LP2995MR datasheet(9/13 Pages) NSC

Nome de Peças	LP2995MR

Descrição Electrónicos	DDR Termination Regulator

PDF	13 Pages

Scroll/Zoom	100%

Fabricante Electrônico	NSC [National Semiconductor (TI)]

Página de início	http://www.national.com

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9 / 13 page

Typical Application Circuits

The typical application circuit used for SSTL-2 termination

schemes with DDR-SDRAM can be seen in Figure 5.

For SSTL-3 and other applications it may be desirable to

change internal reference voltage scaling from VDDQ * 0.5.

An external resistor in series with the VDDQ pin can be used

to lower the reference voltage. Internally two 50 k

Ω resistors

set the output V

TT to be equal to VDDQ * 0.5. The addition

of a 11.1 k

Ω external resistor will change the internal refer-

ence voltage causing the two outputs to track VDDQ * 0.45.

An implementation of this circuit can be seen in Figure 6.

Another application that is sometimes required is to increase

the V

TT output voltage from the scaling factor of VDDQ * 0.5.

This can be accomplished independently of V

REF by using a

resistor divider network between V

TT,VSENSE and Ground.

An example of this circuit can be seen in Figure 7.

20039306

SSTL-2 Implementation

FIGURE 5.

20039307

SSTL-3 Implementation

FIGURE 6.

20039303

FIGURE 7.

LP2995MR Folha de dados(PDF) 9 Page - National Semiconductor (TI)