LP2998EVAL National Semiconductor, LP2998EVAL Datasheet - Page 14

• Manufacturer Part Number: LP2998EVAL
• Description: BOARD EVALUATION FOR LP2998
• Manufacturer: National Semiconductor

Specifications of LP2998EVAL

• Channels Per Ic: 1 - Single
• Current - Output: 1.5A
• Voltage - Input: 2.2 ~ 5.5V
• Regulator Type: Positive Fixed
• Operating Temperature: -40°C ~ 125°C
• Board Type: Fully Populated
• Utilized Ic / Part: LP2998
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Output: -

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LEVEL SHIFTING
If standards other than SSTL-2 are required, such as SSTL-3,
it may be necessary to use a different scaling factor than 0.5
times V
are available to scale the output to any voltage required. One
method is to level shift the output by using feedback resistors
Conversely, the R2 resistor can be placed between V
and V
ence voltage of VDDQ/2. The equation relating to VTT and
the resistors can be used as shown:
HSTL APPLICATIONS
The LP2998 can be easily adapted for HSTL applications by
connecting V
DDQ
DDQ
to shift the V
for regulating the output voltage. Several options
DDQ
to the 1.5V rail. This will produce a V
TT
output lower than the internal refer-
FIGURE 9. Decreasing VTT by Level Shifting
FIGURE 8. Increasing VTT by Level Shifting
FIGURE 10. HSTL Application
TT
SENSE
and
14
from V
8
level shift V
2. To calculate the exact voltage at V
can be used.
V
sistors. AVIN and PVIN should be connected to a 2.5V rail for
optimal performance.
REF
and
voltage of approximately 0.75V for the termination re-
TT
Figure
to the V
TT
9.
above the internal reference voltage of VDDQ/
Figure 8
SENSE
V
V
TT
TT
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= VDDQ/2 (1 + R1/R2)
= VDDQ/2 (1 - R1/R2)
30026915
pin. This has been illustrated in
shows how to use two resistors to
30026917
TT
the following equation
Figure