12A Highly Integrated SupIRBuck
TM
IR3476
FEATURES
•
Input Voltage Range: 3V to 27V
•
Output Voltage Range: 0.5V to 12V
•
Continuous 12A Load Capability
•
Constant On‐Time Control
•
Compensation Loop not Required
•
Excellent Efficiency at Very Low Output Currents
•
Programmable Switching Frequency and Soft Start
•
Thermally Compensated Over Current Protection
•
Power Good Output
•
Precision Voltage Reference (0.5V, +/‐1%)
•
Enable Input with Voltage Monitoring Capability
•
Pre‐bias Start Up
•
Thermal Shut Down
•
Under/Over Voltage Fault Protection
•
Forced Continuous Conduction Mode Option
•
Small, Low Profile 5mm x 6mm QFN Package
DESCRIPTION
The IR3476 SupIRBuck
TM
is an easy‐to‐use, fully integrated
and highly efficient DC/DC voltage regulator. The onboard
constant on time hysteretic controller and MOSFETs make
IR3476 a space‐efficient solution that delivers up to 12A of
precisely controlled output voltage.
Programmable switching frequency, soft start, and
thermally compensated over current protection allows for
a very flexible solution suitable for many different
applications and an ideal choice for battery powered
applications.
Additional features include pre‐bias startup, very precise
0.5V reference, under/over voltage shutdown, thermal
protection, power good output, and enable input with
voltage monitoring capability.
APPLICATIONS
•
Notebook and Desktop Computers
•
Consumer Electronics – STB, LCD, TV, Printers
•
12V and 24V Distributed Power Systems
•
General Purpose POL DC‐DC Converters
•
Game Consoles and Graphics Cards
BASIC APPLICATION
EFFICIENCY
95%
85%
Efficiency
75%
65%
55%
45%
0.01
19VIN
12VIN
8VIN
0.1
Figure 1: IR3476 Basic Application Circuit
1
10
Load Current (A)
100
Figure 2: IR3476 Efficiency
1
March 27, 2013 | V2.2 | PD97603
12A Highly Integrated SupIRBuck
TM
IR3476
ORDERING INFORMATION
IR3476
―
Package
M
M
PBF – Lead Free
TR – Tape and Reel
M – Package Type
Tape & Reel Qty
750
4000
Part Number
IR3476MTR1PBF
IR3476MTRPBF
MARKING INFORMATION
PIN DIAGRAM
Site/Date/Marking Code
Lot Code
Pin 1 Identifier
3476
?YWW?
xxxxx
θ
JA
=
30
o
C
/
W
θ
J
-
PCB
=
2
o
C
/
W
2
March 27, 2013 | V2.2 | PD97603
12A Highly Integrated SupIRBuck
TM
IR3476
FUNCTIONAL BLOCK DIAGRAM
Figure 3: IR3476 Functional Block Diagram
3
March 27, 2013 | V2.2 | PD97603
12A Highly Integrated SupIRBuck
TM
IR3476
TYPICAL APPLICATION
+3.3V
VCC
R1
10K
R2
10K
TP4
EN
4
3
TP3
FCCM
EN
FCCM
R3
200K
R4
10.5K
VSW
ISET
VSW
1
2
C4
0.22uF
L1
1.5uH
17
14
16
15
13
U1
IR3476
VOUT
+Vin1s
TP20
+Vin1s
C1
1uF
C2
22uF
+
C3
68uF
VIN
+Vins
TP1
VINS
TP2
VIN
SW1
EN / FCCM
TP5
PGND
-Vins
TP6
PGNDS
TP23
+Vsws
TP7
VOUT
1
2
R6
open
C13
open
C6
open
C7
open
C8
open
C9
330uF
C10
47uF
C11
open
C12
0.1uF
3
4
5
TP8
VOUTS
+3.3V
GND
C5
open
R5
10K
TP11
PGOOD
PGOOD
BOOT
VIN
EN
FF
1
2
3
4
FB
5
6
C20
0.1uF
7
FCCM
ISET
PGOOD
GND1
FB
SS
3
3VCBP
NC1
PGND
4
PHASE
12
IR3476
TP13
SS
SS
2
1
TP22
+Vsws
5
TP12
VSWS
TP21
-Vsws
TP9
+Vout1s
TP24
+Vsws
TP10
PGND
C15
open
C16
open
C17
open
C18
open
C19
open
C26
open
C27
open
8
9
10
VCC
NC2
TP14
+3.3V
+3.3V
+Vdd2s
C21
1uF
11
-Vout1s
TP15
-Vout1s
TP25
-Vin1s
-Vout1s
-Vdd2s
TP26
AGND
+Vdd1s
C25
1uF
C22
open
-Vdd1s
C24
open
-Vout1s
+Vout1s -Vout1s
10
+Vout2s -Vout2s
9
-Vdd1s
7
-Vdd1s
-Vins
TP16
VCC
TP17
PGND
VCC
C23
open
-Vdd2s
C14
open
R7
2.80K
6
8
-Vdd2s
TP18
VOLTAGE SENSE
+Vdd1s
2
+Vdd1s
+Vdd2s
+Vin1s
R12
open
R8
2.55K
R13
open
R14
open
Vout
TP19
FB
R11
open
1
3
+Vdd2s
+Vins
4
5
Figure 4: Demoboard Schematic for VOUT = 1.05V, F
S
= 300kHz
DEMOBOARD BILL OF MATERIALS
QTY
3
1
2
1
1
1
1
1
3
1
1
1
1
1
1
REFERENCE DESIGNATOR
C1, C21, C25
C10
C12, C20
C2
C3
C4
C9
L1
R1, R2, R5
R3
R4
R7
R8
SW1
U1
VALUE
1.00uF
47uF
0.100uF
22.0uF
68uF
0.22uF
330uF
1.5uH
10.0K
200K
10.5K
2.80K
2.55K
Switch
IR3476
DESCRIPTION
capacitor, X7R, 1.00uF, 25V, 0.1, 0603
capacitor, 47uF, 6.3V, 805
capacitor, X7R, 0.100uF, 50V, 0.1, 603
capacitor, X5R, 22.0uF, 16V, 20%, 1206
capacitor, electrolytic, 68uF, 25V, 0.2, SMD
capacitor, Y5V, 0.22uF, 50V, ‐20%, +80%, 0603
capacitor, 330uF, 2.5V, SMD
inductor, ferrite, 1.5uH, 16.0A, 3.8mOhm,
SMT
resistor, thick film, 10.0K, 1/10W, 0.01, 0603
resistor, thick film, 200K, 1/10W, 0.01, 603
resistor, thick film, 10.5K, 1/10W, 0.01, 603
resistor, thick film, 2.80K, 1/10W, 0.01, 603
resistor, thick film, 2.55K, 1/10W, 0.01, 0603
switch, DIP, SPST, 2 position, SMT
5mm x 6mm QFN
MANUFACTURER
Murata
TDK
TDK
Taiyo Yuden
Panasonic
Murata
Sanyo
Cyntec
KOA
KOA
KOA
KOA
KOA
C&K Components
IRF
PART NUMBER
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C2012X5R0J476M
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GRM188F51H224ZA01D
2R5TPE330M9
PIMB104T‐1R5MS‐39
RK73H1J1002F
RK73H1JLTD2003F
RK73H1JLTD1052F
RK73H1JLTD2801F
RK73H1J2551F
SD02H0SK
IR3476MTRPBF
4
March 27, 2013 | V2.2 | PD97603
12A Highly Integrated SupIRBuck
TM
IR3476
PIN DESCRIPTIONS
PIN #
1
2
3
4, 17
5
6
7
8
9
10
11
12
13
14
15
16
PIN NAME
FCCM
ISET
PGOOD
GND
FB
SS
NC
3VCBP
NC
VCC
PGND
PHASE
VIN
BOOT
FF
EN
I/O LEVEL
3.3V
5V
Reference
3.3V
3.3V
‐
3.3V
‐
5V
Reference
VIN
VIN
VIN + VCC
VIN
5V
PIN DESCRIPTION
Forced Continuous Conduction Mode (CCM). Ground this pin to enable diode
emulation mode or discontinuous conduction mode (DCM). Pull this pin to 3.3V
to operate in CCM under all load conditions.
Connecting resistor to PHASE pin sets over current trip point.
Power good open drain output – pull up with a resistor to 3.3V
Bias return and signal reference.
Inverting input to PWM comparator, OVP / PGOOD sense.
Soft start/shutdown. This pin provides user programmable soft‐start function.
Connect an external capacitor from this pin to GND to set the startup time of the
output voltage. The converter can be shutdown by pulling this pin below 0.3V.
‐
For internal LDO. Bypass with a 1.0µF capacitor to GND.
‐
VCC input. Gate drive supply. A minimum of 1.0µF ceramic capacitor is required.
Power return.
Phase node (or switching node) of MOSFET half bridge.
Input voltage for the system.
Bootstrapped gate drive supply – connect a capacitor to PHASE.
Input voltage feed forward – sets on‐time with a resistor to VIN.
Enable pin to turn on and off the device. Use two external resistors to set the
turn on threshold (see Electrical Specifications) for input voltage monitoring.
5
March 27, 2013 | V2.2 | PD97603
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