lx1675 Microsemi Corporation, lx1675 Datasheet

no-image

lx1675

Manufacturer Part Number
lx1675
Description
Multiple Output Loadshare?? Pwm Production Data Sheet
Manufacturer
Microsemi Corporation
Datasheet
Copyright © 2004
Rev. 1.2a, 2006-02-16
power supply controller IC featuring
three voltage mode PWM switching
regulator stages with an additional
onboard linear regulator driver.
phases can be easily configured for a
single Bi-Phase high current output or
operated as two independently regulated
outputs. All outputs (PWM phases and
LDO) have separate, programmable soft-
start sequencing. This versatility yields
either
regulated
sequencing capability giving system
designers the ultimate flexibility in power
supply design.
is provided by monitoring the voltage
drop across the lower MOSFET power
stage during conduction, utilizing the
Rds(on) impedance. This eliminates the
need
resistors. Once current limit has been
reached and persist for 4 clock cycles, the
output is shut off and Soft Start is
initialized to force a hiccup mode for
protection.
IMPORTANT: For the most current data, consult MICROSEMI’s website:
LoadSHARE is a Trademark of Microsemi Corporation
Protected by U.S. Patents 6,285,571 and 6,292,378
VIN 4.5V to 24V
VOUT4
The LX1675 is a highly integrated
Two of the constant frequency PWM
Current limit for each PWM regulator
for
TM
three
outputs
expensive
or
four
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
with
P R O D U C T H I G H L I G H T
current
VIN
VSLR
LDGD
LDFB
SSX
AGND
EOX
independently
full
D E S C R I P T I O N
LX1675
VCCL
power
sense
HOX
driven to provide an LDO output of 5A
and 15A for each PWM controller. This
is useful for I/O, memory, termination,
and other supplies surrounding today’s
micro-processor based designs.
supply voltage ranging from 4.5V to 24V.
Each PWM regulator output voltage is
programmed via a simple voltage-divider
network.
engineers
respect to the MOSFET supply.
phase can utilize different supply voltages
for efficient use of available supply rails.
configured
LoadSHARE
programmed via inductor ESR selection.
The split phase operation reduces power
loss, noise due to the ESR of the input
capacitors and allows for reduction in
capacitance values while maximizing
regulator response time.
reference voltage is buffered and brought
out on a separate pin to be used as an
external reference voltage.
VCX
HRX
CSX
LOX
PGX
FBX
Additionally, when two phases are
High current MOSFETs can be directly
The LX1675 accepts a wide range of
ONE OF 3 PWM SECTIONS
Integrated Products Division
Microsemi
maximum
®
The LX1675 design gives
http://www.microsemi.com
in
Bi-Phase
topology
5µh
flexibility
Multiple Output LoadSHARE™ PWM
The internal
output,
VOUT1, 2, 3
can
Each
with
P
the
RODUCTION
be
Note: Available in Tape & Reel. Append the
-40 to 85
P A C K A G E O R D E R I N F O
T
0 to 85
A
Four Independently Regulated
Outputs
Single Input Supply with Wide
Voltage Range: 4.5-24V
Outputs As Low As 0.8V
Generated From a Precision
Internal Reference
Selectable PWM Frequency of
300KHz or 600KHz
Buffered Reference Voltage
Output
Multiphase Output Reduces
Need for Large Input
Capacitance at High Currents
Integrated High Current
MOSFET Drivers
Independent Soft-Start and
Power Sequencing
Adjustable Linear Regulator
Driver Output
No Current-Sense Resistors
DDR Termination Compliant
RoHS Compliant for Pb Free
Multi-Output Power Supplies
Video Card Power Supplies
PC Peripherals
Portable PC Processor and I/O
Supply
(°C)
D
letters “TR” to the part number. (i.e.
LX1675CLQ-TR)
ATA
K E Y F E A T U R E S
A P P L I C A T I O N S
S
LQ
RoHS Compliant / Pb-free
HEET
LX1675CLQ
LX1675ILQ
38-Pin
Plastic MLPQ
LX1675
Page 1

Related parts for lx1675

lx1675 Summary of contents

Page 1

... LDO output of 5A and 15A for each PWM controller. This is useful for I/O, memory, termination, and other supplies surrounding today’s micro-processor based designs. The LX1675 accepts a wide range of supply voltage ranging from 4.5V to 24V. Each PWM regulator output voltage is programmed via a simple voltage-divider network. ...

Page 2

... Multiple Output LoadSHARE™ PWM ® ................................................ 1A (200ns ................................................. 1.5A (200ns) X CCL . , θ 55°C/W MBIENT JA x θ Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET LO2 1 31 HR2 2 30 HO2 3 ...

Page 3

... Copyright © 2004 Rev. 1.2a, 2006-02-16 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Multiple Output LoadSHARE™ PWM ® Description Microsemi Integrated Products Division LX1675 D S RODUCTION ATA HEET Page 3 ...

Page 4

... TM For the LX1675ILQ the following specifications apply over the ambient temperature -40°C < TA < 85°C and for the LX1675CLQ 0°C ≤ T 85°C except where otherwise noted and the following test conditions Load 300KHz). Parameter SWITCHING REGULATORS Input Voltage ...

Page 5

... For the LX1675ILQ the following specifications apply over the ambient temperature -40°C < TA < 85°C and for the LX1675CLQ 0°C < T < 85°C except where otherwise noted and the following test conditions Load 300KHz) ...

Page 6

... AGND SF Figure 1 – Typical Block Diagram for Phases 1, and 3 VSLR 9.6V Regualtor SSL + LDOEA - 20K V REF F 500k LDOFLT SF Figure 2 – LDO Controller Block Diagram Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET +5V VIN VCx C IN HOx LX HRx ESR LOx C OUT PGx ...

Page 7

... SET PWM CYCLE COUNTER Hiccup Vref BG SS COMP Regulator - + RAMP CLK F S FAULT UVLO R SSMSK TSD AGND Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET +5V VIN VC2 C IN HO2 L2 HR2 ESR LO2 C OUT PGx VIN + VIN +5V +5V + VCCL ...

Page 8

... TP17 TP18 R16 R21 C26 22pF 45.3K 20 TP13 R17 88.7K R15 100K R18 24.3K 1.2nF C25 1.5nF C24 Bootstrapped Microsemi Integrated Products Division LX1675 D S RODUCTION ATA HEET +VIN C2 + 470uF 16V TP36 TP38 L1 6.8uh Q1A FDS6898A C4 + 470uF TP35 16V Q1B FDS6898A TP34 ...

Page 9

... NDER OLTAGE OCKOUT At power up, the LX1675 monitors the supply voltage at the VCCL pin. The VIN supply voltage has to be sufficient to produce a voltage greater that 4.4 volts at the VCCL pin before the controller will come out of the under-voltage lock-out state. The soft-start (SS) pin is held low to prevent soft-start from beginning and the oscillator is disabled and all MOSFETs are held off ...

Page 10

... V2. The high DC gain of the error amplifier will force LPF2 to always be equal to LPF1. The following calculations determine the value of the resistor divider necessary to satisfy this example. 4.67A 1.5V @ 12A 18W 7.33A Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET SHARE ( ...

Page 11

... FB2 Generator Figure 8 – LoadSHARE Using Feedback Divider Offset V 1 × K 100 then TBD 5.814 − Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET + ESR L1 V1 1.5V 10mΩ 4.67A +46.7mV Phase 1 - Offset Voltage + 1.5V @ 12A ESR L2 V2 10mΩ ...

Page 12

... Offset Amp Vos Rin - Rf Phase 2 Error Amp PWM Input - Generator FB2 62k Rb 1M Figure 9 – LoadSHARE Using Proportional Control Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET + ESR L1 1.5V V 10mΩ 1 4.67A +46.7mV Phase 1 - Offset Voltage + 1 ...

Page 13

... Max offset Error = 6mV ⎞ +5% ESR L1 = 6.3 mΩ ⎟ ⎠ -5% ESR L2 = 5.7 mΩ Phase Phase 2 current is 2.32A greater than Phase 1. Input bias current also contributes to imbalance. Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET SHARE ( ERIES ESISTOR ETHOD ...

Page 14

... The CDE Polymer AL-EL (ESRE) filter series provides excellent ESR performance at a reasonable cost. Beware of off- brand, very low-cost filter capacitors, which have been shown to degrade in both ESR and general electrolytic characteristics over time. D × Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET ( ) × + < ...

Page 15

... PWM cycles. If the current limit condition goes away t after a count of 2 the counter will be reset. This mode will prevent a single cycle current or noise glitch from starting the hiccup mode current limit. Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET equal to 0.1µF or greater are unlikely to result ...

Page 16

... VDD is generally equal to VDDQ so that only V VDDQ are required. The LX1675 can supply both voltages by using two of the three PWM phases. Since the currents for V are quite often several amps, ( common) a switching ) which ...

Page 17

... This will allow a smooth ramp up of the LDO voltage rail. The voltage rail for the LDO pass transistor can come from any of the other PWM phases if desirable. If the VIN power supply Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET ...

Page 18

... Recommended Solder Pad Layout 7.50mm 6.10mm 5.20mm 0.25mm 3.15mm Microsemi Integrated Products Division LX1675 RODUCTION ATA HEET M I ILLIMETERS NCHES MIN MAX MIN MAX 0.80 1.00 0.031 0.039 0 0.05 0 0.002 0.20 REF 0.008 REF 0.18 ...

Page 19

... Copyright © 2004 Rev. 1.2a, 2006-02-16 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Multiple Output LoadSHARE™ PWM ® P RODUCTION Microsemi Integrated Products Division LX1675 D S ATA HEET Page 19 ...

Related keywords