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

MAX1742EEE+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
MAX1742/MAX1842
1A/2.7A, 1MHz, Step-Down Regulators with
Synchronous Rectification and Internal Switches
________________________________________________________________ Maxim Integrated Products 1
19-1760; Rev 2; 9/05
General Description
The MAX1742/MAX1842 constant-off-time, pulse-width-
modulated (PWM) step-down DC-DC converters are ideal
for use in 5V and 3.3V to low-voltage conversion neces-
sary in notebook and subnotebook computers. These
devices feature internal synchronous rectification for high
efficiency and reduced component count. They require
no external Schottky diode. The internal 90mΩ PMOS
power switch and 70mΩ NMOS synchronous-rectifier
switch easily deliver continuous load currents up to 1A.
The MAX1742/MAX1842 produce a preset 2.5V, 1.8V, or
1.5V output voltage or an adjustable output from 1.1V to
V
IN
. They achieve efficiencies as high as 95%.
The MAX1742/MAX1842 use a unique current-mode,
constant-off-time, PWM control scheme, which includes
Idle Mode™ to maintain high efficiency during light-load
operation. The programmable constant-off-time architec-
ture sets switching frequencies up to 1MHz, allowing the
user to optimize performance trade-offs between effi-
ciency, output switching noise, component size, and
cost. Both devices are designed for continuous output
currents up to 1A. The MAX1742 uses a peak current
limit of 1.3A (min) and is suitable for applications requir-
ing small external component size and high efficiency.
The MAX1842 has a higher current limit of 3.1A (min)
and is intended for applications requiring an occasional
burst of output current up to 2.7A. Both devices also fea-
ture an adjustable soft-start to limit surge currents during
startup, a 100% duty cycle mode for low-dropout opera-
tion, and a low-power shutdown mode that disconnects
the input from the output and reduces supply current
below 1µA. The MAX1742/MAX1842 are available in 16-
pin QSOP packages.
For similar devices that provide continuous output cur-
rents up to 2A and 3A, refer to the MAX1644 and
MAX1623 data sheets.
Applications
5V or 3.3V to Low-Voltage Conversion
CPU I/O Ring
Chipset Supplies
Notebook and Subnotebook Computers
Features
♦ ±1% Output Accuracy
♦ 95% Efficiency
♦ Internal PMOS and NMOS Switches
90mΩ On-Resistance at V
IN
= 4.5V
110mΩ On-Resistance at V
IN
= 3V
♦ Output Voltage
2.5V, 1.8V, or 1.5V Pin Selectable
1.1V to V
IN
Adjustable
♦ 3V to 5.5V Input Voltage Range
♦ 600μA (max) Operating Supply Current
♦ <1μA Shutdown Supply Current
♦ Programmable Constant-Off-Time Operation
♦ 1MHz (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 QSOP Package
Ordering Information
Idle Mode is a trademark of Maxim Integrated Products.
Typical Configuration
TOFF
COMP
V
CC
FBSEL
SHDN
IN
PGND
GND
REF
SS
LX
FB
MAX1742
MAX1842
OUTPUT
1.1V TO
V
IN
INPUT
3V TO
5.5V
0.01μF
1μF
2.2μF
470pF
10Ω
Pin Configuration appears at end of data sheet.
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
MAX1742EEE
-40°C to +85°C
16 QSOP
MAX1742EEE+
-40°C to +85°C
16 QSOP
MAX1842EEE
-40°C to +85°C
16 QSOP
MAX1842EEE+
-40°C to +85°C
16 QSOP
+ Denotes lead-free package.
MAX1742/MAX1842
1A/2.7A, 1MHz, Step-Down Regulators 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.
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
Input Voltage
V
IN
, V
CC
3.0 5.5 V
T
A
= +25°C
to +85°C
2.500 2.525 2.550
FBSEL =
V
CC
T
A
= +0°C
to +85°C
2.487 2.525 2.563
T
A
= +25°C
to +85°C
1.500 1.515 1.530
FBSEL =
unconnected
T
A
= +0°C
to +85°C
1.492 1.515 1.538
T
A
= +25°C
to +85°C
1.800 1.818 1.836
FBSEL =
REF
T
A
= +0°C
to +85°C
1.791 1.818 1.845
T
A
= +25°C
to +85°C
1.089 1.100 1.111
Preset Output Voltage V
OUT
V
IN
= 3V to
5.5V,
I
LOAD
= 0
to 1A for
MAX1742,
I
LOAD
= 0
to 2.5A for
MAX1842,
V
FB
= V
OUT
FBSEL =
GND
T
A
= +0°C
to +85°C
1.084 1.100 1.117
V
Adjustable Output Voltage
Range
V
IN
= V
CC
= 3V to 5.5V, I
LOAD
= 0,
FBSEL = GND
V
REF
V
IN
V
AC Load Regulation Error 2%
DC Load Regulation Error 0.4 %
Dropout Voltage V
DO
V
IN
= V
CC
= 3V, I
LOAD
= 1A
250
mV
T
A
= +25°C to +85°C
1.089 1.100 1.111
Reference Voltage V
REF
T
A
= +0°C to +85°C
1.084 1.100 1.117
V
Reference Load Regulation
ΔV
REF
I
REF
= -1µA to +10µA 0.5 2 mV
V
IN
= 4.5V 90
200
PMOS Switch
On-Resistance
R
ON
,
P
I
LX
= 0.5A
V
IN
= 3V
110 250
V
IN
= 4.5V 70
150
NMOS Switch
On-Resistance
R
ON
,
N
I
LX
= 0.5A
V
IN
= 3V 80
200
mΩ
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).............................................................±4.7A
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)...............................1W
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.
MAX1742/MAX1842
1A/2.7A, 1MHz, Step-Down Regulators 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.)
PARAMETER
SYMBOL
CONDITIONS
TYP
MAX
UNITS
MAX1742 1.3 1.5 1.7
Current-Limit Threshold I
LIMIT
MAX1842 3.1 3.6 4.1
A
RMS LX Output Current 3.1 A
MAX1742 0.1 0.3 0.5
Idle Mode Current Threshold I
IM
MAX1842 0.3 0.6 0.9
A
Switching Frequency f (Note 2) 1
MHz
No-Load Supply Current
I
IN
+ I
CC
V
FB
= 1.2V
350 600
µA
Shutdown Supply Current
I
CC
(SHDN)
SHDN = GND <1 5 µA
PMOS Switch Off-Leakage
Current
I
IN
SHDN = GND 15 µA
Thermal Shutdown Threshold
T
SHDN
Hysteresis = 15°C
160
°C
Undervoltage Lockout Threshold
V
UVLO
V
IN
falling, hysteresis = 90mV 2.5 2.6 2.7 V
FB Input Bias Current I
FB
V
FB
= 1.2V 0 60
250
nA
R
TOFF
= 110kΩ 0.9
1.00
1.1
R
TOFF
= 30.1kΩ
0.24 0.30 0.37
Off-Time Default Period t
OFF
R
TOFF
= 499kΩ 3.8 4.5 5.2
µs
Off-Time Startup Period t
OFF
FB = GND 4
✕
t
OFF
µs
On-Time Period t
ON
(Note 2) 0.4 µs
SS Source Current I
SS
4 5 6 µA
SS Sink Current I
SS
V
SS
= 1V
100
µA
SHDN Input Current
I
SHDN
V
SHDN
= 0 to V
CC
-1 1 µA
SHDN Input Low Threshold V
IL
0.8 V
SHDN Input High Threshold V
IH
2.0 V
FBSEL Input Current -4 +4 µA
FBSEL = GND 0.2
FBSEL = REF 0.9 1.3
FBSEL = unconnected
0.7
✕
VCC
- 0.2
0.7
✕
VCC
+0.2
FBSEL Logic Thresholds
FBSEL = V
CC
V
CC
- 0.2
V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MAX1742EEE+T

Mfr. #:
Buy MAX1742EEE+T
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators 1A/2.7A 1MHz Step Down Regulator
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet