MAX8643AETG+ Maxim Integrated Products, MAX8643AETG+ Datasheet

IC REG STP DWN 3A 24-TQFN

MAX8643AETG+

Manufacturer Part Number
MAX8643AETG+
Description
IC REG STP DWN 3A 24-TQFN
Manufacturer
Maxim Integrated Products
Type
Step-Down (Buck)r
Datasheet
1.MAX8643AETG.pdf (16 pages)

Specifications of MAX8643AETG+

Internal Switch(s)
Yes
Synchronous Rectifier
Yes
Number Of Outputs
1
Voltage - Output
0.6 ~ 3.2 V
Current - Output
3A
Frequency - Switching
500kHz ~ 2MHz
Voltage - Input
2.35 ~ 3.6 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
24-TQFN Exposed Pad
Power - Output
2.22W
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
The MAX8643A high-efficiency switching regulator
delivers up to 3A load current at output voltages from
0.6V to (0.9 x V
making it ideal for on-board point-of-load and postregu-
lation applications. Total output error is less than ±1%
over load, line, and temperature.
The MAX8643A features fixed-frequency PWM mode
operation with a switching frequency range of 500kHz
to 2MHz set by an external resistor. High-frequency
operation allows for an all-ceramic capacitor design.
The high operating frequency also allows for small-size
external components.
The low-resistance on-chip nMOS switches ensure high
efficiency at heavy loads while minimizing critical induc-
tances, making the layout a much simpler task with
respect to discrete solutions. Following a simple layout
and footprint ensures first-pass success in new designs.
The MAX8643A comes with a high-bandwidth (> 14MHz)
voltage-error amplifier. The voltage-mode control archi-
tecture and the voltage-error amplifier permit a type III
compensation scheme to be utilized to achieve maxi-
mum loop bandwidth, up to 20% of the switching fre-
quency. High loop bandwidth provides fast transient
response, resulting in less required output capacitance
and allowing for all-ceramic capacitor designs.
The MAX8643A provides two three-state logic inputs to
select one of nine preset output voltages. The preset
output voltages allow customers to achieve ±1% out-
put-voltage accuracy without using expensive 0.1%
resistors. In addition, the output voltage can be set to
any customer value by either using two external resis-
tors at the feedback with 0.6V internal reference or
applying an external reference voltage to the REFIN
input. The MAX8643A offers programmable soft-start
time using one capacitor to reduce input inrush current.
The MAX8643A is available in a lead-free, 24-pin, 4mm
x 4mm thin QFN package.
Pin Configuration appears at end of data sheet.
19-0767; Rev 2; 10/09
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
POLs
ASIC/CPU/DSP Core and I/O Voltages
DDR Power Supplies
Base-Station Power Supplies
Telecom and Networking Power Supplies
RAID Control Power Supplies
IN
). The IC operates from 2.35V to 3.6V,
________________________________________________________________ Maxim Integrated Products
General Description
Applications
3A, 2MHz Step-Down Regulator
with Integrated Switches
o Internal 37mΩ R
o Continuous 3A Output Current
o ±1% Output Accuracy Over Load, Line,
o Operates from 2.35V to 3.6V Supply
o Adjustable Output from 0.6V to (0.9 x V
o Soft-Start Reduces Inrush Supply Current
o 500kHz to 2MHz Adjustable Switching Frequency
o Compatible with Ceramic, Polymer, and
o VID-Selectable Output Voltages
o Fully Protected Against Overcurrent
o Safe-Start into Prebiased Output
o Sink/Source Current in DDR Applications
o Lead-Free, 24-Pin, 4mm x 4mm Thin QFN Package
+ Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
* EP = Exposed pad.
M AX 8643AE TG+
M AX 8643AE TG/V +
2.4V TO 3.6V
and Temperature
Electrolytic Output Capacitors
and Overtemperature
INPUT
0.6, 0.7, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, and 2.5V
PART
Typical Operating Circuit
DSON
IN
EN
V
CTL1
CTL2
FREQ
REFIN
SS
PREBIAS
DD
TEMP RANGE
- 40°C to + 85°C
- 40°C to + 85°C
Ordering Information
MAX8643A
GND
MOSFETs
PWRGD
COMP
PGND
OUT
BST
LX
FB
PIN-PACKAGE
24 Thin QFN-EP*
24 Thin QFN-EP*
Features
IN
)
V
DD
OUTPUT
1.8V, 3A
1

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MAX8643AETG+ Summary of contents

Page 1

... Base-Station Power Supplies Telecom and Networking Power Supplies RAID Control Power Supplies Pin Configuration appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 3A, 2MHz Step-Down Regulator with Integrated Switches o Internal 37mΩ ...

Page 2

Step-Down Regulator with Integrated Switches ABSOLUTE MAXIMUM RATINGS IN PWRGD to GND ......................................-0.3V to +4.5V DD COMP, FB, REFIN, OUT, CTL_, EN, SS, FREQ to GND...................-0. Current (Note 1) .....................................................-4A to +4A BST ...

Page 3

ELECTRICAL CHARACTERISTICS (continued 3.3V 0.5V -40°C to +85°C. Typical values are PARAMETER Open-Loop Voltage Gain 1kΩ from COMP to GND Error-Amplifier Unity-Gain Parallel 10kΩ, 40pF from ...

Page 4

Step-Down Regulator with Integrated Switches ELECTRICAL CHARACTERISTICS (continued 3.3V 0.5V -40°C to +85°C. Typical values are PARAMETER ENABLE EN Input Logic-Low, Falling EN Input ...

Page 5

3.3V EFFICIENCY vs. OUTPUT CURRENT 100 1.8V OUT 1.5V OUT 1.2V 70 OUT ...

Page 6

Step-Down Regulator with Integrated Switches (Typical values are 3.3V INPUT CURRENT vs. INPUT VOLTAGE 2.2 ...

Page 7

PIN NAME Leave pin unconnected to prevent discharging of output capacitor during soft-start. Connect to GND 1 PREBIAS otherwise. (See the Soft-Starting into a Prebiased Output section.) Supply Voltage and Bypass Input. Connect capacitor from V ...

Page 8

Step-Down Regulator with Integrated Switches SHUTDOWN EN CONTROL BIAS GENERATOR VOLTAGE REFERENCE SS SOFT-START REFIN OUT 8kΩ FB CTL1 VID VOLTAGE- CONTROL CTL2 CIRCUITRY COMP COMP LOW DETECTOR 8 _______________________________________________________________________________________ V DD UVLO CIRCUITRY CURRENT-LIMIT COMPARATOR CONTROL LOGIC ...

Page 9

INPUT 2. 22µF 0.1µF R1 10Ω 1µF R2 10kΩ C6 0.01µF C8 6800pF Figure 1. 1MHz, All-Ceramic Capacitor Design with V Detailed Description The MAX8643A high-efficiency, voltage-mode switch- ing regulator is capable of ...

Page 10

Step-Down Regulator with Integrated Switches The internal, high-side MOSFET has a typical 5.5A peak current-limit threshold. When current flowing out of LX exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. The synchro- ...

Page 11

The logic states of CTL1 and CTL2 should be pro- grammed only before power-up. Once the part is enabled, CTL1 and CTL2 should not be changed. If the output voltage needs to be reprogrammed, cycle power or EN and reprogram ...

Page 12

Step-Down Regulator with Integrated Switches Input-Capacitor Selection The input capacitor reduces the current peaks drawn from the input power supply and reduces switching noise in the IC. The total input capacitance must be equal to or greater than ...

Page 13

COMPENSATION TRANSFER FUNCTION DOUBLE POLE GAIN (dB) POWER-STAGE TRANSFER FUNCTION FIRST AND SECOND ZEROS Figure 4. Type III Compensation Illustration π ...

Page 14

Step-Down Regulator with Integrated Switches where C is the output capacitor age the soft-start time set by the soft-start capacitor and I is the peak-to-peak inductor ripple current SS P-P (as ...

Page 15

Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 3A, 2MHz Step-Down Regulator with Integrated Switches For the latest package outline information and land patterns www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package ...

Page 16

... 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. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2009 Maxim Integrated Products ...

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