AIC1568
4-bit DAC, Step-Down PWM Power Controller
Analog Integrations Corporation
4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan
DS-1568-01 012102
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
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FEATURE
l
Compatible with HIP6008.
l
Simple Voltage-Mode PWM Control.
l
Fast Transient Response.
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1.5% 4-Bit Digital-to-Analog Output Voltage.
l
Adjustable Current Limit without External Sense
Resistors.
l
Full 0% to 100% Duty Ratio.
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200KHz Free-Running Oscillator, Programmable
up to 350KHz.
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Power-Good Output Voltage Monitor.
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Short Circuit Protection with Low Short Circuit
Output Current.
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TTL Compatible 4-bit Digital-to-Analog Core
Output Voltage Selection, with range from 2.0V to
3.5V in 0.1V increments.
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APPLICATIONS
l
Power Supply for Pentium
,
Pentium Pro
,
Power
PC
and Alpha
Microprocessors.
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High-Power 5V to 3.xV DC/DC Regulators.
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Low-Voltage Distributed Power Supplies.
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DESCRIPTION
The AIC1568 is a high power, high efficiency
switching controller optimized for high
performance microprocessor applications. It is
designed to drive an N-channel MOSFET in a
standard buck topology. Featuring a digitally
programmable switching regulator, the AIC1568
includes monitoring and protection capabilities in
addition to all the essential PWM control
functions.
The internal 4-bit Digital-to-Analog Converter
(DAC) adjusts the output voltage from 2.0V to
3.5V in 0.1V increments. The precision reference
and voltage-mode control can provide output
regulation within
1.5% over temperature and line
voltage shifts.
The AIC1568 includes an internal 200KHz free-
running oscillator that can be adjusted up to
350KHz. The resulting PWM duty ratio ranges
from 0% to 100%. The error amplifier features a
11MHz bandwidth and 6V/
S slew rate, which
enables high converter bandwidth for fast
transient response.
The AIC1568 provides adjustable over current
and short circuit protections. It senses the output
current by using the R
DS(ON)
of the N-channel
MOSFET without an external low value sense
resistor. It also monitors the output voltage with a
window comparator and issues a power good
signal when the output is within 10% of the rated
output voltage.
AIC1568
2
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TYPICAL APPLICATION CIRCUIT
C1
1
F
C2
0.1
F
C6
1000P
C5
0.1
F
C8
0.1
F
C9
1000P
+
C3
1000
F x 2
R4
15K
R3 47K
R6
90.9K
R1
R2
2.2K
L1
1
H
L2
D1
BYV118
RFP45N03L
M1
AIC1568
OCSET
COMP
F B
SS
VID0
VID1
VID2
VID3
R7
1.2M
+
JUMPER
C4
1000
F x 6
12V
2.0V
V
O U T
3.5V
at 10A
5V
BOOT
GND
PHASE
RT/OVP
UDRI
VCC
VSEN
PGOOD
C7
33P
7
H
10
V
IN
V
DRI
R5
3.01K
Switching DC/DC Converter
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ORDERING INFORMATION
PIN CONFIGURATION
SO-16
TOP VIEW
VSEN
RT/OVP
VCC
BOOT
UGATE
PHASE
PGOOD
GND
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
OCSET
SS
VID0
VID1
VID2
VID3
COMP
FB
AIC1568CXXX
PACKING TYPE
TR: TAPE & REEL
TB: TUBE
PACKAGING TYPE
S: SMALL OUTLINE
Example: AIC1568CSTR
in SO-16 Package & Taping &
Reel Packing Type
AIC1568
3
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ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
....... .................................................. ... ... ... ... .............................
15V
Boot Voltage, V
BOOT
... ... ... .......................... .............. ... ... ... ........................................
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 ~ 70
C
Maximum Operating Junction Temperature............. ......... ............. ... ... ... ................... 100
C
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 ~150
C
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.
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TEST CIRCUIT
Refer to TYPICAL APPLICATION CIRCUIT.
AIC1568
4
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ELECTRICAL CHARACTERISTICS
(VCC= 12V, T
A
=25
C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
SYMBOL
MIN.
TYP.
MAX.
UNIT
VCC Supply Current
Nominal Supply
U
GATE
Open
I
VCC
2
mA
Power-On Reset
V
CC
Threshold
V
OCSET
=4.5V
7
8.5
V
Rising V
OCSET
Threshold
1.26
V
Oscillator
Free Running Frequency
RT Open
170
200
230
KHz
Total Variation
6K
<R
T
<200K
-20
+20
%
Ramp Amplitude
RT Open
V
OSC
1.5
V
P-P
DAC Output Voltage
DAC Output Voltage Accuracy
-1.5
+1.5
%
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
Over-Voltage Trip (V
VSEN
/VDAC)
106
115
125
%
OCSET Current Source
V
OCSET
=4.5VDC
I
OCSET
170
200
230
A
OVP Sourcing Current
V
VSEN
=5.5V, V
OVP
=0V
I
OVP
30
mA
SS Current
I
SS
10
A
SS Sink Current under
Current Limit
V
VSEN
=VDAC, V
OCSET
=5.0V,
V
PHASE
=0V, V
FB
=V
DAC
- 50mV
130
A
SS Sink Current under Hard
Current Limit
V
VSEN
=0, V
OCSET
=5.0V,
V
PHASE
=0V, V
FB
=0V
65
mA
Power Good
Upper Threshold (V
VSEN
/VDAC)
V
VSEN
rising
106
114
%
Lower Threshold (V
VSEN
/VDAC)
V
VSEN
falling
84
94
%
Hysteresis (V
VSEN
/VDAC)
Upper and lower threshold
2
%
PGOOD Voltage Low
I
PGOOD
=5mA
V
PGOOD
0.5
V
AIC1568
5
n
BLOCK DIAGRAM
PHASE
GND
BOOT
UGATE
OVER
CURRENT
VSEN
OCSET
+
-
SOFT
SATRT
1
A
4V
FB
I
OCSET
200
A
CONTROL
LOGIC
OVP
POWER-ON
RESET
VCC
-
+
50%
POWER GOOD
SS
-
+
PGOOD
-
+
-
+
ERROR
AMP
OSCILLATOR
PWM
COMPARATOR
REFERENCE
RT/OVP
VID0
VID1
VID2
VID3
COMP
4BITS
DAC
-
+
+
-
+
VDAC
90%
110%
115%
1
11
13
1
14
10
3
5
2
16
4
6
7
8
12
9
15
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PIN DESCRIPTIONS
PIN 1: OCSET- Current limit sense pin. Connect
a resistor R
OCSET
from this pin to
the drain of the external
MOSFET. R
OCSET
, an internal 200
A current source (I
OCSET
), and
the external MOSFET on-
resistance (R
DS( ON)
) jointly set the
over current trip point according
to the following equation:
I
I
R
R
PEAK
OCSET
OCSET
DS(ON
=
)
If FB pin voltage is sensed to be
below 50% of the internal
voltage reference VDAC, the
over current comparator cycles
the soft-start function.
PIN 2: SS
- Soft start pin. Connect a
capacitor from this pin to ground.
An internal 10
A current source
provides soft start function for
the converter.
PIN 3: VID0
PIN 4: VID1
PIN 5: VID2
PIN 6: VID3
- 4-bit DAC voltage select pin. TTL
inputs used to set the internal
voltage reference VDAC. When
left open, these pins are
internally pulled up to 5V and
provide logic ones. The level of
VDAC sets the converter output
voltage as well as the PGOOD
and OVP thresholds.
Table 1 specifies the VDAC
voltage for the 16 combinations
of DAC inputs.
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