
LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
W
M
.
C
Mobile AMD Athlon
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
D E S C R I P T I O N
The LX1676 is a highly integrated
VRM power supply controller IC
featuring
two
PWM
regulator stages.
The
two
constant
voltage-mode
PWM
configured as a single biphase high
current output core supply.
In biphase operation, the high
current (>25A) output is generated by
a LoadSHARE
TM
technique that
balances the currents in the two
phases. Power loss and noise, due to
the ESR of the input capacitors, are
minimized by operating the PWMs
180
°
out of phase.
A
synchronized
Correction Loop provides except-
ional control of the output droop and
overshoot during very high di/dt load
changes, the circuit can be configured
for droop only, overshoot only or
both.
This architecture also minimizes
capacitor
requirements
IMPORTANT:
For the most current data, consult
MICROSEMI
’s website:
http://www.microsemi.com
Patent numbers US6292378,US6285571,US6356063, US6605931
switching
frequency
phases
are
Transient
while
maximizing regulator response.
A true differential input amplifier is
used for remote voltage sensing at the
processor core.
A VID code generator provides an
internal reference that will set the
output voltage. This VID code can be
changed during operation and the
reference will slew the output voltage to
its new setting at a preset rate. During
VID changes on the fly the Power Good
indication will stay valid.
Current through the lower phase 1
MOSFET will be sampled using its
R
DS(ON)
for current limit and shut
down.
For further protection, an over
voltage circuit will trip at a specified
setting and clamp the output by turning
off the upper MOSFETs and turning on
the lower MOSFETs.
The upper MOSFET drivers will use
a bootstrap capacitor to provide the
upper drive voltage over the input
voltage range of 6 to 24 volts.
K E Y F E A T U R E S
High Current Biphase
Operation
Outputs As Low As 0.925V
Biphase LoadSHARE
Transient Correction Loop
Reduces Required
Capacitance
Differential Amplifier For
Remote Voltage Sensing
Integrated High Current
MOSFET Drivers
200KHz to 1MHz Frequency
Operation
Programmable Slew Rate
Control For Start-Up Sequence
and VID change
VID Changes On The Fly
Power Good Indicator
Short Circuit Protection
Output Over Voltage and
Under Voltage Protection
No current-sense resistors
A P P L I C A T I O N S
AMD Mobile Athlon
or
Duron
Processor Core
Voltage Supply
Voltage Regulator Modules
P R O D U C T H I G H L I G H T
L X 1 6 7 6
5 B it V ID
7 0 n H
T r a n s ie n t C o r r e c tio n L o o p
V in 6 to 2 4 V
V in 6 to 2 4 V
V o u t
V in + 5 V
P A C K A G E O R D E R I N F O
Plastic TSSOP
38-Pin
LX1676-CPW
Note: Available in Tape & Reel.
Append the letters “TR” to the part number.
(i.e. LX1676-CLQTR)
T
J
(
°
C)
PW
LQ
Plastic MLPQ
38-Pin
LX1676-CLQ
0 to 70
L
X
1
6
7
6