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MAX1954AEUB+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18
General Description
The MAX1954A synchronous current-mode, pulse-
width modulation (PWM) buck controller is pin compati-
ble with the popular MAX1954 and is suitable for
applications where cost and size are critical.
The MAX1954A operates from an input voltage range of
3.0V to 13.2V, independent of the IC supply. The output
voltage is adjustable down to 0.8V. The IC operates at
a fixed 300kHz switching frequency and provides up to
25A of output current with efficiency up to 95%. This
controller has excellent transient response resulting in
smaller output capacitance.
The MAX1954A features foldback current limiting that
greatly reduces input current and component power
dissipation during output overload or short-circuit
conditions.
The compensation and shutdown control (COMP) input,
in addition to providing compensation to the error
amplifier, can be pulled low to shut down the converter.
An input undervoltage lockout is provided to ensure
proper operation during power sags to prevent the
external power MOSFETs from overheating. Internal
digital soft-start is included to reduce inrush current
and save an external capacitor.
The MAX1954A is available in a tiny 10-pin µMAX
®
package to minimize PC board space.
Applications
Printers and Scanners
Graphic Cards and Video Cards
PCs and Servers
Microprocessor Cores
Low-Voltage Distributed Power
Telecom/Networks
Features
♦ Current-Mode Controller
♦ Fixed-Frequency PWM
♦ Foldback Current Limit
♦ Output Down to 0.8V with ±1% FB Accuracy
♦ 3.0V to 13.2V Input Voltage
♦ 300kHz Switching Frequency
♦ 25A Output-Current Capability
♦ 93% Efficiency
♦ All-N-Channel-MOSFET Design for Low Cost
♦ No Current-Sense Resistor Needed
♦ Internal Digital Soft-Start
♦ Small 10-Pin µMAX Package
MAX1954A
Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
1
2
3
4
5
10
9
8
7
6
BST
LX
DH
PGNDGND
FB
COMP
HSD
MAX1954A
µMAX
DLIN
Pin Configuration
19-3154; Rev 1; 5/05
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.
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX1954AEUB -40°C to +85°C 10 µMAX
MAX1954AEUB+ -40°C to +85°C 10 µMAX
EVALUATION KIT
AVAILABLE
µMAX is a registered trademark of Maxim Integrated Products, Inc.
+Denotes lead-free package.
MAX1954A
Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
IN, FB to GND...........................................................-0.3V to +6V
LX to BST..................................................................-6V to +0.3V
BST to GND ............................................................-0.3V to +20V
DH to LX................................................... -0.3V to (V
BST
+ 0.3V)
DL, COMP to GND.......................................-0.3V to (V
IN
+ 0.3V)
HSD to GND..............................................................-0.3V to 14V
PGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
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
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V, V
BST
- V
LX
= 5V, T
A
= 0°C to +85°C, unless otherwise noted.)
PARAMETER CONDITIONS
MIN TYP MAX
UNITS
GENERAL
Operating Input Voltage Range
3.0 5.5 V
HSD Voltage Range (Note 1) 3.0
13.2
V
Quiescent Supply Current V
FB
= 1.5V 1 2
mA
Standby Supply Current
V
IN
= V
BST
= 5.5V, V
HSD
= 13.2V, LX = unconnected,
COMP = GND
2
mA
Undervoltage-Lockout Trip Level
Falling V
IN
, 50mV (typ) hysteresis 2.5 2.7 2.9 V
DC-DC CONTROLLER
Output-Voltage Adjust Range
(V
OUT
)
Maximum output voltage depends on external components
and maximum duty cycle
0.8 V
ERROR AMPLIFIER
FB Regulation Voltage
-1.0 +0.8 +1.0
%
Transconductance 70
110 160
µS
Voltage Gain
200
V/ V
FB Input Leakage Current V
FB
= 0.9V 50
500
NA
FB Input Common-Mode Range
-0.1
+1.5
V
COMP Output-Voltage Swing
0.80
2.36
V
Current-Sense Amplifier
Voltage Gain
3.15
3.5
3.85
V / V
V
FB
= 0.8V
110 135 145
Current-Limit Threshold V
PGND
- V
LX
V
FB
= 0V 21 36 51
mV
OSCILLATOR
Switching Frequency MAX1954A
240 300 360
kHz
Maximum Duty Cycle Measured at DH 89 91 93 %
Minimum Duty Cycle V
COMP
= 1.25V, LX = GND, V
BST
= V
IN
= 3.3V 2.5 3 %
MAX1954A
Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V, V
BST
- V
LX
= 5V, T
A
= 0°C to +85°C, unless otherwise noted.)
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
SOFT-START
Soft-Start Period 3.4 ms
Soft-Start Levels
12.5
mV
FET DRIVERS
DH, DL Output Low Voltage I
SINK
= 10mA 0.1 V
DH, DL Output High Voltage I
SOURCE
= 10mA
V
IN
- 0.1V or
V
BS T
- 0.1V
V
DH Pullup/Pulldown,
DL Pullup On-Resistance
1.5 3 Ω
DL Pulldown On-Resistance 1 2 Ω
LX, BST, HSD Leakage Current V
BST
= 18.7V, V
LX
= 13.2V, V
IN
= 5.5V, V
HSD
= 13.2V 30 µA
THERMAL PROTECTION
Thermal Shutdown Rising temperature, 15°C hysteresis
+160
°C
SHUTDOWN CONTROL
COMP Logic-Level Low 3V < V
IN
< 5.5V
0.25
V
COMP Logic-Level High 3V < V
IN
< 5.5V 0.8 V
COMP Pullup Current
100
µA
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V, V
BST
- V
LX
= 5V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER CONDITIONS
MIN
MAX
GENERAL
Operating Input Voltage Range
3.0 5.5 V
HSD Voltage Range (Note 1) 3.0
13.2
V
Quiescent Supply Current V
FB
= 1.5V 2
Standby Supply Current
V
IN
= V
BST
= 5.5V, V
HSD
= 13.2V, LX = unconnected,
COMP = GND
2
Undervoltage Lockout Trip Level
Rising V
IN
3% (typ) hysteresis
2.50
2.93
V
DC-DC CONTROLLER
Output-Voltage Adjust Range
(V
OUT
)
0.8
0.9 x V
IN
V
ERROR AMPLIFIER
FB Regulation Voltage
-2.5
+1.0
%
Transconductance 70
160
µS
FB Input Leakage Current V
FB
= 0.9V
500
NA
FB Input Common-Mode Range
-0.1
+1.5
V
COMP Output-Voltage Swing 0.8 2.2 V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18

MAX1954AEUB+

Mfr. #:
Buy MAX1954AEUB+
Manufacturer:
Maxim Integrated
Description:
Switching Controllers Current-Mode PWM Buck Controller
Lifecycle:
New from this manufacturer.
Delivery:
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