LP2996MRX/NOPB - Texas Instruments

220 PF

36 

VTT

LP2996A

PVIN

VDDQ

VREF

AVIN

VREF = 0.75 V

VSENSE

GND

47 PF+

VDDQ = 1.5 V

VDD = 2.5 V

VTT = 0.75 V

SDSD 0.01PF

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

LP2996-N, LP2996A DDR Termination Regulator

1 Features

1• Minimum VDDQ:

– 1.8 V (LP2996-N)

– 1.35 V (LP2996A)

• Source and Sink Current

• Low Output Voltage Offset

• No External Resistors Required for Setting Output

Voltage

• Linear Topology

• Suspend to Ram (STR) Functionality

• Stable With Ceramic Capacitors With Appropriate

ESR

• Low External Component Count

• Thermal Shutdown

2 Applications

• LP2996-N: DDR1 and DDR2 Termination Voltage

• LP2996A: DDR1, DDR2, DDR3, and DDR3L

Termination Voltage

• FPGA

• Industrial and Medical PC

• SSTL-2 and SSTL-3 Termination

• HSTL Termination

3 Description

The LP2996-N and LP2996A linear regulators are

designed to meet the JEDEC SSTL-2 specifications

for termination of DDR-SDRAM. The device also

supports DDR2, while LP2996A supports DDR3 and

DDR3L VTT bus termination with VDDQ minimum of

1.35 V. The device contains a high-speed operational

amplifier to provide excellent response to load

transients. The output stage prevents shoot through

while delivering 1.5-A continuous current and

transient peaks up to 3 A in the application as

required for DDR-SDRAM termination. The LP2996-N

and LP2996A also incorporate a VSENSE pin to

provide superior load regulation and a VREF output

as a reference for the chipset and DIMMs.

An additional feature found on the LP2996-N and

LP2996A is an active-low shutdown (SD) pin that

provides Suspend To RAM (STR) functionality. When

SD is pulled low the VTT output will tri-state providing

a high impedance output, but VREF remains active. A

power savings advantage can be obtained in this

mode through lower quiescent current.

TI recommends the LP2998 and LP2998-Q1 devices

for automotive applications and DDR applications that

require operating at temperatures below zero.

WEBENCH®design tools can be used by application

designers to generate, optimize, and simlulate

applications using the LP2998 and LP2998-Q1.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LP2996-N SOIC (8) 4.90 mm x 3.90 mm

LP2996-N, LP2996A WSON (8) 4.90 mm x 3.90 mm

LP2996-N WQFN (16) 4.00 mm x 4.00 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Simplified Schematic

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Functions......................... 3

6 Specifications......................................................... 5

6.1 Absolute Maximum Ratings ...................................... 5

6.2 ESD Ratings.............................................................. 5

6.3 Recommended Operating Conditions....................... 5

6.4 Thermal Information.................................................. 5

6.5 Electrical Characteristics........................................... 6

6.6 Typical Characteristics.............................................. 7

7 Detailed Description............................................ 10

7.1 Overview................................................................. 10

7.2 Functional Block Diagram ...................................... 10

7.3 Feature Description................................................. 11

7.4 Device Functional Modes........................................ 11

8 Applications and Implementation ...................... 12

8.1 Application Information............................................ 12

8.2 Typical Applications ................................................ 12

9 Power Supply Recommendations...................... 18

10 Layout................................................................... 19

10.1 Layout Guidelines ................................................. 19

10.2 Layout Examples................................................... 19

10.3 Thermal Considerations........................................ 20

11 Device and Documentation Support................. 23

11.1 Documentation Support ........................................ 23

11.2 Related Links ........................................................ 23

11.3 Receiving Notification of Documentation Updates 23

11.4 Community Resources.......................................... 23

11.5 Trademarks........................................................... 23

11.6 Electrostatic Discharge Caution............................ 23

11.7 Glossary................................................................ 23

12 Mechanical, Packaging, and Orderable

Information........................................................... 23

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision J (March 2013) to Revision K Page

• Added Device Information table, Specifications section, ESD Ratings table, Thermal Information table, Feature

Description section, Device Functional Modes section, Application and Implementation section, Power Supply

Recommendations section, Layout section, Device and Documentation Support section, and Mechanical,

Packaging, and Orderable Information section ...................................................................................................................... 1

• Added LP2996A throughout data sheet ................................................................................................................................. 1

• Added DDR3 support throughout data sheet......................................................................................................................... 1

• Deleted Lead temperature (260°C maximum) from Absolute Maximum Ratings .................................................................. 5

• Changed Thermal Resistance, RθJA, values in Thermal Information From: 151°C/W To: 119.5°C/W (SOIC), From:

151°C/W To: 56.5°C/W (SO), and From: 151°C/W To: 52.7°C/W (WQFN)........................................................................... 5

Changes from Revision I (March 2013) to Revision J Page

• Changed layout of National Semiconductor Data Sheet to TI format .................................................................................... 1

• Added VDDQ Range................................................................................................................................................................. 1

16 NC5VSENSE

1NC 12 PVIN

15 VTT6NC

2GND 11 PVIN

14 VTT7VREF

3NC 10 AVIN

13 NC8VDDQ

4SD 9 NC

Not to scale

Thermal Pad

1GND 8 VTT

2SD 7 PVIN

3VSENSE 6 AVIN

4VREF 5 VDDQ

Not to scale

PowerPAD

1GND 8 VTT

2SD 7 PVIN

3VSENSE 6 AVIN

4VREF 5 VDDQ

Not to scale

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

5 Pin Configuration and Functions

D Package

8-Pin SOIC

Top View

DDA Package

8-Pin SO With PowerPAD

Top View

NHP Package

16-Pin WQFN

Top View

Pin Functions

PIN I/O DESCRIPTION

NAME SO

PowerPAD SOIC WQFN

AVIN 6 6 10 I

Analog input pin. AVIN is used to supply all the internal control circuitry. This pin has the capability

to work from a supply separate from PVIN depending on the application. For SSTL-2 applications, a

good compromise would be to connect the AVIN and PVIN directly together at 2.5 V. This

eliminates the requirement for bypassing the two supply pins separately. The only limitation on input

voltage selection is that PVIN must be equal to or lower than AVIN.

GND 1 1 2 — Ground

PVIN 7 7 11, 12 I

Power input pin. PVIN is used exclusively to provide the rail voltage for the output stage used to

create VTT. This pin has the capability to work from a supply separate from PVIN depending on the

application. Higher voltages on PVIN increases the maximum continuous output current because of

output RDS(ON) limitations at voltages close to VTT. The disadvantage of high values of PVIN is that

the internal power loss also increases, thermally limiting the design. For SSTL-2 applications, a

good compromise would be to connect the AVIN and PVIN directly together at 2.5 V. This

eliminates the requirement for bypassing the two supply pins separately. The only limitation on input

voltage selection is that PVIN must be equal to or lower than AVIN. TI recommends connecting PVIN

to voltage rails equal to or less than 3.3 V to prevent the thermal limit from tripping because of

excessive internal power dissipation. If the junction temperature exceeds the thermal shutdown then

the part enters a shutdown state identical to the manual shutdown where VTT is tri-stated and

VREF remains active.

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

Pin Functions (continued)

PIN I/O DESCRIPTION

NAME SO

PowerPAD SOIC WQFN

SD 2 2 4 I

Shutdown. The LP2996-N and LP2996A contain an active low shutdown pin that can be used to tri-

state VTT. During shutdown VTT must not be exposed to voltages that exceed AVIN. With the

shutdown pin asserted low the quiescent current of the LP2996-N and LP2996A drops, however,

VDDQ always maintains its constant impedance of 100 kΩfor generating the internal reference.

Therefore, to calculate the total power loss in shutdown, both currents must be considered. See

Thermal Considerations for more information. The shutdown pin also has an internal pullup current,

therefore to turn the part on, the shutdown pin can either be connected to AVIN or left open.

VDDQ 5 5 8 I

Input for internal reference equal to VDDQ / 2. VDDQ is the input used to create the internal

reference voltage for regulating VTT. The reference voltage is generated from a resistor divider of

two internal 50-kΩresistors. This ensures that VTT tracks VDDQ / 2 precisely. The optimal

implementation of VDDQ is as a remote sense. This can be achieved by connecting VDDQ directly

to the 2.5-V rail at the DIMM instead of AVIN and PVIN. This ensures that the reference voltage

tracks the DDR memory rails precisely without a large voltage drop from the power lines. For SSTL-

2 applications VDDQ is a 2.5-V signal, which creates a 1.25-V termination voltage at VTT. See

Electrical Characteristics for exact values of VTT over temperature.

VREF 4 4 7 O

Buffered internal reference voltage of VDDQ / 2. VREF provides the buffered output of the internal

reference voltage VDDQ / 2. This output must be used to provide the reference voltage for the

Northbridge chipset and memory. Because these inputs are typically an extremely high impedance,

there must be little current drawn from VREF. For improved performance, an output bypass

capacitor can be placed close to the pin to help reduce noise. TI recommends a ceramic capacitor

from 0.1 µF to 0.01 µF. This output remains active during the shutdown state and thermal shutdown

events for the suspend to RAM functionality.

VSENSE 3 3 5 I

Feedback pin for regulating VTT. The purpose of the sense pin is to provide improved remote load

regulation. In most motherboard applications the termination resistors connect to VTT in a long

plane. If the output voltage was regulated only at the output of the device then the long trace

causes a significant IR drop resulting in a termination voltage lower at one end of the bus than the

other. The VSENSE pin can be used to improve this performance by connecting it to the middle of

the bus. This provides a better distribution across the entire termination bus. If remote load

regulation is not used then the VSENSE pin must still be connected to VTT. Take care when a long

VSENSE trace is implemented in close proximity to the memory. Noise pickup in the VSENSE trace

can cause problems with precise regulation of VTT. A small 0.1-µF ceramic capacitor placed next to

the VSENSE pin can help filter any high frequency signals and preventing errors.

VTT 8 8 14, 15 O

Output voltage for connection to termination resistors. VTT is the regulated output that is used to

terminate the bus resistors. It is capable of sinking and sourcing current while regulating the output

precisely to VDDQ / 2. The LP2996-N and LP2996A are designed to handle peak transient currents

of up to ±3 A with a fast transient response. The maximum continuous current is a function of VDD

and can be seen in Typical Characteristics. If a transient above the maximum continuous current

rating is expected to last for a significant amount of time then the output capacitor must be large

enough to prevent an excessive voltage drop. Despite the fact that the device is designed to handle

large transient output currents it is not capable of handling these for long durations under all

conditions. The reason for this is the standard packages are not able to thermally dissipate the heat

as a result of the internal power loss. If large currents are required for longer durations, then ensure

that the maximum junction temperature is not exceeded. Proper thermal derating must always be

used (see Thermal Considerations). If the junction temperature exceeds the thermal shutdown point

then VTT tri-states until the part returns below the hysteretic trip-point.

NC — — 1, 3, 6,

9, 13, 16 — No internal connection

Thermal

Pad PowerPAD — Thermal

Pad — Exposed pad thermal connection. Connect to Ground.

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and

specifications.

(3) VDDQ voltage must be less than 2 × (AVIN – 1) or 6 V, whichever is smaller.

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)

MIN MAX UNIT

AVIN to GND −0.3 6 V

PVIN to GND –0.3 AVIN V

Input voltage (VDDQ)(3) −0.3 6 V

Junction temperature, TJ150 °C

Storage temperature, Tstg –65 150 °C

(1) The human body model is a 100-pF capacitor discharged through a 1.5-kΩresistor into each pin.

6.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±1000 V

(1) At elevated temperatures, devices must be derated based on thermal resistance.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted) MIN MAX UNIT

AVIN to GND 2.2 5.5 V

PVIN supply voltage 0 AVIN V

SD input voltage 0 AVIN V

TJJunction temperature(1) 0 125 °C

6.4 Thermal Information

THERMAL METRIC

LP2996-N, LP2996A

UNITD (SOIC) DDA (SO) NHP (WQFN)

8 PINS 8 PINS 16 PINS

RθJA Junction-to-ambient thermal resistance 119.5 56.5 52.7 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 65.3 65.1 50.1 °C/W

RθJB Junction-to-board thermal resistance 59.8 36.5 30.1 °C/W

ψJT Junction-to-top characterization parameter 16.7 15.9 0.7 °C/W

ψJB Junction-to-board characterization parameter 59.3 36.5 30.2 °C/W

RθJC(bot) Junction-to-case (bottom) thermal resistance — 8.4 9.8 °C/W

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

(1) VDD is defined as VDD = AVIN = PVIN.

(2) VTT load regulation is tested by using a 10-ms current pulse and measuring VTT.

(3) Quiescent current defined as the current flow into AVIN.

6.5 Electrical Characteristics

Minimum and maximum limits apply over the full operating temperature range (TJ= 0°C to 125°C) and are specified through

test, design, or statistical correlation. Typical values represent the most likely parametric norm (TJ= 25°C), and are provided

for reference purposes only. Unless otherwise specified, AVIN = PVIN = 2.5 V and VDDQ = 2.5 V.(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VREF

VREF voltage (DDR I) VDD = VDDQ = 2.3 V 1.135 1.158 1.185 VVDD = VDDQ = 2.5 V 1.235 1.258 1.285

VDD = VDDQ = 2.7 V 1.335 1.358 1.385

VREF voltage (DDR II) PVIN = VDDQ = 1.7 V 0.837 0.86 0.887 VPVIN = VDDQ = 1.8 V 0.887 0.91 0.937

PVIN = VDDQ = 1.9 V 0.936 0.959 0.986

VREF voltage (DDR III) PVIN = VDDQ = 1.35 V 0.669 0.684 0.699 VPVIN = VDDQ = 1.5 V 0.743 0.758 0.773

PVIN = VDDQ = 1.6 V 0.793 0.808 0.823

ZVREF VREF output impedance IREF = –30 to 30 µA 2.5 kΩ

VTT VTT output voltage (DDR I)(2)

IOUT = 0 A VDD = VDDQ = 2.3 V 1.12 1.159 1.19

VDD = VDDQ = 2.5 V 1.21 1.259 1.29

VDD = VDDQ = 2.7 V 1.32 1.359 1.39

IOUT = ±1.5 A VDD = VDDQ = 2.3 V 1.125 1.159 1.19

VDD = VDDQ = 2.5 V 1.225 1.259 1.29

VDD = VDDQ = 2.7 V 1.325 1.359 1.39

VTT output voltage (DDR II)(2)

IOUT = 0 A, AVIN = 2.5 V PVIN = VDDQ = 1.7 V 0.822 0.856 0.887

PVIN = VDDQ = 1.8 V 0.874 0.908 0.939

PVIN = VDDQ = 1.9 V 0.923 0.957 0.988

IOUT = ±0.5 A, AVIN = 2.5 V PVIN = VDDQ = 1.7 V 0.82 0.856 0.89

PVIN = VDDQ = 1.8 V 0.87 0.908 0.94

PVIN = VDDQ = 1.9 V 0.92 0.957 0.99

VTT output voltage (DDR III)(2)

IOUT = 0 A, AVIN = 2.5 V PVIN = VDDQ = 1.35 V 0.656 0.677 0.698

PVIN = VDDQ = 1.5 V 0.731 0.752 0.773

PVIN = VDDQ = 1.6 V 0.781 0.802 0.823

IOUT = 0.2 A, AVIN = 2.5 V, PVIN = VDDQ = 1.35 V 0.667 0.688 0.71

IOUT = –0.2 A, AVIN = 2.5 V, PVIN = VDDQ = 1.35 V 0.641 0.673 0.694

IOUT = 0.4 A, AVIN = 2.5 V, PVIN = VDDQ = 1.5 V 0.74 0.763 0.786

IOUT = –0.4 A, AVIN = 2.5 V, PVIN = VDDQ = 1.5 V 0.731 0.752 0.773

IOUT = 0.5 A, AVIN = 2.5 V, PVIN = VDDQ = 1.6 V 0.79 0.813 0.836

IOUT = –0.5 A, AVIN = 2.5 V, PVIN = VDDQ = 1.6 V 0.781 0.802 0.823

VOSVtt

VTT output voltage offset

(VREF – VTT) for DDR I(2)

IOUT = 0 A –30 0 30 mVIOUT = –1.5 A –30 0 30

IOUT = 1.5 A –30 0 30

VTT output voltage offset

(VREF – VTT) for DDR II(2)

IOUT = 0 A –30 0 30 mVIOUT = –0.5 A –30 0 30

IOUT = 0.5 A –30 0 30

VTT output voltage offset

(VREF – VTT) for DDR III(2)

IOUT = 0 A –30 0 30

IOUT = ±0.2 A –30 0 30

IOUT = ±0.4 A –30 0 30

IOUT = ±0.5 A –30 0 30

IQQuiescent current(3) IOUT = 0 A 320 500 µA

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

0.5

1.5

2.5

3.5

VSD (V)

-30 -20 -10 0 10 20 30

IREF (uA)

1.10

1.15

1.20

1.25

1.30

1.35

1.40

VREF (V)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

100

150

200

250

300

350

400

IQ (uA)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

150

300

450

600

750

900

1050

IQ (uA)

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

Electrical Characteristics (continued)

Minimum and maximum limits apply over the full operating temperature range (TJ= 0°C to 125°C) and are specified through

test, design, or statistical correlation. Typical values represent the most likely parametric norm (TJ= 25°C), and are provided

for reference purposes only. Unless otherwise specified, AVIN = PVIN = 2.5 V and VDDQ = 2.5 V.(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

ZVDDQ VDDQ input impedance 100 kΩ

ISD Quiescent current in shutdown(3) SD is low 115 150 µA

IQ_SD Shutdown leakage current SD is low 2 5 µA

VIH Minimum shutdown, high level 1.9 V

VIL Maximum shutdown, low level 0.8 V

IVVTT leakage current in shutdown SD is low, VTT = 1.25 V 1 10 µA

ISENSE VSENSE input current 13 nA

TSD Thermal shutdown 165 °C

TSD_HYS Thermal shutdown hysteresis 10 °C

6.6 Typical Characteristics

Unless otherwise specified, AVIN = PVIN = 2.5 V.

Figure 1. IQvs AVIN In Shutdown Figure 2. IQvs AVIN

Figure 3. VIH and VIL Figure 4. VREF vs IREF

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

150

300

450

600

750

900

1050

IQ (uA)

0oC

25oC

85oC

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

0.2

0.4

0.6

0.8

1.2

1.4

OUTPUT CURRENT (A)

0 1 2 3 4 5 6

VDDQ (V)

0.5

1.5

2.5

VTT (V)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

100

150

200

250

300

350

400

IQ(uA)

0oC

125oC

0 1 2 3 4 5 6

VDDQ (V)

0.5

1.5

2.5

VREF (V)

-100 -75 -50 -25 0 25 50 75 100

IOUT (mA)

1.245

1.250

1.255

1.260

1.265

1.270

1.275

VTT (V)

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

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Product Folder Links: LP2996-N LP2996A

Typical Characteristics (continued)

Unless otherwise specified, AVIN = PVIN = 2.5 V.

Figure 5. VREF vs VDDQ Figure 6. VTT vs IOUT

Figure 7. VTT vs VDDQ Figure 8. IQvs AVIN in Shutdown Temperature

Figure 9. IQvs AVIN Temperature VDDQ = 2.5 V PVIN = 1.8 V

Figure 10. Maximum Sourcing Current vs AVIN

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

1.2

1.4

1.6

1.8

2.2

2.4

OUTPUT CURRENT (A)

3 3.5 4 4.5 5 5.5

2.2

2.4

2.6

2.8

OUTPUT CURRENT (A)

AVIN (V)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

OUTPUT CURRENT (A)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

0.2

0.4

0.6

0.8

1.2

1.4

OUTPUT CURRENT (A)

2 2.5 3 3.5 4 4.5 5 5.5

AVIN (V)

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

OUTPUT CURRENT (A)

3 3.5 4 4.5 5 5.5

2.2

2.4

2.6

2.8

OUTPUT CURRENT (A)

AVIN (V)

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

Typical Characteristics (continued)

Unless otherwise specified, AVIN = PVIN = 2.5 V.

VDDQ = 2.5 V PVIN = 2.5 V

Figure 11. Maximum Sourcing Current vs AVIN

VDDQ = 2.5 V PVIN = 3.3 V

Figure 12. Maximum Sourcing Current vs AVIN

VDDQ = 2.5 V

Figure 13. Maximum Sinking Current vs AVIN

VDDQ = 1.8 V PVIN = 1.8 V

Figure 14. Maximum Sourcing Current vs AVIN

VDDQ = 1.8 V

Figure 15. Maximum Sinking Current vs AVIN

VDDQ = 1.8 V PVIN = 3.3 V

Figure 16. Maximum Sourcing Current vs AVIN

VTT

PVIN

VDDQ

GND

AVIN

VSENSE

50k

VREF

VTT

VREF

VDD

CHIPSET

MEMORY

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

7 Detailed Description

7.1 Overview

The LP2996-N and LP2996A devices can be used to provide a termination voltage for additional logic schemes

such as SSTL-3 or HSTL.

Series Stub Termination Logic (SSTL) was created to improve signal integrity of the data transmission across the

memory bus. This termination scheme is essential to prevent data error from signal reflections while transmitting

at high frequencies encountered with DDR-SDRAM. The most common form of termination is Class II single

parallel termination. This involves one RSseries resistor from the chipset to the memory and one RTtermination

resistor. Typical values for RSand RTare 25 Ω, although these can be changed to scale the current

requirements from the LP2996-N or LP2996A. This implementation is shown in Figure 17.

Figure 17. SSTL-Termination Scheme

7.2 Functional Block Diagram

LP2996-N

LP2996A

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SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

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7.3 Feature Description

The LP2996-N and LP2996A are linear bus termination regulators designed to meet the JEDEC requirements of

SSTL-2. The output (VTT) is capable of sinking and sourcing current while regulating the output voltage equal to

VDDQ / 2. The output stage is designed to maintain excellent load regulation while preventing shoot through. The

LP2996-N and LP2996A also incorporate two distinct power rails that separates the analog circuitry from the

power output stage. This allows a split rail approach to be used to decrease internal power dissipation. It also

permits the LP2996-N to provide a termination solution for DDR2-SDRAM, while the LP2996A supports DDR3-

SDRAM and DDR3L-SDRAM memory. TI recommends the LP2998 and LP2998-Q1 for all DDR applications that

require operation at below-zero temperatures.

7.4 Device Functional Modes

7.4.1 Start-Up

During start up when VDDQ is enabled, the error amplifier senses the output voltage is low and drives the pass

element hard causing a large inrush current. If this inrush current is too large, the device shuts down and restarts

due to the internal current limit. Two solutions to prevent large inrush current during start up:

1. Slow down the slew rate of VDDQ. When the slew rate of VDDQ is fast (approximately 60 µs), the input

current can reach over 5 A which exceeds the device’s current limit thus causing a restart. If VDDQ start-up

slew rate is ≥300 µs, the inrush current can be reduced by 90% limiting the input rush current to less than

500mA.

2. In some cases the system designers have very little to no control over the VDDQ voltage supply slew rate,

whether using linear or switching regulators. Some step down voltage regulators do not have soft-start

feature. VDDQ voltage source requires only 18 µA current to enable the DDRII termination voltage.

Therefore placing an RC filter at VDDQ pin can conveniently increase the output voltage slew rate, allowing

a slow rise in capacitor charge current. To keep the VDDQ voltage losses minimum, the resistor value must

be chosen carefully. Using a 100-Ωresistor keeps the VDDQ supply voltage losses down to 1.8 mV,

because the current through VDDQ is only 18 µA for DDRIII configuration.

See Limiting DDR Termination Regulators’ Inrush Current (SNVA758) for more information relating to the inrush

current during start up.

7.4.2 Normal Operation

The device contains a high-speed operational amplifier to provide excellent response to load transients. The

output stage prevents shoot through while delivering 1.5-A continuous current and transient peaks up to 3 A in

the application as required for DDR-SDRAM termination. The LP2996-N and LP2996A also incorporate a

VSENSE pin to provide superior load regulation and a VREF output as a reference for the chipset and DIMMs.

See Electrical Characteristics and Application Information.

7.4.3 Shutdown

The LP2996-N and LP2996A feature an active-low shutdown (SD) pin that provides Suspend To RAM (STR)

functionality. When SD is pulled low, the VTT output tri-states providing a high impedance output, but VREF

remains active. A power savings advantage can be obtained in this mode through lower quiescent current.

During shutdown, VTT must not be exposed to voltages that exceed AVIN. With the shutdown pin asserted low

the quiescent current of the LP2996-N and LP2996A drops, however, VDDQ always maintains its constant

impedance of 100 kΩfor generating the internal reference. Therefore, to calculate the total power loss in

shutdown, both currents must be considered. The shutdown pin also has an internal pullup current, therefore to

turn the part on, the shutdown pin can either be connected to AVIN or left open.

220 PF

36 

VTT

LP2996A

PVIN

VDDQ

VREF

AVIN

VREF = 0.75 V

VSENSE

GND

47 PF+

VDDQ = 1.5 V

VDD = 2.5 V

VTT = 0.75 V

SDSD 0.01PF

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

8 Applications and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LP2996 has split rails to allow flexibility in powering the device. It has a control circuitry rail (AVIN) and an

output power stage rail (PVIN), both separate from the reference voltage input (VDDQ). This allows for different

setups which cater to specific requirements such as high current capabilities, lower thermal dissipation, or

minimum component count. Because the output is always VDDQ / 2 due to two internal 50-kΩresistors, the only

necessary external components are bypass capacitors.

8.2 Typical Applications

8.2.1 Typical SSTL-2 Application Circuit

This circuit permits termination in a minimum amount of board space and component count. Capacitor selection

can be varied depending on the number of lines terminated and the maximum load transient. However, with

motherboards and other applications where VTT is distributed across a long plane, it is advisable to use multiple

bulk capacitors and addition to high frequency decoupling.

Figure 18. Typical SSTL-2 Application Circuit Diagram

8.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 1 as the input parameters.

Table 1. Design Parameters

PARAMETER VALUE

VDDQ 1.5 V

Input to AVIN and PVIN, VDD 2.5 V

VREF 0.75 V

VTT 0.75 V

Input bypass capacitor, CIN 47 µF

Output bypass capacitor, COUT 220 µF

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

8.2.1.2 Detailed Design Procedure

The LP2996 requires voltage be applied to three pins for proper operation: VDDQ, AVIN, and PVIN. VDDQ sets

the internal reference voltage and is divided across two 50-kΩresistors. Therefore, VDDQ must be set at exactly

twice the appropriate DDR termination. AVIN powers the internal control circuitry and must be from 2.2 V to

5.5 V. PVIN is the supply for the power output stage and must be larger than or equal to VDDQ while smaller

than or equal to AVIN. When picking PVIN, note that smaller values reduce internal power dissipation but reduce

the maximum continuous current as well. It is acceptable to tie PVIN to either VDDQ or AVIN to minimize the

number of supplies and bypass capacitors required.

To prevent voltage dips on the output, a bypass capacitor must be placed on the VTT line. The size of this

capacitor does not affect stability, but larger values improve the transient response and must be sized according

to the design requirements. When using ceramic capacitors on the output, large load steps can cause ringing on

VTT. Table 2 shows the range of acceptable equivalent series resistance (ESR) that can be added to dampen

and improve the response.

Table 2. Approximate ESR Values for VTT Capacitors

VTT CAPACITANCE (µF) RECOMMENDED ESR (mΩ)

100 50

150 42

220 36

330 30

Another bypass capacitor on PVIN is recommended to keep current spikes from pulling down the input voltage.

This is especially important if PVIN and VDDQ are on the same supply. A small 0.01-µF capacitor can be placed

on VREF to reduce noise. VSENSE provides a feedback path necessary for regulating the output voltage;

Therefore, it must be connected to VTT. If a long VSENSE trace is necessary, a small ceramic capacitor may be

required to filter out any high frequency noise picked up from switching I/O signals.

8.2.1.2.1 Input Capacitor

The LP2996-N and LP2996A do not require a capacitor for input stability, but it is recommended for improved

performance during large load transients to prevent the input rail from dropping. The input capacitor must be

placed as close as possible to the PVIN pin. Several recommendations exist dependent on the application

required. A typical value recommended for aluminum electrolytic capacitors is 50 µF. Ceramic capacitors can

also be used, a value approximately 10 µF with X5R or better would be an ideal choice. The input capacitance

can be reduced if the LP2996-N or LP2996A is placed close to the bulk capacitance from the output of the 2.5-V

DC-DC converter. If the two supply rails (AVIN and PVIN) are separated then the 47-µF capacitor must be

placed as close to possible to the PVIN rail. An additional 0.1-µF ceramic capacitor can be placed on the AVIN

rail to prevent excessive noise from coupling into the device.

8.2.1.2.2 Output Capacitor

The LP2996-N and LP2996A have been designed to be insensitive of output capacitor size or ESR. This allows

the flexibility to use any capacitor desired. The choice for output capacitor is determined solely on the application

and the requirements for load transient response of VTT. TI recommends the output capacitor be sized above

100 µF with a low ESR for SSTL applications with DDR-SDRAM. The value of ESR is determined by the

maximum current spikes expected and the extent at which the output voltage is allowed to droop. Several

capacitor options are available on the market and a few of these are discussed: Aluminum Electrolytics,Ceramic

Capacitors, and Hybrid Capacitors.

8.2.1.2.2.1 Aluminum Electrolytics

Aluminum electrolytics often only specify impedance at a frequency of 120 Hz, indicating poor high frequency

performance. Only aluminum electrolytics that specified an impedance at higher frequencies, from 20 kHz to

100 kHz, must be used for the LP2996-N and LP2996A. To improve the ESR, many aluminum electrolytics may

be combined in parallel for an overall reduction. Be aware of the extent at which the ESR changes over

temperature. Aluminum electrolytic capacitors' ESR may rapidly increase at cold temperatures.

220 PF

36 

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF = 1.25 V

VSENSE

GND

47 PF+

VDDQ = 2.5 V

VDD = 2.5 V

VTT = 1.25 V

0.01 PF

220 PF

36 

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

8.2.1.2.2.2 Ceramic Capacitors

Ceramic capacitors typically have a low capacitance, from 10 µF to 100 µF, but they have excellent AC

performance for bypassing noise due to very low ESR (typically less than 10 mΩ). However, some dielectric

types do not have good capacitance characteristics as a function of voltage and temperature. Because of the

typically low value of capacitance, TI recommends using ceramic capacitors in parallel with another capacitor

such as an aluminum electrolytic. TI recommends dielectric of X5R or better for all ceramic capacitors.

8.2.1.2.2.3 Hybrid Capacitors

Hybrid capacitors offer a large capacitance while maintaining a low ESR. These are the best solution when size

and performance are critical, although their cost is typically higher than any other capacitor.

8.2.1.2.2.4 PC Application Considerations

With motherboards and other applications where VTT is distributed across a long plane, it is advisable to use

multiple bulk capacitors and addition to high frequency decoupling. Figure 19 shows an example circuit where

two bulk output capacitors could be situated at both ends of the VTT plane for optimal placement. Large

aluminum electrolytic capacitors are used for their low ESR and low cost.

In most PC applications an extensive amount of decoupling is required because of the long interconnects

encountered with the DDR-SDRAM DIMMs mounted on modules. As a result bulk aluminum electrolytic

capacitors approximately 1000 µF are typically used.

Figure 19. Typical SSTL-2 Application Circuit for Motherboards

8.2.1.3 Application Curves

Figure 20. 0.5-A Load Transient With 220-µF VTT Capacitor Figure 21. 1.5-A Load Transient With 220-µF VTT Capacitor

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF = 1.25 V

VSENSE

GND

VDDQ = 2.5 V

AVIN = 2.2 V to 5.5 V

VTT = 1.25 V

PVIN = 1.8 V

CIN

CREF

COUT

ROUT

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF = 1.25 V

VSENSE

GND

VDDQ = 2.5 V

VDD = 2.5 V

VTT = 1.25 V

CIN

CREF

ROUT

COUT

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

8.2.2 Other Application Circuits

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

the LP2996-N or LP2996A.

8.2.2.1 SSTL-2 Applications

For the majority of applications that implement the SSTL-2 termination scheme, TI recommends connecting all

the input rails to the 2.5-V 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 22.

Figure 22. Recommended SSTL-2 Implementation

If power dissipation or efficiency is a major concern, then the LP2996-N or LP2996A has the ability to operate on

split power rails. The output stage (PVIN) can be operated on a lower rail such as 1.8 V and the analog circuitry

(AVIN) can be connected to a higher rail such as 2.5 V, 3.3 V, or 5 V. This allows the internal power dissipation

to be lowered when sourcing current from VTT. The disadvantage of this circuit is that 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 are encountered.

Figure 23. Lower Power Dissipation SSTL-2 Implementation

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

use 2.5 V, is to connect the LP2996-N or LP2996A power rail to 3.3 V. In this situation AVIN is limited to

operation on the 3.3-V or 5-V rail as PVIN can never exceed AVIN. This configuration has the ability to provide

the maximum continuous output current at the downside of higher thermal dissipation. Prevent the device from

experiencing large current levels which cause the junction temperature to exceed the maximum. Because of this

risk, TI recommends not supplying the output stage with a voltage higher than a nominal 3.3-V rail.

COUT

ROUT

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF= 0.9 V

VSENSE

GND

VDDQ = 1.8 V

AVIN = 3.3V or 5.5 V

VTT = 0.9 V

PVIN = 3.3 V

CIN

CREF

COUT

ROUT

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF = 0.9 V

VSENSE

GND

VDDQ = 1.8 V

AVIN = 2.2V to 5.5 V

VTT = 0.9 V

PVIN = 1.8 V

CIN

CREF

COUT

ROUT

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VREF = 1.25 V

VSENSE

GND

VDDQ = 2.5 V

AVIN = 3.3V or 5 V

VTT = 1.25 V

PVIN = 3.3 V

CIN

CREF

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

Figure 24. SSTL-2 Implementation with Higher Voltage Rails

8.2.2.2 DDR-II Applications

With the separate VDDQ pin and an internal resistor divider it is possible to use the LP2996-N and LP2996A in

applications utilizing DDR-II memory. Figure 25 and Figure 26 show implementations of recommended circuit

configurations for DDR-II applications. The output stage is connected to the 1.8-V rail and the AVIN pin can be

connected to either a 3.3-V or 5-V rail. TI recommends the LP2996A, LP2998, or LP2998-Q1 for DDR-III and

DDR-III low power designs.

Figure 25. Recommended DDR-II Termination

If it is not desirable to use the 1.8-V rail it is possible to connect the output stage to a 3.3-V rail. Take care not to

exceed the maximum junction temperature as the thermal dissipation increases with lower VTT output voltages.

For this reason, TI does not recommend powering PVIN from a rail higher than the nominal 3.3 V. The

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

Figure 26. DDR-II Termination with Higher Voltage Rails

DDQ

VR1

V 1

2 R2

æ ö

= ´ -

ç ÷

è ø

COUT

ROUT

LP2996

VDDQ

VDD VTT

VTT

PVIN

VDDQ

GND

AVIN

VSENSE

CIN R2

DDQ

VR1

V 1

2 R2

æ ö

= ´ +

ç ÷

è ø

VTT

LP2996A

PVIN

VDDQ

VREF

AVIN

VREF = 0.75V

VSENSE

GND

VDDQ = 1.5V

AVIN = 2.2V to 5.5V

VTT = 0.75V

PVIN = 1.5V

CIN COUT

CREF

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

8.2.2.3 DDR-III Applications

With the separate VDDQ pin and an internal resistor divider it is possible to use the LP2996A 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 27. Recommended DDR-III Termination Using the LP2996A

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

exceed the maximum junction temperature as the thermal dissipation increases with lower VTT output voltages.

For this reason, TI recommends not to power PVIN off a rail higher than the nominal 3.3-V. The advantage of

this configuration is that it has the ability to source and sink a higher maximum continuous current.

8.2.3 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 VDDQ / 2 for regulating the output voltage. Several options are available to scale the output to any

voltage required. One method is to level shift the output by using feedback resistors from VTT to the VSENSE

pin. This is shown in Figure 28 and Figure 29.Figure 28 shows how to use two resistors to level shift VTT above

the internal reference voltage of VDDQ / 2. Calculate the exact voltage at VTT with Equation 1.

(1)

Figure 28. Increasing VTT by Level Shifting

Conversely, the R2 resistor can be placed between VSENSE and VDDQ to shift the VTT output lower than the

internal reference voltage of VDDQ /2.Equation 2 shows the relation of VTT to the resistors.

(2)

COUT

ROUT

VTT

LP2996

PVIN

VDDQ

VREF

AVIN

VSENSE

GND

VDDQ = 1.5 V

VDD = 2.5 V

VTT = 0.75 V

CIN

CREF

VREF = 0.75 V

COUT

ROUT

LP2996

VDDQ

VDD

VTT

PVIN

VDDQ

GND

AVIN

VSENSE

CIN

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

Figure 29. Decreasing VTT by Level Shifting

8.2.4 HSTL Applications

The LP2996-N and LP2996A can be easily adapted for HSTL applications by connecting VDDQ to the 1.5-V rail.

This produces a VTT and VREF voltage of approximately 0.75 V for the termination resistors. AVIN and PVIN

must be connected to a 2.5-V rail for optimal performance.

Figure 30. HSTL Application

8.2.5 QDR Applications

Quad data rate (QDR) applications use multiple channels for improved memory performance. However, this

increase in bus lines increases the current levels required for termination. TI recommends using a dedicated

LP2996-N or LP2996A for each channel to terminate multiple channels. This simplifies layout and reduces the

internal power dissipation for each regulator. Separate VREF signals can be used for each DIMM bank from the

corresponding regulator with the chipset reference provided by a local resistor divider or one of the LP2996-N or

LP2996A signals. Because VREF and VTT are expected to track and the part to part variations are minor, there

must be little difference between the reference signals of each device.

9 Power Supply Recommendations

There are several recommendations for the LP2996-N and LP2996A input power supply. Although not required,

TI recommends an input capacitor for improved performance during large load transients to prevent the input rail

from dropping. The input capacitor must be placed as close as possible to the PVIN pin.

A typical value recommended for aluminum electrolytic capacitors is 50 µF. Ceramic capacitors can also be

used, a value approximately 10 µF with X5R or better would be an ideal choice. The input capacitance can be

reduced if the LP2996-N or LP2996A is placed close to the bulk capacitance from the output of the 2.5-V DC-DC

converter. If the two supply rails (AVIN and PVIN) are separated then the 47-µF capacitor must be placed as

close to possible to the PVIN rail. An additional 0.1-µF ceramic capacitor can be placed on the AVIN rail to

prevent excessive noise from coupling into the device.

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

10 Layout

10.1 Layout Guidelines

• The input capacitor for the power rail must be placed as close as possible to the PVIN pin.

• VSENSE must be connected to the VTT termination bus at the point where regulation is required. For

motherboard applications an ideal location would be at the center of the termination bus.

• VDDQ can be connected remotely to the VDDQ rail input at either the DIMM or the chipset. This provides the

most accurate point for creating the reference voltage.

• For improved thermal performance excessive top side copper can be used to dissipate heat from the

package. Numerous vias from the ground connection to the internal ground plane helps. Additionally these

can be placed underneath the package if manufacturing standards permit.

• Take care when routing the VSENSE trace to avoid noise pickup from switching I/O signals. A 0.1-µF ceramic

capacitor placed close to VSENSE can also be used to filter any unwanted high frequency signal. This can be

an issue especially if long VSENSE traces are used.

• VREF must be bypassed with a 0.01-µF or 0.1-µF ceramic capacitor for improved performance. This

capacitor must be placed as close as possible to the VREF pin.

10.2 Layout Examples

Figure 31. Layout Example of the SO PowerPAD

Package (Top Layer)

Figure 32. Layout Example of the WQFN Package

(Top Layer)

0 200 400 600 800 1000

AIRFLOW (Linear Feet per Minute)

SOP Board

JEDEC Board

JA

180

170

160

150

140

130

120

110

100

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

10.3 Thermal Considerations

Because the LP2996-N and LP2996A are linear regulators, any current flow from VTT results in internal power

dissipation generating heat. To prevent damaging the part from exceeding the maximum allowable junction

temperature, derate the part according to the maximum expected ambient temperature and power dissipation.

The maximum allowable internal temperature rise (TR(MAX)) can be calculated with Equation 3 given the maximum

ambient temperature (TA(MAX)) of the application and the maximum allowable junction temperature (TJ(MAX)).

TR(MAX) = TJ(MAX) −TA(MAX) (3)

From this equation, the maximum power dissipation (PD(MAX)) of the part can be calculated with Equation 4.

PD(MAX) = TR(MAX) / RθJA (4)

The RθJA of the LP2996-N and LP2996A is dependent on several variables: the package used; the thickness of

copper; the number of vias and the airflow. For instance, the RθJA of the SOIC is 163°C/W with the package

mounted to a standard 8×4 2-layer board with 1-oz copper, no airflow, and 0.5-W dissipation at room

temperature. This value can be reduced to 151.2°C/W by changing to a 3×4 board with 2-oz copper that is the

JEDEC standard. Figure 33 shows how the RθJA varies with airflow for the two boards mentioned.

Figure 33. RθJA vs Airflow (SOIC)

Additional improvements can be made by the judicious use of vias to connect the part and dissipate heat to an

internal ground plane. Using larger traces and more copper on the top side of the board can also help. With

careful layout, it is possible to reduce the RθJA further than the nominal values shown in Figure 33

Layout is also extremely critical to maximize the output current with the WQFN package. By simply placing vias

under the thermal pad, the RθJA can be lowered significantly. Figure 34 shows the WQFN thermal data when

placed on a 4-layer JEDEC board with copper thickness of 0.5 oz, 1 oz, 1 oz, and 0.5 oz (respectively). The

number of vias with a pitch of 1.27 mm is increased to the maximum of 4, where a RθJA of 50.41°C/W can be

obtained. Via wall thickness for this calculation is 0.036 mm for 1-oz copper.

0 100 200 300 400 500 600

AIRFLOW (Linear Feet Per Minute)

qJA (oC/W)

0 1 2 3 4

NUMBER OF VIAS

100

JA(°C/ W)

NUMBER OF VIAS

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

Thermal Considerations (continued)

4-layer JEDEC board

Figure 34. WQFN-16 RθJA vs Number of Vias

Additional improvements in lowering the RθJA can be achieved with a constant airflow across the package.

Maintaining the same conditions as above and utilizing the 2×2 via array, Figure 35 shows how the RθJA varies

with airflow.

JEDEC board with 4 vias

Figure 35. RθJA vs Airflow Speed

LP2996-N

LP2996A

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LP2996-N LP2996A

Thermal Considerations (continued)

Optimizing the RθJA and placing the device in a section of a board exposed to lower ambient temperature allows

the part to operate with higher power dissipation. The internal power dissipation can be calculated by summing

the three main sources of loss: output current at VTT, either sinking or sourcing, and quiescent current at AVIN

and VDDQ. During the active state, when the shutdown pin (SD) is not held low, the total internal power

dissipation can be calculated with Equation 5.

PD= PAVIN + PVDDQ + PVTT

where

• PAVIN = IAVIN × VAVIN

• PVDDQ = VVDDQ × IVDDQ = VVDDQ2 x RVDDQ (5)

To calculate the maximum power dissipation at VTT both conditions (sinking and sourcing current) at VTT must

be examined. Although only one equation is added into the total, because VTT cannot source and sink current

simultaneously.

Calculate sinking with Equation 6.

PVTT = VVTT × ILOAD (6)

Or calculate sourcing with Equation 7.

PVTT =(VPVIN – VVTT) × ILOAD (7)

The power dissipation of the LP2996-N and LP2996A can also be calculated during the shutdown state. During

this condition the output (VTT) is tri-stated; Therefore, that term in the power equation disappears as it cannot

sink or source any current, and leakage is negligible. The only losses during shutdown are the reduced quiescent

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

PD= PAVIN + PVDDQ

where

• PAVIN = IAVIN × VAVIN

• PVDDQ = VVDDQ × IVDDQ = VVDDQ2 × RVDDQ (8)

LP2996-N

LP2996A

www.ti.com

SNOSA40K –NOVEMBER 2002–REVISED DECEMBER 2016

Product Folder Links: LP2996-N LP2996A

11 Device and Documentation Support

11.1 Documentation Support

11.1.1 Related Documentation

For related documentation see the following:

Limiting DDR Termination Regulators’ Inrush Current (SNVA758)

11.2 Related Links

The table below lists quick access links. Categories include technical documents, support and community

resources, tools and software, and quick access to sample or buy.

Table 3. Related Links

PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL

DOCUMENTS TOOLS &

SOFTWARE SUPPORT &

COMMUNITY

LP2996-N Click here Click here Click here Click here Click here

LP2996A Click here Click here Click here Click here Click here

11.3 Receiving Notification of Documentation Updates

To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper

right corner, click on Alert me to register and receive a weekly digest of any product information that has

changed. For change details, review the revision history included in any revised document.

11.4 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

11.5 Trademarks

E2E is a trademark of Texas Instruments.

WEBENCH is a registered trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

11.6 Electrostatic Discharge Caution

This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with

appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more

susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

11.7 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

12 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

www.ti.com 1-Jul-2014

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LP2996AMR/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 LP2996

AMR

LP2996AMRE/NOPB ACTIVE SO PowerPAD DDA 8 250 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 LP2996

AMR

LP2996AMRX/NOPB ACTIVE SO PowerPAD DDA 8 2500 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 LP2996

AMR

LP2996LQ/NOPB ACTIVE WQFN NHP 16 1000 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 L00006B

LP2996LQX/NOPB ACTIVE WQFN NHP 16 4500 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 L00006B

LP2996M NRND SOIC D 8 95 TBD Call TI Call TI 0 to 125 2996M

LP2996M/NOPB ACTIVE SOIC D 8 95 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM 0 to 125 2996M

LP2996MR NRND SO PowerPAD DDA 8 95 TBD Call TI Call TI 0 to 125 LP2996

LP2996MR/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 LP2996

LP2996MRX NRND SO PowerPAD DDA 8 2500 TBD Call TI Call TI 0 to 125 LP2996

LP2996MRX/NOPB ACTIVE SO PowerPAD DDA 8 2500 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR 0 to 125 LP2996

LP2996MX/NOPB ACTIVE SOIC D 8 2500 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM 0 to 125 2996M

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability

information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined.

Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that

lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.

Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between

the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.

PACKAGE OPTION ADDENDUM

www.ti.com 1-Jul-2014

Addendum-Page 2

Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight

in homogeneous material)

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish

value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

LP2996AMRE/NOPB SO

Power

PAD

DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LP2996AMRX/NOPB SO

Power

PAD

DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LP2996LQ/NOPB WQFN NHP 16 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1

LP2996LQX/NOPB WQFN NHP 16 4500 330.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1

LP2996MRX SO

Power

PAD

DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LP2996MRX/NOPB SO

Power

PAD

DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LP2996MX/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 30-Apr-2018

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

LP2996AMRE/NOPB SO PowerPAD DDA 8 250 210.0 185.0 35.0

LP2996AMRX/NOPB SO PowerPAD DDA 8 2500 367.0 367.0 35.0

LP2996LQ/NOPB WQFN NHP 16 1000 210.0 185.0 35.0

LP2996LQX/NOPB WQFN NHP 16 4500 367.0 367.0 35.0

LP2996MRX SO PowerPAD DDA 8 2500 367.0 367.0 35.0

LP2996MRX/NOPB SO PowerPAD DDA 8 2500 367.0 367.0 35.0

LP2996MX/NOPB SOIC D 8 2500 367.0 367.0 35.0

PACKAGE MATERIALS INFORMATION

www.ti.com 30-Apr-2018

Pack Materials-Page 2

www.ti.com

PACKAGE OUTLINE

TYP

6.2

5.8

1.7 MAX

6X 1.27

8X 0.51

0.31

3.81

TYP

0.25

0.10

0 - 8

0.15

0.00

2.34

2.24

2.34

2.24

0.25

GAGE PLANE

1.27

0.40

NOTE 3

5.0

4.8

B4.0

3.8

4218825/A 05/2016

PowerPAD SOIC - 1.7 mm max heightDDA0008A

PLASTIC SMALL OUTLINE

NOTES:

1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing

per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not

exceed 0.15 mm per side.

4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side.

5. Reference JEDEC registration MS-012.

PowerPAD is a trademark of Texas Instruments.

0.25 C A B

PIN 1 ID

AREA

NOTE 4

SEATING PLANE

0.1 C

SEE DETAIL A

DETAIL A

TYPICAL

SCALE 2.400

EXPOSED

THERMAL PAD

www.ti.com

EXAMPLE BOARD LAYOUT

(5.4)

(1.3) TYP

( ) TYP

VIA

0.2

(R ) TYP0.05

0.07 MAX

ALL AROUND

0.07 MIN

ALL AROUND

8X (1.55)

8X (0.6)

6X (1.27)

(2.95)

NOTE 9

(4.9)

NOTE 9

(2.34)

SOLDER MASK

OPENING

(1.3)

TYP

4218825/A 05/2016

PowerPAD SOIC - 1.7 mm max heightDDA0008A

PLASTIC SMALL OUTLINE

SYMM

SEE DETAILS

LAND PATTERN EXAMPLE

SCALE:10X

SOLDER MASK

OPENING

METAL COVERED

BY SOLDER MASK

SOLDER MASK

DEFINED PAD

NOTES: (continued)

6. Publication IPC-7351 may have alternate designs.

7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.

8. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature

numbers SLMA002 (www.ti.com/lit/slma002) and SLMA004 (www.ti.com/lit/slma004).

9. Size of metal pad may vary due to creepage requirement.

10. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown

on this view. It is recommended that vias under paste be filled, plugged or tented.

METAL

SOLDER MASK

OPENING

NON SOLDER MASK

DEFINED

SOLDER MASK DETAILS

OPENING

SOLDER MASK METAL UNDER

SOLDER MASK

DEFINED

www.ti.com

EXAMPLE STENCIL DESIGN

(R ) TYP0.05

8X (1.55)

8X (0.6)

6X (1.27)

(5.4)

(2.34)

BASED ON

0.125 THICK

STENCIL

4218825/A 05/2016

PowerPAD SOIC - 1.7 mm max heightDDA0008A

PLASTIC SMALL OUTLINE

1.98 X 1.980.175

2.14 X 2.140.150

2.34 X 2.34 (SHOWN)0.125

2.62 X 2.620.1

SOLDER STENCIL

OPENING

STENCIL

THICKNESS

NOTES: (continued)

11. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate

design recommendations.

12. Board assembly site may have different recommendations for stencil design.

SOLDER PASTE EXAMPLE

EXPOSED PAD

100% PRINTED SOLDER COVERAGE BY AREA

SCALE:10X

SYMM

BASED ON

0.125 THICK

STENCIL

BY SOLDER MASK

METAL COVERED SEE TABLE FOR

DIFFERENT OPENINGS

FOR OTHER STENCIL

THICKNESSES

MECHANICAL DATA

NHP0016A

www.ti.com

LQA16A (REV A)

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Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Texas Instruments:

LP2996LQ/NOPB LP2996LQX/NOPB LP2996M LP2996M/NOPB LP2996MR LP2996MR/NOPB LP2996MRX

LP2996MRX/NOPB LP2996MX/NOPB