International Rrectifier IR3841WMPbF User Manual

SupIRBuck

TM

INTEGRATED 8A SYNCHRONOUS BUCK REGULATOR

Features

• Greater than 96% Maximum Efficiency

• Wide Input Voltage Range 1.5V to 16V

• Wide Output Voltage Range 0.7V to 0.9*Vin

• Continuous 8A Load Capability

• Integrated Bootstrap-diode

• High Bandwidth E/A for excellent transient

performance

• Programmable Switching Frequency up to 1.5MHz

• Programmable Over Current Protection

• PGood output

• Hiccup Current Limit

• Precision Reference Voltage (0.7V, +/-1%)

• Programmable Soft-Start

• Enable Input with Voltage Monitoring Capability

• Enhanced Pre-Bias Start-up

• Seq input for Tracking applications

o

• -40

• Thermal Protection

• Pin compatible option for 4A,12A, and 14A devices

• 5mm x 6mm Power QFN Package, 0.9 mm height

• Lead-free, halogen-free and RoHS compliant

C to 125oC operating junction temperature

IR3841WMPbF

HIGHLY EFFICIENT

Description

The IR3841W SupIRBuck
fully integrated and highly efficient DC/DC
synchronous Buck regulator. The MOSFETs co­packaged with the on-chip PWM controller make
IR3841W a space-efficient solution, providing
accurate power delivery for low output voltage
applications.

IR3841W is a versatile regulator which offers
programmability of start up time, switching
frequency and current limit while operating in
wide input and output voltage range.

The switching frequency is programmable from
250kHz to 1.5MHz for an optimum solution.

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

TM

is an easy-to-use,

Applications

• Server Applications

• Storage Applications

• Embedded Telecom Systems

1.5V <Vin<16V

4.5V <Vcc<5.5V

PGood

Seq

Vcc

PGood

Rt

SS/ SD

Enable

Gnd

• Distributed Point of Load Power Architectures

• Netcom Applications

• Computing Peripheral Voltage Regulators

• General DC-DC Converters

Vin

Boot

SW

OCSet

Fb

Comp

PGnd

Vo

Rev 5.0

Fig. 1. Typical application diagram

1

IR3841WMPbF

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND unless otherwise specified)

• Vin ……………………………………………………. -0.3V to 25V

• Vcc ……………….….…………….……..……….…… -0.3V to 8V (Note2)

• Boot ……………………………………..……….…. -0.3V to 33V

• SW …………………………………………..……… -0.3V to 25V(DC), -4V to 25V(AC, 100ns)

• Boot to SW ……..…………………………….…..….. -0.3V to Vcc+0.3V (Note1)

• OCSet ………………………………………….……. -0.3V to 30V, 30mA

• Input / output Pins ……………………………….. ... -0.3V to Vcc+0.3V (Note1)

• PGND to GND ……………...………………………….. -0.3V to +0.3V

• Storage Temperature Range ................................... -55°C To 150°C

• Junction Temperature Range ................................... -40°C To 150°C (Note2)

• ESD Classification …………………………… ……… JEDEC Class 1C

• Moisture sensitivity level………………...………………JEDEC Level 3@260 °C

Note1: Must not exceed 8V
Note2: Vcc must not exceed 7.5V for Junction Temperature between -10

o

C and -40oC

Stresses beyond those listed under “Absolute Maximum Ratings” 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 are not implied.

PACKAGE INFORMATION

15

Gnd

4

SW

11

PGnd

10

=

JA

-

PCBJ

V

9

8

5

7

6

CC

PGood

5mm x 6mm POWER QFN

ORDERING INFORMATION

V

IN

Boot

Enable

12

13

14

1

23

Seq FB COMP Gnd Rt SS OCSet

=

o

W/C35θ

o

W/C2θ

Rev 5.0

PACKAGE

DESIGNATOR

M

PACKAGE

DESCRIPTION

IR3841WMTR1PbF

PIN COUNT

15

PARTS PER

REEL

400015IR3841WMTRPbFM

750

2

Block Diagram

IR3841WMPbF

Rev 5.0

Fig. 2. Simplified block diagram of the IR3841W

3

Pin Description

Pin Name Description

1 Seq

2 Fb

3 Comp

4 Gnd Signal ground for internal reference and control circuitry.

5 Rt

6 SS/SD¯¯

7 OCSet

Sequence pin. Use two external resistors to set Simultaneous Power up
sequencing. If this pin is not used connect to Vcc.

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.
Output of error amplifier. An external resistor and capacitor network is
typically connected from this pin to Fb pin to provide loop
compensation.

Set the switching frequency. Connect an external resistor from this pin
to Gnd to set the switching frequency.

Soft start / shutdown. This pin provides user programmable soft-start
function. Connect an external capacitor from this pin to Gnd to set the
start up time of the output voltage. The converter can be shutdown by
pulling this pin below 0.3V.

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

IR3841WMPbF

8 PGood

9

10 PGnd

11

12

13 Boot

14 Enable

15 Gnd Signal ground for internal reference and control circuitry.

V

CC

SW

V

IN

Power Good status pin. Output is open drain. Connect a pull up resistor
from this pin to Vcc. If unused, it can be left open.

This pin powers the internal IC and the drivers. A minimum of 1uF high
frequency capacitor must be connected from this pin to the power
ground (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.

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

Input voltage connection pin.

Supply voltage for high side driver. A 0.1uF capacitor must be
connected from this pin to SW.
Enable pin to turn on and off the device. Use two external resistors to
set the turn on threshold (see Enable section). Connect this pin to Vcc if
it is not used.

Rev 5.0

4

IR3841WMPbF

Recommended Operating Conditions

Symbol Definition Min Max Units

V

mΩ

%

Vin Input Voltage 1.5 16
Vcc Supply Voltage 4.5 5.5
Boot to SW Supply Voltage 4.5 5.5
Vo Output Voltage 0.7 0.9*Vin
Io Output Current 0 8 A
Fs Switching Frequency 225 1650 kHz
Tj Junction Temperature -40 125 oC

Electrical Specifications

Unless otherwise specified, these specification apply over 4.5V< Vcc<5.5V, Vin=12V, 0oC<Tj< 125oC.
Typical values are specified at T

Parameter Symbol Test Condition Min TYP MAX Units

Power Loss

Power Loss

MOSFET R

Top Switch R

Bottom Switch

Reference Voltage

Feedback Voltage VFB 0.7 V

ds(on)

= 25oC.

a

P

Vcc=5V, Vin=12V, Vo=1.8V, Io=8A,

ds(on)_Top

R

ds(on)_Bot

loss

Fs=600kHz, L=1uH, Note4

V

=5V, ID=10A,

Boot -Vsw

Vcc=5V, ID=10A,

0oC<Tj<125oC -1.0 +1.0 Accuracy

o

-40

C<Tj<125oC,

Tj=25oC

Note3

Tj=25oC

-2.0 +2.0

1.5 W

17.8 26.5

8.5 10.7

Supply Current

VCC Supply Current (Standby)

Vcc Supply Current (Dyn) I

Under Voltage Lockout

VCC-Start-Threshold VCC_UVLO_Start

VCC-Stop-Threshold VCC_UVLO_Stop Vcc Falling Trip Level 3.65 3.85 4.05

Enable-Start-Threshold Enable_UVLO_Start

Enable-Stop-Threshold Enable_UVLO_Stop Supply ramping down 0.9 1.0 1.06

Enable leakage current Ien Enable=3.3V 15

I

SS=0V, No Switching, Enable low 500

CC(Standby)

SS=3V, Vcc=5V, Fs=500kHz

CC(Dyn)

Enable high

Vcc Rising Trip Level 3.95 4.15 4.35

Supply ramping up 1.14 1.2 1.36

12 mA

μA

μA

V

Rev 5.0

5

IR3841WMPbF

Electrical Specifications (continued)

Unless otherwise specified, these specification apply over 4.5V< Vcc<5.5V, Vin=12V, 0oC<Tj< 125oC.
Typical values are specified at T

Parameter Symbol Test Condition Min TYP MAX Units

Oscillator

Rt Voltage

Frequency F

Accuracy -10 +10 %

Ramp Amplitude Vramp

Ramp Offset Ramp (os)

Min Pulse Width Dmin(ctrl)

Fixed Off Time

Max Duty Cycle Dmax Fs=250kHz 92 %

Error Amplifier

Input Offset Voltage Vos Vfb-Vseq,

Input Bias Current IFb(E/A) -1 +1

Input Bias Current IVp(E/A) -1 +1

Sink Current Isink(E/A) 0.40 0.85 1.2

Source Current Isource(E/A) 8 10 13

Slew Rate SR

Gain-Bandwidth Product GBWP

DC Gain Gain

Maximum Voltage Vmax(E/A)

Minimum Voltage Vmin(E/A)

Common Mode Voltage

Soft Start/SD

Soft Start Current ISS Source 14 20 26

Soft Start Clamp Voltage Vss(clamp) 2.7 3.0 3.3

Shutdown Output Threshold SD 0.3

Over Current Protection

OCSET Current I

OC Comp Offset Voltage V

SS off time SS_Hiccup 4096 Cycles

Bootstrap Diode

Forward Voltage I(Boot)=30mA 180 260 470 mV

Deadband

Deadband time

S

OCSET

OFFSET

= 25oC.

a

Rt=59K 225 250 275

Rt=28.7K 450 500 550

Rt=9.31K, Note4

Note4

Note4

Note4

Note4

Vseq=0.8V

Note4

Note4

Note4

Vcc=4.5V

Note4

Fs=250kHz 20.8 23.6 26.4

Fs=500kHz 43 48.8 54.6

Fs=1500kHz 136 154 172

Note4

Note4

0.665 0.7 0.735 V

1350 1500 1650

1.8 Vp-p

0.6 V

50

130 200

-10 0 +10 mV

7 12 20

20 30 40 MHz

100 110 120 dB

3.4 3.5 3.75 V

120 220 mV

0 1 V

-10 0 +10 m V

5 10 30 ns

kHz

ns

μA

mA

V/μs

μA

V

μA

Rev 5.0

6

IR3841WMPbF

Electrical Specifications (continued)

Unless otherwise specified, these specification apply over 4.5V< Vcc<5.5V, Vin=12V, 0oC<Tj< 125oC.
Typical values are specified at T

Parameter SYM Test Condition Min TYP MAX Units

Thermal Shutdown

Thermal Shutdown

Hysteresis

Power Good

Power Good upper
Threshold
Upper Threshold
Delay
Power Good lower
Threshold
Lower Threshold
Delay
Delay Comparator
Threshold
Delay Comparator
Hysteresis
PGood Voltage Low PG(voltage) I

Leakage Current I

Switch Node

VPG(upper) Fb Rising 0.770 0.805 0.840 V

VPG(upper)_Dly Fb Rising 256/Fs s

VPG(lower) Fb Falling 0.560 0.595 0.630 V

VPG(lower)_Dly Fb Falling 256/Fs s

PG(Delay) Relative to charge voltage, SS rising 2 2.1 2.3 V

Delay(hys) Note4 260 300 340 mV

leakage

Isw

= 25oC.

a

Note4 140

Note4 20

=-5mA 0.5 V

PGood

0 10

SW=0V, Enable=0V SW Bias Current

SW=0V,Enable=high,SS=3V,Vseq=0V
, Note4

6

o

μA

μA

C

Note3: Cold temperature performance is guaranteed via correlation using statistical quality control. Not tested in production.

Note4: Guaranteed by Design but not tested in production.

Rev 5.0

7

IR3841WMPbF

Typical Efficiency and Power Loss Curves
Vin=12V, Vcc=5V, Io=1A-8A, F

=600kHz, Room Temperature, No Air Flow

s

The table below shows the inductors used for each of the output voltages
in the efficiency measurement.

Vo (V) L (uH) P/N DCR (mOhm)

0.7 0.4 59PR9875N 0.29

0.8 0.4 59PR9875N 0.29

0.9 0.4 59PR9875N 0.29

1.0 0.5 59PR9876N 0.29

1.1 0.5 59PR9876N 0.29

1.2 0.6 MPL104-0R6 1.50

1.5 0.9 MPC1040LR88 2.30

1.8 0.9 MPC1040LR88 2.30

2.5 1.0 MPL105-1R0IR 2.30

3.3 1.2 MPL105-1R0IR 2.30

5.0 1.5 MPL105-1R0IR 2.30

98

96

94

92

90

88

86

Efficiency (%)

84

82

80

12345678

Load Current (A)

0.9V 1.0V 1.1V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V

2.1

1.9

1.7

1.5

1.3

1.1

0.9

Power Loss (W)

0.7

0.5

0.3

0.1
12345678

Load Current (A)

0.9V 1.0V 1.1V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V

Rev 5.0

8

Typical Efficiency and Power Loss Curves
Vin=5V, Vcc=5V, Io=1A-8A, F

For all the output voltages, L=0.51uH (DCR=0.29 mΩ, P/N: 59PR9876N)

97

95

93

91

89

=600kHz, Room Temperature, No Air Flow

s

IR3841WMPbF

Efficiency (%)

87

85

83

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Load Current (A)

0.7V 0.75V 0.9V 1.0V 1.1V 1.2V 1.5V 1.8V 2.5V 3.3V

1.7

1.5

1.3

1.1

0.9

0.7

Power Loss (W)

0.5

Rev 5.0

0.3

0.1

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Load Current (A)

0.7V 0.75V 0.9V 1.0V 1.1V 1.2V 1.5V 1.8V 2.5V 3.3V

9

IR3841WMPbF

TYPICAL OPERATING CHARACTERISTICS (-40oC - 125oC) Fs=500 kHz

Icc(Standby)

290

270

250

230

[uA]

210

190

170

150

-40 -20 0 20 40 60 80 100 120

550

540

530

520

510

500

[kHz]

490

480

470

460

450

-40 -20 0 20 40 60 80 100 120

4.46

4.41

4.36

4.31

4.26

[V]

4.21

4.16

4.11

4.06

-40-200 20406080100120

Temp[ oC]

FREQUENCY

o

Temp[

Vcc(UVLO) Start

C]

Temp[ oC]

1.36

Enable(UVLO) Start

1.34

1.32

1.30

1.28

1.26

[V]

1.24

1.22

1.20

1.18

1.16

1.14

-40 -20 0 20 40 60 80 100 120

Temp[ oC]

26.0

24.0

22.0

20.0

[uA]

18.0

16.0

14.0

-40-200 20406080100120

ISS

Temp[ oC]

12.5

12.4

12.3

12.2

12.1

12.0

[mA]

11.9

11.8

11.7

11.6

11.5

-40-20 0 20406080100120

54.0

53.0

52.0

51.0

50.0

49.0

[uA]

48.0

47.0

46.0

45.0

44.0

43.0

-40-200 20406080100120

4.16

4.11

4.06

4.01

3.96

[V]

3.91

3.86

3.81

3.76

-40-200 20406080100120

1.06

1.04

1.02

1.00

0.98

[V]

0.96

0.94

0.92

0.90

-40 -20 0 20 40 60 8 0 100 120

711

706

701

[mV]

696

691

686

-40-200 20406080100120

Ic(Dyn)

o

Temp[

C]

IOCSET(500kHz)

Temp[ oC]

Vcc(UVLO) Stop

Temp[ oC]

Enable(UVLO) Stop

ο

C]

Temp[

Vfb

Temp[ oC]

Rev 5.0

10

Rdson of MOSFETs Over Temperature at Vcc=5V

28

26

24

22

]

Ω

20

18

16

14

Resistance [m

12

10

8

6

-40 -20 0 20 40 60 80 100 120 140

IR3841WMPbF

Temperature [°C]

Sync-FET Ctrl-FET

Rev 5.0

11