IRF IR3811MPbF, IR3811MTRPBF Datasheet

01/08/08

1

PD-60334

IR3811MPbF

HIGHLY INTEGRATED 7A

WIDE-INPUT VOLTAGE, SYNCHRONOUS BUCK REGULATOR

Features

• Wide Input Voltage Range 2.5V to 21V

• Wide Output Voltage Range 0.6V to 12V

• Continuous 7A Load Capability

• 600kHz High Frequency Operation

• Programmable Over-Current-Protection

• Hiccup Current Limit

• Tracking capability for Memory Application

• Precision Reference Voltage (0.6V)

• Programmable Soft-Start

• Pre-Bias Start-up

• Thermal Protection

• Thermally Enhanced Package

• Small Size 5mmx6mm QFN

• Pb-Free (RoHS Compliant)

Fig. 1. Typical application diagram

Description

The IR3811 SupIRBuckTMis an easy-to-use, fully
integrated and highly efficient DC/DC regulator.
The onboard switching controller and MOSFETs
make the IR3811 a space-efficient solution,
providing accurate power delivery for low output
voltage applications.

The IR3811 operates from a single 4.5V to 14V
input supply and generates an output voltage
adjustable from 0.6V to 0.80*Vin at loads up to 7A.

IR3811 can be configured for tracking
applications to generate termination voltage (VTT)
for memory applications.

A versatile regulator offering programmability of
start up time and current limit, the IR3811’s fixed
600kHz switching frequency allows the use of
small external components.

IR3811 also features important protection
functions, such as Pre-Bias startup, hiccup
current limit and thermal shutdown to provide the
required system level security in the event of fault
conditions.

Applications

• Distributed Point-of-Loads

• Server and Workstations

• Embedded Systems

• Storage Systems

• DDR Applications

• Graphics Cards

• Game Consoles

• Computing Peripheral Voltage Regulators

SupIRBuck

TM

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PD-60334

IR3811MPbF

PACKAGE INFORMATION

5mm x 6mm POWER QFN

Fig. 2: Package outline (Top view)

W/C2θ

W/C35θ

o

PCBJ

o

JA

=

=

-

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND)

•VINSupply Voltage -0.3V to 24V

• Vcc Supply Voltage -0.3V to 16V

• Vc Supply Voltage -0.3V to 30V

• SW -0.3V to 30V

• PGood -0.3V to 16V

• Fb,COMP,SS,Vsns -0.3V to 3.5V

•OCSet 10mA

• AGnd to PGnd -0.3V to +0.3V

• Storage Temperature Range -65°C To 150°C

• Operating Junction Temperature Range -40°C To 150°C

• ESD Classification JEDEC, JESD22-A114

• Moisture Sensitivity Level JEDEC Level 3 @ 260

o

C

Caution: Stresses beyond those listed under “Absolute Maximum Rating” may cause permanent damage to the

device. These are stress ratings only and functional operation of the device at these or any other conditions beyond
those indicated in the operational sections of the specifications is not implied. Exposure to “Absolute Maximum
Rating” conditions for extended periods may affect device reliability.

4000

PARTS

PER REEL

---------------

PARTS

PER TUBE

15

PIN

COUNT

IR3811MTRPBF

PACKAGE

DESCRIPTION

M

PKG

DESIG

ORDERING INFORMATION

12

V

IN

11

SW

10

PGnd

15

AGnd

1

23

4

5

6

7

8

9

14

13

Vp FB COMP AGnd AGnd SS OCSet

Vref

V

CC

HG

Vc

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PD-60334

IR3811MPbF

Block Diagram

Fig. 3. Simplified block diagram of the IR3811.

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PD-60334

IR3811MPbF

Pin Description

Pins 4, 5 and 15 need to be connected together on system board.

Pin Name Description

1 Vp Non-inverting input of error amplifier. This pin can be used for tracking application.

2 Fb Inverting input to the error amplifier. This pin is connected directly to the output of

the regulator via resistor divider to set the output voltage and provide feedback to
the error amplifier.

3 Comp Output of error amplifier. An external resistor and capacitor network is typically

connected from this pin to ground to provide loop compensation.

4 AGnd Signal ground for internal reference and control circuitry.

5 AGnd Signal ground for internal reference and control circuitry.

6 SS/SD Soft start / shutdown. This pin provides user programmable soft-start function.

Connect an external capacitor from this pin to ground to set the start up time of the
output voltage. The converter can be shutdown by pulling this pin below 0.3V.

7 OCSet Current limit set point. A resistor from this pin to SW pin will set the current limit

threshold.

8

V

CC

This pin powers the internal IC as well as low side driver. A minimum of 0.1uF high
frequency capacitor must be connected from this pin to the power ground.

9 Vref

External reference voltage. Drive capability for this pin is 2μA.

10 PGnd Power Ground. This pin serves as a separated ground for the MOSFET drivers and

should be connected to the system’s power ground plane.

11 SW Switch node. This pin is connected to the output inductor

12

V

IN

Input voltage connection pin

13 HG This pin is connected to the high side gate driver. Connect a small capacitor from

this pin to switch node (SW).

14

V

C

This pin powers the high side driver and must be connected to a voltage higher than
input voltage. A minimum of 0.1uF high frequency capacitor must be connected
from this pin to the power ground for the charge-pump high side drive scheme.

15 AGnd Signal ground for internal reference and control circuitry.

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IR3811MPbF

Recommended Operating Conditions

Parameter Symbol Test Condition Min TYP MAX Units

Power Loss

Power Loss

P

loss

Vcc=Vin=12V, Vc=24V, Vo=1.8V,

I

o

=7A, L=1uH, Note3

2.1 W

MOSFET R

ds(on)

Top Switch R

ds(on)_Top

ID=9A, Tj(MOSFET)=25oC

10.5 13.4

Bottom Switch R

ds(on)_Bot

ID=9A, Tj(MOSFET)=25oC

10.5 13.4

mΩ

Reference Voltage

Feedback Voltage VFB 0.6 V

0oC<Tj<105oC -1.35 +1.35 % Accuracy

-40

o

C<Tj<105oC,

Note2

-1.5 +1.5 %

Supply Current

VCC Supply Current (Static)

I

CC(Static)

SS=0V, No Switching 10 13

VC Supply Current
(Static)

I

C(Static)

SS=0V, No Switching 4.5 7

VCC Supply Current
(Dynamic)

I

CC(Dynamic)

SS=3V, Vc=24V, Vcc=Vin=12V.

V

o

=1.8V, Io= 0A

18 25

VC Supply Current
(Dynamic)

I

C(Dynamic)

SS=3V, Vc=24V, Vcc=Vin=12V.

V

o

=1.8V, Io= 0A

18 25

mA

Under Voltage Lockout

VCC-Start-Threshold VCC_UVLO(R) Supply ramping up 4.0 4.4
VCC-Stop-Threshold VCC_UVLO(F) Supply ramping down 3.7 4.1
VCC-Hysteresis Supply ramping up and down 0.15 0.25 0.3
VC-Start-Threshold VC_UVLO(R)

Supply ramping up 3.1 3.5
VC-Stop-Threshold VC_UVLO(F) Supply ramping down 2.85 3.25
VC-Hysteresis Supply ramping up and down 0.15 0.2 0.25

V

Electrical Specifications

Unless otherwise specified, these specification apply over Vin=Vcc=Vc=12V, 0oC<Tj(Ic)< 105oC.
Typical values are specified at T

a

= 25oC.

Symbol Definition Min Max Units

Vin Input Voltage 2.5 21
Vcc Supply Voltage 4.5 14
Vc Supply Voltage Vin + 5V 28
Vo Output Voltage 0.6 12

V

I

o

Note1

Output Current 0 7 A

Tj Junction Temperature -40 125

o

C

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IR3811MPbF

Parameter SYM Test Condition Min TYP MAX Units

Oscillator

Frequency FS

540 600 660 kHz

Ramp Amplitude V

ramp

Note3

1.25 V

Min Pulse Width D

min(ctrl)

Note3

80 ns

Max Duty Cycle D

max

Fb=0V 75 %

Error Amplifier

Input Bias Current I

FB1

SS=3V -0.1 -0.5

Input Bias Current IVp SS=3V -0.1 -0.5

Input Bias Current I

FB2

SS=0V 30 50 70

Source/Sink Current I(source/Sink) 50 70 90

μA

Transconductance gm 1000 1300 1600

μmho

Input Offset Voltage Vos Fb to Vp -4.5 0 +4.5 mV

Vp( (Common Mode Range) 0.2 1.0 V

Soft Start/SD

Soft Start Current ISS SS=0V 15 20 28

μA

Shutdown Output Threshold SD 0.25 V

Over Current Protectio n

OCSET Current I

OCSET

15 20 26

Hiccup Current I

Hiccup

Note3

3

μA

Hiccup Duty Cycle Hiccup(duty)

I

Hiccup

/ I

SS

,

Note3

15 %

Thermal Shutdown

Thermal Shutdown Thres hold

Note3

140

Thermal Shutdown Hysteresis

Note3

20

o

C

Note1: Continuous output current determined by input and ou tput voltag e s et ting a nd the the rm al environment.
Note2: Cold temperature performance is guaranteed via correlation using statistical quality control. Not tested in production.
Note3: Guaranteed by Design but not tested in production.

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IR3811MPbF

TYPICAL OPERATING CHARACTERISTICS (-40oC - 125oC)

Icc(static)

7.0

8.0

9.0

10.0

11.0

12.0

13.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[mA]

Ic(static)

2.0

3.0

4.0

5.0

6.0

7.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[mA]

Icc(dynamic)

13.0

15.0

17.0

19.0

21.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[mA]

Ic(dynamic)

13.0

15.0

17.0

19.0

21.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[mA]

Vfb

585.0

590.0

595.0

600.0

605.0

-40-200 20406080100120

Temp[oC]

[mV]

ISS

15.0

17.0

19.0

21.0

23.0

25.0

27.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[uA]

Transconductance

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

1.55

1.60

-40-200 20406080100120

Tem p[oC]

[mmho]

IOCSET

15.0

16.0

17.0

18.0

19.0

20.0

21.0

22.0

23.0

24.0

25.0

26.0

-40 -20 0 20 40 60 80 100 120

Temp[oC]

[uA]