DDR Termination Regulator

TJ2997

Apr, 2011 - R1.0.1

9/13

HTC

TYPICAL APPLICATION INFORMATION

Several different application circuits have been shown in Figure 2 through Figure 11 to illustrate some

of the options that are possible in configuring the TJ2997.

SSTL-2 APPLICATIONS

For the majority of applications that implement the SSTL-2 termination scheme it is recommended to

connect all the input rails to the 2.5V rail. This provides an optimal trade-off between power dissipation

and component count and selection. An example of this circuit can be seen in Figure 2.

FIGURE 2. Recommended SSTL-2 Implementation

If power dissipation or efficiency is a major concern then the TJ2997 has the ability to operate on split

the maximum continuous current is reduced because of the lower rail voltage, although it is adequate for

all motherboard SSTL-2 applications. Increasing the output capacitance can also help if periods of large

load transients will be encountered.

FIGURE 3. Lower Power Dissipation SSTL-2 Implementation

The third option for SSTL-2 applications in the situation that a 1.8V rail is not available and it is not

provide the maximum continuous output current at the downside of higher thermal dissipation. Care

should be taken to prevent the TJ2997 from experiencing large current levels which cause the junction

temperature to exceed the maximum. Because of this risk it is not recommended to supply the output

stage with a voltage higher than a nominal 3.3V rail.