PD-60334
IR3811MPbF
SupIRBuck
Features
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TM
HIGHLY INTEGRATED 7A
Description
The IR3811
SupIRBuck
TM
is 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 0.75*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.
WIDE-INPUT VOLTAGE, SYNCHRONOUS BUCK REGULATOR
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)
Applications
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Distributed Point-of-Loads
Server and Workstations
Embedded Systems
Storage Systems
DDR Applications
Graphics Cards
Game Consoles
Computing Peripheral Voltage Regulators
Fig. 1. Typical application diagram
10/04/08
1
PD-60334
IR3811MPbF
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND)
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V
IN
Supply Voltage
Vcc Supply Voltage
Vc Supply Voltage
SW
PGood
Fb,COMP,SS,Vsns
OCSet
AGnd to PGnd
Storage Temperature Range
Operating Junction Temperature Range
ESD Classification
Moisture Sensitivity Level
-0.3V to 24V
-0.3V to 16V
-0.3V to 30V
-0.3V to 30V
-0.3V to 16V
-0.3V to 3.5V
10mA
-0.3V to +0.3V
-65°C To 150°C
-40°C To 150°C
JEDEC, JESD22-A114
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.
PACKAGE INFORMATION
5mm x 6mm POWER QFN
12
V
IN
11
SW
10
PGnd
θ
JA
=
35
o
C / W
θ
J
-
PCB
=
2
o
C / W
HG
Vc
13
14
1
Vp
15
AGnd
9
8
Vref
V
CC
2
3
4
5
6
7
FB COMP AGnd AGnd SS OCSet
Fig. 2: Package outline (Top view)
ORDERING INFORMATION
PACKAGE
DESIGNATOR
M
M
10/04/08
PACKAGE
DESCRIPTION
IR3811MTRPBF
IR3811MTR1PBF
PIN
COUNT
15
15
PARTS PER
REEL
4000
750
2
PD-60334
IR3811MPbF
Block Diagram
Fig. 3. Simplified block diagram of the IR3811.
10/04/08
3
PD-60334
IR3811MPbF
Pin Description
Pin
1
2
Name
Vp
Fb
Description
Non-inverting input of error amplifier. This pin can be used for tracking application.
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 ground to provide loop compensation.
Signal ground for internal reference and control circuitry.
Signal ground for internal reference and control circuitry.
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.
Current limit set point. A resistor from this pin to SW pin will set the current limit
threshold.
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.
External reference voltage. Drive capability for this pin is 2μA.
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
This pin is connected to the high side gate driver. Connect a small capacitor from
this pin to switch node (SW).
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.
Signal ground for internal reference and control circuitry.
3
4
5
6
Comp
AGnd
AGnd
SS/SD
7
8
9
10
11
12
13
14
OCSet
V
CC
Vref
PGnd
SW
V
IN
HG
V
C
AGnd
15
Pins 4, 5 and 15 need to be connected together on system board.
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PD-60334
IR3811MPbF
Recommended Operating Conditions
Symbol
V
in
V
cc
V
c
V
o
I
o
Note1
T
j
Definition
Input Voltage
Supply Voltage
Supply Voltage
Output Voltage
Output Current
Junction Temperature
Min
2.5
4.5
Vin + 5V
0.6
0
-40
Max
21
14
28
12
7
125
Units
V
A
C
o
Electrical Specifications
Unless otherwise specified, these specification apply over Vin=V
cc
=V
c
=12V, 0
o
C<T
j
(Ic)< 105
o
C.
Typical values are specified at T
a
= 25
o
C.
Parameter
Power Loss
Power Loss
P
loss
Vcc=V
in
=12V, Vc=24V, V
o
=1.8V,
I
o
=7A, L=1uH,
Note3
2.1
W
Symbol
Test Condition
Min
TYP
MAX
Units
MOSFET R
ds(on)
Top Switch
Bottom Switch
R
ds(on)_Top
R
ds(on)_Bot
I
D
=9A, Tj(MOSFET)=25 C
I
D
=9A, Tj(MOSFET)=25 C
o
o
10.5
10.5
13.4
mΩ
13.4
Reference Voltage
Feedback Voltage
Accuracy
V
FB
0 C<Tj<105 C
-40 C<Tj<105 C,
Note2
o
o
o
o
0.6
-1.35
-1.5
+1.35
+1.5
V
%
%
Supply Current
V
CC
Supply Current (Static)
V
C
Supply Current
(Static)
V
CC
Supply Current
(Dynamic)
V
C
Supply Current
(Dynamic)
I
CC(Static)
I
C(Static)
I
CC(Dynamic)
I
C(Dynamic)
SS=0V, No Switching
SS=0V, No Switching
SS=3V, V
c
=24V, V
cc
=V
in
=12V.
V
o
=1.8V, Io=0A
SS=3V, V
c
=24V, V
cc
=V
in
=12V.
V
o
=1.8V, Io=0A
10
4.5
18
18
13
7
25
25
mA
Under Voltage Lockout
V
CC
-Start-Threshold
V
CC
-Stop-Threshold
V
CC
-Hysteresis
V
C
-Start-Threshold
V
C
-Stop-Threshold
V
C
-Hysteresis
V
C
_UVLO(R)
V
C
_UVLO(F)
V
CC
_UVLO(R)
V
CC
_UVLO(F)
Supply ramping up
Supply ramping down
Supply ramping up and down
Supply ramping up
Supply ramping down
Supply ramping up and down
4.0
3.7
0.15
3.1
2.85
0.15
0.2
0.25
4.4
4.1
0.3
3.5
3.25
0.25
V
10/04/08
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嵌入式系统
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