LP2998

GND

+

+

+

SD

SD

LP2998

GND

472F

+

+

+

2202F

SD

SD

0.012F

LP2998, LP2998-Q1

www.ti.com

SNVS521K – DECEMBER 2007 – REVISED AUGUST 2014

Application Information (continued)

(6)

(7)

The power dissipation of the LP2998 can also be calculated during the shutdown state. During this condition the

current (leakage is negligible). The only losses during shutdown will be the reduced quiescent current at AVIN

and the constant impedance that is seen at the VDDQ pin.

(8)

(9)

(10)

9.2 Typical Application

Several different application circuits are shown below to illustrate some of the options that are possible in

configuring the LP2998. Graphs of the individual circuit performance can be found in the Typical Characteristics

section. These curves illustrate how the maximum output current is affected by changes in AVIN and PVIN.

Figure 19. Typical Application Circuit

9.2.1 DDR-III Applications

With the separate VDDQ pin and an internal resistor divider it is possible to use the LP2998 in applications

utilizing DDR-III memory. The output stage is connected to the 1.5 V rail and the AVIN pin can be connected to a

2.2 V to 5.5 V rail.

Figure 20. Recommended DDR-III Termination

If it is not desirable to use the 1.5 V - 2.5 V rail it is possible to connect the output stage to a 3.3 V rail. Care

should be taken to not exceed the maximum junction temperature as the thermal dissipation increases with lower

V. The advantage of this configuration is that it has the ability to source and sink a higher maximum continuous

current.

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