MAX8553-MAX8554 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – 4.5V to 28V Input, Synchronous PWM Buck Controllers for DDR Termination and Point-of-Load Applications

19-3017; Rev 0; 10/03
4.5V to 28V Input, Synchronous PWM Buck Controllers
for DDR Termination and Point-of-Load Applications
General Description
The MAX8553 is a 4.5V to 28V input-voltage, synchro-
nous step-down controller that provides a complete
power-management solution for DDR memory. The
MAX8553 generates 1/2 V_REFIN voltage for VTT and
VTTR. The VTT and VTTR tracking voltages are main-
tained within 1% of 1/2 V_REFIN. The MAX8554 is a 4.5V to
28V input voltage, nontracking step-down controller with
a low 0.6V feedback threshold voltage. The MAX8553/
MAX8554 use Maxim’s proprietary Quick-PWM™ archi-
tecture for fast transient response and operate with
selectable pseudo-fixed frequencies. Both controllers
can operate without an external bias supply.
The controllers operate in synchronous-rectification mode
to ensure balanced current sourcing and sinking capabili-
ty of up to 25A. The MAX8553/MAX8554 also provide up
to 95% efficiency, making them ideal for server and point-
of-load applications. Additionally, a low 5µA shutdown
current allows for longer battery life in notebook applica-
tions. Lossless current monitoring is achieved by monitor-
ing the low-side MOSFET’s drain-to-source voltage. The
MAX8553/MAX8554 have an adjustable foldback current
limit to withstand a continuous output overload and short
circuit. Digital soft-start provides control of inrush current
during power-up. Overvoltage protection shuts the con-
verter down and discharges the output capacitor. The
MAX8553/MAX8554 come in space-saving 16-pin QSOP
packages.
Applications
Wide-Input Power Supplies
Servers and Storage Applications
ASIC and CPU Core Voltages
Notebook and LCD-PC Power Supplies
DDR I and DDR II Memory Power Supplies
AGTL Bus Termination Supplies
PART
MAX8553EEE
MAX8554EEE
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 QSOP
Features
o Up to 25A Output-Current Capability
o Quick-PWM Control for Fast Loop Response
o Up to 95% Efficiency
o 4.5V to 28V Input Voltage Range
o No External Bias Supply Required
o 0 to 3.6V Input REFIN Range (MAX8553)
o Automatically Sets VTT and VTTR to within ±1%
of 1/2 V_REFIN- (MAX8553)
o Low 0.6V Feedback Threshold (MAX8554)
o 200kHz/300kHz/400kHz/550kHz Selectable
Switching Frequencies
o Adjustable Foldback Current Limit
o Overvoltage Protection
o Digital Soft-Start
Typical Operating Circuit
VIN
+5V
POK
REFIN
V+
EN/HSD
DH
MAX8553
POK
VL
REFIN
BST
V+
LX
VOUT
REF
DL
ILIM
PGND
FSEL
VTT
VTTR
GND
VTTR
Pin Configurations appear at end of data sheet.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ 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.