Rainbow Electronics MAX1625 - Manual

_______________General Description
The MAX1624/MAX1625 are ultra-high-performance,
step-down DC-DC controllers for CPU power in high-end
computer systems. Designed for demanding applications
in which output voltage precision and good transient
response are critical for proper operation, they deliver
over 35A from 1.1V to 3.5V with ±1% total accuracy from
a +5V ±10% supply. Excellent dynamic response cor-
rects output transients caused by the latest dynamically
clocked CPUs. These controllers achieve over 90% effi-
ciency by using synchronous rectification. Flying-capaci-
tor bootstrap circuitry drives inexpensive, external
N-channel MOSFETs.
The switching frequency is resistor programmable from
100kHz to 1MHz. High switching frequencies allow the
use of a small surface-mount inductor and decrease out-
put filter capacitor requirements, reducing board area
and system cost.
The MAX1624 is available in a 24-pin SSOP and offers
additional features such as a digitally programmable out-
put in 100mV increments; adjustable transient response;
selectable 0.5%, 1%, or 2% AC load regulation; and gate
drive for a current-boost MOSFET. The MAX1625 is resis-
tor adjustable and comes in a 16-pin narrow SO pack-
age. Other features in both controllers include internal
digital soft-start, a power-good output, and a 3.5V ±1%
reference output. For a similar controller compatible with
the latest Intel V
RM /V ID specification, see the MAX1638*
data sheet.
________________________Applications
Pentium Pro™, Pentium II™, PowerPC™, Alpha™,
and K6™ Systems
Desktop Computers
LAN Servers
Industrial Computers
GTL Bus Termination
____________________________Features
♦ Better than ±1% Output Accuracy Over
Line and Load
♦ 90% Efficiency
♦ Excellent Transient Response
♦ Resistor-Programmable Fixed Switching
Frequency from 100kHz to 1MHz
♦ Over 35A Output Current
♦ Digitally Programmable Output from 1.1V to 3.5V
in 100mV Increments (MAX1624)
♦ Resistor-Adjustable Output down to 1.1V
(MAX1625)
♦ Remote Sensing
♦ Adjustable AC Loop Gain (MAX1624)
♦ GlitchCatcher™ Circuit for Fast Load-Transient
Response (MAX1624)
♦ Power-Good (PWROK) Output
♦ Current-Mode Feedback
♦ Digital Soft-Start
♦ Strong 2A Gate Drivers
♦ Current-Limited Output
MAX1624/MAX1625
High-Speed Step-Down Controllers with
Synchronous Rectification for CPU Power
________________________________________________________________ Maxim Integrated Products 1
19-1227; Rev 1; 6/97
PART
MAX1624 EAG
MAX1625 ESE -40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-PACKAGE
24 SSOP
16 Narrow SO
______________Ordering Information
__________Typical Operating Circuit
Pin Configurations appear at end of data sheet.
* Future product.
Pentium Pro and Pentium II are trademarks of Intel Corp.
PowerPC is a trademark of IBM Corp.
Alpha is a trademark of Digital Equipment Corp.
K6 is a trademark of Advanced Micro Devices.
GlitchCatcher is a trademark of Maxim Integrated Products.
EVALUATION KIT
AVAILABLE
V
CC
FREQ
CC2
CC1
REF
AGND
(SIMPLIFIED)
FB
DL
DH
PWROK
BST
CSL
CSH
LX
TO V
DD
TO AGND
PGND
OUTPUT
1.1V TO 4.5V
INPUT
+5V
V DD
N
N
MAX1625
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.