MAX15003 Datasheet, PDF (14/32 Pages) Maxim Integrated Products – Triple-Output Buck Controller with Tracking/Sequencing

Triple-Output Buck Controller with
Tracking/Sequencing
Functional Diagrams (continued)
PWM CONTROLLERS 2 AND 3
MAX15003
VREF
DOWN2/3
EN/
TRACK2/3
FB2/3
DIGITAL
CLK2/3
SOFT-START
SEL_
AND
VREF
SOFT-STOP
VR2/3
E/A
SEQ_
EN
CONFIG
COMP2/3
CLK2/3
RAMP
CPWM
LEVEL
SHIFT
CLK2/3
EN1
1.24VON
1.12VOFF
EN_ SHDN ^EN2/3
SEQ_
OVL
OVL_
CONFIG
OVL2/3 ^RES
OVERLOAD
IMAX2/3 _MANAGEMENT
CLK2/3
0.925
x
V_REF
FB2/3
R
Q
SET
DOMINANT
S
PGPD2/3
CSP2/3
CSN2/3
CURRENT-
LIMIT
SET
ILIM2/3
BST2/3
DH2/3
LX2/3
DREG2/3
DL2/3
PGND2/3
PGOOD2/3
Detailed Description
The MAX15003 is a triple-output, pulse-width-modulat-
ed (PWM), step-down, DC-DC controller with tracking
and sequencing options. The device operates over the
input voltage range of 5.5V to 23V or 5V ±10%. Each
PWM controller provides an adjustable output down to
0.6V and delivers up to 15A load current with excellent
load and line regulation.
Each of the MAX15003 PWM sections utilizes a volt-
age-mode control scheme for good noise immunity and
offers external compensation allowing for maximum
flexibility with a wide selection of inductor values and
capacitor types. The device operates at a fixed switch-
ing frequency that is programmable from 200kHz to
2.2MHz and can be synchronized to an external clock
signal using the SYNC input. Each converter, operating
at up to 2.2MHz with 120° out-of-phase, increases the
input capacitor ripple frequency up to 6.6MHz, reduc-
ing the RMS input ripple current and the size of the
input bypass capacitor requirement significantly.
The MAX15003 provides either coincident tracking,
ratiometric tracking, or sequencing. This allows tailor-
ing of the power-up/power-down sequence depending
on the system requirements.
The MAX15003 features lossless valley-mode current-
limit protection by monitoring the voltage drop across
the synchronous MOSFET’s on-resistance to sense the
inductor current. The MAX15003’s internal current
source exhibits a positive temperature coefficient to help
compensate for the MOSFET’s temperature coefficient.
Use an external voltage-divider when a more precise
current limit is desired. This divider along with a preci-
sion shunt resistor allows for more accurate current limit.
The MAX15003 includes internal undervoltage lockout
with hysteresis, digital soft-start/soft-stop for glitch-free
power-up and power-down of the converters. The
power-on reset (RESET) with adjustable timeout period
monitors all three outputs and provides a RESET signal
to a system controller/processor indicating when all
outputs are within regulation. Protection features
include lossless valley-mode current limit and hiccup
mode output short-circuit protection.
14 ______________________________________________________________________________________