AIC1579/L
Step-Down Switching Regulator Controller
Analog Integrations Corporation
4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC
www.analog.com.tw
DS-1579-01 Nov 9, 00
TEL: 886-3-5772500
FAX: 886-3-5772510
1
FEATURES
Operation Voltage up to 15V.
Simple Voltage-Mode PWM Control.
Fast Transient Response.
2V and 1.3V
2% Feedback Voltage Reference
Option.
Adjustable Current Limit without External Sense
Resistors.
200KHz Free-Running Oscillator.
Short-Circuit Protection with Low Short Circuit
Output Current.
APPLICATIONS
Power Supply for Motherboard V
GTL
(1.5V Output)
Power Supply for Motherboard V
I/O
.
High-Power 5V to 3.xV DC/DC Regulators.
Low-Voltage Distributed Power Supplies.
DESCRIPTION
The AIC1579 is a high-power, high-efficiency
voltage-mode switching regulator controller for
motherboard V
I/O
power supply applications.
Designed to drive an N-channel MOSFET in a
standard buck topology, the AIC1579 features a
high voltage CMOS output driver, short-circuit
protection, and 8-pin package.
An external 4-bit Digital-to-Analog Converter
(DAC) can be used along with the AIC1579 to
adjust the output voltage from 2.0V to 3.5V in
0.1V increments. Table 1 on the following page
specifies the corresponding output voltage for
16 combinations of DAC inputs as in the typical
application circuit.
The 200KHz switching frequency allows for
using small external components while
maintaining high conversion efficiency. The
11MHz bandwidth and 6V/
S slew rate of the
error amplifier ensures high converter
bandwidth and fast transient response.
The AIC1579 provides adjustable overcurrent
and short-circuit protections by sensing the
output current across the on resistance of the
external N-channel MOSFET rather than an
external low value sense resistor.
The AIC1579L provides lower reference voltage
(1.30V) than the default (2.00V, AIC1579) for
lower V
OUT
requirement.
AIC1579/L
2
ORDERING INFORMATION
ORDER NUMBER
AIC1579CN
AIC1579LCN
(PLASTIC DIP)
AIC1579CS
AIC1579LCS
(PLASTIC SO)
PIN CONFIGURATION
TOP VIEW
PHASE
1
3
4
2
VCC
SS
COMP
FB*
UGATE
GND
8
6
5
7
OCSET
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C=0
C~+70C
REFERENCE VOLTAGE
DEFAULT: 2.00V
L: 1.30V
AIC1579 XXX
*AIC1579: 2.00V
AIC1579L: 1.30V
TYPICAL APPLICATION CIRCUIT
AIC1579
OCSET
COMP
FB
GND
PHASE
SS
UGATE
VCC
C7
1000pF
C6
33P
C5
0.1
F
C2
1000pF
+
C4
1000
F x 6
+
C3
1000
Fx2
R3
3.01K
R2
90.9K 1%
R1
2.2K
7
H
L1
1
H
D1
BYV118
M1
RFP45N03L
5V
3.3V/10A
1%
R4
1%
*C1 MUST BE VERY CLOSE TO VCC PIN
C1*
1
F
12V
L2
V
OUT
VID2
VID3
VID1
VID0
R7
7.5K
R6
15.0K
R5
30.1K
60.4K 1%
1%
1%
1%
10
R8
Switching Regulator for Pentium
V
CORE
Supply
AIC1579/L
3
Table 1. Output Voltage Program
VID3
VID2
VID1
VID0
VOUT
1
1
1
1
2.00V
1
1
1
0
2.10V
1
1
0
1
2.20V
1
1
0
0
2.30V
1
0
1
1
2.40V
1
0
1
0
2.50V
1
0
0
1
2.60V
1
0
0
0
2.70V
0
1
1
1
2.80V
0
1
1
0
2.90V
0
1
0
1
3.00V
0
1
0
0
3.10V
0
0
1
1
3.20V
0
0
1
0
3.30V
0
0
0
1
3.40V
0
0
0
0
3.50V
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
.................................................................................................... 15V
Input, Output, or I/O Voltage .................................................... GND - 0.3V to VCC+0.3V
ESD Classification ................................................................................................. Class 2
Recommended Operating Conditions
Supply Voltage, V
CC
........................................................................................... 12V
10%
Ambient Temperature Range ............................................................................ 0
C~70C
Junction Temperature Range ......................................................................... 0
C~ 100C
Thermal Information
Thermal Resistance,
JA
(Typical, Note 1)
SOIC Package ....................................................................................... 100
C/W
SOIC Package (with 3 in
2
of Copper) ..................................................... 90
C/W
Maximum Junction Temperature (Plastic Package) .............................................. 150
C
Maximum Storage Temperature Range ................................................... 65
C~150C
Maximum Lead Temperature (Soldering 10 Sec) ................................................ 300
C
Note 1:
JA
is measured with the component mounted on an evaluation PC board in free air.
TEST CIRCUIT
Refer to TYPICAL APPLICATION CIRCUIT.
AIC1579/L
4
ELECTRICAL CHARACTERISTICS
(VCC= 12V, Ta=25
C, unless otherwise
specified.)
PARAMETER
TEST CONDITIONS
SYMBOL MIN.
TYP.
MAX.
UNIT
VCC Supply Current
Nominal Supply
UGATE Open
I
VCC
2.3
mA
Power-On Reset
V
CC
Threshold
V
OCSET
=4.5V
10.4
V
Oscillator
Frequency
160
200
240
KHz
Max. Duty Cycle
100
%
Internal Reference Voltage
Reference Voltage
AIC1579
AIC1579L
1.96
1.27
2.00
1.30
2.04
1.33
V
Error Amplifier
DC Gain
76
dB
Gain-Bandwidth Product
GBW
11
MHz
Slew Rate
SR
6
V/
S
Gate Driver
Upper Gate Source
R
UGATE
8
12
Upper Gate Sink
R
UGATE
5.5
10
Protection
OCSET Current Source
V
OCSET
=4.5VDC
I
OCSET
170
200
230
A
SS Current
I
SS
10
A
TYPICAL PERFORMANCE CHARACTERISTICS
1
2
3
4
5
6
7
8
9
10
11
30
40
50
60
70
80
90
100
Vo=3.5V
Vo=2.0V
Vo=1.3V
E
f
f
i
c
i
enc
y
(%
)
I
OUT
(A)
Efficiency vs. Load Current
Cl
set
(
A
)
Temperature (
C)
OCSET Current vs. Temperature
-40
-20
0
20
40
60
80
100
120
140
160
192
194
196
198
200
Tc=134ppm/ C@ 0~100
C
AIC1579/L
5
TYPICAL PERFORMANCE CHARACTERISTICS(
Continued
)
Sof
t
St
ar
t
(
A
)
Temperature (
C)
SS Current vs. Temperature
-40
-
20
0
20
40
60
80
100
120 140 160
9.3
9.4
9.5
9.6
9.7
9.8
9.9
Tc = 306 ppm/
C @ 0~100C
Over-Current Operation
Soft Start Initiates Output
Transient Response
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