19-4106; Rev 0; 5/08
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Tracking/Sequencing Capability
The MAX15021 is a dual-output, pulse-width-modulated
(PWM), step-down DC-DC regulator with tracking (coin-
cident 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 (reg-
ulator 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 regula-
tors 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 power-
down operation. When sequencing, it powers up glitch-
free 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 ther-
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.
RFID Reader Cards
Power-over-Ethernet (PoE) IP Phones
-40°C to +125°C
+Denotes a lead-free package.
*EP = Exposed pad.
o 2.5V to 5.5V Input-Voltage Range
o Dual-Output Synchronous Buck Regulators
o Integrated Switches for 4A and 2A Output
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
o Digital Soft-Start into a Prebiased Load for
o Sequencing or Coincident/Ratiometric Tracking
o Programmable Switching Frequency from 500kHz
o Thermal Shutdown and Hiccup-Mode Short-
o 20µA Shutdown Current
o 100% Maximum Duty Cycle
o Space-Saving (5mm x 5mm) 28-Pin TQFN
21 20 19 18 17 16 15
*EP = EXPOSED PAD.
(5mm x 5mm)
________________________________________________________________ Maxim Integrated Products 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.