LM2734ZMKX/NOPB - Texas Instruments High-Performance Analog

LM2734Z

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SNVS334E –JANUARY 2005–REVISED APRIL 2013

LM2734Z/LM2734ZQ Thin SOT 1A Load Step-Down DC-DC Regulator

Check for Samples: LM2734Z

1FEATURES DESCRIPTION

The LM2734Z regulator is a monolithic, high

23• Thin SOT-6 Package, or 6 Lead WSON frequency, PWM step-down DC/DC converter

Package assembled in a 6-pin Thin SOT and WSON non pull

• 3.0V to 20V Input Voltage Range back package. It provides all the active functions to

• 0.8V to 18V Output Voltage Range provide local DC/DC conversion with fast transient

response and accurate regulation in the smallest

• 1A Output Current possible PCB area.

• 3MHz Switching Frequency With a minimum of external components and online

• 300mΩNMOS Switch design support through WEBENCH™, the LM2734Z

• 30nA Shutdown Current is easy to use. The ability to drive 1A loads with an

• 0.8V, 2% Internal Voltage Reference internal 300mΩNMOS switch using state-of-the-art

0.5µm BiCMOS technology results in the best power

• Internal Soft-Start density available. The world class control circuitry

• Current-Mode, PWM Operation allows for on-times as low as 13ns, thus supporting

• Thermal Shutdown exceptionally high frequency conversion over the

entire 3V to 20V input operating range down to the

• LM2734ZQ is AEC-Q100 Grade 1 Qualified and minimum output voltage of 0.8V. Switching frequency

is Manufactured on an Automotive Grade Flow is internally set to 3MHz, allowing the use of

extremely small surface mount inductors and chip

APPLICATIONS capacitors. Even though the operating frequency is

• DSL Modems very high, efficiencies up to 85% are easy to achieve.

External shutdown is included, featuring an ultra-low

• Local Point of Load Regulation stand-by current of 30nA. The LM2734Z utilizes

• Battery Powered Devices current-mode control and internal compensation to

• USB Powered Devices provide high-performance regulation over a wide

range of operating conditions. Additional features

• Automotive include internal soft-start circuitry to reduce inrush

current, pulse-by-pulse current limit, thermal

shutdown, and output over-voltage protection.

1Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2WEBENCH is a trademark of Texas Instruments, Inc..

3All other trademarks are the property of their respective owners.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

BOOST

GND

VIN

DAP

BOOST

GND

FB EN

VIN

LM2734

VIN VIN

BOOST

GND

VOUT

C3 L1

OFF

LM2734Z

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Typical Application Circuit Efficiency vs Load Current

VIN = 5V, VOUT = 3.3V

Connection Diagrams

Figure 1. 6-Lead SOT Figure 2. 6-Lead WSON (3mm x 3mm)

See Package Number DDC (R-PDSO-G6) See Package Number NGG0006A

PIN DESCRIPTIONS

Pin Name Function

1 BOOST Boost voltage that drives the internal NMOS control switch. A bootstrap

capacitor is connected between the BOOST and SW pins.

2 GND Signal and Power ground pin. Place the bottom resistor of the feedback

network as close as possible to this pin for accurate regulation.

3 FB Feedback pin. Connect FB to the external resistor divider to set output

voltage.

4 EN Enable control input. Logic high enables operation. Do not allow this pin to

float or be greater than VIN + 0.3V.

5 VIN Input supply voltage. Connect a bypass capacitor to this pin.

6 SW Output switch. Connects to the inductor, catch diode, and bootstrap

capacitor.

DAP GND The Die Attach Pad is internally connected to GND

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

Product Folder Links: LM2734Z

LM2734Z

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SNVS334E –JANUARY 2005–REVISED APRIL 2013

Absolute Maximum Ratings(1)(2)

VIN -0.5V to 24V

SW Voltage -0.5V to 24V

Boost Voltage -0.5V to 30V

Boost to SW Voltage -0.5V to 6.0V

FB Voltage -0.5V to 3.0V

EN Voltage -0.5V to (VIN + 0.3V)

Junction Temperature 150°C

ESD Susceptibility(3) 2kV

Storage Temp. Range -65°C to 150°C

Infrared/Convection Reflow (15sec) 220°C

Soldering Information Wave Soldering Lead Temp. (10sec) 260°C

(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for

which the device is intended to be functional, but specific performance is not ensured. For specific specifications and the test conditions,

see Electrical Characteristics.

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

specifications.

(3) Human body model, 1.5kΩin series with 100pF.

Operating Ratings(1)

VIN 3V to 20V

SW Voltage -0.5V to 20V

Boost Voltage -0.5V to 25V

Boost to SW Voltage 1.6V to 5.5V

Junction Temperature Range −40°C to +125°C

Thermal Resistance θJA(2) SOT–6 118°C/W

(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for

which the device is intended to be functional, but specific performance is not ensured. For specific specifications and the test conditions,

see Electrical Characteristics.

(2) Thermal shutdown will occur if the junction temperature exceeds 165°C. The maximum power dissipation is a function of TJ(MAX) ,θJA

and TA. The maximum allowable power dissipation at any ambient temperature is PD= (TJ(MAX) – TA)/θJA . All numbers apply for

packages soldered directly onto a 3” x 3” PC board with 2oz. copper on 4 layers in still air. For a 2 layer board using 1 oz. copper in still

air, θJA = 204°C/W.

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Electrical Characteristics

Specifications with standard typeface are for TJ= 25°C, and those in boldface type apply over the full Operating

Temperature Range (TJ= -40°C to 125°C). VIN = 5V, VBOOST - VSW = 5V unless otherwise specified. Datasheet min/max

specification limits are specified by design, test, or statistical analysis.

Symbol Parameter Conditions Min(1) Typ(2) Max(1) Units

VFB Feedback Voltage 0.784 0.800 0.816 V

Feedback Voltage Line

ΔVFB/ΔVIN VIN = 3V to 20V 0.01 % / V

Regulation

IFB Feedback Input Bias Current Sink/Source 10 250 nA

Undervoltage Lockout VIN Rising 2.74 2.90

UVLO Undervoltage Lockout VIN Falling 2.0 2.3 V

UVLO Hysteresis 0.30 0.44 0.62

FSW Switching Frequency 2.2 3.0 3.6 MHz

DMAX Maximum Duty Cycle 78 85 %

DMIN Minimum Duty Cycle 8 %

VBOOST - VSW = 3V 300 600 mΩ

(SOT Package)

RDS(ON) Switch ON Resistance VBOOST - VSW = 3V 340 650 mΩ

(WSON Package)

ICL Switch Current Limit VBOOST - VSW = 3V 1.2 1.7 2.5 A

IQQuiescent Current Switching 1.5 2.5 mA

Quiescent Current (shutdown) VEN = 0V 30 nA

IBOOST Boost Pin Current (Switching) 4.25 6mA

Shutdown Threshold Voltage VEN Falling 0.4

VEN_TH V

Enable Threshold Voltage VEN Rising 1.8

IEN Enable Pin Current Sink/Source 10 nA

ISW Switch Leakage 40 nA

(1) Specified to Texas Instruments' Average Outgoing Quality Level (AOQL).

(2) Typicals represent the most likely parametric norm.

Product Folder Links: LM2734Z

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SNVS334E –JANUARY 2005–REVISED APRIL 2013

Typical Performance Characteristics

All curves taken at VIN = 5V, VBOOST - VSW = 5V, L1 = 2.2 µH and TA= 25°C, unless specified otherwise.

Efficiency vs Load Current VOUT = 5V Efficiency vs Load Current VOUT = 3.3V

Figure 3. Figure 4.

Efficiency vs Load Current VOUT = 1.5V Oscillator Frequency vs Temperature

Figure 5. Figure 6.

Line Regulation Line Regulation

VOUT = 1.5V, IOUT = 500mA VOUT = 3.3V, IOUT = 500mA

Figure 7. Figure 8.

Product Folder Links: LM2734Z

BOOST

Output

Control

Logic

Current

Limit

Thermal

Shutdown

Under

Voltage

Lockout

Corrective Ramp

Reset

Pulse

PWM

Comparator

Current-Sense Amplifier RSENSE

Internal

Regulator

and

Enable

Circuit

Oscillator

Driver 0.3:

Switch

Internal

Compensation

GND

Error Amplifier -

+VREF

0.8V

COUT

OFF

VBOOST

VSW

CBOOST

VOUT

CIN

VIN

ISENSE

-0.88V

OVP

Comparator

Error

Signal

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

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Block Diagram

APPLICATION INFORMATION

THEORY OF OPERATION

The LM2734Z is a constant frequency PWM buck regulator IC that delivers a 1A load current. The regulator has

a preset switching frequency of 3MHz. This high frequency allows the LM2734Z to operate with small surface

mount capacitors and inductors, resulting in a DC/DC converter that requires a minimum amount of board space.

The LM2734Z is internally compensated, so it is simple to use, and requires few external components. The

LM2734Z uses current-mode control to regulate the output voltage.

The following operating description of the LM2734Z will refer to the Simplified Block Diagram (Block Diagram)

and to the waveforms in Figure 9. The LM2734Z supplies a regulated output voltage by switching the internal

NMOS control switch at constant frequency and variable duty cycle. A switching cycle begins at the falling edge

of the reset pulse generated by the internal oscillator. When this pulse goes low, the output control logic turns on

the internal NMOS control switch. During this on-time, the SW pin voltage (VSW) swings up to approximately VIN,

and the inductor current (IL) increases with a linear slope. ILis measured by the current-sense amplifier, which

generates an output proportional to the switch current. The sense signal is summed with the regulator’s

corrective ramp and compared to the error amplifier’s output, which is proportional to the difference between the

feedback voltage and VREF. When the PWM comparator output goes high, the output switch turns off until the

next switching cycle begins. During the switch off-time, inductor current discharges through Schottky diode D1,

which forces the SW pin to swing below ground by the forward voltage (VD) of the catch diode. The regulator

loop adjusts the duty cycle (D) to maintain a constant output voltage.

Product Folder Links: LM2734Z

LM2734

BOOST

GND

COUT

CBOOST

VOUT

CIN

VIN

VBOOST

VIN

TON

Inductor

Current

D = TON/TSW

VSW

TOFF

TSW

IPK

Voltage

LM2734Z

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Figure 9. LM2734Z Waveforms of SW Pin Voltage and Inductor Current

BOOST FUNCTION

Capacitor CBOOST and diode D2 in Figure 10 are used to generate a voltage VBOOST. VBOOST - VSW is the gate

drive voltage to the internal NMOS control switch. To properly drive the internal NMOS switch during its on-time,

VBOOST needs to be at least 1.6V greater than VSW. Although the LM2734Z will operate with this minimum

voltage, it may not have sufficient gate drive to supply large values of output current. Therefore, it is

recommended that VBOOST be greater than 2.5V above VSW for best efficiency. VBOOST – VSW should not exceed

the maximum operating limit of 5.5V.

5.5V > VBOOST – VSW > 2.5V for best performance.

Figure 10. VOUT Charges CBOOST

When the LM2734Z starts up, internal circuitry from the BOOST pin supplies a maximum of 20mA to CBOOST.

This current charges CBOOST to a voltage sufficient to turn the switch on. The BOOST pin will continue to source

current to CBOOST until the voltage at the feedback pin is greater than 0.76V.

There are various methods to derive VBOOST:

1. From the input voltage (VIN)

2. From the output voltage (VOUT)

3. From an external distributed voltage rail (VEXT)

4. From a shunt or series zener diode

Product Folder Links: LM2734Z

LM2734

VIN BOOST

GND

CBOOST

CIN

VIN

COUT

VOUT

VBOOST

LM2734Z

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In the Simplifed Block Diagram of Block Diagram, capacitor CBOOST and diode D2 supply the gate-drive current

for the NMOS switch. Capacitor CBOOST is charged via diode D2 by VIN. During a normal switching cycle, when

the internal NMOS control switch is off (TOFF) (refer to Figure 9), VBOOST equals VIN minus the forward voltage of

D2 (VFD2), during which the current in the inductor (L) forward biases the Schottky diode D1 (VFD1). Therefore the

voltage stored across CBOOST is

VBOOST - VSW = VIN - VFD2 + VFD1 (1)

When the NMOS switch turns on (TON), the switch pin rises to

VSW = VIN – (RDSON x IL), (2)

forcing VBOOST to rise thus reverse biasing D2. The voltage at VBOOST is then

VBOOST = 2VIN – (RDSON x IL) – VFD2 + VFD1 (3)

which is approximately

2VIN - 0.4V (4)

for many applications. Thus the gate-drive voltage of the NMOS switch is approximately

VIN - 0.2V (5)

An alternate method for charging CBOOST is to connect D2 to the output as shown in Figure 10. The output

voltage should be between 2.5V and 5.5V, so that proper gate voltage will be applied to the internal switch. In

this circuit, CBOOST provides a gate drive voltage that is slightly less than VOUT.

In applications where both VIN and VOUT are greater than 5.5V, or less than 3V, CBOOST cannot be charged

directly from these voltages. If VIN and VOUT are greater than 5.5V, CBOOST can be charged from VIN or VOUT

minus a zener voltage by placing a zener diode D3 in series with D2, as shown in Figure 11. When using a

series zener diode from the input, ensure that the regulation of the input supply doesn’t create a voltage that falls

outside the recommended VBOOST voltage.

(VINMAX – VD3) < 5.5V (6)

(VINMIN – VD3) > 1.6V (7)

Figure 11. Zener Reduces Boost Voltage from VIN

An alternative method is to place the zener diode D3 in a shunt configuration as shown in Figure 12. A small

350mW to 500mW 5.1V zener in a SOT or SOD package can be used for this purpose. A small ceramic

capacitor such as a 6.3V, 0.1µF capacitor (C4) should be placed in parallel with the zener diode. When the

internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The

0.1 µF parallel shunt capacitor ensures that the VBOOST voltage is maintained during this time.

Resistor R3 should be chosen to provide enough RMS current to the zener diode (D3) and to the BOOST pin. A

recommended choice for the zener current (IZENER) is 1 mA. The current IBOOST into the BOOST pin supplies the

gate current of the NMOS control switch and varies typically according to the following formula:

IBOOST = (D + 0.5) x (VZENER – VD2) mA (8)

where D is the duty cycle, VZENER and VD2 are in volts, and IBOOST is in milliamps. VZENER is the voltage applied to

the anode of the boost diode (D2), and VD2 is the average forward voltage across D2. Note that this formula for

IBOOST gives typical current. For the worst case IBOOST, increase the current by 25%. In that case, the worst case

boost current will be

IBOOST-MAX = 1.25 x IBOOST (9)

Product Folder Links: LM2734Z

LM2734

VIN BOOST

GND

VBOOST

CBOOST

VIN

CIN

VOUT

COUT

LM2734Z

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SNVS334E –JANUARY 2005–REVISED APRIL 2013

R3 will then be given by

R3 = (VIN - VZENER) / (1.25 x IBOOST + IZENER) (10)

For example, let VIN = 10V, VZENER = 5V, VD2 = 0.7V, IZENER = 1mA, and duty cycle D = 50%. Then

IBOOST = (0.5 + 0.5) x (5 - 0.7) mA = 4.3mA (11)

R3 = (10V - 5V) / (1.25 x 4.3mA + 1mA) = 787Ω(12)

Figure 12. Boost Voltage Supplied from the Shunt Zener on VIN

ENABLE PIN / SHUTDOWN MODE

The LM2734Z has a shutdown mode that is controlled by the enable pin (EN). When a logic low voltage is

applied to EN, the part is in shutdown mode and its quiescent current drops to typically 30nA. Switch leakage

adds another 40nA from the input supply. The voltage at this pin should never exceed VIN + 0.3V.

SOFT-START

This function forces VOUT to increase at a controlled rate during start up. During soft-start, the error amplifier’s

reference voltage ramps from 0V to its nominal value of 0.8V in approximately 200µs. This forces the regulator

output to ramp up in a more linear and controlled fashion, which helps reduce inrush current.

OUTPUT OVERVOLTAGE PROTECTION

The overvoltage comparator compares the FB pin voltage to a voltage that is 10% higher than the internal

reference Vref. Once the FB pin voltage goes 10% above the internal reference, the internal NMOS control

switch is turned off, which allows the output voltage to decrease toward regulation.

UNDERVOLTAGE LOCKOUT

Undervoltage lockout (UVLO) prevents the LM2734Z from operating until the input voltage exceeds 2.74V(typ).

The UVLO threshold has approximately 440mV of hysteresis, so the part will operate until VIN drops below

2.3V(typ). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic.

CURRENT LIMIT

The LM2734Z uses cycle-by-cycle current limiting to protect the output switch. During each switching cycle, a

current limit comparator detects if the output switch current exceeds 1.7A (typ), and turns off the switch until the

next switching cycle begins.

Product Folder Links: LM2734Z

L = VO + VD

IO x r x fSx (1-D)

r = 'iL

D = VO + VD

VIN + VD - VSW

D = VO

VIN

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THERMAL SHUTDOWN

Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature

exceeds 165°C. After thermal shutdown occurs, the output switch doesn’t turn on until the junction temperature

drops to approximately 150°C.

Design Guide

INDUCTOR SELECTION

The Duty Cycle (D) can be approximated quickly using the ratio of output voltage (VO) to input voltage (VIN):

(13)

The catch diode (D1) forward voltage drop and the voltage drop across the internal NMOS must be included to

calculate a more accurate duty cycle. Calculate D by using the following formula:

(14)

VSW can be approximated by:

VSW = IOx RDS(ON) (15)

The diode forward drop (VD) can range from 0.3V to 0.7V depending on the quality of the diode. The lower VDis,

the higher the operating efficiency of the converter.

The inductor value determines the output ripple current. Lower inductor values decrease the size of the inductor,

but increase the output ripple current. An increase in the inductor value will decrease the output ripple current.

The ratio of ripple current (ΔiL) to output current (IO) is optimized when it is set between 0.3 and 0.4 at 1A. The

ratio r is defined as:

(16)

One must also ensure that the minimum current limit (1.2A) is not exceeded, so the peak current in the inductor

must be calculated. The peak current (ILPK) in the inductor is calculated by:

ILPK = IO+ΔIL/2 (17)

If r = 0.5 at an output of 1A, the peak current in the inductor will be 1.25A. The minimum specified current limit

over all operating conditions is 1.2A. One can either reduce r to 0.4 resulting in a 1.2A peak current, or make the

engineering judgement that 50mA over will be safe enough with a 1.7A typical current limit and 6 sigma limits.

When the designed maximum output current is reduced, the ratio r can be increased. At a current of 0.1A, r can

be made as high as 0.9. The ripple ratio can be increased at lighter loads because the net ripple is actually quite

low, and if r remains constant the inductor value can be made quite large. An equation empirically developed for

the maximum ripple ratio at any current below 2A is:

r = 0.387 x IOUT-0.3667 (18)

Note that this is just a guideline.

The LM2734Z operates at frequencies allowing the use of ceramic output capacitors without compromising

transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple.

See the OUTPUT CAPACITOR section for more details on calculating output voltage ripple.

Now that the ripple current or ripple ratio is determined, the inductance is calculated by:

(19)

Product Folder Links: LM2734Z

IRMS-OUT = IO x r

'VO = 'iL x (RESR + 1

8 x fS x CO)

IRMS-IN = IO x D x r2

1-D +

LM2734Z

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where fsis the switching frequency and IOis the output current. When selecting an inductor, make sure that it is

capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden

reduction in inductance and prevent the regulator from operating correctly. Because of the speed of the internal

current limit, the peak current of the inductor need only be specified for the required maximum output current. For

example, if the designed maximum output current is 0.5A and the peak current is 0.7A, then the inductor should

be specified with a saturation current limit of >0.7A. There is no need to specify the saturation or peak current of

the inductor at the 1.7A typical switch current limit. The difference in inductor size is a factor of 5. Because of the

operating frequency of the LM2734Z, ferrite based inductors are preferred to minimize core losses. This presents

little restriction since the variety of ferrite based inductors is huge. Lastly, inductors with lower series resistance

(DCR) will provide better operating efficiency. For recommended inductors see Example Circuits.

INPUT CAPACITOR

An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The

primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent

Series Inductance). The recommended input capacitance is 10µF, although 4.7µF works well for input voltages

below 6V. The input voltage rating is specifically stated by the capacitor manufacturer. Make sure to check any

recommended deratings and also verify if there is any significant change in capacitance at the operating input

voltage and the operating temperature. The input capacitor maximum RMS input current rating (IRMS-IN) must be

greater than:

(20)

It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always

calculate the RMS at the point where the duty cycle, D, is closest to 0.5. The ESL of an input capacitor is usually

determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL

and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2734Z, certain

capacitors may have an ESL so large that the resulting impedance (2πfL) will be higher than that required to

provide stable operation. As a result, surface mount capacitors are strongly recommended. Sanyo POSCAP,

Tantalum or Niobium, Panasonic SP or Cornell Dubilier ESR, and multilayer ceramic capacitors (MLCC) are all

good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use

X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to see how rated capacitance varies over

operating conditions.

OUTPUT CAPACITOR

The output capacitor is selected based upon the desired output ripple and transient response. The initial current

of a load transient is provided mainly by the output capacitor. The output ripple of the converter is:

(21)

When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the

output ripple will be approximately sinusoidal and 90° phase shifted from the switching action. Given the

availability and quality of MLCCs and the expected output voltage of designs using the LM2734Z, there is really

no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to

bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic

capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not.

Since the output capacitor is one of the two external components that control the stability of the regulator control

loop, most applications will require a minimum at 10 µF of output capacitance. Capacitance can be increased

significantly with little detriment to the regulator stability. Like the input capacitor, recommended multilayer

ceramic capacitors are X7R or X5R. Again, verify actual capacitance at the desired operating voltage and

temperature.

Check the RMS current rating of the capacitor. The RMS current rating of the capacitor chosen must also meet

the following condition:

(22)

Product Folder Links: LM2734Z

K = POUT

POUT + PLOSS

K = POUT

R1 =VO- 1

VREF x R2

LM2734Z

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CATCH DIODE

The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching

times and low forward voltage drop. The catch diode should be chosen so that its current rating is greater than:

ID1 = IOx (1-D) (23)

The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin.

To improve efficiency choose a Schottky diode with a low forward voltage drop.

BOOST DIODE

A standard diode such as the 1N4148 type is recommended. For VBOOST circuits derived from voltages less than

3.3V, a small-signal Schottky diode is recommended for greater efficiency. A good choice is the BAT54 small

signal diode.

BOOST CAPACITOR

A ceramic 0.01µF capacitor with a voltage rating of at least 6.3V is sufficient. The X7R and X5R MLCCs provide

the best performance.

OUTPUT VOLTAGE

The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and

R1 is connected between VOand the FB pin. A good value for R2 is 10kΩ.

(24)

PCB Layout Considerations

When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The

most important consideration when completing the layout is the close coupling of the GND connections of the CIN

capacitor and the catch diode D1. These ground ends should be close to one another and be connected to the

GND plane with at least two through-holes. Place these components as close to the IC as possible. Next in

importance is the location of the GND connection of the COUT capacitor, which should be near the GND

connections of CIN and D1.

There should be a continuous ground plane on the bottom layer of a two-layer board except under the switching

node island.

The FB pin is a high impedance node and care should be taken to make the FB trace short to avoid noise pickup

and inaccurate regulation. The feedback resistors should be placed as close as possible to the IC, with the GND

of R2 placed as close as possible to the GND of the IC. The VOUT trace to R1 should be routed away from the

inductor and any other traces that are switching.

High AC currents flow through the VIN, SW and VOUT traces, so they should be as short and wide as possible.

However, making the traces wide increases radiated noise, so the designer must make this trade-off. Radiated

noise can be decreased by choosing a shielded inductor.

The remaining components should also be placed as close as possible to the IC. Please see Application Note

AN-1229 for further considerations and the LM2734Z demo board as an example of a four-layer layout.

Calculating Efficiency, and Junction Temperature

The complete LM2734Z DC/DC converter efficiency can be calculated in the following manner.

(25)

(26)

Product Folder Links: LM2734Z

6PCOND + PSW + PDIODE + PIND + PQ + PBOOST = PLOSS

D = VO + VD + VDCR

VIN + VD - VSW

D = VOUT + VD

VIN + VD - VSW

LM2734Z

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SNVS334E –JANUARY 2005–REVISED APRIL 2013

Calculations for determining the most significant power losses are shown below. Other losses totaling less than

2% are not discussed.

Power loss (PLOSS) is the sum of two basic types of losses in the converter, switching and conduction.

Conduction losses usually dominate at higher output loads, where as switching losses remain relatively fixed and

dominate at lower output loads. The first step in determining the losses is to calculate the duty cycle (D).

(27)

VSW is the voltage drop across the internal NFET when it is on, and is equal to:

VSW = IOUT x RDSON (28)

VDis the forward voltage drop across the Schottky diode. It can be obtained from the Electrical Characteristics

section. If the voltage drop across the inductor (VDCR) is accounted for, the equation becomes:

(29)

This usually gives only a minor duty cycle change, and has been omitted in the examples for simplicity.

The conduction losses in the free-wheeling Schottky diode are calculated as follows:

PDIODE = VDx IOUT(1-D) (30)

Often this is the single most significant power loss in the circuit. Care should be taken to choose a Schottky

diode that has a low forward voltage drop.

Another significant external power loss is the conduction loss in the output inductor. The equation can be

simplified to:

PIND = IOUT2x RDCR (31)

The LM2734Z conduction loss is mainly associated with the internal NFET:

PCOND = IOUT2x RDSON x D (32)

Switching losses are also associated with the internal NFET. They occur during the switch on and off transition

periods, where voltages and currents overlap resulting in power loss. The simplest means to determine this loss

is to empirically measuring the rise and fall times (10% to 90%) of the switch at the switch node:

PSWF = 1/2(VIN x IOUT x freq x TFALL) (33)

PSWR = 1/2(VIN x IOUT x freq x TRISE) (34)

PSW = PSWF + PSWR (35)

Table 1. Typical Rise and Fall Times vs Input Voltage

VIN TRISE TFALL

5V 8ns 4ns

10V 9ns 6ns

15V 10ns 7ns

Another loss is the power required for operation of the internal circuitry:

PQ= IQx VIN (36)

IQis the quiescent operating current, and is typically around 1.5mA. The other operating power that needs to be

calculated is that required to drive the internal NFET:

PBOOST = IBOOST x VBOOST (37)

VBOOST is normally between 3VDC and 5VDC. The IBOOST rms current is approximately 4.25mA. Total power

losses are:

(38)

Product Folder Links: LM2734Z

RT = 'T

Power

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

Design Example 1:

Operating Conditions

VIN 5.0V POUT 2.5W

VOUT 2.5V PDIODE 151mW

IOUT 1.0A PIND 75mW

VD0.35V PSWF 53mW

Freq 3MHz PSWR 53mW

IQ1.5mA PCOND 187mW

TRISE 8ns PQ7.5mW

TFALL 8ns PBOOST 21mW

RDSON 330mΩPLOSS 548mW

INDDCR 75mΩ

D0.568

η= 82%

Calculating the LM2734Z Junction Temperature

Thermal Definitions:

TJ= Chip junction temperature

TA= Ambient temperature

RθJC = Thermal resistance from chip junction to device case

RθJA = Thermal resistance from chip junction to ambient air

Figure 13. Cross-Sectional View of Integrated Circuit Mounted on a Printed Circuit Board

Heat in the LM2734Z due to internal power dissipation is removed through conduction and/or convection.

Conduction: Heat transfer occurs through cross sectional areas of material. Depending on the material, the

transfer of heat can be considered to have poor to good thermal conductivity properties (insulator vs conductor).

Heat Transfer goes as:

silicon→package→lead frame→PCB.

Convection: Heat transfer is by means of airflow. This could be from a fan or natural convection. Natural

convection occurs when air currents rise from the hot device to cooler air.

Thermal impedance is defined as:

(39)

Product Folder Links: LM2734Z

6PCOND + PSWF + PSWR + PQ + PBOOST = PINTERNAL

PINTERNAL = 322 mW

TJ = (RTJC x Power) + TC = 80oC/W x 322 mW + TC

RTJA = TJ - TC

Power

RTJA = TJ - TA

Power

LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

Thermal impedance from the silicon junction to the ambient air is defined as:

(40)

This impedance can vary depending on the thermal properties of the PCB. This includes PCB size, weight of

copper used to route traces and ground plane, and number of layers within the PCB. The type and number of

thermal vias can also make a large difference in the thermal impedance. Thermal vias are necessary in most

applications. They conduct heat from the surface of the PCB to the ground plane. Four to six thermal vias should

be placed under the exposed pad to the ground plane if the WSON package is used. If the Thin SOT-6 package

is used, place two to four thermal vias close to the ground pin of the device.

The datasheet specifies two different RθJA numbers for the Thin SOT–6 package. The two numbers show the

difference in thermal impedance for a four-layer board with 2oz. copper traces, vs. a four-layer board with 1oz.

copper. RθJA equals 120°C/W for 2oz. copper traces and GND plane, and 235°C/W for 1oz. copper traces and

GND plane.

Method 1:

To accurately measure the silicon temperature for a given application, two methods can be used. The first

method requires the user to know the thermal impedance of the silicon junction to case. (RθJC) is approximately

80°C/W for the Thin SOT-6 package. Knowing the internal dissipation from the efficiency calculation given

previously, and the case temperature, which can be empirically measured on the bench we have:

(41)

Therefore:

TJ= (RθJC x PLOSS) + TC(42)

Design Example 2:

Operating Conditions

VIN 5.0V POUT 2.5W

VOUT 2.5V PDIODE 151mW

IOUT 1.0A PIND 75mW

VD0.35V PSWF 53mW

Freq 3MHz PSWR 53mW

IQ1.5mA PCOND 187mW

TRISE 8ns PQ7.5mW

TFALL 8ns PBOOST 21mW

RDSON 330mΩPLOSS 548mW

INDDCR 75mΩ

D0.568

(43)

The second method can give a very accurate silicon junction temperature. The first step is to determine RθJA of

the application. The LM2734Z has over-temperature protection circuitry. When the silicon temperature reaches

165°C, the device stops switching. The protection circuitry has a hysteresis of 15°C. Once the silicon

temperature has decreased to approximately 150°C, the device will start to switch again. Knowing this, the RθJA

for any PCB can be characterized during the early stages of the design by raising the ambient temperature in the

given application until the circuit enters thermal shutdown. If the SW-pin is monitored, it will be obvious when the

internal NFET stops switching indicating a junction temperature of 165°C. Knowing the internal power dissipation

from the above methods, the junction temperature and the ambient temperature, RθJA can be determined.

Product Folder Links: LM2734Z

RTJA = 165oC - 94oC

322 mW = 220oC/W

6PCOND + PSWF + PSWR + PQ + PBOOST = PINTERNAL

PINTERNAL = 322 mW

RTJA = 165oC - TA

PINTERNAL

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

(44)

Once this is determined, the maximum ambient temperature allowed for a desired junction temperature can be

found.

Design Example 3:

Operating Conditions

Package SOT-6

VIN 12.0V POUT 2.475W

VOUT 3.30V PDIODE 523mW

IOUT 750mA PIND 56.25mW

VD0.35V PSWF 108mW

Freq 3MHz PSWR 108mW

IQ1.5mA PCOND 68.2mW

IBOOST 4mA PQ18mW

VBOOST 5V PBOOST 20mW

TRISE 8ns PLOSS 902mW

TFALL 8ns

RDSON 400mΩ

INDDCR 75mΩ

D30.3%

(45)

Using a standard Texas Instruments Thin SOT-6 demonstration board to determine the RθJA of the board. The

four layer PCB is constructed using FR4 with 1/2oz copper traces. The copper ground plane is on the bottom

layer. The ground plane is accessed by two vias. The board measures 2.5cm x 3cm. It was placed in an oven

with no forced airflow.

The ambient temperature was raised to 94°C, and at that temperature, the device went into thermal shutdown.

(46)

If the junction temperature was to be kept below 125°C, then the ambient temperature cannot go above 54.2°C.

TJ- (RθJA x PLOSS) = TA(47)

The method described above to find the junction temperature in the Thin SOT-6 package can also be used to

calculate the junction temperature in the WSON package. The 6 pin WSON package has a RθJC = 20°C/W, and

RθJA can vary depending on the application. RθJA can be calculated in the same manner as described in method

#2 (see example 3).

Product Folder Links: LM2734Z

4SW

VIN

BOOST

GND

LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

WSON PACKAGE

The LM2734Z is packaged in a Thin SOT-6 package and the 6–pin WSON. The WSON package has the same

footprint as the Thin SOT-6, but is thermally superior due to the exposed ground paddle on the bottom of the

package.

Figure 14. No Pullback WSON Configuration

RθJA of the WSON package is normally two to three times better than that of the Thin SOT-6 package for a

similar PCB configuration (area, copper weight, thermal vias).

Figure 15. Dog Bone

For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 15). By

increasing the size of ground plane, and adding thermal vias, the RθJA for the application can be reduced.

Design Example 4:

Operating Conditions

Package WSON-6

VIN 12.0V POUT 2.475W

VOUT 3.3V PDIODE 523mW

IOUT 750mA PIND 56.25mW

VD0.35V PSWF 108mW

Freq 3MHz PSWR 108mW

IQ1.5mA PCOND 68.2mW

IBOOST 4mA PQ18mW

VBOOST 5V PBOOST 20mW

TRISE 8ns PLOSS 902mW

TFALL 8ns

RDSON 400mΩ

INDDCR 75mΩ

D30.3%

Product Folder Links: LM2734Z

RTJAa = 165oC - 113oC

322 mW = 161oC/W

6PCOND + PSWF + PSWR + PQ + PBOOST = PINTERNAL

PINTERNAL = 322 mW

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

(48)

This example follows example 2, but uses the WSON package. Using a standard Texas Instruments WSON-6

demonstration board, use Method 2 to determine RθJA of the board. The four layer PCB is constructed using FR4

with 1/2oz copper traces. The copper ground plane is on the bottom layer. The ground plane is accessed by four

vias. The board measures 2.5cm x 3cm. It was placed in an oven with no forced airflow.

The ambient temperature was raised to 113°C, and at that temperature, the device went into thermal shutdown.

(49)

If the junction temperature is to be kept below 125°C, then the ambient temperature cannot go above 73.2°C.

TJ- (RθJA x PLOSS) = TA(50)

Package Selection

To determine which package you should use for your specific application, variables need to be known before you

can determine the appropriate package to use.

1. Maximum ambient system temperature

2. Internal LM2734Z power losses

3. Maximum junction temperature desired

4. RθJA of the specific application, or RθJC (WSON or Thin SOT-6)

The junction temperature must be less than 125°C for the worst-case scenario.

Product Folder Links: LM2734Z

LM2734

VIN VIN

BOOST

GND

VOUT

C3 L1

OFF

C1 R3

LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

LM2734Z Design Examples

Figure 16. VBOOST Derived from VIN

Operating Conditions: 5V to 1.5V/1A

Table 2. Bill of Materials for Figure 16

Part ID Part Value Part Number Manufacturer

U1 1A Buck Regulator LM2734ZX Texas Instruments

C1, Input Cap 10µF, 6.3V, X5R C3216X5ROJ106M TDK

C2, Output Cap 10µF, 6.3V, X5R C3216X5ROJ106M TDK

C3, Boost Cap 0.01uF, 16V, X7R C1005X7R1C103K TDK

D1, Catch Diode 0.3VFSchottky 1A, 10VR MBRM110L ON Semi

D2, Boost Diode 1VF@ 50mA Diode 1N4148W Diodes, Inc.

L1 2.2µH, 1.8A ME3220–222MX Coilcraft

R1 8.87kΩ, 1% CRCW06038871F Vishay

R2 10.2kΩ, 1% CRCW06031022F Vishay

R3 100kΩ, 1% CRCW06031003F Vishay

Product Folder Links: LM2734Z

LM2734

VIN

BOOST

GND

VOUT

C3 L1

OFF

VIN

C1 R3

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

Figure 17. VBOOST Derived from VOUT

12V to 3.3V/1A

Table 3. Bill of Materials for Figure 17

Part ID Part Value Part Number Manufacturer

U1 1A Buck Regulator LM2734ZX Texas Instruments

C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK

C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK

C3, Boost Cap 0.01µF, 16V, X7R C1005X7R1C103K TDK

D1, Catch Diode 0.34VFSchottky 1A, 30VR SS1P3L Vishay

D2, Boost Diode 0.6VF@ 30mA Diode BAT17 Vishay

L1 3.3µH, 1.3A ME3220–332MX Coilcraft

R1 31.6kΩ, 1% CRCW06033162F Vishay

R2 10.0 kΩ, 1% CRCW06031002F Vishay

R3 100kΩ, 1% CRCW06031003F Vishay

Product Folder Links: LM2734Z

LM2734

VIN VIN

BOOST

GND

VOUT

C3 L1

OFF

C1 R3

LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

Figure 18. VBOOST Derived from VSHUNT

18V to 1.5V/1A

Table 4. Bill of Materials for Figure 18

Part ID Part Value Part Number Manufacturer

U1 1A Buck Regulator LM2734ZX Texas Instruments

C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK

C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK

C3, Boost Cap 0.01µF, 16V, X7R C1005X7R1C103K TDK

C4, Shunt Cap 0.1µF, 6.3V, X5R C1005X5R0J104K TDK

D1, Catch Diode 0.4VFSchottky 1A, 30VR SS1P3L Vishay

D2, Boost Diode 1VF@ 50mA Diode 1N4148W Diodes, Inc.

D3, Zener Diode 5.1V 250Mw SOT BZX84C5V1 Vishay

L1 3.3µH, 1.3A ME3220–332MX Coilcraft

R1 8.87kΩ, 1% CRCW06038871F Vishay

R2 10.2kΩ, 1% CRCW06031022F Vishay

R3 100kΩ, 1% CRCW06031003F Vishay

R4 4.12kΩ, 1% CRCW06034121F Vishay

Product Folder Links: LM2734Z

LM2734

VIN VIN

BOOST

GND

VOUT

C3 L1

OFF

C1 R3

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

Figure 19. VBOOST Derived from Series Zener Diode (VIN)

15V to 1.5V/1A

Table 5. Bill of Materials for Figure 19

Part ID Part Value Part Number Manufacturer

U1 1A Buck Regulator LM2734ZX Texas Instruments

C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK

C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK

C3, Boost Cap 0.01µF, 16V, X7R C1005X7R1C103K TDK

D1, Catch Diode 0.4VFSchottky 1A, 30VR SS1P3L Vishay

D2, Boost Diode 1VF@ 50mA Diode 1N4148W Diodes, Inc.

D3, Zener Diode 11V 350Mw SOT BZX84C11T Diodes, Inc.

L1 3.3µH, 1.3A ME3220–332MX Coilcraft

R1 8.87kΩ, 1% CRCW06038871F Vishay

R2 10.2kΩ, 1% CRCW06031022F Vishay

R3 100kΩ, 1% CRCW06031003F Vishay

Product Folder Links: LM2734Z

LM2734

VIN VIN

BOOST

GND

VOUT

C3 L1

OFF

D2 D3

C1 R3

LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

Figure 20. VBOOST Derived from Series Zener Diode (VOUT)

15V to 9V/1A

Table 6. Bill of Materials for Figure 20

Part ID Part Value Part Number Manufacturer

U1 1A Buck Regulator LM2734ZX Texas Instruments

C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK

C2, Output Cap 22µF, 16V, X5R C3216X5R1C226M TDK

C3, Boost Cap 0.01µF, 16V, X7R C1005X7R1C103K TDK

D1, Catch Diode 0.4VFSchottky 1A, 30VR SS1P3L Vishay

D2, Boost Diode 1VF@ 50mA Diode 1N4148W Diodes, Inc.

D3, Zener Diode 4.3V 350mw SOT BZX84C4V3 Diodes, Inc.

L1 2.2µH, 1.8A ME3220–222MX Coilcraft

R1 102kΩ, 1% CRCW06031023F Vishay

R2 10.2kΩ, 1% CRCW06031022F Vishay

R3 100kΩ, 1% CRCW06031003F Vishay

Product Folder Links: LM2734Z

LM2734Z

SNVS334E –JANUARY 2005–REVISED APRIL 2013

www.ti.com

REVISION HISTORY

Changes from Revision D (April 2013) to Revision E Page

• Changed layout of National Data Sheet to TI format .......................................................................................................... 23

Product Folder Links: LM2734Z

PACKAGE OPTION ADDENDUM

www.ti.com 7-Oct-2013

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2734ZMK/NOPB ACTIVE SOT DDC 6 1000 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SFTB

LM2734ZMKX/NOPB ACTIVE SOT DDC 6 3000 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SFTB

LM2734ZQMK/NOPB ACTIVE SOT DDC 6 1000 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SVBB

LM2734ZQMKE/NOPB ACTIVE SOT DDC 6 250 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SVBB

LM2734ZQMKX/NOPB ACTIVE SOT DDC 6 3000 Green (RoHS

& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SVBB

LM2734ZQSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L238B

LM2734ZQSDE/NOPB ACTIVE WSON NGG 6 250 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L238B

LM2734ZQSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L238B

LM2734ZSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L163B

LM2734ZSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS

& no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L163B

(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.

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)

PACKAGE OPTION ADDENDUM

www.ti.com 7-Oct-2013

Addendum-Page 2

(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.

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.

OTHER QUALIFIED VERSIONS OF LM2734Z, LM2734Z-Q1 :

•Catalog: LM2734Z

•Automotive: LM2734Z-Q1

NOTE: Qualified Version Definitions:

•Catalog - TI's standard catalog product

•Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects

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

LM2734ZMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM2734ZMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM2734ZQMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM2734ZQMKE/NOPB SOT DDC 6 250 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM2734ZQMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM2734ZQSD/NOPB WSON NGG 6 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1

LM2734ZQSDE/NOPB WSON NGG 6 250 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1

LM2734ZQSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1

LM2734ZSD/NOPB WSON NGG 6 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1

LM2734ZSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 23-Oct-2013

Pack Materials-Page 1

*All dimensions are nominal

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

LM2734ZMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0

LM2734ZMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0

LM2734ZQMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0

LM2734ZQMKE/NOPB SOT DDC 6 250 210.0 185.0 35.0

LM2734ZQMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0

LM2734ZQSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0

LM2734ZQSDE/NOPB WSON NGG 6 250 213.0 191.0 55.0

LM2734ZQSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0

LM2734ZSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0

LM2734ZSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0

PACKAGE MATERIALS INFORMATION

www.ti.com 23-Oct-2013

Pack Materials-Page 2

MECHANICAL DATA

NGG0006A

www.ti.com

SDE06A (Rev A)

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