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PDF MAX1644 Data sheet ( Hoja de datos )
| Número de pieza | MAX1644 | |
| Descripción | Advanced Chemistry-Independent / Level 2 Battery Charger with Input Current Limiting | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX1644 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
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19-1457; Rev 3; 8/05
omEVAALVUAAILTAIOBNLEKIT
Synchh2erAoe,nt4LoUou.cws -RVeoclttaifgicea, tSiotenpa-DnodwInnteRrengaul lSawtoirtcwhiethsGeneral Description
SThe MAX1644 constant-off-time, PWM step-down DC-
taDC converter is ideal for use in applications such as PC
acards, CPU daughter cards, and desktop computer
.Dbus-termination boards. The device features internal
synchronous rectification for high efficiency and
wreduced component count. It requires no external
wSchottky diode. The internal 0.10Ω PMOS power switch
wand 0.10Ω NMOS synchronous-rectifier switch easily
deliver continuous load currents up to 2A. The
mMAX1644 produces a preset +3.3V or +2.5V output
voltage or an adjustable output from +1.1V to VIN. It
oachieves efficiencies as high as 95%.
.cThe MAX1644 uses a unique current-mode, constant-
off-time, PWM control scheme, which includes an Idle
Mode™ to maintain high efficiency during light-load
Uoperation. The programmable constant-off-time archi-
tecture sets switching frequencies up to 350kHz, allow-
t4ing the user to optimize performance trade-offs
between efficiency, output switching noise, component
size, and cost. The device also features an adjustable
esoft-start to limit surge currents during start-up, a 100%
duty cycle mode for low-dropout operation, and a low-
epower shutdown mode that disconnects the input from
the output and reduces supply current below 1µA. The
hMAX1644 is available in a 16-pin SSOP package.
SApplications
ta+5V to +3.3V/+2.5V Conversion
CPU I/O Supply
a+3.3V PC Card and CardBus Applications
Notebook and Subnotebook Computers
.DDesktop Bus-Termination Boards
CPU Daughter Card Supply
wTypical Operating Circuit
wINPUT
+3V TO
m+5.5V
w Sheet4U.coRTOFF
IN LX
MAX1644 FB
VCC
FBSEL
SHDN
COMP
TOFF
PGND
GND
REF
SS
OUTPUT
+1.1V TO
VIN
Features
♦ ±1% Output Accuracy
♦ 95% Efficiency
♦ Internal PMOS and NMOS Switches
70mΩ On-Resistance at VIN = +4.5V
100mΩ On-Resistance at VIN = +3V
♦ Output Voltage
+3.3V or +2.5V Pin-Selectable
+1.1V to VIN Adjustable
♦ +3V to +5.5V Input Voltage Range
♦ 360µA (max) Operating Supply Current
♦ < 1µA Shutdown Supply Current
♦ Programmable Constant-Off-Time Operation
♦ 350kHz (max) Switching Frequency
♦ Idle Mode Operation at Light Loads
♦ Thermal Shutdown
♦ Adjustable Soft-Start Inrush Current Limiting
♦ 100% Duty Cycle During Low-Dropout Operation
♦ Output Short-Circuit Protection
♦ 16-Pin SSOP Package
Ordering Information
PART
TEMP RANGE
MAX1644EAE
40°C to +85°C
MAX1644EAE+
40°C to +85°C
+Denotes lead-free package.
PIN-PACKAGE
16 SSOP
16 SSOP
Pin Configuration
TOP VIEW
SHDN 1
IN 2
LX 3
IN 4
SS 5
COMP 6
TOFF 7
FB 8
MAX1644
SSOP
16 LX
15 PGND
14 LX
13 PGND
12 VCC
11 FBSEL
10 REF
9 GND
ataIdle Mode is a trademark of Maxim Integrated Products, Inc.
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
.D________________________________________________________________ Maxim Integrated Products 1
wwFor pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
w1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
Typical Operating Characteristics (continued)
(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
LINE-TRANSIENT RESPONSE
LOAD-TRANSIENT RESPONSE
(FBSEL = REF)
4V
VIN
3V
VOUT = 1.5V, IOUT = 2A
VOUT
20mV/div
2A
IL
0
VOUT
50mV/div
VIN = 3.3V, VOUT = 1.5V
20μs/div
20μs/div
Pin Description
PIN
1
2, 4
3, 14, 16
5
6
7
8
9
10
11
12
13, 15
NAME
SHDN
IN
LX
SS
COMP
TOFF
FB
GND
REF
FBSEL
VCC
PGND
FUNCTION
Shutdown Control Input. Drive SHDN low to disable the reference, control circuitry, and internal
MOSFETs. Drive high or connect to VCC for normal operation.
Supply Voltage Input for the internal PMOS power switch
Connection for the drains of the PMOS power switch and NMOS synchronous-rectifier switch. Connect
the inductor from this node to output filter capacitor and load.
Soft-Start. Connect a capacitor from SS to GND to limit inrush current during start-up.
Integrator Compensation. Connect a capacitor from COMP to VCC for integrator compensation. See the
Integrator Amplifier section.
Off-Time Select Input. Sets the PMOS power switch off-time during constant-off-time operation. Connect a
resistor from TOFF to GND to adjust the PMOS switch off-time.
Feedback Input for both preset-output and adjustable-output operating modes. Connect directly to
output for fixed-voltage operation or to a resistor-divider for adjustable operating modes.
Analog Ground
Reference Output. Bypass REF to GND with a 1µF capacitor.
Feedback Select Input. Selects AC load-regulation error and output voltage. See Table 2 for program-
ming instructions.
Analog Supply Voltage Input. Supplies internal analog circuitry. Bypass VCC with a 10Ω and 2.2µF low-
pass filter. See Figure 1.
Power Ground. Internally connected to the internal NMOS synchronous-rectifier switch.
_______________________________________________________________________________________ 5
5 Page 
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
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.)
21
EH
INCHES
MILLIMETERS
DIM MIN MAX MIN MAX
A 0.068 0.078 1.73 1.99
A1 0.002 0.008 0.05 0.21
B 0.010 0.015 0.25 0.38
C 0.004 0.008 0.09 0.20
D SEE VARIATIONS
E 0.205 0.212 5.20 5.38
e 0.0256 BSC
0.65 BSC
H 0.301 0.311 7.65 7.90
L 0.025 0.037 0.63 0.95
0∞ 8∞ 0∞ 8∞
INCHES MILLIMETERS
MIN MAX MIN MAX N
D 0.239 0.249 6.07 6.33 14L
D 0.239 0.249 6.07 6.33 16L
D 0.278 0.289 7.07 7.33 20L
D 0.317 0.328 8.07 8.33 24L
D 0.397 0.407 10.07 10.33 28L
N
A
e
D
B
A1
L
NOTES:
1. D&E DO NOT INCLUDE MOLD FLASH.
2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").
3. CONTROLLING DIMENSION: MILLIMETERS.
4. MEETS JEDEC MO150.
5. LEADS TO BE COPLANAR WITHIN 0.10 MM.
C
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, SSOP, 5.3 MM
APPROVAL
DOCUMENT CONTROL NO.
21-0056
REV.
C
1
1
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
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet MAX1644.PDF ] | |
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