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2016-03-0004

PT0489-5

04/29/16

8

PI5PD2560/2561

Dual Channel,

Adjustable Current-Limited Power Switch

Under-voltage Lockout (UVLO)

The under-voltage lockout (UVLO) circuit disables the power switch until the input voltage reaches the UVLO turn-on threshold.

Built-in hysteresis prevents unwanted on/off cycling due to input voltage droop during turn on.

Enable (ENx OR /ENx)

The logic enables control the power switches and device supply current. The supply current is reduced to less than 2μA when a

logic high is present on /ENx or when a logic low is present on ENx. A logic low input on /ENx or a logic high input on ENx

enables the driver, control circuits, and power switches. The enable inputs are compatible with both TTL and CMOS logic levels.

Thermal Sense

The PI5PD2560/2561 self protect by using two independent thermal sensing circuits that monitor the operating temperature of the

power switch and disable operation if the temperature exceeds recommended operating conditions. Each channel of the

PI5PD2560/2561 operate in constant-current mode during over-current conditions, which increases the voltage drop across the

power switch. The power dissipation in the package is proportional to the voltage drop across the power switch, which increases

the junction temperature during an over-current condition. The first thermal sensor (OTSD) turns off the individual power switch

channel when the die temperature exceeds 135°C (min) and the channel is in current limit. Hysteresis is built into the thermal

sensor, and the switch turns on after the device has cooled approximately 20°C.

The PI5PD2560/2561 also have a second ambient thermal sensor (OTSD2). The ambient thermal sensor turns off both power

switch channels when the die temperature exceeds 155°C (min) regardless of whether the power switch channels are in current

limit and will turn on the power switches after the device has cooled approximately 20°C. The PI5PD2560/2561 continue to cycle

off and on until the fault is removed.

APPLICATION INFORMATION

INPUT AND OUTPUT CAPACITANCE

Input and output capacitance improves the performance of the device; the actual capacitance should be optimized for the particular

application. For all applications, a 0.1μF or greater ceramic bypass capacitor between IN and GND is recommended as close to the

device as possible for local noise decoupling. This precaution reduces ringing on the input due to power-supply transients.

Additional larger input capacitance with low ESR is needed on the input to reduce voltage overshoot from exceeding the absolute

maximum voltage of the device during heavy transient conditions. This is especially important during bench testing when long,

inductive cables are used to connect the evaluation board to the bench power supply.

Output capacitance is not required, but placing a high-value electrolytic capacitor on the output pin is recommended when large

transient currents are expected on the output.

PROGRAMMING THE CURRENT-LIMIT THRESHOLD

The over-current threshold is user programmable via an external resistor, RILIM. RILIM sets the current-limit threshold for both

channels. The PI5PD2560/2561 use an internal regulation loop to provide a regulated voltage on the ILIM pin. The current-limit

threshold is proportional to the current sourced out of ILIM. The recommended 1% resistor range for RILIM is 20 kΩ ≤ RILIM ≤

187 kΩ to ensure stability of the internal regulation loop. Many applications require that the minimum current limit is above a

certain current level or that the maximum current limit is below a certain current level, so it is important to consider the tolerance

of the over-current threshold when selecting a value for RILIM. The following equations calculates the resulting overcurrent

threshold for a given external resistor value (RILIM). The traces routing the RILIM resistor to the PI5PD2560/2561 should be as

short as possible to reduce parasitic effects on the current-limit accuracy.

52850V

56000V

61200V