ITE LSP5526

LSP5526
2A 23V Synchronous Buck Converter
Features
z
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R
19
，
51
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The LSP5526 is a monolithic synchronous
buck regulator. The device integrates 95mΩ
MOSFETS that provide 2A continuous load
current over a wide operating input voltage
of 4.5V to 23V. Current mode control
provides fast transient response and cycleby-cycle current limit. An adjustable softstart prevents inrush current at turn on.
QQ
:
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2A Output Current
Wide 4.5V to 23V Operating Input Range
Integrated Power MOSFET
Switches
Output Adjustable from 0.925V to 18V
Up to 96% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output
Capacitors
Fixed 340KHZ Frequency
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Package： SOP-8L
58
5
z
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General Description
66
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18
Distributed Power Systems
Networking Systems
FPGA, DSP, ASIC Power Supplies
z Green Electronics/ Appliances
z Notebook Computers
l:
z
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34
1
Applications
公
司
，
Te
Typical Application Circuit
限
技
有
V IN = 1 2 V
C6
10nF
BS
讯
科
R4
100K
合
SW
EN
SS
4 4 .2 K
COMP
C4
1 .6 n F
R3
10K
C5
C7
22uF x 2
R2
10K
NC
深
圳
C3
0 .1 u F
R1
FB
GND
V O U T = 5 V /2 A
10uH
LSP5526
C1
22uF
市
金
L1
V IN
Please be aware that an Important Notice concerning availability, disclaimers, and use in critical
applications of LSC products is at the end of this document.
1 of 16
Rev. 1.2
深圳市博美霖电子有限公司 专业代理 高先生 电话：0755-82546493 13423782956
LSP5526
2A 23V Synchronous Buck Converter
Ordering Information
Package :
S8 : SOP-8L
Package Code
Package
LSP5526-S8A
S8
SOP-8L
19
，
Tape & Reel
Part Number
Quantity
Suffix
51
8
Device
Packing :
A : Tape & Reel
2500
A
SOP-8L
(TOP View)
2
SW
3
GND
4
7
EN
6
COMP
5
FB
Name
BS
2
VIN
限
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5
FB
COMP
7
EN
8
SS
合
6
深
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市
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SW
GND
技
有
3
4
公
1
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Pin Number
，
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l:
Pin Descriptions
SS
34
1
VIN
8
66
4
1
18
BS
58
5
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:
Pin Assignments
71
44
Output Voltage :
Blank : ADJ
廖
R
LSP5526-X X X
Description
Bootstrap. This pin acts as the positive rail for the high-side switch’s
gate driver. Connect a 0.01uF capacitor between BS and SW.
Input Supply. Bypass this pin to GND with a low ESR capacitor. See
Input Capacitor in the Application Information section.
Switch Output. Connect this pin to the switching end of the inductor.
Ground.
Feedback Input. The voltage at this pin is regulated to 0.925V.
Connect to the resistor divider between output and ground to set
output voltage.
Compensation Pin. See Stability Compensation in the Application
Information section.
Enable Input. When higher than 2.7V, this pin turns the IC on. When
lower than 1.1V, this pin turns the IC off. Output voltage is discharged
when the IC is off. This pin should not be left open. Recommend to put
a 100KΩ pull up resistor to Vin for start up.
Soft-Start Control Input. SS controls the soft-start period. Connect a
capacitor from SS to GND to set the soft-start period. A 0.1uF
capacitor sets the soft-start period to 15ms. To disable the soft-start
feature, leave SS unconnected.
2 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
Block Diagram
CURRENT
SENSE
AMPLIFIER
1.1V
RAMP
2 VIN
廖
R
OVP
5V
FB 5
19
，
OSCILLATOR
340/120KHz CLK
1
BS
3
SW
ERROR
AMPLIFIER
0.925V
COMP 6
EN 7
CURRENT
COMPARATOR
6uA
EN OK
QQ
:
SS 8
GND
58
5
IN
INTERNAL
34
1
SHUTDOWN
COMPARATOR
REGULATORS
18
66
4
1.5V
4
OVP
IN<4.10V
1.2V
LOCKOUT
COMPARATOR
2.5V
71
44
S Q
R Q
51
8
0.3V
l:
Absolute Maximum Ratings
Parameter
技
有
限
公
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，
Te
Input Supply Voltage
SW Voltage
BS Voltage
EN, FB, COMP Voltage
Continuous SW Current
Junction to Ambient Thermal Resistance (θJA)
(Test on Approximately 3 in2 Copper Area 1oz copper FR4 board)
SOP-8L Power Dissipation
Maximum Junction Temperature
Storage Temperature Range
Value
Unit
-0.3 to 25
-0.3 to VIN + 0.3
VSW – 0.3 to VSW + 6
-0.3 to 5.
Internally limited
V
V
V
V
A
87
°C/W
Internal limit
150
-65 to 150
W
°C
°C
合
讯
科
(Note: Exceeding these limits may damage the device. Exposure to absolute maximum rating conditions for long periods
may affect device reliability.)
深
圳
市
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Recommended Operating Conditions
Parameter
Input Supply Voltage
Operating Junction Temperature
Min
Max
Unit
4.5
-20
23
+125
V
°C
3 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
Electrical Characteristics
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，
司
3.3
A/V
920
480
340
120
92
220
1.4
uA/V
V/V
KHz
KHz
%
nS
V
19
，
Unit
V
V
mΩ
mΩ
uA
A
71
44
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ΔICOMP = ±10uA
QQ
:
VEN = 0V, VSW = 0V
Minimum Duty Cycle
34
1
VFB = 0
VFB = 0.8V
18
66
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VEN Rising
VEN = 0
VEN = 3V, VFB = 1.0V
VEN Rising
VSS = 0V
CSS = 0.1uF
Hysteresis = 25°C
1.1
2
180
2.2
3.80
2.5
130
0.3
1.3
4.05
100
6
15
160
mV
2.7
3.0
1.5
4.40
V
mV
uA
mA
V
mV
uA
mS
°C
限
公
Min
Typ
Max
0.900 0.925 0.950
1.1
95
95
10
2.7
3.5
51
8
Test Conditions
4.5V ≤ VIN ≤ 23V
l:
Parameter
Symbol
Feedback Voltage
VFB
Feedback Overvoltage Threshold
High-Side Switch-On Resistance*
Low-Side Switch-On Resistance*
High-Side Switch Leakage
Upper Switch Current Limit
COMP to Current
GCOMP
Limit Transconductance
Error Amplifier Transconductance
GEA
Error Amplifier DC Gain*
AVEA
Switching Frequency
fSW
Short Circuit Switching Frequency
Maximum Duty Cycle
DMAX
Minimum On Time*
EN Shutdown Threshold Voltage
EN Shutdown Threshold Voltage
Hysteresis
EN Lockout Threshold Voltage
EN Lockout Hysteresis
Supply Current in Shutdown
IC Supply Current in Operation
Input UVLO Threshold Rising
UVLO
Input UVLO Threshold Hysteresis
Soft-start Current
Soft-start Period
Thermal Shutdown Temperature*
廖
R
(VIN = 12V, TA= 25°C unless otherwise specified.)
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合
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技
有
Note: * Guaranteed by design
4 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
廖
R
Application Description
BS
SW
10uH
LSP5526
EN
SS
GND
C4
1 .6 n F
R3
10K
C5
NC
R2
10K
C7
22uF
x 2
D1
B 1 3 0/S K 1 3
(O p tio n )
58
5
C3
0 .1 u F
4 4 .2 K
COMP
QQ
:
C1
22uF
R1
FB
51
8
R4
100K
V O U T = 5 V /2 A
L1
V IN
71
44
V IN = 1 2 V
19
，
C6
10nF
市
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合
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技
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限
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，
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18
66
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34
1
LSP5526 Circuit, 5V/2A output
LSP5526 Circuit, 3.3V/2A output
深
圳
Note: C6 is required for separate EN signal.
5 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
Output Voltage Setting
廖
R
VOUT
19
，
R1
51
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FB
71
44
R2
QQ
:
Figure1. Output Voltage Setting
Figure 1 shows the connections for setting the output voltage. Select the proper ratio of the two
feedback resistors R1 and R2 based on the output voltage. Typically, use R2 ≈ 10KΩ and
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1
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5
determine R1 from the following equation:
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Table1－ Recommended Resistance Values
VOUT
R1
R2
1.0V
1.2V
1.8V
2.5V
3.3V
5V
12V
1.0 KΩ
3.0 KΩ
9.53 KΩ
16.9 KΩ
26.1 KΩ
44.2 KΩ
121 KΩ
12 KΩ
10 KΩ
10 KΩ
10 KΩ
10 KΩ
10 KΩ
10 KΩ
Inductor Selection
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，
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18
(1)
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技
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The inductor maintains a continuous current to the output load. This inductor current has a ripple
that is dependent on the inductance value: higher inductance reduces the peak-to-peak ripple
current. The trade off for high inductance value is the increase in inductor core size and series
resistance, and the reduction in current handling capability. In general, select an inductance value
L based on the ripple current requirement:
L=
VOUT • ( VIN − VOUT )
V IN f SW I OUTMAX K RIPPLE
(2)
where VIN is the input voltage, VOUT is the output voltage, fSW is the switching frequency, IOUTMAX is
the maximum output current, and KRIPPLE is the ripple factor. Typically, choose KRIPPLE = 30% to
correspond to the peak-to-peak ripple current being 30% of the maximum output current.
With this inductor value, the peak inductor current is IOUT • (1 + KRIPPLE / 2). Make sure that this
peak inductor current is less than the upper switch current limit. Finally, select the inductor core
6 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
size so that it does not saturate at the current limit. Typical inductor values for various output
voltages are shown in Table 2.
19
，
廖
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VOUT 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V 5V
9V
L
4.7uH 4.7uH 10uH 10uH 10uH 10uH 10uH 33uH
Table 2. Typical Inductor Values
58
5
QQ
:
71
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51
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Input Capacitor
The input capacitor needs to be carefully selected to maintain sufficiently low ripple at the supply
input of the converter. A low ESR capacitor is highly recommended. Since large current flows in
and out of this capacitor during switching, its ESR also affects efficiency.
The input capacitance needs to be higher than 10uF. The best choice is the ceramic type; however,
low ESR tantalum or electrolytic types may also be used provided that the RMS ripple current
rating is higher than 50% of the output current. The input capacitor should be placed close to the
VIN and GND pins of the IC, with the shortest traces possible. In the case of tantalum or
electrolytic types, they can be further away if a small parallel 0.1uF ceramic capacitor is placed
right next to the IC.
，
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l:
18
66
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34
1
Output Capacitor
The output capacitor also needs to have low ESR to keep low output voltage ripple. In the case of
ceramic output capacitors, RESR is very small and does not contribute to the ripple. Therefore, a
lower capacitance value can be used for ceramic capacitors. In the case of tantalum or electrolytic
capacitors, the ripple is dominated by RESR multiplied by the ripple current. In that case, the output
capacitor is chosen to have sufficiently low ESR.
For ceramic output capacitors, typically choose a capacitance of about 22uF. For tantalum or
electrolytic capacitors, choose a capacitor with less than 50mΩ ESR.
技
有
限
公
司
Optional Schottky Diode
During the transition between high-side switch and low-side switch, the body diode of the low side
power MOSFET conducts the inductor current. The forward voltage of this body diode is high. An
optional Schottky diode may be paralleled between the SW pin and GND pin to improve overall
efficiency. Table 3 lists example Schottky diodes and their Manufacturers.
Voltage/Current
Rating
Vendor
B130
SK13
30V, 1A
30V, 1A
Lite-on semiconductor corp.
Lite-on semiconductor corp.
讯
科
Part Number
深
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金
合
Table 3－Diode Selection Guide
7 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
Stability Compensation
COMP
CCOMP
19
，
廖
R
RCOMP
CCOMP2 is needed only for high ESR output capacitor
QQ
:
Figure 2. Stability Compensation
71
44
51
8
CCOMP2
0 . 925 V
AVEA G COMP
I OUT
(4)
34
1
AVDC =
58
5
The feedback loop of the IC is stabilized by the components at the COMP pin, as shown in Figure
2. The DC loop gain of the system is determined by the following equation:
G EA
2πAVEACCOMP
(5)
18
f P1 =
66
4
The dominant pole P1 is due to CCOMP:
I OUT
(6)
2πVOUT C OUT
Te
fP 2 =
l:
The second pole P2 is the output pole:
司
，
The first zero Z1 is due to RCOMP and CCOMP:
1
fZ 1 =
(7)
限
公
2πR COMP C COMP
1
2πR COMP C COMP 2
(8)
讯
科
fP 3 =
技
有
And finally, the third pole is due to RCOMP and CCOMP2 (if CCOMP2 is used):
合
The following steps should be used to compensate the IC:
市
金
STEP1. Set the crossover frequency at 1/10 of the switching frequency via RCOMP:
深
圳
RCOMP =
2πVOUT C OUT f SW
10G EA G COMP • 0.925V
(9)
but limit RCOMP to 10KΩ maximum.
STEP2. Set the zero fZ1 at 1/4 of the crossover frequency. If RCOMP is less than 10KΩ, the
equation for CCOMP is:
8 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
0.637
(F )
RCOMP × fc
(10)
19
，
STEP3. If the output capacitor’s ESR is high enough to cause a zero at lower than 4 times
the crossover frequency, an additional compensation capacitor CCOMP2 is required. The
51
8
condition for using CCOMP2 is:
π × COUT × RESR × fs ≥ 1
71
44
(11)
QQ
:
And the proper value for CCOMP2 is:
C OUT R ESRCOUT
(12)
58
5
R COMP
34
1
C COMP 2 =
A reference table as follows:
Ccomp (C4)
(nF)
3.3
3.9
5.6
8.2
10
10
5.6
4.7
3.3
2.2
2
3.3
l:
18
Rcomp (R3)
(kΩ)
Te
Ccomp2 (C5)
(pF)
none
none
none
none
none
none
限
技
有
Inductor
(uH)
4.7
4.7
10
10
10
10
4.7
470uF/
6.3V/
120mΩ
10
6.8
680
10
深
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金
合
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22uF x2
Ceramic
，
1.0
1.2
1.8
2.5
3.3
5
1.0
1.2
1.8
2.5
3.3
5
司
5 – 12
5 - 15
5 - 23
5 - 23
5 - 23
5 - 23
5 - 12
5 - 15
5 - 23
5 - 23
5 - 23
5 - 23
Cout
公
Vout
(V)
66
4
Table 4－ Component Selection Guide for Stability Compensation
Vin Range
(V)
廖
R
C COMP =
9 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
Comp=5.6k/3.3nF L=10uH
19
，
Comp=8.2k/2.2nF L=10uH
Comp=8.2k/2.2nF L=4.7uH
51
8
Comp=10k/3.3nF L=10uH
34
1
58
5
QQ
:
71
44
Comp=10k/2.2nF L=10uH
1
1.5
2
2.5
3
3.5
Vout, V
4
4.5
5
5.5
18
0.5
66
4
Vout overshoot, mV
Comp=3.3k/5.6nF L= 4.7uH
Vout Overshoot vs Vout
(Vin=12V, Cout=44uF, dIout =1A)
廖
R
Comp=3.3k/5.6nF L=10uH
Te
l:
Figure 3. Load Transient Testing vs Compensation Value
司
，
Typical Performance Characteristics
Heavy Load Operation (2A Load)
公
Light Load Operation (No load)
Vin=12V, Vout=3,3V
深
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市
金
合
讯
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技
有
限
Vin=12V, Iin=8.2 mA, Vout=3,3V
Startup Vin=12V, Vout=3.3V, Iout=1A
10 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
through Enable.
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:
71
44
51
8
19
，
廖
R
through Vin.
深
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合
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限
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，
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1
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Short Circuit Protection Vin=12V
11 of 16
Rev. 1.2
LSP5526
18
SWITCHES RdsON vs
JUNCTION TEMPERATURE (Vin=12V)
公
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，
Te
l:
0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
30
50
70
90
110 130
JUNCTION TEMPERATURE (C)
150
170
深
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合
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技
有
10
限
SWITCHES RdsON
66
4
34
1
58
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:
71
44
51
8
19
，
廖
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2A 23V Synchronous Buck Converter
12 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
LOGO
19
，
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Marking Information
LSC
51
8
Part ID
LSP5526
QQ
:
71
44
VYYWWUZ
34
1
Internal Code
Date code
58
5
V YYWW UZ
66
4
YY：Year(09=2009,10=2010,11=2011,12=2012...)
WW：Week(01~53)
Output Voltage
深
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合
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技
有
限
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，
Te
l:
18
Blank：ADJ
13 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
1.35
1.75
A1
0.10
0.25
B
0.33
0.51
C
0.19
0.25
D
4.70
5.10
E
3.70
4.10
公
限
技
有
讯
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合
Te
Max
，
Min
A
E
1.27BSC
H
5.80
6.20
L
0.40
1.27
θ
0
8°
深
圳
市
金
Dimensions In Millimeters
司
Symbol
l:
18
66
4
34
1
58
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QQ
:
71
44
51
8
19
，
廖
R
SOP-8L
14 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
深
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合
讯
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技
有
限
公
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，
Te
l:
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66
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34
1
58
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QQ
:
71
44
51
8
19
，
廖
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Tape/Reel
15 of 16
Rev. 1.2
LSP5526
2A 23V Synchronous Buck Converter
IPC/JEDEC J-STD-020D.1 Moisture Sensitivity Levels Table
SOAK REQUIREMENTS
2a
4 weeks
3
168 hours
4
72 hours
5
48 hours
24 hours
6
NA
NA
NA
NA
NA
168
85 °C /85%
RH
+5/-0
RH
≤30 °C /60%
168
85 °C /60%
RH
+5/-0
RH
≤30 °C /60%
696
RH
+5/-0
≤30 °C /60%
192
30 °C /60%
40
52
RH
+5/-0
RH
-1/+0
-1/+0
≤30 °C /60%
96
RH
+2/-0
≤30 °C /60%
72
RH
+2/-0
2
2
2
2
2
≤30 °C /60%
48
RH
+2/-0
Time on Label
≤30 °C /60%
(TOL)
RH
30 °C /60%
120
168
RH
-1/+0
-1/+0
30 °C /60%
20
RH
+0.5/-0
30 °C /60%
15
20
RH
+0.5/-0
+0.5/-0
30 °C /60%
RH
30 °C /60%
TOL
24
+0.5/-0
RH
10
13
+0.5/-0
+0.5/-0
NA
NA
NA
60 °C/ 60% RH
60 °C/ 60% RH
60 °C/ 60% RH
60 °C/ 60% RH
60 °C/ 60% RH
NA
66
4
5a
CONDITION
≤30 °C /85%
19
，
1 year
TIME
(hours)
51
8
2
TIME
(hours)
QQ
:
Unlimited
CONDITION
(hours)
eV
0.30-0.39
58
5
1
TIME
CONDITION
eV
0.40-0.48
34
1
TIME
LEVEL
Standard
71
44
FLOOR LIFE
1
廖
R
Accelerated Equivalent
Note 1: CAUTION - To use the ‘‘accelerated equivalent’’ soak conditions, correlation of damage response (including electrical, after soak and
18
reflow), should be established with the ‘‘standard’’ soak conditions. Alternatively, if the known activation energy for moisture diffusion
of the package materials is in the range of 0.40 - 0.48 eV or 0.30 - 0.39 eV, the ‘‘accelerated equivalent’’ may be used. Accelerated soak
times may vary due to material properties (e.g .mold compound, encapsulant, etc.). JEDEC document JESD22-A120 provides a method
l:
for determining the diffusion coefficient.
Te
Note 2: The standard soak time includes a default value of 24 hours for semiconductor manufacturer’s exposure time (MET) between bake and
bag and includes the maximum time allowed out of the bag at the distributor’s facility. If the actual MET is less than 24 hours the soak
，
time may be reduced. For soak conditions of 30 °C/60% RH, the soak time is reduced by 1 hour for each hour the MET is less than 24
司
hours. For soak conditions of 60 °C/60% RH, the soak time is reduced by 1 hour for each 5 hours the MET is less than 24 hours. If the
公
actual MET is greater than 24 hours the soak time must be increased. If soak conditions are 30 °C/60% RH, the soak time is increased 1
hour for each hour that the actual MET exceeds 24 hours. If soak conditions are 60 °C/60% RH, the soak time is increased 1 hour for
Important Notice and Disclaimer
讯
科
技
有
限
each 5 hours that the actual MET exceeds 24 hours.
深
圳
市
金
合
LSC reserves the right to make changes to this document and its products and specifications at
any time without notice. Customers should obtain and confirm the latest product information
and specifications before final design, purchase or use.
LSC makes no warranty, representation or guarantee regarding the suitability of its products for
any particular purpose, nor does LSC assume any liability for application assistance or customer
product design. LSC does not warrant or accept any liability with products which are purchased
or used for any unintended or unauthorized application.
No license is granted by implication or otherwise under any intellectual property rights of LSC.
LSC products are not authorized for use as critical components in life support devices or
systems without express written approval of LSC.
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