National Semiconductor LP2994 Technical data
LP2994
DDR Termination Regulator
LP2994 DDR Termination Regulator
June 2005
General Description
The LP2994 regulator is designed to provide a linear solution
to meet the JEDEC SSTL-2 and SSTL-3 specifications (Series Stub Termination Logic) for active termination of DDRSDRAM. The device utilizes an internal operational amplifier
to provide linear regulation of V
expensive external components. The output stage prevents
shoot through while delivering 1.5A continuous current and
maintaining excellent load regulation. The LP2994 also incorporates an active low shutdown pin to tri-state the output
during Suspend To Ram (STR) states.
Patents Pending
without the need for
TT
Typical Application Circuit
Features
n Source and sink current
n Low external component count
n Independent analog and power rails
n Linear topology
n Small package SO-8
n Low cost and easy to use
n Shutdown pin
Applications
n SSTL-2
n SSTL-3
n DDR-SDRAM Termination
n DDR-II Termination
20045904
FIGURE 1. SSTL-2 VTTTermination
© 2005 National Semiconductor Corporation DS200459 www.national.com
Connection Diagram
LP2994
SO-8 (M08A) Package
Top View
20045902
Pin Descriptions
SO-8 Pin Name Function
1 NC No internal connection
2 GND Ground
3 VSENSE Feedback pin for regulating VTT
4SD
5 VDDQ Input for internal reference equal to VDDQ/2
6 AVIN Analog input pin
7 PVIN Power input pin
8 VTT Output voltage for connection to termination resistors
Active low shutdown pin
Ordering Information
Order Number Package Type
LP2994M SO-8 M08A 95 Units per Rail
LP2994MX SO-8 M08A 2500 Units Tape and Reel
NSC Package
Drawing
Supplied As
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LP2994
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
PVIN, AVIN, VTT, VDDQ, SD to GND −0.3V to +6V
Storage Temp. Range −65˚C to +150˚C
Junction Temperature 150˚C
PVIN Supply Voltage -0.3V to (AVIN +
0.3V)
SD Input Voltage -0.3V to (AVIN +
0.3V)
VTT Output Voltage -0.3V to (PVIN +
0.3V)
SO-8 Thermal Resistance (θ
) 151˚C/W
JA
Lead Temperature (Soldering, 10 sec) 260˚C
ESD Rating (Note 2) 2kV
Operating Range
Junction Temp. Range (Note 3) 0˚C to +125˚C
AVIN Supply Voltage 2.2V to 5.5V
Electrical Characteristics Specifications with standard typeface are for T
type apply over the full Operating Temperature Range (T
AVIN = PVIN = 2.5V, VDDQ = 2.5V (Note 4).
Symbol Parameter Conditions Min Typ Max Units
V
TT
VTTOutput Voltage
= 0A (Note 5)
I
OUT
VIN=VDDQ = 2.3V 1.108 1.138 1.168
VIN=VDDQ = 2.7V 1.305 1.334 1.360
I
q
Quiescent Current I
OUT
(Note 6)
Z
I
QSD
VDDQ
VDDQ Input Impedance 86 100 kΩ
Quiescent current in
shutdown
I
SD
V
IH
Shutdown Leakage
Current
Minimum Shutdown High
SD=0V
SD = 2.5V
Level
V
IL
Maximum Shutdown Low
Level
∆V
TT/VTT
Load Regulation
(Note 7)
I
SENSE
Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating range indicates conditions for which the device is
intended to be functional, but does not guarantee specific performance limits. For guaranteed specifications and test conditions see Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed
test conditions.
Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
Note 3: At elevated temperatures, devices must be derated based on thermal resistance. The device in the SO-8 package must be derated at θ
junction to ambient with no heat sink.
Note 4: Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Average Outgoing Quality Level (AOQL).
Note 5: VIN is defined as the VIN = AVIN = PVIN
Note 6: Quiescent current defined as the current flow into AVIN.
Note 7: Load regulation is tested by using a 10ms current pulse and measuring V
SENSE Input Current 100 pA
I
I
OUT
OUT
= 0˚C to +125˚C). Unless otherwise specified,
J
=0A
1.9 V
= 0 to 1.5A -0.4 %
= 0 to −1.5A +0.4
.
TT
= 25˚C and limits in boldface
J
272 400 µA
21 45 µA
2
5 µA
2
0.8 V
= 151.2˚ C/W
JA
nA
VVIN=VDDQ = 2.5V 1.210 1.236 1.260
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Typical Performance Characteristics
LP2994
Iq vs Temperature ( VIN= 2.5V) ISDvs VIN(25˚C)
Iq vs VIN(25˚C) Iq vs VIN(0, 25, and 125˚C)
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20045916
ISDvs VIN(0, 25, and 125˚C) ISDvs Temperature ( VIN= 2.5V)
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20045917
20045919
Typical Performance Characteristics (Continued)
LP2994
V
and VIHvs AVIN(25˚C)
IL
Maximum Sourcing Current vs AV
(V
= 2.5V, PVIN= 2.5V)
DDQ
Maximum Sourcing Current vs AV
(V
= 2.5V, PVIN= 1.8V)
DDQ
20045920 20045921
IN
Maximum Sourcing Current vs AV
(V
= 2.5V, PVIN= 3.3V)
DDQ
IN
IN
Maximum Sinking Current vs AV
(V
= 2.5V)
DDQ
20045922 20045923
IN
20045924 20045925
Maximum Sourcing Current vs AV
(V
= 1.8V, PVIN= 1.8V)
DDQ
IN
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