Ricoh R5524 Series - USB High Side Protection Switch

Traditionally all semiconductor products by Ricoh are made using a CMOS process. As a result the R5524 has a significantly lower supply and standby current compared to a common bi-polar USB protection ICs.

The new R5524 USB protection switch has an improved current limit threshold accuracy level which results in a much better assurance when the protection circuit will be triggered. The enhanced current limit circuit either prevents the 5V host power supply to fail or to cut off the USB supply voltage too early.

Two current limit types are now available for the R5524; depending on the preference, users can select from a latched or constant current limit type. The latched type circuit is triggered when the current limit threshold is exceeded. It turns the USB switch off and remains in this state. It is released when the chip is re-enabled or if the system is powered up again. The constant current type circuit is also triggered when exceeding the current limit threshold but remains active and provides a constant current to the output.

In comparison with our previously launched USB protection switch ICs, the R5524 is now using an N-channel MOSFET switch. It enables both a low on-resistance value as well as a reverse current protection is now possible by blocking some reverse current flow from the USB switch output to the input.

The UVLO (Under Voltage Lock Out) circuit is added for additional protection. It keeps the chip disabled as long as the input voltage is below a specific minimum level, preventing that the chip from operating below the required input voltage specifications.

A thermal protection is also embedded. If the temperature of the chip increases above 135°C the internal circuits are disabled, once the temperature decreases below 120°C the chip resumes to normal operation.

The R5524 features a false flag protection circuit to prevent false flags being set during USB hot plug-in events, caused by in-rush current or momentary faults of less than 20ms. The flag output turns active low when the UVLO, current limit or thermal shutdown protection circuits are triggered. A delay in reporting the fault condition makes an external RC delay network unnecessary.

An optional feature is the auto-discharge function; this popular feature, adopted from other power management ICs, quickly discharges external capacitors connected to the USB switch output.

The R5524 is available in SOT23-5 package, making it convenient to use on high density and small circuit boards.

R5524N Features: