IRU3033
1
Rev. 1.7
07/17/02
www.irf.com
8-PIN PWM SWITCHER AND LINEAR CONTROLLER IC
TYPICAL APPLICATION
Figure 1 - Typical application of IRU3033 in a flexible mother board designed for
Intel P55
TM
, P54
TM
, AMD K5, K6
TM
as well as Cyrix M1
TM
and M2
TM
applications.
T
A
(C) 8-PIN PLASTIC SOIC (S)
0 To 70 IRU3033CS
Notes: P54C, P55C, Pentium II are
trademarks of Intel Corp. K5 & K6
are trademarks of AMD Corp. Cyrix
6X86L, M1, M2 are trademarks of
Cyrix Corp. Power PC is trademark
of IBM Corp.
DESCRIPTION
The IRU3033 IC combines a switching controller and a
linear regulator controller all in a compact 8-pin surface
mount package, providing a total solution for dual sup-
ply processor applications such as an Intel P55C
TM
, AMD
K6
TM
, as well as Cyrix 6X86L
TM
and the M2
TM
proces-
sors. Typically in these applications a dual supply regu-
lator converts 5V to 3.3V for I/O supply and a jumper
programmable supply of 1.25V to 3.5V for Core supply.
The linear regulator controller portion in the IRU3033 is a
programmable controller allowing flexibility for the I/O
regulator and has a minimum of 50mA drive current ca-
pability designed to provide ample current for an exter-
nal pass transistor. The IC uses an internal regulator
generated from the 12V supply to power the controller
as well as the 12V supply to drive the power MOSFET,
allowing a low cost N-channel MOSFET switch to be
used. The IC also includes an error comparator for fast
transient response, a precise voltage reference for set-
ting the output voltage as well as a direct drive of the
MOSFET for the minimum part count.
PACKAGE ORDER INFORMATION
Data Sheet No. PD94147
FEATURES
LDO Controller allows the use of a low cost pass
transistor for the I/O supply
8-Pin SOIC combines switching and linear
controller
Internal pre-regulator eliminates cross talk
between switching and linear regulators
Automatic shut down of the linear regulator when
connected to the Vcc2 detect pin
On-Board MOSFET Driver
Fastest transient response of any controller
method (0 to 100% Duty Cycle in 100ns)
1% Internal Voltage Reference
Internal Under-Voltage Lockout protects MOSFET
during start-up
Dual supply low voltage processor applications,
such as: P55C
TM
, CYRIX M2
TM
, POWER PC
TM
and AMD K6
TM
Simple 5V to 3.3V switcher for Pentium with AGP
or Pentium II
TM
applications
APPLICATIONS
CPU
I/O
Vcc2 Det
Core
5V
5V
12V
Q1
C1
L1
C3
Q2
D1
C2
L2
R4
R5
C7
R6
R7
C6
R8
R3
C5
D2
R10
C8
R9
Drv1
V
12(SW)
V
FB1
V
HYST
Gnd
V
FB2
Drv2
V
12
IRU3033
IRU3033
2
Rev. 1.7
07/17/02
www.irf.com
ABSOLUTE MAXIMUM RATINGS
V
12
,V
12(SW)
Supply Voltages ....................................... 20V
Fb Pin Voltages ........................................................ -0.3V To 5V
Storage Temperature Range ...................................... -65C To 150C
Operating Junction Temperature ................................ 0C To 150C
PACKAGE INFORMATION
8-PIN PLASTIC SOIC (S)
Linear Controller Section
Fb Voltage Initial Accuracy
Fb Voltage Total Variation
Fb Voltage Line Regulation
Fb Input Bias Current
Maximum Drive Current
V
12
Supply Current
Switching Controller Section
Fb Voltage Initial Accuracy
Fb Voltage Total Variation
Fb Voltage Line Regulation
Fb Input Bias Current
Min On Time
Min Off Time
V
HYST
Pin Output-HI
V
HYST
Pin Output-LO
Supply Current
Maximum Duty Cycle
Minimum Duty Cycle
Gate Drive Rise/Fall Time
Unless otherwise specified, the following specification applies over V
12
=V
12(SW)
=12V and T
A
=0 to 70C. Low duty
cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature.
PARAMETER
SYM TEST CONDITION MIN TYP MAX UNITS
u
JA
=160
8
C/W
ELECTRICAL SPECIFICATIONS
Drv1
V
12(SW)
V
FB1
V
HYST
Gnd
V
FB2
Drv2
V
12
4
3
2
1
5
6
7
8
TOP VIEW
V
FB2
I
FB2
I
DRV(max)
I
12
V
FB1
I
FB1
I
12(SW)
D
MAX
D
MIN
V
GATE
T
J
=25
8
C, Drv2=V
FB2
, C
L
=100
m
F
Drv2=V
FB2
, C
L
=100
m
F
10<V
12
<14V, Drv2=V
FB2
, C
L
=100
m
F
V
FB2
=1.25V
V
FB2
=1V, V
FB1
=1.5V
V
FB2
=1V, V
FB1
=1.5V, I
DRV2
=0
T
J
=25
8
C
V
FB1
=1.25V
V
FB1
is sq wave with 300ns on
time and 2
m
s off time
V
FB1
is sq wave with 300ns off
time and 2
m
s on time
I
SOURCE
=500
m
A, V
FB1
=1.5V
I
SINK
=500
m
A, V
FB1
=1V
V
FB1
=1V, V
FB2
=1.5V
V
FB1
=1V
V
FB1
=1.5V
Load=IRL3303
1.237
1.225
-1
1.237
1.225
-1
11
0
1.250
1.250
0.2
50
5
1.250
1.250
0.2
800
800
10
70
1.262
1.275
+1
1.262
1.275
+1
1
100
V
V
%
m
A
mA
mA
V
V
%
m
A
ns
ns
V
V
mA
%
%
ns
IRU3033
3
Rev. 1.7
07/17/02
www.irf.com
PIN DESCRIPTIONS
BLOCK DIAGRAM
Figure 2 - Simplified block diagram of the IRU3033.
The PWM output of the switching controller. This pin is a totem pole drive that is con-
nected to the gate of the power MOSFET. A resistor may be placed from this pin to the
gate in order to reduce switching noise.
This pin supplies the voltage to the PWM drive and hysteresis circuitry and it is connected
to the 12V supply. A 1
m
F, high frequency capacitor must be connected from this pin to
ground to provide the peak current for charging and discharging of the MOSFET.
A resistor divider from this pin to the output of the switching regulator and ground sets the
Core supply voltage.
A resistor and a 10pF capacitor is connected from this pin to the V
FB1
pin to set the output
ripple voltage for the switching regulator.
This pin is connected to the IC substrate and must be connected to the lowest potential in
the system.
The feedback pin of the linear regulator. A resistor divider from this pin to the output of the
linear regulator and ground sets the I/O supply voltage.
The drive pin of the linear regulator. This pin controls the base of a transistor or the gate
of a MOSFET acting as the series pass element for the linear regulator.
This pin provides the biasing for the chip and drive for the linear regulator controller. It is
connected to 12V supply. A 10
V
resistor in series from this pin to the 12V supply and a
1
m
F, high frequency capacitor connected from this pin to ground is required to filter the
switching noise of the switching regulator.
PIN # PIN SYMBOL
PIN DESCRIPTION
1
2
3
4
5
6
7
8
Drv1
V
12(SW)
V
FB1
V
HYST
Gnd
V
FB2
Drv2
V
12
V
REF
UVLO
1.25V
PWM Control
V
12(SW)
V
HYST
V
FB2
Drv 1
Gnd
V
FB1
Drv2
5
1
2
4
3
6
7
V
12
8
5V Reg
IRU3033
4
Rev. 1.7
07/17/02
www.irf.com
TYPICAL APPLICATION
Pentium Dual Supply Application
0 = Jumper block is installed.
1 = Jumper block is not installed.
JP1
1-2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
JP1
3-4
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
JP1
5-6
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
JP1
7-8
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Output
Voltage
3.5
3.4
3.3
3.2
3.1
3.0
2.9
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
Figure 3 - Typical application of IRU3033 in a flexible motherboard with the 4-bit VID output voltage selection. This
circuit uses a single jumper that programs the output voltage in 16 steps with 0.1V steps from 2V to 3.5V, designed
for Intel P55
TM
,P54
TM
, AMD K5 & K6
TM
as well as Cyrix M1
TM
and M2
TM
applications. The Vcc2 Det pin automati-
cally shuts down the I/O regulator when a single plane processor is dropped in the socket.
5V
5V
12V
Q1
C1
C3
R6
R7
C6
R8
R3
C5
D2
R10
C8
R9
L1
Q2
C2
L2
R4
C7
1
D1
R2
C4
R5A
R5B
R5C
R5D
R5E
2
3
4
5
6
7
8
JP1
R1
CPU
I/O
Vcc2 Det
Core
R13
C9
R11
Drv1
V
12(SW)
V
FB1
V
HYST
Gnd
V
FB2
Drv2
V
12
U1
IRU3033
5
Rev. 1.7
07/17/02
www.irf.com
Ref Desig
Description Qty
Part #
Manuf
U1
LDO/Switcher IC
1
IRU3033CS (8-Pin SOIC)
IR
Q1
MOSFET
1
MTP3055 (TO-220)
Motorola
Q2
MOSFET
1
IRL3303 (TO-220)
IR
IRL3103S (TO-263) (Note 1)
D2
Diode, GP
1
1N4148
D1
Schottky Diode
1
MBR1045CT (TO-220)
MBRB1545CT (TO-263) (Note1)
Motorola
L2
Inductor
1
Core: T50-18, L=4
m
H
Micro Metal
Turns: 10T, 18 AWG
(core)
L1
Inductor
1
L=2
m
H
R1
Resistor
1
22
V
, 5%, SMT 1206 size
R2
Resistor
1
10
V
, 5%, SMT 1206 size
R3
Resistor
1
324K
V
, 1%, SMT 0805 size
R4A*
Resistor
1
806
V
, 1%, SMT 0805 size
R4B*
Resistor
1
90.9K
V
, 1%, SMT 0805 size
R5A
Resistor
1
1.24K
V
, 1%, SMT 0805 size
R5B
Resistor
1
2.49K
V
, 1%, SMT 0805 size
R5C
Resistor
1
4.99K
V
, 1%, SMT 0805 size
R5D
Resistor
1
1K
V
, 1%, SMT 0805 size
R5E
Resistor
1
1.30K
V
, 1%, SMT 0805 size
R6
Resistor
1
2 K
V
, 1%, SMT 0805 size
R7
Resistor
1
1.21K
V
,1%, SMT 0805 size
R8
Resistor
1
1 K
V
, 5%, SMT 0805 size
R9
Resistor
1
10
V
, 5%, SMT 0805 size
R10
Resistor
1
1K
V
, 5%, SMT 0805 size
R11
Resistor
1
2.4K
V
, 5%, SMT 0805 size
R13
Resistor
1
7.5K
V
, 5%, SMT 0805 size
C1
Capacitor
1
6MV1500GX, 1500
F, 6.3V, Elect
C2
Capacitor
1
6MV1500GX, 1500
F, 6.3V, Elect
Sanyo
C3
Capacitor
1
1
m
F, Ceramic, SMT 0805 size
C4
Capacitor
1
470pF, Ceramic, SMT 0805 size
Sanyo
C5
Capacitor
1
10pF, Ceramic, SMT 0805 size
Sanyo
C6
Capacitor
1
6MV1500GX, 1500
m
F, 6.3V, Elect
Sanyo
C7
Capacitor
4
6MV1500GX, 1500
m
F, 6.3V, Elect
Sanyo
C8
Capacitor
1
1
m
F, Ceramic, SMT 0805 size
C9
Capacitor
1
470p, Ceramic, SMT 0805 size
HS1
Heat Sink
1
For MOSFET, 577002
Aavid
HS2
Heat Sink
1
For Schottky Diode , 577002
Aavid
HS3
Heat Sink
1
For Q1, 507222 (I/O curren<5A)
Aavid
576602 (I/O current< 3.5A)
*R4 is a parallel combination of R4A and R4B.
Note 1: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and
MBR1545CT for D2 in TO-263 packages with minimum of 1" square copper pad can be used.
APPLICATION PARTS LIST
Pentium Dual Supply
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