DataSheet8.cn


PDF ( 数据手册 , 数据表 ) LX1665A

零件编号 LX1665A
描述 DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC
制造商 Microsemi Corporation
LOGO Microsemi Corporation LOGO 


1 Page

No Preview Available !

LX1665A 数据手册, 描述, 功能
T H E I N F I N I T E P O W E R O F I N N O VAT I O N
LX1664/64A, LX1665/65A
DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC
PRODUCTION DATA SHEET
DESCRIPTION
The LX1664/64A and LX1665/65A are
monolithic switching regulator con-
troller IC’s designed to provide a low cost,
high performance adjustable power supply
for advanced microprocessors and other
applications requiring a very fast transient
response and a high degree of accuracy.
Short-circuit Current Limiting with-
out Expensive Current Sense Resistors.
Current-sensing mechanism can use PCB
trace resistance or the parasitic resistance of
the main inductor. The LX1664A and
LX1665A have reduced current sense com-
parator threshold for optimum perfor-
mance using a sense resistor. For applica-
tions requiring a high degree of accuracy, a
conventional sense resistor can be used to
sense current.
Programmable Synchronous Recti-
fier Driver for CPU Core. The main
output is adjustable from 1.3V to 3.5V using
a 5-bit code. The IC can read a VID signal
set by a DIP switch on the motherboard, or
hardwired into the processor’s package (as
in the case of Pentium® Pro and Pentium II
processors). The 5-bit code adjusts the
output voltage between 1.30 and 2.05V in
50mV increments and between 2.0 and 3.5V
in 100mV increments, conforming to the
Intel Corporation specification. The device
can drive dual MOSFET’s resulting in typical
efficiencies of 85 - 90% even with loads in
excess of 10 amperes. For cost sensitive
applications, the bottom MOSFET can be
replaced with a Schottky diode (non-syn-
chronous operation).
Linear Regulator Driver. The LX1664/
65 family of devices have a secondary
regulator output. This can drive a MOSFET
or bipolar transistor as a pass element to
construct a low-cost adjustable linear regu-
lator suitable for powering a 1.5V GTL+ bus
or 2.5V clock supply.
(continued next page)
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
KEY FEATURES
I 5-bit Programmable Output For CPU Core
Supply
I Adjustable Linear Regulator Driver Output
I No Sense Resistor Required For Short-
Circuit Current Limiting
I Designed To Drive Either Synchronous Or
Non-Synchronous Output Stages
I Soft-Start Capability
I Modulated, Constant Off-Time Architecture
For Fast Transient Response And Simple
System Design
I Available Over-Voltage Protection (OVP)
Crowbar Driver And Power Good Flag
(LX1665 only)
A P P L I C AT I O N S
I Socket 7 (Pentium Class) Microprocessor
Supplies (including Intel Pentium Processor,
AMD-K6TM And Cyrix® 6x86TM, Gx86TM and
M2TM Processors)
I Pentium II and Deschutes Processor & L2-
Cache Supplies
I Voltage Regulator Modules
PRODUCT HIGHLIGHT
LX1665 IN A PENTIUM II SINGLE-CHIP POWER SUPPLY SOLUTION
C3
0.1µF
VID0
VID1
VID2
VID3
VID4
12V
U1
LX1665
1 SS
2 INV
V3
CC_CORE
4 VID0
5 VID1
6 VID2
7 VID3
8 VID4
9 LFB
VC1 18
TDRV 17
GND 16
BDRV 15
VCC 14
CT 13
OV 12
LDRV 11
PWRGD 10
18-pin
Wide-Body SOIC
F1 20A
5V
L2
1µH
C5
1µF
Q1
IRL3102
Q2
IRL3303
6.3V
1500µF x3
C2
L1
2.5µH
R1
0.0025
Supply Voltage
for CPU Core
VOUT
C1
6.3V, 1500µF x 3**
C8
680pF
Q4
IRLZ44
C9
330µF
** Three capacitors for Pentium
Four capacitors for Pentium II
Supply Voltage
For I/O Chipset or GTL+ Bus
R5 C7
OV 330µF
PWRGD
R6
TA (°C)
PACKAGE ORDER INFORMATION
N
Plastic DIP
16-pin
N
Plastic DIP
18-pin
D
Plastic SOIC
16-pin
DW
Plastic
18-pin
SOIC
Wide
0 to 70
LX1664CN
LX1665CN
LX1664CD
LX1665CDW
LX1664ACN
LX1665ACN
LX1664ACD
LX1665ACDW
Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (e.g. LX1664CDT)
Copyright © 1999
Rev. 1.2 11/99
LINFINITY MICROELECTRONICS INC.
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570
1







LX1665A pdf, 数据表
PRODUCT DATABOOK 1996/1997
LX1664/64A, LX1665/65A
DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC
PRODUCTION DATA SHEET
THEORY OF OPERATION
IC OPERATION
Referring to the block diagram and typical application circuit, the
output turns ON the top MOSFET, allowing the inductor current to
increase. At the error comparator threshold, the PWM latch is reset,
the top MOSFET turns OFF and the synchronous MOSFET turns ON.
The OFF-time capacitor CT is now allowed to discharge. At the
valley voltage, the synchronous MOSFET turns OFF and the top
MOSFET turns on. A special break-before-make circuit prevents
simultaneous conduction of the two MOSFETS.
The VCC_CORE pin is offset by +40mV to enhance transient
response. The INV pin is connected to the positive side of the
current sense resistor, so the controller regulates the positive side
of the sense resistor. At light loads, the output voltage will be
regulated above the nominal setpoint voltage. At heavy loads, the
output voltage will drop below the nominal setpoint voltage. To
minimize frequency variation with varying output voltage, the OFF-
time is modulated as a function of the voltage at the VCC_CORE pin.
ERROR VOLTAGE COMPARATOR
The error voltage comparator compares the voltage at the positive
side of the sense resistor to the set voltage plus 40mV. An external
filter is recommended for high-frequency noise.
CURRENT LIMIT
Current limiting is done by sensing the inductor current. Exceeding
the current sense threshold turns the output drive OFF and latches
it OFF until the PWM latch Set input goes high again. See Current
Limit Section in "Using The LX1664/65 Devices" later in this data
sheet.
OFF-TIME CONTROL TIMING
The timing capacitor CT allows programming of the OFF-time. The
timing capacitor is quickly charged during the ON time of the top
MOSFET and allowed to discharge when the top MOSFET is OFF.
In order to minimize frequency variations while providing different
supply voltages, the discharge current is modulated by the voltage
at the VCC_CORE pin. The OFF-time is inversely proportional to the
VCC_CORE voltage.
UNDER VOLTAGE LOCKOUT
The purpose of the UVLO is to keep the output drive off until the
input voltage reaches the start-up threshold. At voltages below the
start-up voltage, the UVLO comparator disables the internal biasing,
and turns off the output drives. The SS (Soft-Start) pin is pulled low.
SYNCHRONOUS CONTROL
The synchronous control section incorporates a unique break-
before-make function to ensure that the primary switch and the
synchronous switch are not turned on at the same time. Approxi-
mately 100 nanoseconds of deadtime is provided by the break-
before-make circuitry to protect the MOSFET switches.
PROGRAMMING THE OUTPUT VOLTAGE
The output voltage is set by means of a 5-bit digital Voltage
Identification (VID) word (See Table 1). The VID code may be hard-
wired into the package of the processor which do not have a VID
code, the output voltage can be set by means of a DIP switch or
jumpers. For a low or '0' signal, connect the VID pin to ground (DIP
switch ON); for a high or '1' signal, leave the VID pin open (DIP
switch OFF).
The five VID pins on the LX166x series are designed to interface
directly with a Pentium Pro or Pentium II processor. Therefore, all
inputs are expected to be either ground or floating. Any floating
input will be pulled high by internal connections. If using a Socket
7 processor, or other load, the VID code can be set directly by
connecting jumpers or DIP switches to the VID[0:4] pins.
The VID pins are not designed to take TTL inputs, and
should not be connected high. Unpredictable output voltages
may result. If the LX166x devices are to be connected to a logic
circuit, such as BIOS, for programming of output voltage, they
should be buffered using a CMOS gate with open-drain, such as a
74HC125 or 74C906.
POWER GOOD SIGNAL (LX1665 only)
An open collector output is provided which presents high imped-
ance when the output voltage is between 90% and 117% of the
programmed VID voltage, measured at the SS pin. Outside this
window the output presents a low impedance path to ground. The
Power Good function also toggles low during OVP operation.
OVER-VOLTAGE PROTECTION
The controller is inherently protected from an over-voltage condi-
tion due to its constant OFF-time architecture. However, should a
failure occur at the power switch, an over-voltage drive pin is
provided (on the LX1665 only) which can drive an external SCR
crowbar (Q3), and so blow a fuse (F1). the fault condition must be
removed and power recycled for the LX1665 to resume normal
operation (See Figure 9).
LINEAR REGULATOR
The product highlight application shows an application schematic
using a MOSFET as the pass element for a linear regulator. this
output is suitable for converting the 5V system supply to 3.3V for
processor I/O buffers, memory, chipset and other components. The
output can be adjusted to any voltage between 1.5V and 3.6V in
order to supply other (lower) power requirements on a mother-
board. See section "Using the LX1664/1665 Devices" at the end of
this data sheet.
8 Copyright © 1999
Rev. 1.2 11/99







LX1665A equivalent, schematic
PRODUCT DATABOOK 1996/1997
LX1664/64A, LX1665/65A
DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC
PRODUCTION DATA SHEET
USING THE LX1664/65 DEVICES
LINEAR REGULATOR (continued)
TABLE 6 -
Resistors Settings for Linear Regulator Output Voltage
Nominal
Set Point (V)
3.3
3.2
3.1
3.0
2.9
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
1.5
R5 (k)
12
11.3
11.3
11
10.3
10
10
10
9.76
8.87
8.87
8.87
8.87
8.87
8.87
7.15
7.15
7.15
7.15
R6 (k)
10
10
10.7
11
11
11.5
12.4
13.7
14.7
14.7
16.5
18.7
22.1
26.7
21
35.7
53.6
100
VOUT (V)
3.30
3.20
3.08
3.00
2.90
2.80
2.71
2.59
2.50
2.41
2.31
2.21
2.10
2.00
2.13
1.80
1.70
1.61
1.50
Capacitor Selection
Referring to the Product Highlight schematic on the front page, the
standard value to use as the linear regulator stage output capacitor
is on the order of 330µF. This provides sufficient hold-up for all
expected transient load events in memory and I/O circuitry.
Disabling Linear Output
Linear regulator output can be disabled by pulling feedback pin
(LFB) up to 5V as shown in Figure 14.
TABLE 7 - Linear Enable (LIN EN) Function Table
LIN EN
LIN OUTPUT
H Disabled
L Enabled
5V
LIN EN
LX1664
LDRV 10
C10
0.1µF
C9
330µF
LFB 9
10k 10k
Q4
IRLZ44
Supply Voltage
For I/O Chipset
R5
C7
330µF
2N2222
R6
LAYOUT GUIDELINES - THERMAL DESIGN
A great deal of time and effort were spent optimizing the thermal
design of the demo boards. Any user who intends to implement
an embedded motherboard would be well advised to carefully
read and follow these guidelines. If the FET switches have been
carefully selected, external heatsinking is generally not required.
However, this means that copper trace on the PC board must now
be used. This is a potential trouble spot; as much copper area as
possible must be dedicated to heatsinking the FET switches, and
the diode as well if a non-synchronous solution is used.
In our VRM module, heatsink area was taken from internal
ground and VCC planes which were actually split and connected
with VIAS to the power device tabs. The TO-220 and TO-263
cases are well suited for this application, and are the preferred
packages. Remember to remove any conformal coating from all
exposed PC traces which are involved in heatsinking.
General Notes
As always, be sure to provide local capacitive decoupling close to
the chip. Be sure use ground plane construction for all high-
frequency work. Use low ESR capacitors where justified, but be
alert for damping and ringing problems. High-frequency designs
demand careful routing and layout, and may require several
iterations to achieve desired performance levels.
Power Traces
To reduce power losses due to ohmic resistance, careful consid-
eration should be given to the layout of traces that carry high
currents. The main paths to consider are:
I Input power from 5V supply to drain of top MOSFET.
I Trace between top MOSFET and lower MOSFET or Schottky
diode.
I Trace between lower MOSFET or Schottky diode and
ground.
I Trace between source of top MOSFET and inductor, sense
resistor and load.
Input
5V or 12V
LX166x
Output
FIGURE 14 Enabling Linear Regulator
FIGURE 15 Power Traces
16 Copyright © 1999
Rev. 1.2 11/99










页数 17 页
下载[ LX1665A.PDF 数据手册 ]


分享链接

Link :

推荐数据表

零件编号描述制造商
LX1665DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DACMicrosemi Corporation
Microsemi Corporation
LX1665ADUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DACMicrosemi Corporation
Microsemi Corporation
LX1665ACDWDUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DACMicrosemi Corporation
Microsemi Corporation
LX1665ACNDUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DACMicrosemi Corporation
Microsemi Corporation

零件编号描述制造商
STK15C88256-Kbit (32 K x 8) PowerStore nvSRAMCypress Semiconductor
Cypress Semiconductor
NJM4556DUAL HIGH CURRENT OPERATIONAL AMPLIFIERNew Japan Radio
New Japan Radio
EL1118-G5 PIN LONG CREEPAGE SOP PHOTOTRANSISTOR PHOTOCOUPLEREverlight
Everlight


DataSheet8.cn    |   2020   |  联系我们   |   搜索  |  Simemap