OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

MAX1644EAE-T

P1-P3P4-P6P7-P9P10-P11
General Description
The MAX1644 constant-off-time, PWM step-down DC-
DC converter is ideal for use in applications such as PC
cards, CPU daughter cards, and desktop computer
bus-termination boards. The device features internal
synchronous rectification for high efficiency and
reduced component count. It requires no external
Schottky diode. The internal 0.10Ω PMOS power switch
and 0.10Ω NMOS synchronous-rectifier switch easily
deliver continuous load currents up to 2A. The
MAX1644 produces a preset +3.3V or +2.5V output
voltage or an adjustable output from +1.1V to V
IN
. It
achieves efficiencies as high as 95%.
The MAX1644 uses a unique current-mode, constant-
off-time, PWM control scheme, which includes an Idle
Mode™ to maintain high efficiency during light-load
operation. The programmable constant-off-time archi-
tecture sets switching frequencies up to 350kHz, allow-
ing the user to optimize performance trade-offs
between efficiency, output switching noise, component
size, and cost. The device also features an adjustable
soft-start to limit surge currents during start-up, a 100%
duty cycle mode for low-dropout operation, and a low-
power shutdown mode that disconnects the input from
the output and reduces supply current below 1µA. The
MAX1644 is available in a 16-pin SSOP package.
Applications
+5V to +3.3V/+2.5V Conversion
CPU I/O Supply
+3.3V PC Card and CardBus Applications
Notebook and Subnotebook Computers
Desktop Bus-Termination Boards
CPU Daughter Card Supply
Features
♦ ±1% Output Accuracy
♦ 95% Efficiency
♦ Internal PMOS and NMOS Switches
70mΩ On-Resistance at V
IN
= +4.5V
100mΩ On-Resistance at V
IN
= +3V
♦ Output Voltage
+3.3V or +2.5V Pin-Selectable
+1.1V to V
IN
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
MAX1644
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
SHDN LX
PGND
LX
PGND
V
CC
FBSEL
REF
GND
TOP VIEW
MAX1644
SSOP
IN
LX
COMP
IN
SS
TOFF
FB
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
19-1457; Rev 3; 8/05
Pin Configuration
Ordering Information
Idle Mode is a trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit
TOFF
COMP
V
CC
FBSEL
SHDN
IN
PGND
GND
REF
SS
LX
FB
MAX1644
R
TOFF
OUTPUT
+1.1V TO
V
IN
INPUT
+3V TO
+5.5V
________________________________________________________________ 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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE
PIN-PACKAGE
MAX1644EAE 40°C to +85°C 16 SSOP
MAX1644EAE+ 40°C to +85°C 16 SSOP
+Denotes lead-free package.
MAX1644
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= V
CC
= +3.3V, FBSEL = GND, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
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.
V
CC
, IN to GND ........................................................-0.3V to +6V
IN to V
CC
.............................................................................±0.3V
GND to PGND.....................................................................±0.3V
All Other Pins to GND.................................-0.3V to (V
CC
+ 0.3V)
LX Current (Note 1)...........................................................±3.75A
REF Short Circuit to GND Duration ............................Continuous
ESD Protection .....................................................................±2kV
Continuous Power Dissipation (T
A
= +70°C)
SSOP (derate 16.7mW/°C above +70°C;
part mounted on 1 in.
2
of 1oz. copper)............................1.2W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed
the IC’s package power dissipation limits.
Hysteresis = 15°C
SHDN = GND
SHDN = GND
I
LOAD
= 0 to
2A,
V
FB
= V
OUT
V
FB
= 1.2V
(Note 2)
V
IN
= V
CC
= 3V, I
LOAD
= 1A, FBSEL = V
CC
I
LX
= 0.5A
FBSEL = REF, V
CC
, or unconnected
V
IN
= V
CC
= 3V to 5.5V,
I
LOAD
= 0, FBSEL = GND or REF
FBSEL = GND
I
REF
= -1µA to +10µA
CONDITIONS
°C150T
SHDN
Thermal Shutdown
Threshold
µA15I
IN
PMOS Switch Off-Leakage
Current
µA<1 3I
CC(SHDN)
Shutdown Supply Current
µA240 360I
IN
+ I
CC
No-Load Supply Current
kHz350fSwitching Frequency
A0.25 0.45 0.65I
IM
Idle Mode Current
Threshold
A2.5 2.9 3.3I
LIMIT
Current-Limit Threshold
mΩ
100 200
R
ON, P
PMOS Switch
On-Resistance
70 150
mV0.5 1ΔV
REF
Reference Load Regulation
2.500 2.525 2.550 V
3.300 3.333 3.366
V3.0 5.5V
IN
, V
CC
Input Voltage
V1.089 1.100 1.111V
REF
Reference Voltage
mV200V
DO
Dropout Voltage
%
0.4
1.089 1.100 1.111
V
OUT
Preset Output Voltage
Adjustable Output Voltage
Range
VV
REF
V
IN
0.2
DC Load Regulation Error
UNITSMIN TYP MAXSYMBOLPARAMETER
V
IN
= V
CC
= 4V to 5.5V,
FBSEL = unconnected
V
IN
= V
CC
= 3V to 5.5V,
FBSEL = V
CC
V
IN
= V
CC
= 3V to 5.5V,
FBSEL = REF
V
IN
= 4.5V
V
IN
= 3V
I
LX
= 0.5A mΩ
100 200
R
ON, N
NMOS Switch
On-Resistance
70 150V
IN
= 4.5V
V
IN
= 3V
FBSEL = GND
FBSEL = REF, V
CC
, or unconnected
1
AC Load Regulation Error %
2
A2.5RMS LX Output Current
MAX1644
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
CC
= +3.3V, FBSEL = GND, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
ELECTRICAL CHARACTERISTICS
(V
IN
= V
CC
= +3.3V, FBSEL = GND, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
Note 2: Recommended operating frequency, not production tested.
Note 3: Specifications from 0°C to -40°C are guaranteed by design, not production tested.
R
TOFF
= 150kΩ
V
FB
= 1.2V
V
FB
= 1.2V
I
LX
= 0.5A
V
IN
= 3.0V to 5.5V, I
LOAD
= 0,
FBSEL = GND or REF
I
LX
= 0.5A
CONDITIONS
µs1.03 1.63t
OFF
Off-Time Default Period
nA0 250I
FB
FB Input Bias Current
µA360I
IN
+ I
CC
No-Load Supply Current
A0.2 0.7I
IM
Idle Mode Current
Threshold
A2.3 3.5I
LIMIT
Current-Limit Threshold
mΩ
200
R
ON, P
PMOS Switch
On-Resistance
mΩ
150
200
R
ON, N
2.48 2.57
3.276 3.390
V3.0 5.5V
IN
Input Voltage
V1.08 1.12V
REF
Reference Voltage
VV
REF
V
IN
Adjustable Output Voltage
1.08 1.12
UNITSMIN TYP MAXSYMBOLPARAMETER
V
IN
= V
CC
= 4V to 5.5V,
FBSEL = unconnected
V
IN
= 3V to 5.5V, FBSEL = V
CC
V
IN
= 3V to 5.5V, FBSEL = REF
V
IN
= 4.5V
V
IN
= 3V
NMOS Switch
On-Resistance
150V
IN
= 4.5V
V
IN
= 3V
V
I
LOAD
= 0 to 2A,
V
FB
= V
OUT
V
OUT
Preset Output Voltage
Maximum Output RMS
Current
A
RMS
SS Sink Current I
SS
100 µA
SHDN Input Current
I
SHDN
-0.5 0.5 µA
SS Source Current I
SS
3.5 5 6.5 µA
SHDN Input Low Threshold
V
IL
0.8 V
SHDN Input High Threshold
V
IH
2.0 V
FBSEL Input Current -5 +5 µA
0.9 1.3
5.8
V
SS
= 1V
V
SHDN
= 0 to V
CC
FBSEL = REF
PARAMETER SYMBOL MIN TYP MAX UNITS
Undervoltage Lockout
Threshold
V
UVLO
2.5 2.6 2.7 V
FB Input Bias Current I
FB
0 80 200 nA
t
OFF
1.13 1.33 1.53
0.20 0.33
Off-Time Start-Up Period t
OFF
4 · t
OFF
µs
On-Time Period t
ON
0.4 µs
CONDITIONS
V
FB
= 1.2V
R
TOFF
= 150kΩ
R
TOFF
= 30.1kΩ
V
IN
falling, hysteresis = 40mV
FB = GND
Off-Time Default Period
4.3 5.6
µs
R
TOFF
= 499kΩ
FBSEL Logic Thresholds
0.2
V
FBSEL = GND
0.7 · V
CC
0.7 · V
CC
- 0.2 + 0.2
FBSEL = unconnected
V
CC
- 0.2FBSEL = V
CC
P1-P3P4-P6P7-P9P10-P11

MAX1644EAE-T

Mfr. #:
Buy MAX1644EAE-T
Manufacturer:
Maxim Integrated
Description:
IC REG BUCK ADJ/PROG 2A 16SSOP
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet