Datasheet LM2725MX, LM2725MWC, LM2725M, LM2725MDC Datasheet (NSC)

LM2725/LM2726
High Speed Synchronous MOSFET Drivers

General Description

The LM2725/LM2726 is a family of dual MOSFET drivers
that can drive both the top MOSFET and bottom MOSFET in
a push-pull structure simultaneously. It takes a logic level
PWM input and splits it into two complimentary signals with
a typical 20ns dead time in between. The built-in
shoot-through protection circuitry prevents the top and bot­tom FETs from turning on simultaneously. With a bias volt­age of 5V, the peak sourcing and sinking current for each
driver of the LM2725 is about 1.2AandthatoftheLM2726is
about 3A. In an SO-8 package, each driver is able to handle
50mA average current. Input UVLO
(Under-Voltage-Lock-Out) ensures that all the driver outputs
stay low until the supply rail exceeds the power-on threshold
during system power on, or after the supply rail drops below
power-on threshold by a specified hysteresis during system
power down. The cross-conduction protection circuitry de­tects both the driver outputs and will not turn on a driver until
the other driver output is low. The top gate bias voltage

needed by the top MOSFET can be obtained through an
external bootstrap structure. Minimum pulse width is as low
as 55ns.

Features

n High peak output current
n Adaptive shoot-through protection
n 36V SW pin absolute maximum voltage
n Input Under-Voltage-Lock-Out
n Typical 20ns internal delay
n Plastic 8-pin SO package

Applications

n High Current DC/DC Power Supplies
n High Input Voltage Switching Regulators
n Microprocessors

Typical Application

Connection Diagram

DS200072-1

8-Lead Small Outline Package

DS200072-2

Top View

November 2000

LM2725/LM2726 High Speed Synchronous MOSFET Drivers

© 2000 National Semiconductor Corporation DS200072 www.national.com

Ordering Information

Order Number Package Type NSC Package Drawing Supplied As

LM2725 LM2725M

M08A

95 Units/Rail

LM2725MX 2500 Units/Reel

LM2726 LM2726M 95 Units/Rail

LM2726MX 2500 Units/Reel

Pin Description

Pin Name Function

1 SW Top driver return. Should be connected to the common node of

top and bottom FETs
2 HG Top gate drive output
3 CBOOT Bootstrap. Accepts a bootstrap voltage for powering the high-side

driver
4 PWM_IN Accepts a 5V-logic control signal
5 EN Chip Enable
6 VCC Connect to +5V supply
7 LG Bottom gate drive output
8 GND Ground

Block Diagram

DS200072-4

LM2725/LM2726

www.national.com 2

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the NationalSemiconductorSales Office/
Distributors for availability and specifications.

VCC 7.5V
CBOOT 42V
CBOOT to SW 8V
SW to PGND 36V
Junction Temperature +150˚C
Power Dissipation

(Note 2) 720mW

Storage Temperature −65˚ to 150˚C
ESD Susceptibility

Human Body Model (Note 3) 1 kV

Soldering Time, Temperature 10sec., 300˚C

Operating Ratings (Note 1)

VCC 4V to 7V
Junction Temperature Range 0˚ to 125˚C

Electrical Characteristics
LM2725

VCC = CBOOT = 5V, SW = GND = 0V, unless otherwise specified. Typicals and limits appearing in plain type apply for T

A

=TJ= +25˚C. Limits appearing in boldface type apply over the entire operating temperature range.

Symbol Parameter Condition Min Typ Max Units

POWER SUPPLY

I

q_op

Operating Quiescent
Current

PWM_IN = 0V

180 250

µA

I

q_sd

Shutdown Quiescent
Current

EN = 0V, PWM_IN = 0V

0.5 15 µA

TOP DRIVER

Peak Pull-Up Current Test Circuit 1, V

bias

= 5V,

R = 0.1Ω

1.2 A

Pull-Up Rds_on I

CBOOT=IHG

= 0.7A 2.4 Ω

Peak Pull-down Current Test Circuit 2, V

bias

= 5V,

R = 0.1Ω

−1.0 A

Pull-down Rds_on I

SW=IHG

= 0.7A 1.4 Ω

t

4

Rise Time Timing Diagram, C

LOAD

=

3.3nF

17 ns

t

6

Fall Time 10 ns

t

3

Pull-Up Dead Time Timing Diagram 23 ns

t

5

Pull-Down Delay Timing Diagram, from

PWM_IN Falling Edge

21 ns

BOTTOM DRIVER

Peak Pull-Up Current Test Circuit 3, V

bias

= 5V,

R = 0.1Ω

1.2 A

Pull-up Rds_on I

VCC=ILG

= 0.7A 2.6 Ω

Peak Pull-down Current Test Circuit 4, V

bias

= 5V,

R = 0.1Ω

−2 A

Pull-down Rds_on I

GND=ILG

= 0.7A 0.65 Ω

t

8

Rise Time Timing Diagram, C

LOAD

=

3.3nF

18 ns

t

2

Fall Time 6 ns

t

7

Pull-up Dead Time Timing Diagram 28 ns

t

1

Pull-down Delay Timing Diagram, from

PWM_IN Rising Edge

15 ns

LOGIC

V

uvlo_up

Power On Threshold VCC rises from 0V toward

5V

3.0 V

V

uvlo_dn

Under-Voltage-Lock-Out
Threshold

2.5 V

V

uvlo_hys

Under-Voltage-Lock-Out
Hysteresis

0.5 V

LM2725/LM2726

www.national.com3

Electrical Characteristics
LM2725

(Continued)

VCC = CBOOT = 5V, SW = GND = 0V, unless otherwise specified. Typicals and limits appearing in plain type apply for T

A

=TJ= +25˚C. Limits appearing in boldface type apply over the entire operating temperature range.

Symbol Parameter Condition Min Typ Max Units

LOGIC

V

IH_EN

EN Pin High Input 2.4 V

V

IL_EN

EN Pin Low Input 0.8 V

I

leak_EN

EN Pin Leakage Current EN = VCC = 5V −2 2

µA

VCC = 5V, EN = 0V −2 2

t

on_min

Minimum Positive Input
Pulse Width
(Note 4)

55

ns

t

off_min

Minimum Negative Input
Pulse Width
(Note 5)

55

V

IH_PWM

PWM_IN High Level
Input Voltage

When PWM_IN pin goes
high from 0V

2.4

V

V

IL_PWM

PWM_IN Low Level
Input Voltage

When PWM_IN pin goes
low from 5V

0.8

Electrical Characteristics
LM2726

VCC = CBOOT = 5V, SW = GND = 0V, unless otherwise specified. Typicals and limits appearing in plain type apply for T

A

=TJ= +25˚C. Limits appearing in boldface type apply over the entire operating temperature range.

Symbol Parameter Condition Min Typ Max Units

POWER SUPPLY

I

q_op

Operating Quiescent
Current

PWM_IN = 0V

185 250

µA

I

q_sd

Shutdown Quiescent
Current

EN = 0V, PWM_IN = 0V

0.5 15 µA

TOP DRIVER

Peak Pull-Up Current Test Circuit 1, V

bias

= 5V,

R = 0.1Ω

3.0 A

Pull-Up Rds_on I

CBOOT=IHG

= 1.0A 1.2 Ω

Peak Pull-down Current Test Circuit 2, V

bias

= 5V,

R = 0.1Ω

−3.2 A

Pull-down Rds_on I

SW=IHG

= 1.0A 0.5 Ω

t

4

Rise Time Timing Diagram, C

LOAD

=

3.3nF

17 ns

t

6

Fall Time 12 ns

t

3

Pull-Up Dead Time Timing Diagram 19 ns

t

5

Pull-Down Delay Timing Diagram, from

PWM_IN from Falling Edge

27 ns

BOTTOM DRIVER

Peak Pull-Up Current Test Circuit 3, V

bias

= 5V,

R = 0.1Ω

3.2 A

Pull-up Rds_on I

VCC=ILG

= 1.0A 1.1 Ω

Peak Pull-down Current Test Circuit 4, V

bias

= 5V,

R = 0.1Ω

−3.2 A

Pull-down Rds_on I

GND=ILG

= 1.0A 0.6 Ω

t

8

Rise Time Timing Diagram, C

LOAD

=

3.3nF

17 ns

t

2

Fall Time 14 ns

t

7

Pull-up Dead Time Timing Diagram 12 ns

LM2725/LM2726

www.national.com 4

Electrical Characteristics
LM2726

(Continued)

VCC = CBOOT = 5V, SW = GND = 0V, unless otherwise specified. Typicals and limits appearing in plain type apply for T

A

=TJ= +25˚C. Limits appearing in boldface type apply over the entire operating temperature range.

Symbol Parameter Condition Min Typ Max Units

BOTTOM DRIVER

t

1

Pull-down Delay Timing Diagram, from

PWM_IN Rising Edge

13 ns

LOGIC

V

uvlo_up

Power On Threshold VCC rises from 0V toward

5V

2.8 V

V

uvlo_dn

Under-Voltage-Lock-Out
Threshold

2.5 V

V

uvlo_hys

Under-Voltage-Lock-Out
Hysteresis

0.3 V

V

IH_EN

EN Pin High Input 2.4 V

V

IL_EN

EN Pin Low Input 0.25 V

I

leak_EN

EN Pin Leakage Current EN = VCC = 5V −2 2

µA

VCC = 5V, EN = 0V −2 2

t

on_min

Minimum Positive Input
Pulse Width
(Note 4)

55

ns

t

off_min

Minimum Negative Input
Pulse Width
(Note 5)

55

V

IH_PWM

PWM_IN High Level
Input Voltage

When PWM_IN pin goes
high from 0V

2.4

V

V

IL_PWM

PWM_IN Low Level
Input Voltage

When PWM_IN pin goes
low from 5V

0.25

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating ratings are conditions under which the device operates

correctly. Operating Ratings do not imply guaranteed performance limits.
Note 2: Maximum allowable power dissipation is a function of the maximum junction temperature, T

JMAX

, the junction-to-ambient thermal resistance, θJA, and the

ambient temperature, T

A

. The maximum allowable power dissipation at any ambient temperature is calculated using: P

MAX

=(T

JMAX-TA

)/θJA. The junction-to-

ambient thermal resistance, θ

JA

, for LM2725/LM2726 is 172˚C/W. For a T

JMAX

of 150˚C and TAof 25˚C, the maximum allowable power dissipation is 0.7W.

Note 3: ESD machine model susceptibility is 100V.
Note 4: If after a rising edge, a falling edge occurs sooner than the specified value, the IC may intermittently fail to turn on the bottom gate when the top gate isoff.

As the falling edge occurs sooner and sooner, the driver may start to ignore the pulse and produce no output.
Note 5: If after a falling edge, a rising edge occurs sooner than the specified value, the IC may intermittently fail to turn on the top gate when the bottom gate isoff.

As the rising edge occurs sooner and sooner, the driver may start to ignore the pulse and produce no output.

LM2725/LM2726

www.national.com5

Timing Diagram

DS200072-3

LM2725/LM2726

www.national.com 6

Test Circuits

DS200072-5

Test Circuit 1

DS200072-6

Test Circuit 2

DS200072-7

Test Circuit 3

DS200072-8

Test Circuit 4

LM2725/LM2726

www.national.com7

Typical Waveforms

DS200072-13

FIGURE 1. Switching Waveforms of Test Circuit

DS200072-14

FIGURE 2. When Input Goes High

DS200072-15

FIGURE 3. When Input Goes Low

DS200072-16

FIGURE 4. Minimum Positive Pulse

LM2725/LM2726

www.national.com 8

Physical Dimensions inches (millimeters) unless otherwise noted

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COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.

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8-Lead Small Outline Package

NS Package Number M08A

LM2725/LM2726 High Speed Synchronous MOSFET Drivers

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.