MAX1572ETC130+ [MAXIM]
Switching Regulator, Current-mode, 1.65A, 2200kHz Switching Freq-Max, PQCC12, 4 X 4 MM, 0.8 MM HEIGHT, MO220WGGB, QFN-12;
| 型号： | MAX1572ETC130+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switching Regulator, Current-mode, 1.65A, 2200kHz Switching Freq-Max, PQCC12, 4 X 4 MM, 0.8 MM HEIGHT, MO220WGGB, QFN-12 开关 |
| 文件： | 总11页 (文件大小：424K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2837; Rev 0; 4/03
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
General Description
Features
ꢀ Up to 97% Efficiency
The MAX1572 is a fixed-frequency, synchronous step-
down DC-to-DC converter to power low-voltage micro-
processor/DSP cores in portable equipment requiring
high efficiency in a limited PC board area. The features
are optimized for high efficiency over a wide load range,
small external component size, low output ripple, and
excellent transient response. The input supply voltage
range is from 2.6V to 5.5V, while the output is internally
fixed from 0.75V to 2.5V in 50mV increments with a
guaranteed output current of 800mA. The high 2MHz
switching allows tiny low-cost capacitors and a low-pro-
file inductor, while the power-saving pulse-group mode
reduces quiescent current to 48µA (typ) with light loads.
To reduce noise and RF interference, the converter can
be configured to provide forced-PWM operation.
ꢀ 2MHz PWM Switching
ꢀ 800mA Guaranteed Output Current
ꢀ Low 48µA Quiescent Current
ꢀ Power-Saving Modes: Pulse-Group, Pulse-Skip,
Forced-PWM Mode
ꢀ 0.75V to 2.5V Preset Output Range
(in 50mV Increments)
ꢀ Voltage-Positioning Load Transients
ꢀ 5mV
Output Ripple
P-P
ꢀ Tiny 2.2µH Inductor
ꢀ 10µF Ceramic Output Capacitor
ꢀ Low 0.1µA Shutdown Current
ꢀ No External Schottky Diode Required
ꢀ Soft-Start with Zero Inrush Current
ꢀ 170ms (min) RESET Output
ꢀ Small 12-Pin, 4mm x 4mm Thin QFN Package
Ordering Information
The MAX1572 includes a low on-resistance internal
MOSFET switch and synchronous rectifier to maximize
efficiency and minimize external component count. No
external diode is needed. Other features include soft-
start to eliminate inrush current at startup and a 170ms
(min) RESET output to provide power-on/undervoltage
reset. The MAX1572 is available in a 12-pin, 4mm x
4mm thin QFN package with exposed paddle.
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
MAX1572ETC075
MAX1572ETC130
MAX1572ETC150
MAX1572ETC180
MAX1572ETC250
MAX1572ETCxyz*
12 Thin QFN-EP**
12 Thin QFN-EP**
12 Thin QFN-EP**
12 Thin QFN-EP**
12 Thin QFN-EP**
12 Thin QFN-EP**
Applications
Cell Phones and Smart Phones
PDAs, Palmtops, and Notebook Computers
MP3 and DVD Players
Digital Cameras and Camcorders
PCMCIA Cards
Hand-Held Instruments
*xyz is for the output voltage (e.g., MAX1572ETC165 has a
1.65V output). Minimum order quantity is 2500.
**EP = Exposed paddle.
Selector Guide appears at end of data sheet.
Typical Operating Circuit
Pin Configuration
OUTPUT
0.75V TO 2.5V
800mA
TOP VIEW
INPUT
2.6V TO 5.5V
2.2µH
BATT
LX
9
1
8
7
3
EN1
EN2
GND
OUT
10
11
12
6
5
4
MAX1572
PGND
ABATT
GND
MAX1572
ABATT
EN1
EN2
SS
OUT
RESET
MODE
SELECT
2
GND
4mm x 4mm
THIN QFN
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
ABSOLUTE MAXIMUM RATINGS
ABATT, BATT, EN1, EN2, RESET, OUT,
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
SS to GND ............................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
LX Current (Note 1)............................................................. 2.1A
Output Short-Circuit Duration ............................................Infinite
Continuous Power Dissipation (T = +70°C)
A
12-Pin Thin QFN (derate 16.9mW/°C above +70°C)...1349mW
Note 1: LX has internal clamp diodes to PGND and BATT. Applications that forward bias these diodes should take care not to
exceed the IC’s package power dissipation limits.
Stresses beyond those listed under “Absolute Maximum Ratings” 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.
ELECTRICAL CHARACTERISTICS
(V
= 3.6V, T = +0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
BATT
A
A
PARAMETER
CONDITIONS
MIN
2.6
TYP
MAX
5.5
UNITS
BATT Input Voltage
V
V
Undervoltage Lockout Threshold
V
rising and falling, 1% hysteresis
2.20
2.35
48
2.55
80
BATT
EN1 = GND, EN2 = BATT, no switching
EN1 = BATT, EN2 = GND, no switching
Quiescent Supply Current
µA
700
0.1
Shutdown Supply Current
Maximum Output Current
OUT Bias Current
EN1 = EN2 = GND, T = +25°C
1
µA
mA
µA
A
800
-0.4
6
1.2
9
No load, EN1 = EN2 = BATT
100mA load
3.2
+0.8
0
+2.0
Output-Voltage Accuracy
(Voltage Positioning)
300mA load
%
550mA load
-1
800mA load
-2
Line Regulation
0.3
%/V
V
V
V
V
= 3.6V
= 2.6V
= 3.6V
= 2.6V
0.28
0.33
0.18
0.20
1.25
-0.52
40
0.45
0.30
BATT
BATT
BATT
BATT
P-Channel On-Resistance
I
I
= 180mA
= 180mA
Ω
LX
N-Channel On-Resistance
Ω
LX
P-Channel Current-Limit Threshold
N-Channel Current-Limit Threshold
N-Channel Zero-Crossing Threshold
LX Output Current
1.00
-0.68
15
1.65
-0.37
65
A
A
EN1 = EN2 = BATT
EN1 = BATT, EN2 = GND
(Note 2)
mA
1.4
A
RMS
LX Leakage Current
EN1 = EN2 = GND
0.1
10
µA
%
Maximum Duty Cycle
100
EN1 = BATT, EN2 = GND or
EN1 = GND, EN2 = BATT
0
Minimum Duty Cycle
%
EN1 = EN2 = BATT
16.7
2
17.3
2.2
Switching Frequency
SS Output Impedance
1.8
65
MHz
100
150
kΩ
2
_______________________________________________________________________________________
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
ELECTRICAL CHARACTERISTICS (continued)
(V
= 3.6V, T = +0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
BATT
A
A
PARAMETER
CONDITIONS
EN1 = EN2 = GND
MIN
TYP
MAX
UNITS
SS Discharge Resistance
100
200
Ω
V
V
> 4.2V
1.6
1.4
ABATT
ABATT
EN_ Logic Input High
V
≤ 4.2V
EN_ Logic Input Low
0.4
1
V
µA
%
EN_ Logic Input Current
0.1
90
RESET Threshold
Percent of nominal, measured at OUT
From V > 90% to RESET = HI
87
93
RESET Timer Delay Time
RESET Output Low Level
RESET Internal Pullup Resistance to OUT
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
170
200
0.015
14
230
0.075
20
ms
V
OUT
I
= 1mA
SINK
9
kΩ
°C
°C
T rising
J
160
20
ELECTRICAL CHARACTERISTICS
(V
= 3.6V, T = -40°C to +85°C, unless otherwise noted.) (Note 3)
A
BATT
PARAMETER
CONDITIONS
MIN
2.6
TYP
MAX
5.5
2.55
80
UNITS
V
BATT Input Voltage
Undervoltage Lockout Threshold
Quiescent Supply Current
Shutdown Supply Current
Maximum Output Current
OUT Bias Current
V
rising and falling, 1% hysteresis
2.20
V
BATT
EN1 = GND, EN2 = BATT, no switching
EN1 = EN2 = GND
µA
µA
mA
µA
3
800
-1.2
9
No load, EN1 = EN2 = BATT
100mA load
3.2
Output-Voltage Accuracy
(Voltage Positioning)
%
+2.8
0.45
0.3
P-Channel On-Resistance
N-Channel On-Resistance
N-Channel Current-Limit Threshold
N-Channel Zero-Crossing Threshold
LX Output Current
I
LX
I
LX
= 180mA
= 180mA
Ω
Ω
EN1 = EN2 = BATT
EN1 = BATT, EN2 = GND
(Note 2)
-0.68
10
-0.22
65
A
mA
1.4
A
RMS
LX Leakage Current
EN1 = EN2 = GND
10
µA
%
Maximum Duty Cycle
100
Minimum Duty Cycle
EN1 = EN2 = BATT
17.3
2.2
%
Switching Frequency
1.8
65
MHz
kΩ
Ω
SS Output Impedance
150
200
SS Discharge Resistance
EN1 = EN2 = GND
V
V
> 4.2V
1.6
1.4
ABATT
ABATT
EN_ Logic Input High
V
≤ 4.2V
_______________________________________________________________________________________
3
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
ELECTRICAL CHARACTERISTICS (continued)
(V
= 3.6V, T = -40°C to +85°C, unless otherwise noted.) (Note 2)
A
BATT
PARAMETER
CONDITIONS
MIN
TYP
MAX
0.4
1
UNITS
V
EN_ Logic Input Low
EN_ Logic Input Current
RESET Threshold
µA
%
Percent of nominal, measured at OUT
From V > 90% to RESET = HI
87
93
RESET Timer Delay Time
RESET Output Low Level
RESET Internal Pullup Resistance to OUT
170
230
0.2
20
ms
V
OUT
I
= 1mA
SINK
9
kΩ
Note 2: Guaranteed by design, not production tested.
Note 3: Specifications to -40°C are guaranteed by design and not production tested.
Typical Operating Characteristics
(V
= 3.6V, V
= 1.5V, EN1 = GND, EN2 = BATT, T = +25°C, unless otherwise noted.)
OUT
BATT
A
EFFICIENCY vs. LOAD CURRENT
WITH 2.5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
WITH 1.8V OUTPUT
EFFICIENCY vs. LOAD CURRENT
WITH 1.5V OUTPUT
100
90
100
90
100
90
80
70
60
50
80
70
60
50
80
70
60
50
V
= 2.6V
IN
V
IN
= 3.6V
V
IN
= 5V
V
= 5V
V
= 2.6V
V = 3.6V
IN
IN
IN
V
= 2.6V
V = 3.6V
IN
V
= 5V
IN
IN
40
40
40
1
10
100
1000
1
10
100
1000
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUTPUT VOLTAGE
vs. LOAD CURRENT
OUTPUT VOLTAGE vs. INPUT VOLTAGE
WITH 100mA LOAD
EFFICIENCY vs. LOAD CURRENT
vs. MODE
1.58
1.56
1.54
1.52
1.50
1.55
1.53
1.51
100
90
PULSE-
GROUP MODE
T = +85°C
A
T = +85°C
A
80
70
60
50
PULSE-
SKIP MODE
T = +25°C
A
1.48
1.46
1.44
T = +25°C
A
T = -40°C
A
1.49
1.47
1.45
T = -40°C
A
FORCED-
PWM MODE
1.42
1.40
40
0
200
400
600
800
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1
10
100
1000
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
4
_______________________________________________________________________________________
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
Typical Operating Characteristics (continued)
(V
= 3.6V, V
= 1.5V, EN1 = GND, EN2 = BATT, T = +25°C, unless otherwise noted.)
OUT
BATT
A
INPUT CURRENT vs. INPUT VOLTAGE
WITH NO LOAD
HEAVY-LOAD SWITCHING WAVEFORMS
MAX1572 toc08
60
50
40
V
2V/div
LX
V
OUT
RIPPLE
10mV/div
30
20
10
500mA/div
I
L
I
= 500mA
LOAD
0
2.0
2.5 3.0 3.5
4.0 4.5 5.0 5.5
200ns/div
INPUT VOLTAGE (V)
LIGHT-LOAD SWITCHING WAVEFORMS
SOFT-START/SHUTDOWN WAVEFORMS
MAX1572 toc09
MAX1572 toc10
V
V
2V/div
1V/div
V
EN2
2V/div
LX
OUT
V
OUT
20mV/div
500mA/div
RIPPLE
100mA/div
I
IN
I
L
I
= 20mA
LOAD
2µs/div
200µs/div
RESET WAVEFORM
LOAD TRANSIENT, FORCED-PWM MODE
MAX1572 toc11
MAX1572 toc12
V
2V/div
1V/div
EN2
100mV/div
500mA/div
V
OUT
V
OUT
1V/div
V
RESET
I
LOAD
100mA/div
I
IN
I
= 20mA TO 550mA
LOAD
100ms/div
4µs/div
_______________________________________________________________________________________
5
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
Typical Operating Characteristics (continued)
(V
= 3.6V, V
= 1.5V, EN1 = GND, EN2 = BATT, T = +25°C, unless otherwise noted.)
OUT
BATT
A
LOAD TRANSIENT, PULSE-SKIP MODE
LOAD TRANSIENT, PULSE-GROUP MODE
MAX1572 toc13
MAX1572 toc14
100mV/div
500mA/div
V
OUT
V
OUT
100mV/div
500mA/div
I
LOAD
I
LOAD
I
= 20mA TO 550mA
I
= 20mA TO 550mA
LOAD
LOAD
4µs/div
4µs/div
LINE TRANSIENT
MAX1572 toc15
V
20mV/div
1V/div
OUT
V
IN
200mA/div
I
L
V
= 3.5V TO 4.0V
IN
40µs/div
6
_______________________________________________________________________________________
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
Pin Description
PIN
NAME
FUNCTION
Active-Low RESET Output. Open-drain output with internal 14kΩ pullup to OUT. RESET is driven LOW in
shutdown.
1
RESET
Soft-Start Control. Connect a capacitor from SS to GND to set the soft-start time. Use a 1000pF or larger
capacitor to eliminate inrush current during startup. With greater than 10µF total output capacitance, increase
2
SS
C
to C /10,000 for soft-start. In shutdown, SS is discharged internally with 100Ω to GND.
OUT
SS
3, 5, 11
4
GND
OUT
EN2
Ground. Connect all ground pins to the exposed paddle.
Output Sense Input. Connect to the output of the regulator. In shutdown, OUT is discharged internally with
14kΩ to GND.
6
7
Enable/Mode Control Input 2. See Table 1.
PGND Power Ground. Connect to exposed paddle.
8
LX
Inductor Connection. LX is high impedance in shutdown.
9
BATT
EN1
Supply Voltage Input. Connect to a 2.6V to 5.5V source. Connect a 10µF ceramic capacitor from BATT to GND.
Enable/Mode Control Input 1. See Table 1.
10
12
ABATT Analog Supply Input. Connect to BATT through a 10Ω resistor. Connect a 0.1µF capacitor from ABATT to GND.
Exposed
—
Exposed Paddle. Connect to GND and PGND.
Paddle
Table 1. Mode Select Truth Table
MODE
EN1
EN2
Shutdown
0
0
1
1
0
1
0
1
CLOCK
2MHz
Pulse group
Pulse skip
ABATT
BATT
EN2
EN1
MODE
0.1µF
SELECT
10Ω
INPUT
Forced PWM
2.6V TO 5.5V
CURRENT
SENSE
A zero represents EN_ being driven low or connected to GND.
A 1 represents EN_ being driven high or connected to BATT.
OUTPUT
0.75V TO 2.5V
800mA
PWM
CONTROL
10µF
SLOPE
COMP
LX
2.2µH
C
Detailed Description
OUT
MAX1572
PGND
OUT
Figure 1 is the functional diagram.
RESET
TIMER
170ms
RESET
PWM Control Scheme
The MAX1572 uses a 2MHz fixed-frequency, pulse-
width-modulated (PWM), current-mode control scheme.
The heart of the current-mode PWM controller is an
open-loop comparator that compares the error amp
voltage-feedback signal against the sum of the ampli-
fied current-sense signal and the slope compensation
ramp. At each rising edge of the internal clock, the
internal high-side P-channel MOSFET turns on until the
PWM comparator trips. During this on-time, current
ramps up through the inductor, sourcing current to the
EA
REFERENCE
GND
THERMAL
SHUTDOWN
SS
1000pF
Figure 1. Functional Diagram
_______________________________________________________________________________________
7
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
output and storing energy in the inductor’s magnetic
field. The current-mode feedback system regulates the
peak inductor current as a function of the output voltage
error signal. Since the average inductor current is nearly
the same as the peak inductor current (assuming that
the inductor value is relatively high to minimize ripple
current), the circuit acts as a switch-mode transconduc-
tance amplifier. This pushes the output LC filter pole,
normally found in a voltage-mode PWM, to a higher fre-
quency. To preserve inner-loop stability and eliminate
inductor staircasing, an internal slope-compensation
ramp is summed into the main PWM comparator. During
the second half of the switching cycle (off-time), the
internal high-side P-channel MOSFET turns off and the
internal low-side N-channel MOSFET turns on. Now the
inductor releases the stored energy as its current ramps
down while still providing current to the output. The output
capacitor stores charge when the inductor current
exceeds the load current and discharges when the
inductor current is lower, smoothing the voltage across
the load. Under overload conditions, when the inductor
current exceeds the current limit, the high-side MOSFET
is turned off and the low-side MOSFET remains on for
the remainder of the cycle to let the inductor current
ramp down.
pulse-group mode. In pulse-skip mode, the output volt-
age ripple is lower, and the load-transient response
faster. However, the quiescent current is higher than in
pulse-group mode.
Forced-PWM Mode
In forced-PWM mode, the MAX1572 operates at a con-
stant 2MHz switching frequency without pulse skipping.
This is desirable in noise-sensitive applications, since the
output ripple is minimized and has a predictable noise
spectrum. Forced-PWM mode requires higher supply
current with light loads due to constant switching.
100% Duty-Cycle Operation
The MAX1572 can operate at 100% duty cycle. In this
state, the high-side P-channel MOSFET is turned on (not
switching). This occurs when the input voltage is close to
the output voltage. The dropout voltage is the voltage
drop due to the output current across the on-resistance
of the internal P-channel MOSFET (R
) and the
DS(ON)P
inductor resistance (R ):
L
V
= I
× ( R + R )
DS(ON)P L
DROPOUT
OUT
R
is given in the Electrical Characteristics sec-
DS(ON)P
tion. R , for a few recommended inductors, is given in
L
Table 2.
Pulse-Group Mode
Pulse-group mode is used to minimize the supply cur-
rent with a light load. In pulse-group mode, the IC shuts
Load-Transient Response/
Voltage Positioning
The MAX1572 uses voltage positioning that matches
the load regulation to the voltage droop seen during
load transients. In this way, the output voltage does not
overshoot when the load is removed, which results in
the total output-voltage variation being half as wide as
in a conventional design. Figure 2 shows an example of
a voltage-positioned and a nonvoltage-positioned load
transient. Additionally, the MAX1572 uses a wide-band-
width feedback loop to respond more quickly to a load
transient than regulators using conventional integrating
feedback loops.
off most internal circuitry when V
is +0.8% above
OUT
nominal regulation. When V
drops below +0.8% of
OUT
the nominal regulation voltage, the IC powers up its cir-
cuits and resumes switching.
Pulse-Skip Mode
Pulse-skip mode is also used to minimize the supply
current with a light load. The difference between pulse-
group and pulse-skip modes is that when V
rises
OUT
above the +0.8% regulation point, pulse-group mode
stops switching and completely turns off a number of
circuits. Under the same conditions, pulse-skip mode
stops switching but leaves all circuits on. The delay
coming out of pulse-skip mode is shorter than with
The load line used to achieve voltage positioning is
shown in Figure 3. This assumes a nominal operating
point of 3.6V input at 300mA load.
Table 2. Recommended Inductors
MANUFACTURER
PART
LQH32CN
CDRH3D16
CDRH2D11
D312F
VALUE (µH)
R
(mΩ)
97
I
(mA)
SIZE (mm)
2.5 x 3.2 x 2.0
3.8 x 3.8 x 1.8
3.2 x 3.2 x 1.2
3.6 x 3.6 x 1.2
4.8 x 4.8 x 1.2
SHIELDED
L
SAT
Murata
2.2
2.2
2.2
2.2
2.2
790
No
Yes
Yes
No
50
1200
780
Sumida
TOKO
78
170
140
1200
1330
D412F
No
8
_______________________________________________________________________________________
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
NORMAL OPERATION
FORCED-PWM
+1
V
V
= 3.6V
IN
OUT
(VOLTAGE POSITIONING)
CHANGE IN
0
OUTPUT
V
IN
= 5.5V
VOLTAGE (%)
V
OUT
(CONVENTIONAL)
-1
V
= 2.6V
IN
I
OUT
-2
0
200
400
LOAD CURRENT (mA)
600
800
Figure 2. Load Transient Response, With and Without Voltage
Positioning
Figure 3. Voltage-Positioning Load Line
current. For maximum efficiency, the inductor’s DC
resistance should be as low as possible. See Table 2
for recommended inductors and manufacturers.
Soft-Start
Soft-start is used to prevent input-current overshoot dur-
ing startup. For most applications using a 10µF output
capacitor, connect a 1000pF capacitor from SS to GND.
If a larger output capacitor is used, then use the follow-
ing formula to find the value of the soft-start capacitor
needed to prevent input-current overshoot:
Capacitor Selection
Ceramic 10µF input and output capacitors are recom-
mended for most applications. For output voltages
below 1.5V, output capacitance should be increased to
22µF. For best stability over a wide temperature range,
use capacitors with an X5R or better dielectric.
C
SS
= C
/104
OUT
During soft-start, the output voltage rises from 0 to
with a time constant equal to C times
V
OUT(nom)
SS
ABATT Input Filter
In normal applications, an RC filter on ABATT keeps
power-supply noise from entering the IC. Connect a
10Ω resistor between BATT and ABATT and connect a
0.1µF capacitor from ABATT to GND.
100kΩ (see the Typical Operating Characteristics).
170ms RESET
RESET is an open-drain output with an internal 14kΩ
pullup resistor to OUT. During startup, RESET is held low
until 200ms (typ) after the output voltage reaches 90% of
its nominal regulation voltage. When the output voltage
drops below 90% of its nominal regulation voltage,
RESET pulls low again. See the Typical Operating
Characteristics section for RESET waveforms during
startup and shutdown.
PC Board Layout and Routing
Due to fast-switching waveforms and high-current
paths, careful PC board layout is required. An evalua-
tion kit (MAX1572EVKIT) is available to speed design.
When laying out a board, minimize trace lengths
between the IC, the inductor, the input capacitor, and the
output capacitor. Keep these traces short, direct, and
wide. Keep noisy traces, such as the LX node trace,
away from OUT. The input bypass capacitors should be
placed as close to the IC as possible. Connect PGND
and GND directly to the exposed paddle underneath the
IC. The ground connections of the input and output
capacitors should be as close together as possible.
Applications Information
Inductor Selection
A 2.2µH inductor with a saturation current of at least 1A
is recommended for full-load (800mA) applications. For
lower load currents, the inductor current rating may be
reduced. For most applications, use an inductor with a
current rating 1.25 times the maximum required output
_______________________________________________________________________________________
9
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
Selector Guide
Chip Information
TRANSISTOR COUNT: 3697
PART
V
(V)
TOP MARK
AABW
AACW
AABX
AABY
AABZ
—
OUT
PROCESS: BiCMOS
MAX1572ETC075
MAX1572ETC130
MAX1572ETC150
MAX1572ETC180
MAX1572ETC250
MAX1572ETCxyz
0.75
1.30
1.50
1.80
2.50
*
*xyz is for output voltage (e.g., MAX1572ETC165 has a 1.65V
output).
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE
12,16,20,24L QFN THIN, 4x4x0.8 mm
21-0139
A
10 ______________________________________________________________________________________
800mA, 2MHz, PWM DC-to-DC
Step-Down Converter with RESET
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE
12,16,20,24L QFN THIN, 4x4x0.8 mm
21-0139
A
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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