Document
19-4106; Rev 0; 5/08
Dual, 4A/2A, 4MHz, Step-Down DC-DC Regulator with Tracking/Sequencing Capability
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General Description
Features
o 2.5V to 5.5V Input-Voltage Range o Dual-Output Synchronous Buck Regulators o Integrated Switches for 4A and 2A Output Currents o 180° Out-Of-Phase Operation o Output Voltage Adjustable from 0.6V to VAVIN o Lossless, Cycle-by-Cycle Current Sensing o External Compensation for Maximum Flexibility o Digital Soft-Start and Soft-Stop for Tracking Applications o Digital Soft-Start into a Prebiased Load for Sequencing Applications o Sequencing or Coincident/Ratiometric Tracking o Programmable Switching Frequency from 500kHz to 4MHz o Thermal Shutdown and Hiccup-Mode ShortCircuit Protection o 20µA Shutdown Current o 100% Maximum Duty Cycle o Space-Saving (5mm x 5mm) 28-Pin TQFN Package
MAX15021
The MAX15021 is a dual-output, pulse-width-modulated (PWM), step-down DC-DC regulator with tracking (coincident and ratiometric) and sequencing options. The device operates from 2.5V to 5.5V and each output can be adjusted from 0.6V to the input supply (VAVIN). The MAX15021 delivers up to 4A (regulator 1) and 2A (regulator 2) of output current. This device offers the ability to adjust the switching frequency from 500kHz to 4MHz and provides the capability of optimizing the design in terms of size and performance. The MAX15021 utilizes a voltage-mode control scheme with external compensation to provide good noise immunity and maximum flexibility in selecting inductor values and capacitor types. The dual switching regulators operate 180° out-of-phase, thereby reducing the RMS input ripple current and thus the size of the input bypass capacitor significantly. The MAX15021 offers the ability to track (coincident or ratiometric) or sequence during power-up and powerdown operation. When sequencing, it powers up glitchfree into a prebiased output. Additional features include an internal undervoltage lockout with hysteresis and a digital soft-start/soft-stop for glitch-free power-up and power-down. Protection features include lossless cycle-by-cycle current limit, hiccup-mode output short-circuit protection, and thermal shutdown. The MAX15021 is available in a space-saving, 5mm x 5mm, 28-pin TQFN-EP package and is specified for operation from -40°C to +125°C temperature range.
Pin Configuration
PGND2 PVIN2 N.C. N.C. N.C. 15 14 13 12 N.C. N.C. COMP1 FB1 EN1 DVDD1 PGND1 11 10 9 8 2 PGND1 3 LX1 4 PVIN1 5 PVIN1 6 LX1 7 PGND1 LX2
TOP VIEW
Applications
RFID Reader Cards Power-over-Ethernet (PoE) IP Phones Automotive Multimedia Multivoltage Supplies Networking/Telecom
N.C. 22 COMP2 23 FB2 24 EN2 25 SGND 26 AVIN 27 RT 28
21
20
19
18
17
16
MAX15021
Ordering Information
PART MAX15021ATI+ TEMP RANGE -40°C to +125°C PIN-PACKAGE 28 TQFN-EP*
+
1 SEL
*EP
+Denotes a lead-free package. *EP = Exposed pad.
*EP = EXPOSED PAD.
THIN QFN (5mm x 5mm)
________________________________________________________________ Maxim Integrated Products
DVDD2
1
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.
Dual, 4A/2A, 4MHz, Step-Down DC-DC Regulator with Tracking/Sequencing Capability MAX15021
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ABSOLUTE w . d a t a MAXIMUM s h e e t RATINGS 4 u . c o m AVIN, PVIN_, DVDD_, EN_, FB_, RT, SEL to SGND .........................................................-0.3V to +6V COMP_ to SGND .....................................-0.3V to (VAVIN + 0.3V) PGND_ to SGND ...................................................-0.3V to +0.3V LX_ Current (Note 1) Regulator 1...............................................................................6A Regulator 2...............................................................................3A Current into Any Pin other than PVIN_, LX_, and PGND_ ..............................................................50mA
Continuous Power Dissipation (TA = +70°C) 28-Pin TQFN (derate 34.5mW/°C above +70°C) .....2758.6mW Junction-to-Case Thermal Resistance (θJC)(Note 2) .........2°C/W Junction-to-Ambient Thermal Resistance (θJA)(Note 2) ..29°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
Note 1: LX_ has internal diodes to PGND_ and PVIN_. Applications that forward bias these diodes should take care not to exceed the IC’s package power dissipation. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations see www.maxim-ic.com/thermal-tutorial.
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 .