DESCRIPTION GÉNÉRALE

The ADP7118 is a CMOS, low dropout (LDO) linear regulator that operates from 2.7 V to 20 V and provides up to 200 mA of output current. This high input voltage LDO is ideal for the regulation of high performance analog and mixed-signal circuits operating from 19 V down to 1.2 V rails. Using an advanced proprietary architecture, the device provides high power supply rejection, low noise, and achieves excellent line and load transient response with a small 2.2 µF ceramic output capacitor. The ADP7118 regulator output noise is 11 μV rms independent of the output voltage for the fixed options of 5 V or less.

The ADP7118 is available in 16 fixed output voltage options. The following voltages are available from stock: 1.2 V (adjustable), 1.8 V, 2.5 V, 3.3 V, 4.5 V, and 5.0 V. Additional voltages available by special order are 1.5 V, 1.85 V, 2.0 V, 2.2 V, 2.75 V, 2.8 V, 2.85 V, 3.8 V, 4.2 V, and 4.6 V. Each fixed output voltage can be adjusted above the initial set point with an external feedback divider. This allows the ADP7118 to provide an output voltage from 1.2 V to VIN − VDO with high PSRR and low noise.

User programmable soft start with an external capacitor is available in the LFCSP and SOIC packages.

The ADP7118 is available in a 6-lead, 2 mm × 2 mm LFCSP making it not only a very compact solution, but it also provides excellent thermal performance for applications requiring up to 200 mA of output current in a small, low profile footprint. The ADP7118 is also available in a 5-lead TSOT and an 8-lead SOIC.

 

THERMAL DATA

Absolute maximum ratings apply individually only, not in combination. The ADP7118 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 have 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 of the device is dependent on the ambient temperature, the power dissipation (PD) of the device, and the junction-to-ambient thermal resistance of the package (θJA).

 

THÉORIE DU FONCTIONNEMENT

The ADP7118 is a low quiescent current, LDO linear regulator that operates from 2.7 V to 20 V and provides up to 200 mA of output current. Drawing a low 180 μA of quiescent current (typical) at full load makes the ADP7118 ideal for portable equipment.

Typical shutdown current consumption is less than 3 µA at room temperature.

Optimized for use with small 2.2 µF ceramic capacitors, the ADP7118 provides excellent transient performance.

Internally, the ADP7118 consists of a reference, an error amplifier, and a PMOS pass transistor. 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 is pulled 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 is pulled higher, allowing less current to pass and decreasing the output voltage.

 

Condensateur de sortie

The ADP7118 is designed for operation with small, space-saving ceramic capacitors, but functions with general-purpose capacitors as long as care is taken with regard to the effective series resistance (ESR) value. The ESR of the output capacitor affects the stability of the LDO control loop. A minimum of 2.2 µF capacitance with an ESR of 0.3 Ω or less is recommended to ensure the stability of the ADP7118. Transient response to changes in load current is also affected by output capacitance. Using a larger value of output capacitance improves the transient response of the ADP7118 to large changes in load current.