General Description
The MAX8537/MAX8539 controllers provide a complete
power-management solution for both double-data-rate
(DDR) and combiner supplies. The MAX8537 and
MAX8539 are configured for out-of-phase and in-phase
DDR power-supply operations, respectively, and gener-
ate three outputs: the main memory voltage (V
DDQ
), the
tracking sinking/sourcing termination voltage (V
TT
), and
the termination reference voltage (V
TTR
). The MAX8538
is configured as a dual out-of-phase controller for point-
of-load supplies. Each buck controller can source or
sink up to 25A of current, while the termination refer-
ence can supply up to 15mA output.
The MAX8537/MAX8538/MAX8539 use constant-
frequency voltage-mode architecture with operating
frequencies of 200kHz to 1.4MHz. An internal high-
bandwidth (25MHz) operational amplifier is used as an
error amplifier to regulate the output voltage. This
allows fast transient response, reducing the number of
output capacitors. An all-N-FET design optimizes effi-
ciency and cost. The MAX8537/MAX8538/MAX8539
have a 1% accurate reference. The second synchro-
nous buck controller in the MAX8537/MAX8539 and the
VTTR amplifier generate 1/2 V
DDQ
voltage for V
TT
and
V
TTR
, and track the V
DDQ
within ±1%.
This family of controllers uses a high-side current-sense
architecture for current limiting. ILIM pins allow the set-
ting of an adjustable, lossless current limit for different
combinations of load current and R
DSON
. Alternately,
more accurate overcurrent limit is achieved by using
a sense resistor in series with the high-side FET.
Overvoltage protection is achieved by latching off the
high-side MOSFET and latching on the low-side MOSFET
when the output voltage exceeds 17% of its set output.
Independent enable, power-good, and soft-start features
enhance flexibility.
Applications
DDR Memory Power Supplies
Notebooks and Desknotes
Servers and Storage Systems
Broadband Routers
XDSL Modems and Routers
Power DSP Core Supplies
Power Combiner in Advanced VGA Cards
Networking Systems
RAMBUS Memory Power Supplies
Features
♦ MAX8537/MAX8539: Complete DDR Supplies
♦ MAX8538: Dual Nontracking Controller
♦ Out-of-Phase (MAX8537/MAX8538) or In-Phase
(MAX8539) Operation
♦ 4.5V to 23V Wide Input Range (Operate Down to
1.8V Input with External 5V Supply)
♦ Tracking Supply Maintains V
TT
= V
TTR
= 1/2 V
DDQ
♦ Adjustable Output from 0.8V to 3.6V with 1%
Accuracy
♦ VTTR Reference Sources and Sinks Up to 15mA
♦ 200kHz to 1.4MHz Adjustable Switching
Frequency
♦ All-Ceramic Design Achievable
♦ >90% Efficiency
♦ Independent POK_ and EN_
♦ Adjustable Soft-Start and Soft-Stop for Each
Output
♦ Lossless Adjustable-Hiccup Current Limit
♦ Output Overvoltage Protection
♦ 28-Pin QSOP Package
MAX8537/MAX8538/MAX8539
Dual-Synchronous Buck Controllers for Point-of-
Load, Tracking, and DDR Memory Power Supplies
________________________________________________________________ Maxim Integrated Products 1
19-3141; Rev 1; 6/05
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.
EVALUATION KIT
AVAILABLE
Ordering Information
