Microsemi LX1736CLD-TR 5v 1.25a 1.0mhz pwm/pfm step down regulator Datasheet

LX1736
®
TM
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
P RODUCTION D ATA S HEET
KEY FEATURES
DESCRIPTION
ƒ Few External Components
ƒ 800mv Internal Reference
ƒ Tight Regulation over Line,
Load and Temperature
ƒ 4.5V to 5.5V Input Range
ƒ Internal Soft Start Controls
Inrush Current
ƒ High Efficiency
ƒ Low Quiescent Current, 600μA
ƒ Fully Fault Protected
ƒ Thin MO-229, 6-Pin Package
The regulator is capable of providing an
output load current up to 1.25A and has
no minimum load current requirement
for stable operation. Current limit
senses on a cycle-by cycle basis to
protect the switch. Power conversion
efficiency is maximized with PFM
mode of operation and low regulator
quiescent current.
The LX1736 operational supply voltage
range covers 4.0V to 6.0V, features
include: power on delay; soft start to
limit inrush currents and thermal
shutdown during fault conditions.
The 6-pin JEDEC MO-229 package
provides a small form factor and low
profile at 3x3x1mm with excellent
power dissipation capability on surface
mount PCB’s.
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The LX1736 operates as a Current
Mode PWM Buck regulator that
switches to PFM mode under light
loads. The entire regulator function is
implemented with only a few, lowcost external components.
The LX1736 responds quickly to
dynamic load changes using a high
bandwidth error amplifier and internal
compensation. Tight output voltage
regulation is maintained with the
temperature compensated 800mV,
bandgap reference achieving +/-3.5%
regulation tolerance for all line, load
and thermal conditions. The output
voltage is easily programmed, from
800mV to 90% of VIN with two
external resistors
APPLICATIONS
ƒ Point of Load Regulation
ƒ DSP, ASIC and Core Voltage
Supplies
ƒ Hard Disk Drives
ƒ Set Top Boxes
ƒ RoHS compliant product
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
PRODUCT HIGHLIGHT
Efficiency @ VIN=5V,
VO=1.25V (Lower)
VO=3.3V (Upper)
95%
85%
75%
65%
55%
45%
35%
25%
1
1000
LX1736
Figure 1 – LX1736 Application Circuit and Typical Efficiency Performance
10
100
OUTPUT CURRENT, mA
PACKAGE ORDER INFO
TA (°C)
LD
Plastic MLPD
6 pin 3mm x 3mm
RoHS Compliant / Pb-free
0 to 125
LX1736CLD
Note: Available in Tape & Reel. Append the letters “TR” to
the part number. (i.e. LX1736CLD-TR)
Copyright © 2007
Rev. 1.1., 11/25/2008
Package Marking
3049
xxxx
MSC
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
LX1736
®
TM
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
P RODUCTION D ATA S HEET
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
1
6
2
5
3
4
NC
FB
GND
VCC
SW
VPWR
LD PACKAGE
(Top View)
RoHS / Pb-free 100% matte Tin Pin Finish
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Input Voltage (VCC or VPWR) ..................................................................... -0.3V to 7.0V
SW to GND........................................................................................ -0.3V to (VIN + 0.3V)
VFB to GND................................................................................................... -0.3V to +2V
SW Peak Current .....................................................................................Internally Limited
Junction Operating Temperature Range........................................................0°C to +125°C
Storage Temperature Range, TA..................................................................-65°C to 150°C
Maximum Junction Temperature ............................................................................... 150°C
Package Peak Temp. for Solder Reflow (40 seconds max. exposure)........... 260°C (+0, -5)
THERMAL DATA
LD
Plastic MLP 3x3mm MO-229, 6-Pin
THERMAL RESISTANCE-JUNCTION TO CASE, θJC
4°C/W
25 to 50°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of
the above assume no ambient airflow.
FUNCTIONAL PIN DESCRIPTION
Name Pin #
Description
VCC
5
Unregulated supply voltage input, ranging from +4V to 6.0V for internal analog control circuitry.
VPWR
4
Unregulated supply voltage input (+4V to 6.0V), high current path, supplies PMOSFET Drain of PWM switch.
FB
1
Feedback input for setting programming output voltage.
GND
2
Circuit ground for IC analog circuitry and high frequency gate drive bias, exposed pad area on bottom of
package may be connected to ground or left floating.
SW
3
Inductor and commutation diode connection point. Connects to internal PMOSFET Source of PWM Switch
output.
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min
LX1736
Typ
Max
Unit
`
Input Operating Voltage Range
4.5
5.5
V
Continuous Output Current Range
IOUT
0
0.9
A
Output Voltage Range
VOUT
0.8
80% of VIN
V
TJ
0
125
°C
Operating Junction Temperature
DEVICE
VIN
DATA
Copyright © 2007
Rev. 1.1., 11/25/2008
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
LX1736
®
TM
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
P RODUCTION D ATA S HEET
ELECTRICAL CHARACTERISTICS
Feedback Threshold
VFBT
4.0V < VIN < 6.0V
Feedback Input Current
IFB-IN
VFB = VFBT + 10mV
PWM Frequency
FOP-PWM
PWM Mode
PFM Mode Transition
IO-PFM
PFM mode
Minimum DC Output Current
Maximum DC Output Current
Maximum Duty Cycle
Closed Loop Load Regulation
DMAX
VOUT Load
REG
Efficiency
η
Quiescent Current
IQ
ISW = IOUT max
10mA<IOUT<IOUT MAX
1450
Khz
80
mA
mA
1.25 or
0.7/duty
cycle
whichever
is less
80
A
%
-0.5
0.5
%VOUT
70
%
VFB = VFBT + 10mV
Peak Current at Switch Pin (Not DC
Current)
TJ ≤ 70˚C
TSD
nA
VIN=5V, VOUT>1.1V, IOUT≥ 150mA
ISW CL
Thermal Shutdown
75
%
P-Channel Switch Current Limit
VO-SR
mV
55
ISW = 0.9A
Soft Start, VOUT Slew Rate
828
VIN=5V, VOUT≥1.1V, IOUT= 10mA
RDS(ON)
ISW LKG
800
TJ ≤ 70˚C
P-Channel Switch ON
Resistance
P-Channel Switch Leakage
800
0
IOUT
IOUTMAX
772
600
900
0.375
μA
Ω
1.1
A
1.4
VFB = VFBT + 10mV
Initial Power On or After a Short
Circuit,
COUT = 20µF
(Silicon Temperature)
21
135
5
μA
50
V/ms
150
°C
IINRUSH
VIN ramping from 0V to 5V having a
slew rate of 0.1V/S min to 0.5V/uS max
and COUT = 20µF
550
mA
Output Voltage Overshoot
(From either removal of a short
circuit condition from VOUT or
applied power during start up)
VO OS
Applied power VIN ramp rate of 0.1V/S
min to 0.5V/uS max
5
%
Output Voltage Response to
Dynamic Load Change
VO OS
Output load current change from
100ma to 700ma or 700ma to 100ma,
transition time <100ns
-5
5
%
Circuit Output Capacitance
COUT
Closed Loop stability
20
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
ELECTRICALS
DC Average In-Rush Current at
VCC and VPWR (summed)
Copyright © 2007
Rev. 1.1., 11/25/2008
WWW . Microsemi .C OM
Specifications are guaranteed over the junction temperature range of: 0°C < T < 125°C for VIN = 4.5V to 5.5V (unless noted otherwise),
not all of these parameters are production tested but are assured by design, characterization and correlation with statistical process
controls.. Typical values are at TA=23°C.
LX1736
Parameter
Symbol
Test Conditions
Units
Min
Typ
Max
μF
Page 3
LX1736
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
®
TM
P RODUCTION D ATA S HEET
WWW . Microsemi .C OM
APPLICATION SUPPORT
Vout
Cout
INDUCTOR
DIODE
Cout
Cout
LX1736
Vpwr
Sw
Cin
Vin
Gnd
n/c
FB
Cout
Rf
Vin
Rf
Ground
PCB Layout Considerations
1-
Maintain separate traces leading from the decoupling capacitor, CIN, to the supply input pins of the IC for VCC and VPWR. This
ensures that the noise and voltage drops associated with the high dI/dt pulses from the PWM switching are minimized for the
internal control circuitry of the IC.
Diode ground should return to COUT ground with minimum physical distance before joining the IC Ground connection.
23- Feed back resistor return path to ground should be located closely to the IC Pin 2 to avoid VOUT offsets induced by ground drops
and noise.
APPLICATION
Copyright © 2007
Rev. 1.1., 11/25/2008
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
LX1736
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
®
TM
P RODUCTION D ATA S HEET
SIMPLIFIED BLOCK DIAGRAM
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VPWR
VCC
UVLO
Bias
CL
Clock And
Ramp
PWM
S
R
SW
920mV
REF
EA
OVP
BG REF
800mV
LX1736
GND
FB
APPLICATION PERFORMANCE
Dynamic Load Change Response
CH1 = Vout AC Coupled
CH2 = Load Switch
CH4 = Output Current, 100mA to 750mA
VIN=5V, L=3.3uH, COUT = 20uF
APPLICATION
Copyright © 2007
Rev. 1.1., 11/25/2008
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
LX1736
TM
®
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
P RODUCTION D ATA S HEET
WWW . Microsemi .C OM
Start-up Inrush Current Control
CH1 = SW Pin
CH2 = Vout @ 3.32V
CH4 = Input Current
VIN=5V, No Output load, COUT = 20uF
VOUT Response to Short Circuit Removal
CH1 = Vout programmed at 1.2V
CH2 = Short CKT Duration
CH4 = Output Current
COUT = 20uF
APPLICATION
Copyright © 2007
Rev. 1.1., 11/25/2008
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
LX1736
5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR
®
TM
P RODUCTION D ATA S HEET
PACKAGE DIMENSIONS
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LD
MO-229 6-Pin Plastic 3 x 3 x .9 mm
D
L1
D2
Pin 1 ID
E
E2
L
b
A1
e
K
A
Dim
A
A1
K
e
L
b
D2
E2
D
E
L1
MILLIMETERS
MIN MAX
0.80 1.00
0.00 0.05
0.20 MIN
0.95 BSC
0.30 0.50
0.30 0.45
1.90 2.40
1.15 1.65
3.00 BSC
3.00 BSC
0.00 0.15
INCHES
MIN
MAX
0.031
0.039
0.000
0.002
0.008 MIN
0.037 BSC
0.012
0.020
0.012
0.018
0.075
0.094
0.045
0.065
0.118 BSC
0.118 BSC
0.000
0.006
Note:
1.
2.
Dimensions do not include mold flash or
protrusions;
these
shall
not
exceed
0.155mm(.006”) on any side. Lead dimension
shall not include solder coverage.
Exposed heatsink pad on bottom may be left
floating or connected to ground.
NOTES
MECHANICAL
PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current as of
publication date. This document may not be modified in any way without the express written consent of Microsemi.
Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
Copyright © 2007
Rev. 1.1., 11/25/2008
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
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