DIO7164

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DIO7164• Rev 0.3

 

Application Information

Power Supply Considerations

A 10μF ceramic capacitor from VIN to GND to prevent the input voltage from dropping during the hot-plug

condition is strongly recommended. However higher capacitance could help reduce the voltage drop. Further

more, bypassing the output with a 10μF ceramic capacitor improves the immunity of the device to short-circuit

transients, because an output short will cause ringing on the input without the input capacitor. It could destroy the

internal circuitry when the input transient voltage exceeds the absolute maximum supply voltage even for a short

duration.

Enable

The logic enable controls the power switch, the bias for the charge pump, driver, and other circuitry to reduce the

supply current. The CTL control pin must be driven to a logic high or a logic low for a clearly defined signal input.

Floating these control lines may cause unpredictable operation.

Over-Current Protection

The DIO7164 responds to over current conditions by limiting output current to the ILIM levels. When an over

current condition is detected, the device maintains a constant output current and reduces the output voltage

accordingly. Complete shutdown occurs only if the fault is present long enough to activate thermal limit.

Two possible overload conditions can occur. In the first condition, an excessive load occurs while the device is

enabled. When the excessive load occurs, very high currents may flow for a short time before the current limit

circuit can react. After the current limit circuit has tripped (reached the overcurrent trip threshold) the device

switches into constant current mode to limit the current close to ILIM.

In the second condition, the load is gradually increasing beyond the recommended operating current. The current

is permitted to rise until the currentlimit threshold (ILIM) is reached or until the thermal limit of the device is

exceeded. The DIO7164 is capable of delivering current up to the currentlimit threshold (ILIM) without damaging

the device. Once the threshold has been reached, the device switches into its constant current mode.

Thermal Protection

Thermal protection prevents damage to the IC when heavy overload or short circuit conditions are present for

extended periods of time. The conditions force the DIO7164 into constant current mode, and under short circuit

conditions, the voltage across the switch is equal to the input voltage. The increased dissipation causes the

junction temperature to rise to high levels. The protection circuit senses the junction temperature of the switch

and shuts it off. Hysteresis is built into the thermal sense circuit, and after the device has cooled approximately

20 degrees, the switch turns back on. The switch continues to cycle in this way until the overload or input power

is removed.