ОБЩЕЕ ОПИСАНИЕ

The ADP7159 is an adjustable linear regulator that operates from 2.3 V to 5.5 V and provides up to 2 A of output current.Output voltages from 1.2 V to 3.3 V are possible depending on the model.Using an advanced proprietary architecture,the device provides high power supply rejection and ultralow noise,achieving excellent line and load transient response with only a 10μF ceramic output capacitor.

The ADP7159 is available in four models that optimize power dissipation and PSRR performance as a function of the input and output voltage.See Table 9 and Table 10 for selection guides.

The typical output noise of the ADP7159 regulator is 0.9μV rms from 100 Hz to 100 kHz and 1.7 nV/√Hz for noise spectral density from 10 kHz to 1 MHz.The ADP7159 is available in 10-lead,3 mm×3 mm LFCSP and 8-lead SOIC packages,making it not only a very compact solution,but also providing excellent thermal performance for applications requiring up to 2 A of output current in a small,low profile footprint.

 

THERMAL DATA

Absolute maximum ratings apply individually only,not in combination.The ADP7159 can be damaged when the junction temperature limits are exceeded.Monitoring ambient temperature does not guarantee that TJ is within the specified temperature limits.In applications with high power dissipation and poor thermal resistance,the maximum ambient temperature may need to be derated.

In applications with moderate power dissipation and low printed circuit board(PCB)thermal resistance,the maximum ambient temperature can exceed the maximum limit as long as the junction temperature is within specification limits.The junction temperature(TJ)of the device is dependent on the ambient temperature(TA),the power dissipation of the device(PD),and the junction to ambient thermal resistance of the package(θJA).

 

ТЕОРИЯ ЭКСПЛУАТАЦИИ

The ADP7159 is an ultralow noise,high PSRR linear regulator targeting radio frequency(RF)applications.The input voltage range is 2.3 V to 5.5 V,and the device delivers up to 2 A of load current.The typical shutdown current consumption is 0.2μA at room temperature.

Optimized for use with 10μF ceramic capacitors,the ADP7159 provides excellent transient performance.

Internally,the ADP7159 consists of a reference,an error amplifier,and a P-channel MOSFET pass transistor.The output current is delivered via the PMOS pass device,which is controlled by the error amplifier.The error amplifier compares the reference voltage with the feedback voltage from the output and amplifies the difference.If the feedback voltage is lower than the  reference voltage,the gate of the PMOS device pulls lower,allowing more current to pass and increasing the output voltage.If the feedback voltage is higher than the reference voltage,the gate of the PMOS device pulls higher,allowing less current to pass and decreasing the output voltage.By heavily filtering the reference voltage,the ADP7159 achieves 1.7 nV/√Hz output typical from 10 kHz to 1 MHz.Because the error amplifier is always in unity gain,the output noise is independent of the output voltage.

 

CAPACITOR SELECTION

Multilayer ceramic capacitors(MLCCs)combine small size,low ESR,low effective series inductance(ESL),and wide operating temperature range,making them an ideal choice for bypass

capacitors.They are not without faults,however.Depending on the dielectric material,the capacitance can vary dramatically with temperature,dc bias,and ac signal level.Therefore,selecting the proper capacitor results in the best circuit performance.

Выходной конденсатор

The ADP7159 is designed for operation with ceramic capacitors but functions with most commonly used capacitors when care is taken with regard to the ESR value.The ESR of the output capacitor affects the stability of the LDO control loop.A minimum of 10µF capacitance with an ESR of 0.2Ωor less is recommended to ensure the stability of the ADP7159.Output capacitance also affects transient response to changes in load current.Using a larger value of output capacitance improves the transient response of the ADP7159 to large changes in load current.

Current limit and thermal shutdown protections are intended to protect the device against accidental overload conditions. Cases with a hard short from VOUT to ground or an extremely long soft-start timer typically cause the device to experience thermal oscillations between the current limit and thermal shutdown.