MAX1945REUI+ Maxim Integrated Products, MAX1945REUI+ Datasheet

IC REG STP DWN 6A 28-TSSOP

MAX1945REUI+

Manufacturer Part Number
MAX1945REUI+
Description
IC REG STP DWN 6A 28-TSSOP
Manufacturer
Maxim Integrated Products
Type
Step-Down (Buck)r
Datasheet
1.MAX1945REUI.pdf (19 pages)

Specifications of MAX1945REUI+

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
1.8V, 2.5V, Adj
Current - Output
6A
Frequency - Switching
1MHz
Voltage - Input
2.6 ~ 5.5 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
Power - Output
1.19W
Output Voltage
1.8 V to 2.5 V
Input Voltage
2.6 V to 5.5 V
Supply Current
12 mA
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
The MAX1945R/MAX1945S high-efficiency pulse-width
modulation (PWM) switching regulators deliver up to 6A
of output current. The devices operate from an input
supply range of 2.6V to 5.5V and provide selectable
output voltages of 1.8V, 2.5V, and adjustable output
voltages from 0.8V to 85% of the supply voltage. With
V
2.25V. The MAX1945R/MAX1945S are ideal for on-
board post-regulation applications. Total output voltage
error is less than ±1% over load, line, and temperature.
The MAX1945R/MAX1945S operate at a selectable
fixed frequency (500kHz or 1MHz) or can be synchro-
nized to an external clock (400kHz to 1.2MHz). The
high operating frequency minimizes the size of external
components. The high bandwidth of the internal error
amplifier provides excellent transient response. The
MAX1945R/MAX1945S have internal dual N-channel
MOSFETs to lower heat dissipation at heavy loads. Two
MAX1945R/MAX1945Ss can operate 180 degrees out-
of-phase of each other to minimize input capacitance.
The devices provide output voltage margining for
board-level testing. The MAX1945R provides a ±4%
voltage margining. The MAX1945S provides a ±9%
voltage margining.
The MAX1945R/MAX1945S are available in 28-pin
TSSOP-EP packages and are specified over the -40°C
to +85°C industrial temperature range. An evaluation kit
is available to speed designs.
19-2640; Rev 1; 7/04
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.
CC
at 3.3V/5V, the input voltage can be as low as
Low-Voltage, High-Density Distributed Power
Supplies
ASIC, CPU, and DSP Core Voltages
RAM Power Supply
Base Station, Telecom, and Networking
Equipment Power Supplies
Server and Notebook Power Supplies
________________________________________________________________ Maxim Integrated Products
1MHz, 1% Accurate, 6A Internal Switch
General Description
Applications
♦ 6A PWM Step-Down Regulator with 95%
♦ 1MHz/500kHz Switching for Small External
♦ 0.76in
♦ External Components’ Height <3mm
♦ ±1% Output Accuracy over Load, Line, and
♦ Operate from 2.6V to 5.5V Supply
♦ Operate from 2.5V Input with V
♦ Preset Output Voltage of 1.8V or 2.5V
♦ Adjustable Output from 0.8V to 85% of Input
♦ Voltage Margining: ±4% (MAX1945R) or ±9%
♦ Synchronize to External Clock
♦ SYNCOUT Provides 180-Degree Out-of-Phase
♦ All-Ceramic or Electrolytic Capacitor Designs
*EP = Exposed pad.
SYNCHRONIZATION
MAX1945REUI
MAX1945SEUI
Efficiency
Components
Temperature
(MAX1945S)
Clock Output
Step-Down Regulators
2.6V TO 5.5V
PART
INPUT
CLOCK
MARGINING
2
VOLTAGE
Complete 6A Regulator Footprint
ON/OFF
Typical Operating Circuit
V
IN
V
CTL1
CTL2
SYNC
COMP
FBSEL
DD
CC
-40°C to +85°C
-40°C to +85°C
TEMP RANGE
Ordering Information
MAX1945R
MAX1945S
GND
BST
SYNCOUT
PGND
REF
LX
FB
CC
180° OUT-OF-PHASE
at 3.3V/5V
PIN-PACKAGE
28 TSSOP-EP*
28 TSSOP-EP*
Features
OUTPUT
0.8V TO
0.85 x V
6A
IN
,
1

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MAX1945REUI+ Summary of contents

Page 1

... Base Station, Telecom, and Networking Equipment Power Supplies Server and Notebook Power Supplies Pin Configuration appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. Step-Down Regulators ♦ ...

Page 2

Accurate, 6A Internal Switch Step-Down Regulators ABSOLUTE MAXIMUM RATINGS CTL1, CTL2, IN, SYNC GND ...............-0. SYNCOUT, COMP, FB, FBSEL, REF to GND ............................................-0. Current (Note 1) .....................................................-9A ...

Page 3

Accurate, 6A Internal Switch ELECTRICAL CHARACTERISTICS (continued 3.3V, SYNC = GND, FBSEL = High- CTL1 CTL2 DD otherwise noted. Typical values are at +25°C.) PARAMETER ...

Page 4

Accurate, 6A Internal Switch Step-Down Regulators ELECTRICAL CHARACTERISTICS (continued 3.3V, SYNC = GND, FBSEL = High- CTL1 CTL2 DD otherwise noted. Typical values are at ...

Page 5

Accurate, 6A Internal Switch ELECTRICAL CHARACTERISTICS (continued 3.3V, SYNC = GND, FBSEL = High- CTL1 CTL2 DD otherwise noted. Typical values are at +25°C.) PARAMETER ...

Page 6

Accurate, 6A Internal Switch Step-Down Regulators ELECTRICAL CHARACTERISTICS (continued 3.3V, SYNC = GND, FBSEL = High- CTL1 CTL2 DD otherwise noted.) (Note 2) PARAMETER SYMBOL ...

Page 7

Accurate, 6A Internal Switch ELECTRICAL CHARACTERISTICS (continued 3.3V, SYNC = GND, FBSEL = High- CTL1 CTL2 DD otherwise noted.) (Note 2) PARAMETER SYMBOL LX Minimum ...

Page 8

Accurate, 6A Internal Switch Step-Down Regulators ( 5V 1.8V 6A OUT OUT EFFICIENCY vs. OUTPUT CURRENT 100 ...

Page 9

Accurate, 6A Internal Switch ( 5V 1.8V 6A OUT OUT PGND-MEASURED TEMPERATURE vs. OUTPUT CURRENT 140 120 AMBIENT TEMP: +85°C 100 AMBIENT TEMP: 80 +25° ...

Page 10

Accurate, 6A Internal Switch Step-Down Regulators ( 5V 1.8V 6A OUT OUT VOLTAGE MARGINING (9%) MAX1945 toc18 V CTL1 2V/div V OUT 200mV/div 400µs/div PIN NAME Bootstrap Voltage. ...

Page 11

Accurate, 6A Internal Switch PIN NAME 19, 21, 23, Power Ground. Connect all PGND together close to the device. Star connect GND to PGND (see the PC PGND 25 Board Layout Considerations section). Output Margining Control Inputs. When ...

Page 12

Accurate, 6A Internal Switch Step-Down Regulators The MAX1945R/MAX1945S employs digital soft-start to reduce supply in-rush current during startup conditions. When the device exits undervoltage lockout (UVLO), shutdown mode, or restarts following a thermal-overload event, the digital soft-start circuitry ...

Page 13

Accurate, 6A Internal Switch Use a low-loss inductor with the lowest possible DC resistance that fits in the allotted dimensions. Ferrite core types are often the best choice for performance. With any core material the core must be ...

Page 14

Accurate, 6A Internal Switch Step-Down Regulators Compensation Design The double pole formed by the inductor and the output capacitor of most voltage-mode controllers introduces a large phase shift, which requires an elaborate com- pensation network to stabilize the ...

Page 15

Accurate, 6A Internal Switch Set the error-amplifier compensation zero formed by R and C equal to the load-impedance pole frequency maximum load. Calculate C PLOAD ✕ OUT OUT The ...

Page 16

Accurate, 6A Internal Switch Step-Down Regulators Table 3. Compensation Values for Output Voltages (1MHz) VOUT (V) 0.8 R (1%) 100kΩ (10%) 330pF C mum zero-crossing frequency should be less than one- third of the load-impedance zero ...

Page 17

Accurate, 6A Internal Switch fz = [1/(2π ✕ [1/(2 ESR OUT ESR 0.005)] = 339kHz. For a 0.68µH output inductor, choose the closed-loop unity-gain crossover frequency (f Determine the switching regulator DC gain: G ...

Page 18

Accurate, 6A Internal Switch Step-Down Regulators IN BST SYNCOUT AC DETECT SYNC CTL1 CONTROL CTL2 V CC REFERENCE GND COMP FB FB FBSEL Pin Configuration TOP VIEW BST ...

Page 19

... 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 ____________________ 19 © 2004 Maxim Integrated Products ...

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