Document
19-3656; Rev 1; 2/07
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1A, 40V, MAXPower Step-Down DC-DC Converters
General Description
The MAX5080/MAX5081 are 250kHz PWM step-down DC-DC converters with an on-chip, 0.3 Ω high-side switch. The input voltage range is 4.5V to 40V for the MAX5080 and 7.5V to 40V for the MAX5081. The output is adjustable from 1.23V to 32V and can deliver up to 1A of load current. Both devices utilize a voltage-mode control scheme for good noise immunity in the high-voltage switching environment and offer external compensation allowing for maximum flexibility with a wide selection of inductor values and capacitor types. The switching frequency is internally fixed at 250kHz and can be synchronized to an external clock signal through the SYNC input. Light load efficiency is improved by automatically switching to a pulse-skip mode. All devices include programmable undervoltage lockout and soft-start. Protection features include cycle-bycycle current limit, hiccup-mode output short-circuit protection, and thermal shutdown. Both devices are available in a space-saving, high-power (2.7W), 16-pin TQFN package and are rated for operation over the -40°C to +125°C temperature range.
Features
♦ 4.5V to 40V (MAX5080) or 7.5V to 40V (MAX5081) Input Voltage Range ♦ 1A Output Current ♦ VOUT Range From 1.23V to 32V ♦ Internal High-Side Switch ♦ Fixed 250kHz Internal Oscillator ♦ Automatic Switchover to Pulse-Skip Mode at Light Loads ♦ External Frequency Synchronization ♦ Thermal Shutdown and Short-Circuit Protection ♦ Operates Over the -40°C to +125°C Temperature Range ♦ Space-Saving (5mm x 5mm) High-Power 16-Pin TQFN Package
MAX5080/MAX5081
Ordering Information
PART MAX5080ATE MAX5081ATE TEMP RANGE -40°C to +125°C -40°C to +125°C PINPACKAGE 16 TQFN-EP* 16 TQFN-EP* PKG CODE T1655-2 T1655-2
Applications
FireWire® Power Supplies Distributed Power Automotive Industrial
*EP = Exposed pad. Pin Configurations appear at end of data sheet. FireWire is a registered trademark of Apple Computer, Inc.
Typical Operating Circuits
VIN 4.5V TO 40V CF D1
IN R1
DVREG
C-
C+
BST LX
CBST L1 VOUT C6
C1
REG
MAX5080
ON/OFF SYNC SGND PGND C2 PGND SS CSS FB
D2
C5 R6
R3
C8 R2 COMP R5 C7 R4
PGND
Typical Operating Circuits continued at end of data sheet. ________________________________________________________________ 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.
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1A, 40V, MAXPower Step-Down DC-DC Converters MAX5080/MAX5081
ABSOLUTE MAXIMUM RATINGS
IN, ON/OFF to SGND..............................................-0.3V to +45V LX to SGND .................................................-0.3V to (VIN + 0.3V) BST to SGND ................................................-0.3V to (VIN + 12V) BST to LX................................................................-0.3V to +12V PGND to SGND .....................................................-0.3V to +0.3V REG, DVREG, SYNC to SGND ...............................-0.3V to +12V FB, COMP, SS to SGND ...........................-0.3V to (VREG + 0.3V) C+ to PGND (MAX5080 only)................(VDVREG - 0.3V) to +12V C- to PGND (MAX5080 only) ................-0.3V to (VDVREG + 0.3V) Continuous current through internal power MOSFET (pins 11/12 connected together and pins 13/14 connected together) TJ = +125°C.........................................................................3A TJ = +150°C.........................................................................2A Continuous Power Dissipation* (TA = +70°C) 16-Pin TQFN (derate 33.3mW/°C above +70°C) ...2666.7mW 16-Pin TQFN (θJA)........................................................30°C/W 16-Pin TQFN (θJC).......................................................1.7°C/W Operating Temperature Range .........................-40°C to +125°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C *As per JEDEC 51 Standard
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.
ELECTRICAL CHARACTERISTICS
(VIN = VON/OFF = 12V, VREG = VDVREG, VSYNC = PGND = SGND, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA= + 25°C.) (Note 1)
PARAMETER Input Voltage Range Undervoltage Lockout Threshold Undervoltage Lockout Hysteresis Switching Supply Current (PWM Operation) Efficiency No-Load Supply Current (PFM Operation) Shutdown Current ON/OFF CONTROL Input Voltage Threshold Input Voltage Hyst.