AP2182AFGEG-7 View Datasheet(PDF) - Diodes Incorporated.

Part Name

Description

Manufacturer

AP2182AFGEG-7

1.5A DUAL CHANNEL CURRENT-LIMITED POWER SWITCH

Diodes Incorporated. 

AP2182A/ AP2192A

Application Information

Power Supply Considerations

A 0.1μF to 1μF X7R or X5R ceramic bypass capacitor between IN and GND, close to the device, is recommended. Placing a high-value electrolytic

capacitor on the input and output pin(s) is recommended when the output load is heavy. This precaution reduces power-supply transients that may

cause ringing on the input. Additionally, bypassing the output with a 1μF ceramic capacitor improves the immunity of the device to short-circuit

transients.

Overcurrent and Short Circuit Protection

An internal sensing FET is employed to check for overcurrent conditions. Unlike current-sense resistors, sense FETs do not increase the series

resistance of the current path. When an overcurrent condition is detected, the device maintains a constant output current and reduces the output

voltage accordingly. Complete shutdown occurs only if the fault stays long enough to activate thermal limiting.

Three possible overload conditions can occur. In the first condition, the output has been shorted to GND before the device is enabled or before VIN

has been applied. The AP2182A/AP2192A senses the short circuit and immediately clamps output current to a certain safe level namely ILIMIT.

In the second condition, an output short or an overload occurs while the device is enabled. At the instance the overload occurs, higher inrush

current may flow for a very short period of time before the current limit function can react. The input capacitor(s) rapidly discharge through the

device, activating current limit circuitry. Protection is achieved by momentarily opening the P-MOS high-side power switch and then gradually

turning it on. After the current limit function has tripped (reached the over-current trip threshold), the device switches into current limiting mode and

the current is clamped at ILIMIT. The threshold for activating current limiting is 2A typical per channel.

In the third condition, the load has been gradually increased beyond the recommended operating current. The current is permitted to rise until the

current-limit threshold (ITRIG) is reached or until the thermal limit of the device is exceeded. The AP2182A/AP2192A is capable of delivering current

up to the current-limit threshold without damaging the device. Once the threshold has been reached, the device switches into its current limiting

mode and is set at ILIMIT.

FLG Response

When an overcurrent or overtemperature shutdown condition is encountered, the FLG open-drain output goes active low after a nominal 7-ms

deglitch timeout. The FLG output remains low until both overcurrent and overtemperature conditions are removed. Connecting a heavy capacitive

load to the output of the device can cause a momentary overcurrent condition, which does not trigger the FLG due to the 7-ms deglitch timeout.

The AP2182A/AP2192A is designed to eliminate false over-current reporting without the need of external components to remove unwanted pulses.

Power Dissipation and Junction Temperature

The low on-resistance of the internal MOSFET allows the small surface-mount packages to pass large current. Using the maximum operating

ambient temperature (TA) and RDS(ON), the power dissipation can be calculated by:

PD = RDS(ON)× I2

Finally, calculate the junction temperature:

Where:

TJ = PD x RJA + TA

TA = Ambient temperature C

RθJA = Thermal resistance

PD = Total power dissipation

Thermal Protection

Thermal protection prevents the IC from damage when heavy-overload or short-circuit faults are present for extended periods of time. The

AP2182A/AP2192A implements a thermal sensing to monitor the operating junction temperature of the power distribution switch. Once the die

temperature rises to approximately 140°C due to excessive power dissipation in an overcurrent or short-circuit condition the internal thermal sense

circuitry turns the power switch off, thus preventing the power switch from damage. Hysteresis is built into the thermal sense circuit allowing the

device to cool down approximately 25°C before the switch turns back on. The switch continues to cycle in this manner until the load fault or input

power is removed. The FLG open-drain output is asserted when an overtemperature shutdown or overcurrent occurs with 7-ms deglitch.

AP2182A_92A

Document number: DS32193 Rev. 4 - 2

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www.diodes.com

October 2016

© Diodes Incorporated

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