MAX1533A Datasheet, PDF (1/38 Pages) Maxim Integrated Products – High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers

19-4023; Rev 0; 4/06
EVAALVUAAILTAIOBNLEKIT
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
General Description
The MAX1533A/MAX1537A are dual step-down, switch-
mode power-supply (SMPS) controllers with synchro-
nous rectification, intended for main 5V/3.3V power
generation in battery-powered systems. Fixed-frequen-
cy operation with optimal interleaving minimizes input
ripple current from the lowest input voltages up to the
26V maximum input. Optimal 40/60 interleaving allows
the input voltage to go down to 8.3V before duty-cycle
overlap occurs, compared to 180° out-of-phase regula-
tors where the duty-cycle overlap occurs when the
input drops below 10V. Output current sensing pro-
vides accurate current limit using a sense resistor.
Alternatively, power dissipation can be reduced using
lossless inductor current sensing.
Internal 5V and 3.3V linear regulators power the
MAX1533A/MAX1537A and their gate drivers, as well as
external keep-alive loads, up to a total of 100mA. When
the main PWM regulators are in regulation, automatic
bootstrap switches bypass the internal linear regulators,
providing currents up to 200mA from each linear output.
An additional 5V to 23V adjustable internal 150mA linear
regulator is typically used with a secondary winding to
provide a 12V supply.
The MAX1533A/MAX1537A include on-board power-up
sequencing, a power-good (PGOOD) output, digital
soft-start, and internal soft-shutdown output discharge
that prevents negative voltages on shutdown. The
MAX1533A is available in a 32-pin 5mm x 5mm thin
QFN package, and the MAX1537A is available in a 36-
pin 6mm x 6mm thin QFN package. The exposed back-
side pad improves thermal characteristics for
demanding linear keep-alive applications.
Applications
2 to 4 Li+ Cells Battery-Powered Devices
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1533AETJ -40°C to +85°C 32 Thin QFN 5mm x 5mm
MAX1533AETJ+ -40°C to +85°C 32 Thin QFN 5mm x 5mm
MAX1537AETX -40°C to +85°C 36 Thin QFN 6mm x 6mm
MAX1537AETX+ -40°C to +85°C 36 Thin QFN 6mm x 6mm
+Denotes lead-free package.
Dual Mode is a trademark of Maxim Integrated Products, Inc.
Features
♦ Fixed-Frequency, Current-Mode Control
♦ 40/60 Optimal Interleaving
♦ Accurate Differential Current-Sense Inputs
♦ Internal 5V and 3.3V Linear Regulators with
100mA Load Capability
♦ Auxiliary 12V or Adjustable 150mA Linear
Regulator (MAX1537A Only)
♦ Dual Mode™ Feedback—3.3V/5V Fixed or
Adjustable Output (Dual Mode) Voltages
♦ 200kHz/300kHz/500kHz Switching Frequency
♦ Versatile Power-Up Sequencing
♦ Adjustable Overvoltage and Undervoltage
Protection
♦ 6V to 26V Input Range
♦ 2V ±0.75% Reference Output
♦ Power-Good Output
♦ Soft-Shutdown
♦ 5µA (typ) Shutdown Current
Pin Configurations
TOP VIEW
32 31 30 29 28 27 26 25
ON5 1
ON3 2
FSEL 3
ILIM3 4
ILIM5 5
REF 6
GND 7
V_CC 8
MAX1533A
24 FB5
23 LDO5
22 DL5
21 PGND
20 DL3
19 LDO3
18 FB3
17 CSL3
9 10 11 12 13 14 15 16
THIN QFN
5mm x 5mm
Pin Configurations 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.