and an over-current protection which limits or latches off the current when a large current over the limit flows.
- FLG pin has N-channel open drain output, therefore pull-up resistance is necessary when it is used. The output of FLG pin becomes "L" when the thermal shutdown or over-current limit-function works.
- According to the USB standard,120 µF or more capacitor attachment is recommended, however, as an IC, changing capacitor is acceptable considering other usage.
Rectifier Switch IC
The rectifier switch controls the output polarity in one direction regardless of the inserting direction of a dry cell battery.
Although cutting off the output is a prevailing measure against reverse insertion, our rectifier switch IC can output a normal voltage efficiently even without considering the inserting direction of a battery.
The R5590 allows batteries to be placed in any direction without regard to positive or negative polarity.
Load Switch IC
Load switch ICs conduct ON/OFF control of the power supply distributed by a regulator (secondary power supply switch).
Low ON resistance of the switch (internal transistor) contributes to reducing power loss, and therefore load switch ICs are suitable for applications requiring power saving characteristics at standby and sleep modes.
Battery Line Switch IC
Battery line switches are equipped with protections for the battery line (primary power supply switches).
The protections include an inrush current protection at the start-up and a reverse current protection at the ON/OFF switch-over.
They can also be used as load switches, and the validity of a discharge function is selectable.
Intelligent Power Switch IC
Although the basic functions are the same as load switches, intelligent power switches have two-step abnormal current detectors and a voltage detector.
The detection delay time of the lower abnormal current is set longer than that of the higher, and thus the difference enables the intelligent power switches to recognize the momentarily permissible current.
These ICs are suitable for applications which require sophisticated protections for their power supply line.
OVP Switch IC / External Power Switch IC
As portable devices such as smartphones and tablets correspond to various charging methods, for example, via an AC adapter, a USB cable, even a wireless way, etc., they have to switch the power supply lines ON/OFF according to the charging methods.
Also, in order to protect the system from the abnormal voltage which occurs at the plug-in or plug-out of an abnormal adapter, our OVP switch IC / external power switch IC include an overvoltage protection (OVP) function.
