DIO7758

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© 2022 DIOO MICROCIRCUITS CO., LTD

DIO7758• Rev. 1.6

Detailed Description

Overview

The DIO7758 series of LDO linear regulators is low quiescent current devices with excellent line and load transient

performance. These LDOs are designed for power-sensitive applications. A precision bandgap and error amplifier

provide overall 1% accuracy. Low output noise, very high PSRR, and low dropout voltage make this series of

devices ideal for most battery-operated handheld equipment. All device versions have integrated thermal

shutdown, and current limit.

Block Diagram

Internal Current Limit

The DIO7758 internal current limit helps to protect the regulator during fault conditions. During the current limit,

the output sources a fixed amount of current that is largely independent of the output voltage. In such a case, the

output voltage is not regulated and is VOUT = ICL × RLOAD. The PMOS pass transistor dissipates (VIN – VOUT) × ICL

until the thermal shutdown is triggered and the device turns off. As the device cools down, it is turned on by the

internal thermal shutdown circuit. If the fault condition continues, the device cycles between the current limit and

thermal shutdown.

The PMOS pass element in the DIO7758 has a built-in body diode that conducts current when the voltage at OUT

exceeds the voltage at IN. This current is not limited, so if extended reverse voltage operation is anticipated,

external limiting to 5% of the rated output current is recommended.

Shut down

The enable pin (EN) is active high. The device is enabled when the voltage at EN pin goes above 1 V. The device

is turned off when the EN pin is held at less than 0.4 V. When shutdown capability is not required, EN can be

connected to the IN pin.

Dropout Voltage

The DIO7758 uses a PMOS pass transistor to achieve low dropout. When (VIN – VOUT) is less than the dropout

voltage (VDO), the PMOS pass device is in the linear region of operation and the input-to-output resistance is the

RDS(on) of the PMOS pass element. VDO scales approximately with output current because the PMOS device

behaves as a resistor in dropout.

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OUT